| 1. |
- Wu, Xue, 1986, et al.
(author)
-
Ammonium recovery from reject water combined with hydrogen production in a bioelectrochemical reactor
- 2013
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In: Bioresource Technology. - : Elsevier BV. - 0960-8524 .- 1873-2976. ; 146, s. 530-536
-
Journal article (peer-reviewed)abstract
- In this study, a bioelectrochemical reactor was investigated for simultaneous hydrogen production and ammonium recovery from reject water, which is an ammonium-rich side-stream produced from sludge treatment processes at wastewater treatment plants. In the anode chamber of the reactor, microorganisms converted organic material into electrical current. The electrical current was used to generate hydrogen gas at the cathode with 96±6% efficiency. Real or synthetic reject water was fed to the cathode chamber where proton reduction into hydrogen gas resulted in a pH increase which led to ammonium being converted into volatile ammonia. The ammonia could be stripped from the solution and recovered in acid. Overall, ammonium recovery efficiencies reached 94% with synthetic reject water and 79% with real reject water. This process could potentially be used to make wastewater treatment plants more resource-efficient and further research is warranted.
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| 2. |
- Hai, Faisal Ibney, et al.
(author)
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Application of membrane technology for the development of sustainable biotechnology processes
- 2013
-
In: Membrane Processes for Sustainable Growth. ; , s. 193-224
-
Book chapter (other academic/artistic)abstract
- The scope of application of membranes in biotechnology has widened significantly in the recent years. Although many of the membrane options are yet to achieve wide industrial applications, they show tremendous potential for the transformation and synthesis of value-added products, energy production, therapeutic applications and environmental remediation. This chapter provides an overview of membrane applications in selected established and emerging biotechnology processes. Approaches to overcoming the technology bottlenecks that impede the scale-up of such systems have been discussed in this chapter.
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| 3. |
- Hai, Faisal Ibney, et al.
(author)
-
Biocatalytic membrane reactors for the removal of recalcitrant and emerging pollutants from wastewater
- 2013
-
In: Handbook of Membrane Reactors Volume 2: Reactor types and industrial applications. - : Elsevier. ; 2, s. 763-807
-
Book chapter (other academic/artistic)abstract
- The potential fields of application of the biocatalytic membrane reactors have widened considerably in the recent years. Although biocatalytic membrane reactors, in general, are yet to achieve broad industrial applications, in the not too far future, they are expected to play a major role not only for the production, transformation and valorization of raw materials but also for environmental remediations. This chapter comprehensively reviews the laboratory scale studies which demonstrate the potential of biocatalytic membrane reactors in wastewater treatment applications. Studies reported in the literature, however, serves as proof of concept only. Issues that need to be addressed in order to achieve scale-up of such systems have been discussed in this chapter.
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| 4. |
- Kharazmi, Parastou, 1977-
(author)
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Evaluation of Innovative Rehabilitation Technologies Utilising Polymer Composites for Aging Sewer Systems
- 2019
-
Doctoral thesis (other academic/artistic)abstract
- Water and wastewater sewer system maintenance is among the costliest aspects of infrastructure investment. The replacement of deteriorated lines is a difficult and expensive process that causes community disturbance and is generally not conducted fast enough to meet demand. To keep up with the rate of deterioration, the use of alternative rehabilitation technologies using polymer linings has increased significantly in recent years, both within Sweden and worldwide. Compared to the traditional pipe replacement method, these technologies are cost-effective, create less community disturbance, and offer a quick return to the service for the line. The main function of polymeric lining is to stabilise the condition of the pipeline, eliminate deterioration, and thereby extend the pipeline’s service life. Although rehabilitation technologies employing polymeric systems have been in use for over 30 years, there have been few technical assessments of either these technologies or the materials involved. Data gathered through the evaluation of these innovative technologies can make their benefits and limitations more widely understood, and can also be used to increase the effectiveness of the rehabilitation process in future.The main objective of this work was to contribute to an improved understanding of the most commonly used materials and methods employed in rehabilitation of wastewater and other applicable sewer lines in residential buildings in Sweden. The primary objective was not to prove that the emerging rehabilitation technologies work, but rather to increase knowledge of their weaknesses and strengths, identify any issues, and provide a technical assessment to support realistic expectations of pipeline rehabilitation. Gathering technical information in this way will help with the planning of future investigations; moreover, collecting extensive data will help to increase the effectiveness of the renewal works, aid progress in the field, and improve predictions regarding longevity and service life. As pipeline rehabilitation is still considered novel, and owing to the general lack of available data on the subject, a multi-approach study was carried out: this included evaluation of the polymeric materials’ performance in the presence of deteriorative factors, assessing the in-service state of the materials and lined sewers previously installed, monitoring the level of quality control implemented during previous rehabilitation works, and evaluating the environmental impacts of using pipe-lining technologies compared to pipe replacement. The techniques discussed included rehabilitation with epoxy and polyester resin-based lining materials, applied with brush-on and spray-on techniques, and cured-in-place pipe lining (installed by sending a resin-impregnated flexible tube inside the host pipe). Degradation of the resin-based lining materials was investigated via artificial aging involving immersion in water at elevated temperatures. The changes in materials that occurred during accelerated laboratory aging were tracked by means of various tests, including thermal and mechanical analyses, water absorption measurements and microscopy. The analysis focused on reinforced polyester-based and toughened epoxy-based lining materials in order to gain a better understanding of their performance as pipe lining. Moreover, the previously installed lined pipes and lining materials were also studied during laboratory examinations to evaluate the in-service performance of the materials and techniques under operating conditions over time, as well as to identify common defects. The state of the materials and the lined pipe were studied by means of different investigative methods, including visual inspection, microscopy, Fourier transform infrared spectroscopy, thickness measurement, thermal and mechanical analyses. This PhD work also includes an investigation to determine the level of quality control carried during some previous rehabilitation works. Data on the quality evaluation of previous rehabilitation works were gathered during visits to the work sites, as well as by analysing lined pipes that had already been installed. Finally, a comparative life-cycle assessment was undertaken to compare the environmental impacts of pipe replacement with those of alternative innovative rehabilitations, such as CIPP and coatings with polyester and epoxy polymeric systems. Data obtained from an LCA tool were used to facilitate comparison from an environmental perspective.Results from artificial aging in the lab indicated that the properties of polymeric lining materials changed significantly when high temperatures were combined with water exposure. However, the aging testing conducted for this study also found that the materials performed relatively well at temperatures close to the average temperatures inside sewerage systems. The results revealed that the polyester-based lining material was less sensitive when compared with epoxy-based lining materials during stimulated aging. Moreover, results from the in-service field demonstration (involving examination of 12 samples with up to 10 years of service, including reinforced polyester and modified epoxy linings or cured-in-place pipe (CIPP) lining) showed minimal evidence that the materials underwent significant deterioration after installation; instead, a majority of the common defects were found to be related to poor-quality installation practices. Because very few field samples were available to study, conclusions regarding overall performance could not be drawn. However, there is no evidence that these materials will not perform as expected during their service life when properly installed.Evaluating quality control of previous rehabilitation work revealed a gap between theory and practice where the level of quality control and documentation was concerned; furthermore, it also emerged that quality control and documentation is crucial to both the prevention of common issues and the overall effectiveness of the rehabilitation. Accordingly, a series of recommendations regarding the development of comprehensive quality control and quality assurance procedures (QC/QA) are provided in this work. These recommendations highlight the aspects that are most important to consider at each of several key stages (before installation, during installation, and after rehabilitation work is completed).Results from comparative life-cycle assessment (LCA) showed that alternative technologies, including cured-in-place (flexible sleeve) and coating techniques, have some advantages over pipe replacement from an environmental perspective. However, the choice to use one rehabilitation technology over another is a multi-stage decision-making process that should not be based solely on a single factor.This PhD work promotes an improved understanding of the limitations and benefits of polymeric lining through the testing performed and analyses conducted. This work highlights the need for improved quality control, and further suggests that developing a detailed and comprehensive quality control plan for each technology would provide higher and more consistent quality overall. The study also demonstrates that the long-term strength of any rehabilitation work depends on various factors, and that selecting one method over another must be a process based on extensive knowledge and understanding of each rehabilitation technology. No evidence was found to indicate that the materials could not perform well under working conditions if selected and installed appropriately. However, a larger number of field samples with longer in-service time and a more detailed technical history, along with a more extended experimental plan for laboratory investigations based on the results of this PhD work, will allow for the gathering of the data required to answer questions regarding life expectancy with a higher degree of certainty.
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| 5. |
- Modin, Oskar, 1980
(author)
-
A mathematical model of aerobic methane oxidation coupled to denitrification
- 2018
-
In: Environmental Technology (United Kingdom). - : Informa UK Limited. - 1479-487X .- 0959-3330. ; 39:9, s. 1217-1225
-
Journal article (peer-reviewed)abstract
- Aerobic methanotrophic bacteria use methane as their only source of energy and carbon. They release organic compounds that can serve as electron donors for co-existing denitrifiers. This interaction between methanotrophs and denitrifiers is known to contribute to nitrogen losses in natural environments and has also been exploited by researchers for denitrification of nitrate-contaminated wastewater. The purpose of this study was to develop a mathematical model describing aerobic methane oxidation coupled to denitrification in suspended-growth reactors. The model considered the activities of three microbial groups: aerobic methanotrophs, facultative methylotrophs, and facultative heterotrophs. The model was tested against data from the scientific literature and used to explore the effects of the oxygen mass transfer coefficient, the solids retention time, and the fraction methane in the feed gas on nitrate removal. The fraction of methane in the feed gas was found to be critical for the nitrate removal rate. A value of about 15% in air was optimal. A lower methane fraction led to excess oxygen, which was detrimental for denitrification. A higher fraction led to oxygen-limitation, which restricted the growth rate of methanotrophs in the reactor.
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| 6. |
- Modin, Oskar, 1980, et al.
(author)
-
Hill-based dissimilarity indices and null models for analysis of microbial community assembly
- 2020
-
In: Microbiome. - : Springer Science and Business Media LLC. - 2049-2618. ; 8:1
-
Journal article (peer-reviewed)abstract
- BackgroundHigh-throughput amplicon sequencing of marker genes, such as the 16S rRNA gene in Bacteria and Archaea, provides a wealth of information about the composition of microbial communities. To quantify differences between samples and draw conclusions about factors affecting community assembly, dissimilarity indices are typically used. However, results are subject to several biases, and data interpretation can be challenging. The Jaccard and Bray-Curtis indices, which are often used to quantify taxonomic dissimilarity, are not necessarily the most logical choices. Instead, we argue that Hill-based indices, which make it possible to systematically investigate the impact of relative abundance on dissimilarity, should be used for robust analysis of data. In combination with a null model, mechanisms of microbial community assembly can be analyzed. Here, we also introduce a new software, qdiv, which enables rapid calculations of Hill-based dissimilarity indices in combination with null models.ResultsUsing amplicon sequencing data from two experimental systems, aerobic granular sludge (AGS) reactors and microbial fuel cells (MFC), we show that the choice of dissimilarity index can have considerable impact on results and conclusions. High dissimilarity between replicates because of random sampling effects make incidence-based indices less suited for identifying differences between groups of samples. Determining a consensus table based on count tables generated with different bioinformatic pipelines reduced the number of low-abundant, potentially spurious amplicon sequence variants (ASVs) in the data sets, which led to lower dissimilarity between replicates. Analysis with a combination of Hill-based indices and a null model allowed us to show that different ecological mechanisms acted on different fractions of the microbial communities in the experimental systems.ConclusionsHill-based indices provide a rational framework for analysis of dissimilarity between microbial community samples. In combination with a null model, the effects of deterministic and stochastic community assembly factors on taxa of different relative abundances can be systematically investigated. Calculations of Hill-based dissimilarity indices in combination with a null model can be done in qdiv, which is freely available as a Python package (https://github.com/omvatten/qdiv). In qdiv, a consensus table can also be determined from several count tables generated with different bioinformatic pipelines.
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| 7. |
- Modin, Oskar, 1980, et al.
(author)
-
Three promising applications of microbial electrochemistry for the water sector
- 2017
-
In: Environmental Science: Water Research and Technology. - : Royal Society of Chemistry (RSC). - 2053-1419 .- 2053-1400. ; 3:3, s. 391-402
-
Journal article (peer-reviewed)abstract
- Microbial electrochemical technologies are based on the interactions between living microorganisms and electrodes. There is a wide range of possible applications and many are highly relevant for the water sector. The most well-known is probably the microbial fuel cell, which has been proposed as an environmentally-friendly process for simultaneous wastewater treatment and electrical energy production. However, fullscale implementation at wastewater treatment plants is very challenging and there are several other applications of microbial electrochemistry that are less well-known to people outside the research field, but potentially could be widely applied and make an impact on the water sector in a shorter time perspective. In this paper, we highlight three such applications: (i) sensors for biochemical oxygen demand, volatile fatty acids and toxicity; (ii) in situ bioremediation of contaminated sites; and (iii) removal and recovery of metals from wastewaters, leachates and brines.
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| 8. |
- Pawar, Sudhanshu S., et al.
(author)
-
MultiBio: Environmental services from a multipurpose biorefinery
- 2020
-
Reports (other academic/artistic)abstract
- MultiBio project aimed to establish and demonstrate a novel multipurpose biorefinery cascade concept, producing three renewable biobased products: 1) biohydrogen, 2) biopolymers and 3) protein rich meal ingredients for fish farming. The cascade concept exploits the ability of a bacterium (Caldicellulosiruptor saccharolyticus) to transform nutrients present in low-value waste process waters of the pulp and paper industry, to high-value products hydrogen gas, organic acids and microbial biomass. The organic acid rich effluent will then be managed in an open culture microbial process used to achieve discharge water quality objectives and to produce polyhydroxyalkanoate (PHA) biopolymers. Moreover, since C. saccharolyticus protein content is more than 63% of cell dry weight, their potential in formulation of fish feed was evaluated. A fiber sludge containing, CTMP residual stream was found to be a possible feedstock for the MultiBio process concept. Due to safety risks the demo-scale experiments of biohydrogen gas technology were moved from Biorefinery demo plant (Örnsköldsvik) of 40 m3 capacity to ATEX classified pilot-scale facility with 0.4 m3 capacity. Hence, bacterial biomass enough for the large-scale fish feed ingredient could not be produced. Lab-scale experiments with Caldicellulosiruptor cells as fish feed ingredient showed promising results as a protein-rich, sustainable fish feed ingredient. In addition, PHA biopolymer also showed favourable results as fish food ingredient for experiments at Gårdsfisk AB. Lab-scale experimental tests showed that the surplus activated sludge from the mills wastewater treatment could currently accumulate PHA to about 20 % of its dry weight. Mass balance evaluations based on realistically achievable expectations indicated a PHA biopolymer production potential of 3 600 tons of PHA per year from available organic residuals and for the two evaluated mills combined. The MultiBio concept has a positive climate impact in comparison with current treatment and moves developments in a positive direction to achieve 7 of the 10 Swedish environmental goals. Through a detailed feasibility analysis, a natural progression in next steps in scenarios were suggested for PHA production. The MultiBio cascade process can be implemented with further necessary development with good business potential and a positive effect on climate change. However, biohydrogen technology needs further developments before this cascade process concept can be implemented. Alternatively, a scenario with only biopolymer technology shows already a significant business potential and even larger positive effect on climate change. A successful next step in demonstration of the PHA biopolymer production scenario may lead to it being implemented within the next few years. Furthermore, MultiBio has attracted a lot of attention regionally and nationally but also internationally with a total of 65 media listings. A licentiate thesis and three university degree projects linked to the project have been completed. Overall, the MultiBio project has successfully achieved its goals and objectives.
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| 9. |
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| 10. |
- Timmusk, Salme, et al.
(author)
-
Sfp-type PPTase inactivation promotes bacterial biofilm formation and ability to enhance wheat drought tolerance
- 2015
-
In: Frontiers in Microbiology. - : Frontiers Media SA. - 1664-302X. ; 6
-
Journal article (peer-reviewed)abstract
- Paenibacillus polymyxa is a common soil bacterium with broad range of practical applications. An important group of secondary metabolites in P polymyxa are non-ribosomal peptide and polyketide derived metabolites (NRPs/PKs). Modular non-ribosomal peptide synthetases catalyze main steps in the biosynthesis of the complex secondary metabolites. Here we report on the inactivation of an A26 Sfp-type 4'-phosphopantetheinyl transferase (Sfp-type PPTase). The inactivation of the gene resulted in loss of NRPs/PKs production. In contrast to the former Bacillus spp. model the mutant strain compared to wild type showed greatly enhanced biofilm formation ability. A26 Delta sfp biofilm promotion is directly mediated by NRPs/PKs, as exogenous addition of the wild type metabolite extracts restores its biofilm formation level. Wheat inoculation with bacteria that had lost their Sfp-type PPTase gene resulted in two times higher plant survival and about three times increased biomass under severe drought stress compared to wild type. Challenges with P. polymyxa genetic manipulation are discussed.
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| 11. |
- Wadström, Christoffer, et al.
(author)
-
Exploring total economic values in an emerging urban circular wastewater system
- 2023
-
In: Water Research. - : Elsevier BV. - 1879-2448 .- 0043-1354. ; 233
-
Research review (peer-reviewed)abstract
- Circular water management has the potential to close resource and material loops within and across value chains. In the water industry, circular municipal wastewater management through industrial urban symbiosis (IUS) is recognized as a solution to overcome water scarcity in urban environments. IUS involves collaboration between actors with different organizational backgrounds, which can lead to inherent risks of conflicting goals. This study explores how different values drive various organizations to participate in an emerging circular wastewater collaboration. The study comprises a literature review of 34 scientific articles and a case study of a potential circular wastewater system through IUS in Simrishamn, Sweden. It presents an interdisciplinary framework based on the total economic value concept and organizational archetypes for examining actor values in circular wastewater management. This framework provides a novel approach for assessing different values and how they may compete or align. It can also identify the absence of certain values, enabling the achievement of a minimum level of value coherence amongst different actors, and thereby increasing the sustainability and effectiveness of circular wastewater collaborations. Therefore, careful planning and stakeholder interaction, in accordance with economic value perspectives, can enhance the legitimacy and policy development of circular solutions.
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| 12. |
- Abadikhah, Marie, 1992
(author)
-
Influence of electrode material and stochastic factors on the performance and microbial community assembly in microbial electrochemical systems
- 2022
-
Licentiate thesis (other academic/artistic)abstract
- Microbial electrolysis cells (MECs) are systems with microbial communities in the form of biofilms on electrode surfaces. The electrogenic bacteria in the anode biofilm act as catalysts for the oxidization of organic compounds, leading to release of electrons, generation of electrical current, and production of hydrogen and methane at the cathode. In addition to production of energy carriers, MECs can be used for other applications as well; for example, as biosensors to monitor biochemical oxygen demand or toxicity. The performance of MECs is determined by both deterministic and stochastic factors influencing the microbial communities on the electrode surfaces, most of which as still poorly understood. In this thesis, the effects of electrode materials on microbial community assembly and MEC performance was investigated. Two experiments were carried out. In the first, three cathode materials (carbon nanoparticles, titanium, and steel) were compared. In the second, three anode materials (carbon cloth, graphene, and nickel) were compared. The cathode materials had no significant effect on the performance of the MECs, as opposed to the anode materials where carbon cloth MECs had the highest current density and the shortest lag time during startup. The differences seen in lag time of replicate systems at the start of the experiment indicated a stochastic initial attachment of the electrogenic bacteria on the anode. Different microbial communities develop in the biofilms on the anodes and cathodes. Electrogens from the Desulfobacterota phylum dominated the anode, while various hydrogenotrophic methanogens, e.g., Methanobacterium, were found to dominate on the cathodes. Diversity and null model analysis of the electrode communities highlighted stochasticity and not electrode material as the important factor in the community assembly. Network analysis showed that the cathode communities had fewer negative interactions between taxa in comparison to the anode. Since hydrogen gas generated at the cathode surface can diffuse through the biofilm, all microorganisms on the cathode have access to the substrate, reducing the need for competition between species. In contrast, electrogens require a short distance to the anode to be able to use it as electron acceptor. Limited space on the anode and competition between electrogens shaped the anode communities and explain the higher number of negative interactions observed. Based on the findings in this thesis, it is suggested that stochastic factors have more influence than electrode material on the anode community even though there is a selective pressure for electrogenic bacteria.
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| 13. |
- Albers, Eva, 1966, et al.
(author)
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Influence of preservation methods on biochemical composition and downstream processing of cultivated Saccharina latissima biomass
- 2021
-
In: Algal Research. - : Elsevier BV. - 2211-9264. ; 55
-
Journal article (peer-reviewed)abstract
- Saccharina latissima biomass cultivated along the Swedish west coast was subjected to four different scalable preservation methods after harvest; freezing, sun-drying, oven-drying and ensiling. Freeze-drying and freezing at -80 ?C were also included to provide dry and wet references. The effects of the different preservation methods on the composition of Saccharina biomass (on dry weight, DW, basis), and the recovery as well as properties of high-quality protein, alginate and biogas were evaluated. Sun-drying significantly reduced protein, alginate and fatty acid content of the seaweeds and thereby concentrated ash in the biomass compared to the other methods. Protein/amino acids and fatty acids were significantly concentrated in ensiled biomass, while mannitol and laminarin were reduced compared to the other biomasses. Oven-drying and -20 ?C freezing affected the composition the least, with lower ash content and alterations in some specific amino and fatty acids. Sun-drying and ensiling resulted in significantly lower protein solubility at high pH compared to the other biomasses which translated into the lowest total seaweed protein recovery using the pH-shift process. Highest protein yield was obtained with the freeze-dried reference. Ensiling lead to a significant decrease in the molecular weight of alginate, while sun-drying caused a negative effect on alginate by inducing a shift in the guluronic and mannuronic acids composition of alginate. Sun-drying gave the lowest methane yield in the anaerobic digestion experiments while freezing at -80 ?C gave the highest yield, closely followed by freezing at -20 ?C and ensiling. To conclude, preservation methods must be carefully chosen to protect the valuable component in Saccharina latissima, and to achieve an efficient downstream processing ultimately yielding high quality products as part of a seaweed biorefinery.
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| 14. |
- Beijer, Kristina, et al.
(author)
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Removal of pharmaceuticals and unspecified contaminants in sewage treatment effluents by activated carbon filtration and ozonation : Evaluation using biomarker responses and chemical analysis
- 2017
-
In: Chemosphere. - : Elsevier BV. - 0045-6535 .- 1879-1298. ; 176, s. 342-351
-
Journal article (peer-reviewed)abstract
- Traces of active pharmaceutical ingredients (APIs) and other chemicals are demonstrated in effluents from sewage treatment plants (STPs) and they may affect quality of surface water and eventually drinking water. Treatment of effluents with granular activated carbon (GAC) or ozone to improve removal of APIs and other contaminants was evaluated at two Swedish STPs, Kappala and Uppsala (88 and 103 APIs analyzed). Biomarker responses in rainbow trout exposed to regular and additionally treated effluents were determined. GAC and ozone treatment removed 87-95% of the total concentrations of APIs detected. In Kappala, GAC removed 20 and ozonation (7 g O-3/m(3)) 21 of 24 APIs detected in regular effluent. In Uppsala, GAC removed 25 and ozonation (5.4 g O-3/m(3)) 15 of 25 APIs detected in effluent. GAC and ozonation also reduced biomarker responses caused by unidentified pollutants in STP effluent water. Elevated ethoxyresorufin-O-deethylase (EROD) activity in gills was observed in fish exposed to effluent in both STPs. Gene expression analysis carried out in Kappala showed increased concentrations of cytochrome P450 (CYP1A5 and CYP1C3) transcripts in gills and of CYP1As in liver of fish exposed to effluent. In fish exposed to GAC- or ozone-treated effluent water, gill EROD activity and expression of CYP1As and CYP1C3 in gills and liver were generally equal to or below levels in fish held in tap water. The joint application of chemical analysis and sensitive biomarkers proved useful for evaluating contaminant removal in STPs with new technologies.
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| 15. |
- Betsholtz, Alexander, et al.
(author)
-
Tracking 14C-labeled organic micropollutants to differentiate between adsorption and degradation in GAC and biofilm processes
- 2021
-
In: Environmental Science and Technology. - : The American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 55:16, s. 11318-11327
-
Journal article (peer-reviewed)abstract
- Granular activated carbon (GAC) filters can be used to reduce emissions of organic micropollutants via municipal wastewater, but it is still uncertain to which extent biological degradation contributes to their removal in GAC filters. 14C-labeled organic micropollutants were therefore used to distinguish degradation from adsorption in a GAC-filter media with associated biofilm. The rates and extents of biological degradation and adsorption were investigated and compared with other biofilm systems, including a moving bed biofilm reactor (MBBR) and a sand filter, by monitoring 14C activities in the liquid and gas phases. The microbial cleavage of ibuprofen, naproxen, diclofenac, and mecoprop was confirmed for all biofilms, based on the formation of 14CO2, whereas the degradation of 14C-labeled moieties of sulfamethoxazole and carbamazepine was undetected. Higher degradation rates for diclofenac were observed for the GAC-filter media than for the other biofilms. Degradation of previously adsorbed diclofenac onto GAC could be confirmed by the anaerobic adsorption and subsequent aerobic degradation by the GAC-bound biofilm. This study demonstrates the potential use of 14C-labeled micropollutants to study interactions and determine the relative contributions of adsorption and degradation in GAC-based treatment systems.
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| 16. |
- Bodlund, Ida, 1983-
(author)
-
Coagulant Protein from plant materials: Potential Water Treatment Agent
- 2013
-
Licentiate thesis (other academic/artistic)abstract
- Access to fresh water is a human right, yet more than 780 million people, especially in rural areas, rely on unimproved sources and the need for finding ways of treating water is crucial. Although the use of natural coagulant protein in drinking water treatment has been discussed for a long time, the method is still not in practice, probably due to availability of material and limited knowledge. In this study, about hundred different crude extracts made from plant materials found in Southern India were screened for coagulation activity. Extracts of three Brassica species (Mustard, Cabbage and Cauliflower) were showing activity comparable to that of Moringa oleifera and were further investigated. Their protein content and profile were compared against each other and with coagulant protein from Moringa. Mustard (large) and Moringa seed proteins were also studied for their effect against clinically isolated bacterial strains. The protein profiles of Brassica extract showed predominant bands around 9kDa and 6.5kDa by SDS-PAGE. The peptide sequence analysis of Mustard large identified the 6.5kDa protein as Moringa coagulant protein (MO2.1) and the 9kDa protein band as seed storage protein napin3. Of thirteen clinical strains analysed, Moringa and Mustard large were proven effective in either aggregation activity or growth kinetic method or both in all thirteen and nine strains respectively. To my knowledge this is the first report on the presence of coagulant protein in Brassica seeds. Owing to the promising results Brassica species could possibly be used as a substitute to Moringa coagulating agent and chemicals in drinking water treatment.
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| 17. |
- Burzio, Cecilia, 1991
(author)
-
Removal of Organic Micropollutants from Wastewater in Biofilm Systems
- 2020
-
Licentiate thesis (other academic/artistic)abstract
- The presence of organic hazardous substances in the aquatic environment, such as pharmaceutically active compounds and personal care products, has become a worldwide issue of increasing environmental concern. Present at concentration of nano- to milligram per liter, they are defined as organic micropollutants (OMPs). Wastewater treatment plants (WWTPs) have been recognized as the main route of emission of OMPs into the environment and as hotspot for antibiotic resistance. Not being designed for the elimination of micropollutants, the removal is often incomplete, resulting in continuous discharge. Therefore, research currently focuses on the enhancement of conventional WWTPs via physical-chemical and biological treatment processes. Among biological processes, biofilm-based treatment technologies have been found more efficient in the biotransformation of OMPs than conventional activated sludge treatment processes. Aerobic granular sludge (AGS) is a form of free-floating biofilm technique for simultaneous removal of organic carbon, nitrogen, and phosphorus in a single process step. The longer solid retention time, the higher concentration and microbial diversity and the presence of micro-niches of different redox conditions are features of AGS that make this system very attractive for the removal of OMPs. An in-depth understanding of the fate of OMPs in such systems under different operational conditions is still required. The present work investigates the degradation mechanisms of OMPs in biomass from both full-scale treatment plants and laboratory reactors. Specifically, it focuses on the impact of different conformations of AGS on the sorption of selected pharmaceuticals and the potential of different biofilm systems at the full scale WWTP to eliminate OMPs.
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| 18. |
- Devlin, Yuka, et al.
(author)
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On site landfill leachate treatment : investigations into economical and environmental sustainable systmes for Northern Ireland
- 2017
-
In: Ebook: Proceedings of 11th European Waste Water Management Conference.
-
Conference paper (pop. science, debate, etc.)abstract
- This paper presents the potential for the Swedish Laqua system to be used as a sustainable method for on-site landfill leachate management in Northern Ireland, specifically the potential to use locally sourced filter materials from Northern Ireland as part of the filter system. Four carbon containing ashes and four types of peat were tested over a 24 hours period by a shaking test with untreated landfill leachate. Considering the results of this screening test, and the economical and sustainable supply of filter materials, one combination of ash and peat was selected to be column tested. Column testing with artificial leachate containing 7 organic pollutants (3 PAHs and 4 PCBs) and 9 inorganic pollutants showed that locally sourced filter materials effectively removed both organic and inorganic pollutants. A subsequent column test with landfill leachate for 13 weeks demonstrated it was feasible to apply the Laqua system with economical locally sourced filter materials.
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| 19. |
- Ekholm, Jennifer, 1992
(author)
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Application of aerobic granular sludge for municipal wastewater treatment - Process performance and microbial community dynamics under fluctuating conditions
- 2023
-
Doctoral thesis (other academic/artistic)abstract
- Pressures of growing cities, competition for use of urban areas and higher influent loads, are pushing for innovative technologies for wastewater treatment with low demands for land footprint and costs. Furthermore, wastewater treatment is needed to move towards a circular economy by harvest of valuable resources such as nutrients and energy. Aerobic granular sludge (AGS) is a biofilm process without a carrier material for wastewater treatment, exhibiting efficient treatment performance, excellent settleability, high biomass retention, tolerance to toxicity and high loads of organic matter. In this thesis, the first implementation of the AGS process in the Nordic countries was studied to assess the treatment performance, microbial community structure, energy usage, land footprint, and volume needs. The results in this project suggested that selective sludge withdrawal, retaining long solids retention time, sufficient substrate availability, and operational flexibility are important factors for granulation. Both the AGS and parallel conventional activated sludge (CAS) process achieved stable organic matter, nitrogen, and phosphorus removal with low average effluent concentrations. Seasonal variations and environmental factors were identified as important for microbial community succession. The granular biofilm demonstrated higher biomass concentration, diversity, and lower seasonal fluctuations in community composition than the flocculent sludge. A one-year energy comparison resulted in lower specific energy usages (kWh m-3 and kWh reduced P.E.-1) and land footprint for the AGS compared to the CAS process. However, a potential for decreased energy usage was recognised for both systems, leading to the conclusion that operational optimisation and process design might be as important as the type of technology. Additionally, the influence of decreasing temperature on AGS was studied in lab-scale reactors, revealing different responses of the functional groups in the microbial community, and even various response of ASVs at the genus level. In conclusion, the AGS technology for municipal wastewater treatment under fluctuating conditions achieved low average effluent concentrations, was more compact and energy efficient compared to the CAS.
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| 20. |
- Forss, Jörgen, 1973-, et al.
(author)
-
Microbial biotreatment of actual textile wastewater in a continuous sequential rice husk biofilter and the microbial community involved
- 2017
-
In: PLOS ONE. - : PLOS. - 1932-6203. ; 12:1
-
Journal article (peer-reviewed)abstract
- Textile dying processes often pollute wastewater with recalcitrant azo and anthraquinone dyes. Yet, there is little development of effective and affordable degradation systems for textile wastewater applicable in countries where water technologies remain poor. We determined biodegradation of actual textile wastewater in biofilters containing rice husks by spectrophotometry and liquid chromatography mass spectrometry. The indigenous microflora from the rice husks consistently performed >90% decolorization at a hydraulic retention time of 67 h. Analysis of microbial community composition of bacterial 16S rRNA genes and fungal internal transcribed spacer (ITS) gene fragments in the biofilters revealed a bacterial consortium known to carry azoreductase genes, such as Dysgonomonas, and Pseudomonas and the presence of fungal phylotypes such as Gibberella and Fusarium. Our findings emphasize that rice husk biofilters support a microbial community of both bacteria and fungi with key features for biodegradation of actual textile wastewater. These results suggest that microbial processes can substantially contribute to efficient and reliable degradation of actual textile wastewater. Thus, development of biodegradation systems holds promise for application of affordable wastewater treatment in polluted environments.
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| 21. |
- Granström, Karin, 1974-, et al.
(author)
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Biogas from algae farmed in pulp and paper mill wastewater
- 2015
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In: GGROS 2015, Örnsköldsvik, Sweden, 23-25 March 2015..
-
Conference paper (peer-reviewed)abstract
- Pulp and paper mills have waste streams that can be used for the farming of algae. The mills wastewater treatment provides heat to the algae ponds and the flue gas provides carbon dioxide. A current project is aiming at producing oil, for biodiesel or lubricating oil, from mill-farmed algae. Ten pools have been constructed and seeded with different strains of algae. After harvest and separation of oil, there is a leftover algae pulp. The fate of this algae remnant is an important part in achieving economic and energy viability for the whole process.The purpose of this work was to study the potential to produce biogas from algae grown in pulp and paper mill wastewaters, for different algae strains and pond conditions, with differing degrees of oil separation before the anaerobic digestion stage. The methane potential of the various algae pulps was tested by anaerobic digestion batch assays under thermophilic conditions for 23 days. Pre-treatment of substrate is sometimes done in order to reduce the necessary retention time of biogas production. One batch of algae was subjected to either thermal pre-treatment or NaOH or comminution, to assess the effect on these methods on methane production.Ammonia concentration and pH in the digestate was analyzed to monitor the anaerobic digestion process, and the algae pulp’s content of fat, protein and carbohydrates were analyzed to characterize the substrate. In addition, the dewaterability of algae and of algae digestate was examined, as the dewaterability affects transport costs and possible use of the digestate.During the first year of operation, the algae in the range pond produced 186 ml CH4/g VS. The pre-treatments did not significantly affect the methane potential. The second year of operation saw more adapted strains of algae which are expected to produce somewhat different results [data from these experiments can be presented at the conference]. The research is of importance for the development of the biogas market as new substrates are needed to reach the volumes that are necessary to achieve economic viability for biogas plants. By characterizing the algae, it should be easier to see which role they are suitable to play in a co-digestion mix. Furthermore, the production of bio-oil and biogas together benefit the bioenergy system as a whole.
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| 22. |
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| 23. |
- Modin, Oskar, 1980, et al.
(author)
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Bioelectrochemical recovery of Cu, Pb, Cd, and Zn from dilute solutions
- 2012
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In: Journal of Hazardous Materials. - : Elsevier BV. - 1873-3336 .- 0304-3894. ; 235-236, s. 291-297
-
Journal article (peer-reviewed)abstract
- In a microbial bioelectrochemical system (BES) living microorganisms catalyze the anodic oxidation of organic matter at a low anode potential. We used a BES with a biological anode to power the cathodic recovery of Cu, Pb, Cd, and Zn from a simulated municipal solid waste incineration ash leachate. By varying the control of the BES, the four metals could sequentially be recovered from a mixed solution by reduction on a titanium cathode. First, the cell voltage was controlled at zero, which allowed recovery of Cu from the solution without an electrical energy input. Second, the cathode potential was controlled at -0.51 V to recover Pb, which required an applied voltage of about 0.34 V. Third, the cathode potential was controlled at -0.66V to recover Cd, which required an applied voltage of 0.51 V. Finally, Zn was the only metal remaining in solution and was recovered by controlling the anode at +0.2 V to maximize the generated current. The study is the first to demonstrate that a BES can be used for cathodic recovery of metals from a mixed solution, which potentially could be used not only for ash leachates but also for e.g. metallurgical wastewaters and landfill leachates.
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| 24. |
- Nilsson, Charlotte, et al.
(author)
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Efficacy of reactive mineral-based sorbents for phosphate, bacteria, nitrogen and TOC removal - Column experiment in recirculation batch mode
- 2013
-
In: Water Research. - Oxford, United Kingdom : Elsevier BV. - 0043-1354 .- 1879-2448. ; 47:14, s. 5165-5175
-
Journal article (peer-reviewed)abstract
- Two mineral-based materials (Polonite and Sorbulite) intended for filter wells in on-site wastewater treatment were compared in terms of removal of phosphate (PO4-P), total inorganic nitrogen (TIN), total organic carbon (TOC) and faecal indicator bacteria (Escherichia coli and Enterococci). Using an innovative, recirculating system, septic tank effluent was pumped at a hydraulic loading rate of 3000 L m(2) d(-1) into triplicate bench-scale columns of each material over a 90-day period. The results showed that Polonite performed better with respect to removal of PO4-P, retaining on average 80% compared with 75% in Sorbulite. This difference was attributed to higher CaO content in Polonite and its faster dissolution. Polonite also performed better in terms of removal of bacteria because of its higher pH value. The total average reduction in E. coli was 60% in Polonite and 45% in Sorbulite, while for Enterococci the corresponding value was 56% in Polonite and 34% in Sorbulite. Sorbulite removed TIN more effectively, with a removal rate of 23%, while Polonite removed 11% of TIN, as well as TOC. Organic matter (measured as TOC) was accumulated in the filter materials but was also released periodically. The results showed that Sorbulite could meet the demand in removing phosphate and nitrogen with reduced microbial release from the wastewater treatment process.
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| 25. |
- Nordin, Annika, et al.
(author)
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Urea for sanitization of anaerobically digested dewatered sewage sludge
- 2015
-
In: Environmental Engineering Science. - : Mary Ann Liebert Inc. - 1092-8758 .- 1557-9018. ; 32:2, s. 86-94
-
Journal article (peer-reviewed)abstract
- When recycling sewage sludge to agriculture, the risk of disease transmission must be taken into account. Sanitizing treatment prevents disease transmission by reducing dissemination of pathogens early in the reuse chain. Sanitization is commonly achieved by heat treatment of sludge, for example, by prepasteurization before anaerobic digestion or by thermophilic anaerobic digestion. This study evaluated ammonia treatment of anaerobically digested dewatered sewage sludge at pilot scale (65 ton) by urea addition at 0.85% and 1.6% wet weight compared with storage without ammonia addition over 145 days of treatment during the Swedish winter, with ambient temperatures below 0 C. Addition of 1.6% urea reduced indicator organisms Enterococcus spp. and Escherichia coli to below the detection limit of 100 and 10cfu/g, respectively, within 3 months of treatment, whereas the 0.85% urea treatment did inactivate E. coli but not Enterococcus spp. within the study period (145 days). In the control, both indicator bacteria were still present at the end of the study period. Thus, 1.6% treatment with urea is a promising low cost on-demand option for sludge sanitization and can be performed at considerably lower cost than heat treatment.
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| 26. |
- Olsson, Joakim, 1988, et al.
(author)
-
Effects of geographical location on potentially valuable components in Ulva intestinalis sampled along the Swedish coast
- 2020
-
In: Applied Phycology. - : Informa UK Limited. - 2638-8081. ; 1:1, s. 80-92
-
Journal article (peer-reviewed)abstract
- Macroalgal biomass has the potential to become an important source of chemicals and commodities in a future biorefinery. Currently, production of macroalgal biomass is expensive and the content of high-value compounds is often low. Therefore, in this study the biochemical composition of Ulva intestinalis along the Swedish west coast and the east coast up to Stockholm was assessed with the aim of determining how the content of potentially valuable compounds, such as rhamnose, iduronic acid and PUFAs, could be maximized by utilizing natural variation in the choice of marine cultivation site. Along the investigated coastline, the salinity dropped from 19.4‰ at high latitudes along the west coast to 5.4‰ at Stockholm. Nitrogen and phosphorus availability varied, while temperature was similar at all locations. The two major components of biomass, carbohydrates and ash, varied inversely with the highest content of ash in the west and carbohydrates in the east. In addition, total fatty acids were significantly higher in west coast samples at 3.2 g 100 g–1 dw, with a higher proportion of mono- and polyunsaturated fatty acids. Some health-beneficial fatty acids were found, including EPA and DPA, at 10–50 mg 100 g–1 dw, respectively. The metal content and elemental composition varied widely, probably due to the influence of specific local conditions. The P content was correlated with the phosphorus concentration in waters at the locations. In PCA analysis, the monosaccharides constituting the cell wall polysaccharide ulvan were found to vary by geographical location, with higher levels possibly associated with lower salinities. However, only glucuronic acid differed significantly between sites. These results show the considerable geographical variability in the composition of Swedish U. intestinalis and suggest that different salinities could be used to create a lipid- or carbohydrate-rich biomass.
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| 27. |
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| 28. |
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| 29. |
- Svensson, Britt-Marie, 1956-, et al.
(author)
-
Evaluation of filter material for treatment of different types of wastewater
- 2011
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In: Journal of Environmental Protection. - 2152-2197 .- 2152-2219. ; 2:7, s. 888-894
-
Journal article (peer-reviewed)abstract
- This paper presents an evaluation of the suitability of a mixed absorbent based on peat and carbon-containing ash for treatment of wastewaters, such as wastewater from professional car washes, landfill leachate and stormwater. This mixture is very attractive, since it is a low-cost material which has a capability to simultaneously remove inorganic as well as organic pollutants. Since any filter material eventually needs to be replaced either due to saturation of pollutants or reduced infiltration capacity, it is important that the residual can be handled at low cost and that the environment will be not impaired. The tested mixture, used in filter beds, showed low leaching values and high simultaneous removal efficiency of metals as Cu, Cd and Pb, non-polar organic compounds such as PCBs. Polar organic compounds as phenols were also efficiently removed by microbial and/or chemical degradation in the studied treatment plants with the filter bed acted as a biofilter. Filter material used for three years in a full-scale plant for leachate treatment and four years in treatment plants for wastewater from car washes, had sufficiently high energy content indicating that energy recovery is a good alternative for handling after its usage. Results show that the presented filter material is excellent for both small scale applications (e.g. treatment systems for car wash wastewater with capacity between 250 - 3000 m3 per year) as well as large-scale applications (e.g. filter systems for landfill leachates with capacity above 30,000 m3 per year).
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| 30. |
- Svensson, Henric, et al.
(author)
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Treatment of wood leachate with high polyphenols content by peat and carbon-containing fly ash filters
- 2015
-
In: Desalination and Water Treatment. - 1944-3994 .- 1944-3986. ; 53:8, s. 2041-2048
-
Journal article (peer-reviewed)abstract
- In the present study, two combinations of filter materials in filter/columns were examined for removal of total organic carbon (TOC) and polyphenols (PP) found in storm water runoff from wood storage areas in a wooden floor industry. One filter/column was packed with peat mixed with carbon-containing fly ash, while another filter/column contained only peat (without ash). The mixture of peat and ash has shown faster and higher removal capacity for TOC and faster removal with the same final removal capacity for PP (in grams of pollutant per kg of sorbent) at the saturation point. The superiority observed for the peat and ash filter is presumably due to the unique characteristics of peat and ash, which enhanced the treatment efficiency when used together in a mixture. Based on the observed results, filters formed by peat and carbon-containing ashes proved to be a potentially low-cost option for the treatment of storm water generated at storage areas of wood materials such as logs, sawdust and wood chips.
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| 31. |
- Werker, Alan, et al.
(author)
-
The production of biopolymers for bioplastics using pulp and paper mill wastewater and residual fibre streams
- 2020
-
Reports (peer-reviewed)abstract
- As part of the Multibio project, the potential for production of biobased and biodegradable polymers, from organic residuals in process effluent streams, was evaluated for Stora Enso Skoghalls and Rottneros pulp and paper mills in Värmland, Sweden. These biopolymers are thermoplastic polyesters made by naturally occurring bacteria and are from the family of polyhydroxyalkanoates (PHAs). They can be formulated as principal ingredients for plastics, functional chemicals, and composite materials of interest to a diversity of sectors including the pulp and paper industry. They can also be formulated into fish feed to impart pre/pro-biotic benefits in aquaculture. Commercial quantities and qualities of PHAs can be produced as a corollary benefit to biological wastewater treatment processes that are used to treat industrial and municipal wastewaters for environmental protection. The goal of the present study has been to determine the potential quantities of PHA that could be produced as an integral part of the mill residual organics and effluent management. The aim of this Multibio work package has also been to recommend steps forward.It was estimated that Skoghalls and Rottneros mills manage 70 and 15 tons per day of residual organic material on a chemical oxygen demand (COD) basis, and in relation to respective production levels of about 778,000 and 170,000 ton/yr paper and board. These numbers were calculated from mass balances using historical monitoring information provided by the mills and with measurements made in this study on samples from selected locations of the treatment processes. The residual COD is comprised of fibre and surplus activated sludge as well as soluble dissolved organic material. This organic material is a resource to produce a microbial biomass rich in PHA with remaining organic material being used for boiler heat production. Improved sludge dewatering is expected such that COD used for heat production today could be diverted to PHA without undue loss of heat production capacity in the balance.Two process scenarios are presented (Scenario 1 & 2) as a logical progression of risk and development. PHA production requires that some organic feedstock is first converted into volatile fatty acids (VFAs) through acidogenic fermentation. If all the residual organic mass is used to produce VFAs (Scenario 1), it was estimated that about 2 000 and 400 tons PHA per year could be produced at Skoghalls and Rottneros mills, respectively. Production amounts would be increased (Scenario 2) by about 50 % (3 000 and 600 tPHA/yr, respectively) if the residual mass flows of waste activated sludge biomass from the mill aerobic biological wastewater treatment processes could be exploited for a PHA storing potential rather than just being an organic feedstock to yield VFAs. A mill side-line of polymer production anchors in-house supply and experience with PHAs while casting a net for evolving and capturing future interesting materials and business. Future mill economies may foreseeably require standing on wider business footings including fibre as well as from other cellulose derived biobased revenue generating products and services. PHAs can naturally also be made using the prime input lumber starting with hemicellulose and cellulose. Opening a PHA specialty industry first is a way to open the door for discovery that may well motivate directing strategically separated mill upstream organic fractions to successful large commercial revenues from PHAs in the future.
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| 32. |
- Wilen, Britt-Marie, 1966, et al.
(author)
-
The mechanisms of granulation of activated sludge in wastewater treatment, its optimization, and impact on effluent quality
- 2018
-
In: Applied Microbiology and Biotechnology. - : Springer Science and Business Media LLC. - 0175-7598 .- 1432-0614. ; 102:12, s. 5005-5020
-
Journal article (peer-reviewed)abstract
- Granular activated sludge has gained increasing interest due to its potential in treating wastewater in a compact and efficient way. It is well-established that activated sludge can form granules under certain environmental conditions such as batch-wise operation with feast-famine feeding, high hydrodynamic shear forces, and short settling time which select for dense microbial aggregates. Aerobic granules with stable structure and functionality have been obtained with a range of different wastewaters seeded with different sources of sludge at different operational conditions, but the microbial communities developed differed substantially. In spite of this, granule instability occurs. In this review, the available literature on the mechanisms involved in granulation and how it affects the effluent quality is assessed with special attention given to the microbial interactions involved. To be able to optimize the process further, more knowledge is needed regarding the influence of microbial communities and their metabolism on granule stability and functionality. Studies performed at conditions similar to full-scale such as fluctuation in organic loading rate, hydrodynamic conditions, temperature, incoming particles, and feed water microorganisms need further investigations.
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| 33. |
- Yermakovych, Iryna, et al.
(author)
-
Investigation of Hard Biodegradable Pharmaceuticals Pollutants Treatment of Hospital Wastewaters
- 2014
-
In: Book of abstracts. ; , s. 173-
-
Conference paper (other academic/artistic)abstract
- According to the results of the research performed in the different modern research laboratories the remnants of drugs and their derivatives are found in surface waters in France, USA, UK, Germany, Denmark and Sweden. These substances also can be found in sewage sludge, river and ocean sediments and in the municipal landfills filtrates. Some species have been found even in drinking water and ice, grou nd and ocean waters. Many studies confirmed the data of the annual drug releasing into the environment, which counts several hundred of kilograms. Thus, the investigations of negative impact of pharmaceutical substances and their derivatives on aquatic organisms have been performed during more than 20 years and showed an extremely negative presence of any drugs in the waters. Now, they are still considering as emerging organic contaminants in the different type of waters. The main sources of water pollution by pharmaceuticals and their derivatives are wastewater from hospitals, clinics, pharmaceutical industries and domestic sewage as well. However, the main percentage of pharmaceuticals dumped into wastewaters is coming from the hospitals. This is typical for large cities, where is situated a great n um ber of hospitals and health care institutions. In the opinion of one study hospital wastewaters have been found in a 15 times higher potential ecotoxicity than the general urban have. The negative effect of pharmaceuticals influence into environment can be decrease due to application of different kinds of additional wastewater treatment as Advanced Oxidation Processes (AOPs). The main approaches of hospitals wastewater treatment in Ukraine and Sweden by implementation of AOPs method were considered in this study. The main data of this research will be presented.
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| 34. |
- Zambrano, Jesús, et al.
(author)
-
Optimal steady-state design of zone volumes of bioreactors with Monod growth kinetics
- 2015
-
In: Biochemical Engineering Journal. - : Elsevier BV. - 1369-703X .- 1873-295X. ; 100, s. 59-66
-
Journal article (peer-reviewed)abstract
- This paper deals with steady-state analysis and design of bioreactors consisting of a number of completely stirred tank reactors (CSTRs) in series. The study is confined to one consumed (substrate) and one consuming constituent (biomass). The specific microbial growth rate is assumed to be described by Monod kinetics. The death of biomass is assumed to be negligible. Two optimal design problems for a large number of CSTRs in series are studied: to minimize the effluent substrate concentration for a given total volume, and to minimize the total volume for a given effluent substrate concentration. As an appealing alternative to solve these problems numerically, it is proposed to consider the asymptotic case where the number of CSTRs tends to infinity. This is shown to correspond to one CSTR in series with a plug flow reactor (PFR). A CSTR with a sufficient large volume is needed to avoid wash-out of the biomass. The main result is that both design problems for the CSTR + PFR configuration have the same solution with respect to the optimal volume of the CSTR, which is given as an explicit function of the incoming substrate concentration, the volumetric flow rate and the coefficients of the Monod growth rate function. Numerical results indicate that the plug flow approach may be used as a feasible design procedure even for a reasonably low number of CSTRs in series.
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| 35. |
- Anbalagan, Anbarasan, 1988-
(author)
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A passage to wastewater nutrient recovery units : Microalgal-Bacterial bioreactors
- 2018
-
Artistic work (other academic/artistic)abstract
- In recent years, the microalgal–bacterial process has been considered to be a very attractive engineering solution for wastewater treatment. However, it has not been widely studied in the context of conventional wastewater treatment design under Swedish conditions. The technology holds several advantages: as a CO2 sink, ability to withstand cold conditions, ability to grow under low light, fast settling without chemical precipitation, and reducing the loss of valuable nutrients (CO2, N2, N2O, PO4). The process also provides the option to be operated either as mainstream (treatment of municipal wastewater) or side stream (treatment of centrate from anaerobic digesters) to reduce the nutrient load of the wastewater. Furthermore, the application is not only limited to wastewater treatment; the biomass can be used to synthesise platform chemicals or biofuels and can be followed by recovery of ammonium and phosphate for use in agriculture.In the present study, the feasibility of applying the process in Swedish temperature and light conditions was investigated by implementing microalgae within the activated sludge process. In this context, the supporting operational and performance indicators (hydraulic retention time (HRT), sludge retention time (SRT) and nutrients removal) were evaluated to support naturally occurring consortia in photo-sequencing and continuous bioreactor configuration. Furthermore, CO2 uptake and light spectrum-mediated nutrient removal were investigated to reduce the impact on climate and the technical challenges associated with this type of system.The results identified effective retention times of 6 and 4 days (HRT = SRT) under limited lighting to reduce the electrical consumption. From the perspective of nitrogen removal, the process demands effective CO2 input either in the mainstream or side stream treatment. The incorporation of a vertical absorption column demonstrated effective CO2 mass transfer to support efficient nitrogen and phosphorus removal as a side stream treatment. However, the investigation of a continuous single-stage process as the mainstream showed a requirement for a lower SRT in comparison to semi-continuous operation due to faster settlability, regardless of inorganic carbon. Furthermore, the process showed an effective reduction of influent phosphorus and organic compounds (i.e. COD/TOC) load in the wastewater as a result of photosynthetic aeration. Most importantly, the operation was stable at the temperature equivalent of wastewater (12 and 13 ˚C), under different lighting (white, and red-blue wavelengths) and retention times (6 and 1.5 d HRT) with complete nitrification. Additionally, the biomass production was stable with faster settling properties without any physiochemical separation.The outcomes of this thesis on microalgal–bacterial nutrient removal demonstrates that (1) photosynthesis-based aeration at existing wastewater conditions under photo-sequential and continuous photobioreactor setup, (2) flocs with rapid settling characteristics at all studied retention times, (3) the possibility of increasing carbon supplementation to achieve higher carbon to nitrogen balance in the photobioreactor, and (4) most importantly, nitrification-based microalgal biomass uptake occurred at all spectral distributions, lower photosynthetic active radiation and existing wastewater conditions.
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| 36. |
- Bonaglia, Stefano, et al.
(author)
-
Capping with activated carbon reduces nutrient fluxes, denitrification and meiofauna in contaminated sediments
- 2019
-
In: Water Research. - : Elsevier BV. - 0043-1354 .- 1879-2448. ; 148, s. 515-525
-
Journal article (peer-reviewed)abstract
- Sediment capping with activated carbon (AC) is an effective technique used in remediation of contaminated sediments, but the ecological effects on benthic microbial activity and meiofauna communities have been largely neglected. This study presents results from a 4-week experiment investigating the influence of two powdered AC materials (bituminous coal-based and coconut shell-derived) and one control material (clay) on biogeochemical processes and meiofauna in contaminated sediments. Capping with AC induced a 62‒63% decrease in denitrification and a 66‒87 % decrease in dissimilatory nitrate reduction to ammonium (DNRA). Sediment porewater pH increased from 7.1 to 9.0 and 9.7 after addition of bituminous AC and biomass-derived AC, respectively. High pH (>8) persisted for at least two weeks in the bituminous AC and for at least 24 days in the coconut based AC, while capping with clay had no effect on pH. We observed a strong impact (nitrate fluxes being halved in presence of AC) on nitrification activity as nitrifiers are sensitive to high pH. This partly explains the significant decrease in nitrate reduction rates since denitrification was almost entirely coupled to nitrification. Total benthic metabolism estimated by sediment oxygen uptake was reduced by 30 and 43 % in presence of bituminous coal-based AC and coconut shell-derived AC, respectively. Meiofauna abundances decreased by 60‒62 % in the AC treatments. Taken together, these observations suggest that AC amendments deplete natural organic carbon, intended as food, to heterotrophic benthic communities. Phosphate efflux was 91 % lower in presence of bituminous AC compared to untreated sediment probably due to its content of aluminum (Al) oxides, which have high affinity for phosphate. This study demonstrates that capping with powdered AC produces significant effects on benthic biogeochemical fluxes, microbial processes and meiofauna abundances, which are likely due to an increase in porewater pH and to the sequestration of natural, sedimentary organic matter by AC particles.
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| 37. |
- Dalahmeh, Sahar
(author)
-
Bark and charcoal filters for greywater treatment : pollutant removal and recycling opportunities
- 2013
-
Doctoral thesis (other academic/artistic)abstract
- Water scarcity, inappropriate sanitation and wastewater pollution are critically important global issues. Greywater is a sustainable water source for recycling, so this thesis examined simple, robust, low-cost alternatives for on-site treatment of greywater to irrigation water quality. Laboratory-scale pine bark, activated charcoal and sand filters were evaluated as regards their pollutant removal and interactions between medium properties, greywater, microbial activity and bacterial community structure. The effects of hydraulic and organic loading rates (HLR and OLR) were described by general regression models (GRM). The quality of the treated greywater was evaluated against Jordanian standards for irrigation water. A series of experiments examined treatment of artificial greywater in terms of lowering biochemical oxygen demand (BOD5), chemical oxygen demand (COD), phosphorus (Tot-P), nitrogen (Tot-N) and pathogen indicators (total thermotolerant coliforms) and tracer microorganisms (enterohaemorrhagic Escherichia coli (EHEC) and bacteriophage PhiX). Following greywater loading, all filter materials developed biofilms with high bacterial diversity and richness. The driving force shaping bacterial communities in bark material was its organic composition and low pH, while the communities in the charcoal and sand filters were more influenced by the greywater. The GRM indicated that the performance of all filters was influenced by the HLR and OLR of the present and previous runs. The organic matter content and surface and hydraulic properties of the bark filters resulted in high BOD5 removal rates (94-99%), even at increased HLR and OLR, but accompanied by release of dissolved organic substances originating from the bark itself. High nitrification occurred in the bark filters in all loading regimes tested, but with low Tot-N removal. The bark filters demonstrated 1-3 log10 removal of microorganisms, but bark organic nature made its filters more vulnerable to biodegradation and disintegration. The charcoal had large specific surface area, which provided the capacity for intermediate-high removal of BOD5 (83-97%), Tot-N (50-98%) and Tot-P (64-98%), but removal of microorganisms was poor. The sand filters demonstrated low BOD5 removal (67-91%) and high nitrification, but low nitrogen removal. Greywater treatment by bark and charcoal filters reduced their organics content to acceptable irrigation levels. Nitrogen and microorganisms must be further reduced to meet Jordanian standards on treated wastewater for irrigation.
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| 38. |
- Eivazihollagh, Alireza, et al.
(author)
-
On chelating surfactants : Molecular perspectives and application prospects
- 2019
-
In: Journal of Molecular Liquids. - : Elsevier BV. - 0167-7322 .- 1873-3166. ; 278, s. 688-705
-
Journal article (peer-reviewed)abstract
- Chelating agents, molecules that very strongly coordinates certain metal ions, are used industrially as well as in consumer products to minimize disturbances and increase performance of reactions and applications. The widely used sequestering agents, nitrilotriacetic acid (NTA), ethylenediaminetetraacetic acid (EDTA) and diethylenetriaminepentaacetic acid (DTPA) belong to this branch of readily water-soluble compounds. When these chemical structures also have hydrophobic parts, they are prone to adsorb at air-water interfaces and to self-assemble. Such bifunctional molecules can be called chelating surfactants and will have more extended utilization prospects than common chelating agents or ordinary ionic surfactants. The present review attempts to highlight the fundamental behavior of chelating surfactants in solution and at interfaces, and their very specific interactions with metal ions. Methods to recover chelating surfactants from metal chelates are also described. Moreover, utilization of chelating surfactants in applications for metal removal in environmental engineering and mineral processing, as well as for metal control in the fields of biology, chemistry and physics, is exemplified and discussed.
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| 39. |
- Gentili, Francesco, et al.
(author)
-
Algal cultivation in urban wastewater : an efficient way to reduce pharmaceutical pollutants
- 2017
-
In: Journal of Applied Phycology. - : Springer Science and Business Media LLC. - 0921-8971 .- 1573-5176. ; 29:1, s. 255-262
-
Journal article (peer-reviewed)abstract
- The purpose of this study was to investigate whether pharmaceutical pollutants in urban wastewater can be reduced during algal cultivation. A mixed population of wild freshwater green algal species was grown on urban wastewater influent in a 650 L photobioreactor under natural light and with the addition of flue gases. Removal efficiencies were very high (> 90 %), moderate (50-90 %), low (10-50 %), and very low or non-quantifiable (< 10 %) for 9, 14, 11, and 18 pharmaceuticals, respectively, over a 7-day period. High reduction was found in the following pharmaceuticals: the beta-blockers atenolol, bispropol, and metoprolol; the antibiotic clarithromycine; the antidepressant bupropion; the muscle relaxant atracurium; hypertension drugs diltiazem and terbutaline used to relive the symptoms of asthma. Regression analysis did not detect any relationship between the reduction in pharmaceutical contents and light intensity reaching the water surface of the algal culture. However, the reduction was positively correlated with light intensity inside the culture and stronger when data collected during the night were excluded. Algae cultivation can remove partially or totally pharmaceutical pollutants from urban wastewater, and this opens up new possibilities for treating urban wastewater.
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| 40. |
- Laohaprapanon, Sawanya, et al.
(author)
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Anaerobic baffled reactor coupled with chemical precipitation for treatment and toxicity reduction of industrial wastewater
- 2014
-
In: Environmental technology. - : Informa UK Limited. - 0959-3330 .- 1479-487X. ; 35:2, s. 154-162
-
Journal article (peer-reviewed)abstract
- This study describes the reduction of soluble chemical oxygen demand (CODs) and the removal of dissolved organic carbon (DOC), formaldehyde (FA) and nitrogen from highly polluted wastewater generated during cleaning procedures in wood floor manufacturing using a laboratory-scale biological anaerobic baffled reactor followed by chemical precipitation using MgCl2·6H2O+Na2HPO4. By increasing the hydraulic retention time from 2.5 to 3.7 and 5 days, the reduction rates of FA, DOC and CODs of nearly 100%, 90% and 83%, respectively, were achieved. When the Mg:N:P molar ratio in the chemical treatment was changed from 1:1:1 to 1.3:1:1.3 at pH 8, the NH4+ removal rate increased from 80% to 98%. Biologically and chemically treated wastewater had no toxic effects on Vibrio fischeri and Artemia salina whereas chemically treated wastewater inhibited germination of Lactuca sativa owing to a high salt content. Regardless of the high conductivity of the treated wastewater, combined biological and chemical treatment was found to be effective for the removal of the organic load and nitrogen, and to be simple to operate and to maintain. A combined process such as that investigated could be useful for on-site treatment of low volumes of highly polluted wastewater generated by the wood floor and wood furniture industries, for which there is no suitable on-site treatment option available today.
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| 41. |
- Pondja, Estevao
(author)
-
Environmental aspects of coal mine drainage: a regional study of Moatize in Mozambique
- 2017
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Doctoral thesis (other academic/artistic)abstract
- Mozambique is one of the largest coal producers in Africa. Extraction of the coal is carried out in the Moatize district of the Tete province in the center of the country. A surface mining technique is used to extract the coal below ground level. During mining activities, sulfide minerals, which are commonly associated with coal, are exposed to oxygen and water, leading to the generation of acid mine drainage (AMD). AMD is high in acidity and has a high content of metals, metalloids and sulfate that can cause severe damage to the environment. Moatize is inside the lower Zambezi River basin, the pollution that occurs there due to mining activities constituting a risk both for public health and for the water resources. The standard guidelines in Mozambique for wastewater from coal mining are very weak, allowing the coal mining companies to pollute considerably. The prevention, containment and remediation of polluted mine water are measures that should be carried out to avoid the spread of pollution. Prevention is the least expensive strategy, but it cannot always prevent the generation of polluted mine water. Thus containment and treatment need to be put into practice. Both active and passive treatment are used to treat polluted mine water. Since Moatize is a largely unstudied area, both static and leaching tests were carried out to investigate the possibility of AMD being generated. The geochemical processes that could impact on the quality of mine drainage stemming from the waste rock there were assessed. Use of cost-effective methods for the treatment of mine water by use of bioremediation coupled with adsorption, using cassava peels that are readily available in the country as a carbon source and as an adsorbent is proposed. Since climate changes and climate variability can exacerbate the negative impact of surface mining, the possibility of this was assessed. It was found that the production of AMD was likely in at least one of the coal mines in Moatize. The mine water from coal mines in Moatize was found to have a high content of sulfate, calcium, magnesium and manganese. A set of guidelines for coal mine effluents that was developed, based on different guidelines obtained from around the world, was proposed for Mozambique. Sulfate reducing bacteria coupled with adsorption appeared to be appropriate for removing these pollutants. Cassava peels used as adsorbents appeared to be effective in removing calcium, magnesium and manganese. Based on climate data, the period from November on through February was found to be the period in which the pollution load in Moatize was greatest. Since the flow rate in the Revúbué River, which is close to the coal mines, is highly dependent upon the precipitation that occurs during the rainy season, the discharge of polluted mine water should be avoided. To achieve sustainable mining in Moatize, the coal mining companies, the regulators and the stakeholders from water sector there need to work together. A framework for integrating efforts to satisfy the needs of the different stakeholders involved in the water sector in Moatize was proposed.
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| 42. |
- Xafenias, Nikolaos, 1981, et al.
(author)
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Evaluating hexavalent chromium reduction and electricity production in microbial fuel cells with alkaline cathodes
- 2015
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In: International Journal of Environmental Science and Technology. - : Springer Science and Business Media LLC. - 1735-2630 .- 1735-1472. ; 12:8, s. 2435-2446
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Journal article (peer-reviewed)abstract
- The work investigated the efficiency of microbial fuel cells (MFCs) for the treatment of alkaline hexavalent chromium containing wastewater. When lactate was used as the metal chelator in alkaline (pH 8) abiotic cathodes, hexavalent chromium concentration dropped from 10 mg l-1 to undetectable levels within the first 45 h of operation. Power density produced in the pH 8 abiotic cathodes was up to 21.4 mW m-2, and in the pH 9 cathodes up to 2.4 mW m-2; these values were well comparable with other values found in the literature for biologically catalysed cathodes, even at lower pH values. When Shewanella oneidensis MR-1 was present in a hexavalent chromium reducing cathode at pH 8, current production contributed by 26 % to the total hexavalent chromium reduced during the 36 days of operation. On the other hand, when hexavalent chromium (10 mg l-1) was controllably added in the anode where S. oneidensis MR-1 was present, up to 73 % of current decreased immediately after every hexavalent chromium addition; this toxic effect remained even after hexavalent chromium was depleted in the anode and strongly indicates that the presence of hexavalent chromium in the anodes of MFCs must be avoided. Overall, our results indicate that alkaline hexavalent chromium wastewater can be effectively remediated in the cathodes of MFCs, provided that a metal chelator is present in the cathodes and that hexavalent chromium is not present in the anodes.
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| 43. |
- Abd El-Daim, Islam Ahmed Moustafa, et al.
(author)
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Paenibacillus polymyxa A26 Sfp-type PPTase inactivation limits bacterial antagonism against Fusarium graminearum but not of F. culmorum in kernel assay
- 2015
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In: Frontiers in Plant Science. - : Frontiers Media SA. - 1664-462X. ; 6
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Journal article (peer-reviewed)abstract
- Fusarium graminearum and F. culmorum are the causing agents of a destructive disease known as Fusarium head blight (FHB). FHB is a re-emerging disease in small grain cereals which impairs both the grain yield and the quality. Most serious consequence is the contamination of grain with Fusarium mycotoxins that are severe threat to humans and animals. Biological control has been suggested as one of the integrated management strategies to control FHB. Paenibacillus polymyxa is considered as a promising biocontrol agent due to its unique antibiotic spectrum. P. polymyxa A26 is an efficient antagonistic agent against Fusarium spp. In order to optimize strain A26 production, formulation and application strategies traits important for its compatibility need to be revealed. Here we developed a toolbox, comprising of dual culture plate assays and wheat kernel assays, including simultaneous monitoring of FHB causing pathogens, A26, and mycotoxin production. Using this system we show that, besides generally known lipopeptide antibiotic production by P. polymyxa, biofilm formation ability may play a crucial role in the case of stain A26 F. culmorum antagonism. Application of the system for effective strain selection and maintenance is discussed.
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| 44. |
- Abed, S. N., et al.
(author)
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Impact of Storage Time on Characteristics of Synthetic Greywater for Two Different Pollutant Strengths to Be Treated or Recycled
- 2020
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In: Water, Air, and Soil Pollution. - : Springer Science and Business Media LLC. - 0049-6979 .- 1573-2932. ; 231:5
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Journal article (peer-reviewed)abstract
- Storage of greywater is controversial for environmental and health reasons. Artificial greywater was assessed after 2 and 7 days of storage time. Two different greywater pollutant strengths were statistically compared at each storage time. A negative significant (p < 0.05) correlation was evident with increasing storage time for the 5-day biochemical oxygen demand for more than 2 days. However, the concentrations of 5-day biochemical oxygen and chemical oxygen demands reduced significantly at 2 days of storage when compared with freshly prepared greywater. Biodegradability (5-day biochemical oxygen demand/chemical oxygen demand ratio) decreased significantly after storage to between 0.14 and 0.39. The nitrification process was improved significantly with increasing storage time concerning low strength greywater with a significant increase in the removal of ammonia-nitrogen and a non-significant decrease in the removal of nitrate-nitrogen. The correlation was significantly positive between ammonia-nitrogen and 5-day biochemical oxygen demand for stored greywater, while it was significantly negative between total suspended solids and both 5-day biochemical oxygen demand and dissolved oxygen. Significant reductions in colour, total suspended solids and turbidity were correlated positively with storage time. Precipitation of dissolved metals was suspected to occur in storing greywater by binding the inorganic components with the sediment and collide surfaces through adsorption, allowing a significant drop in concentrations of dissolved and undissolved metals with increasing storage time through sedimentation. Synthetic greywater of low mineral pollution had significantly higher removals for almost all concentrations compared with those for high concentrations. More advanced technologies for high trace element removal are required.
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| 45. |
- Abed, Suhail N., et al.
(author)
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Phytoremediation performance of floating treatment wetlands with pelletized mine water sludge for synthetic greywater treatment
- 2019
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In: Journal of Environmental Health Science & Engineering (Online). - : Springer Science and Business Media LLC. - 2052-336X. ; 17:2, s. 581-608
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Journal article (peer-reviewed)abstract
- Purpose: Buckets containing floating reed (Phragmites australis) simulated floating treatment wetlands (FTWs) and were used to improve the remediation performance of synthetic greywater (SGW). The aim of the study was to investigate the behaviour of FTWs for treatment of key contaminants within artificial greywater. Methods: Pelletized ochre based on acid mine water sludge was introduced to selected FTWs, because of its capability in sequestration phosphorus and other trace elements. The impact of the following four operational variables were tested in the experimental set-ups of the FTWs (four replicates each): pollutant strength (high- (HC) and low- (LC) concentrations), treatment time (2- or 7-days of hydraulic retention time (HRT)), presence or absence of macrophytes (P. australis) and cement-ochre pellets. Results: The results showed that 5 - day biochemical oxygen demand (BOD) and chemical oxygen demands (COD) were significantly (p < 0.05) reduced in all wetlands. Nitrate-nitrogen (NO3-N) concentrations were significantly (p < 0.05) higher, and those measurements for PO4-P were significantly (p < 0.05) lower than the corresponding ones determined for the influent. The existence of ochre pellets with P. australis significantly (p < 0.05) decreased B, Cd, Cr, Cu, Mg, Ni and Zn concentrations, but increased Al, Ca, Fe and K concentrations in the effluent, with the exception of sodium (Na). Conclusions: The FTW performances can be improved by utilising ochre-cement pellets to increase the pH of greywater. The presence of P. australis acts as a buffer to neutralise the pH of SGW. Rhizomes and biofilms mitigate increases in turbidity, TSS and colour values.
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| 46. |
- Abedi, Tayebeh
(author)
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Constructed wetland modified by biochar/zeolite addition for enhanced wastewater treatment
- 2019
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In: Environmental technology & innovation. - : Elsevier BV. - 2352-1864. ; 16
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Journal article (peer-reviewed)abstract
- Wastewater treatment for water reuse has received considerable attention owing to water resource shortage. One of the most effective wastewater treatment methods involves the use of constructed wetlands (CWs). In this study, synthetic wastewater was treated by using a biochar/zeolite CW. Phragmites australis (common reed) was translocated into two cylinders (lysimeters) that serve as vertical subsurface flow CWs. One CW (CW1) contained gravels as substrate layer, whereas the other CW (CW2) contained three substrate layers, namely, biochar, zeolite, and gravel layers. Response surface methodology was used for statistical analysis. In this study, CW2 performed better in removing pollutants from wastewater than CW1. At optimum pH (6.3) and retention time (57.4 h), 99.9% (1000 mg/L) COD, 99.9% (1000 mg/L) ammonia, 99.9% (50 mg/L) phenols, 99.9% (50 mg/L) Pb, and 99.9% (50 mg/L) Mn were removed by CW2. During this research, nitrous oxide emission was lower in CW2 than in CW1. (C) 2019 Elsevier B.V. All rights reserved.
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| 47. |
- Abid, Suleman, et al.
(author)
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Synthesis and characterization of glycol chitosan coated selenium nanoparticles acts synergistically to alleviate oxidative stress and increase ginsenoside content in Panax ginseng
- 2021
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In: Carbohydrate Polymers. - : Elsevier BV. - 0144-8617. ; 267
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Journal article (peer-reviewed)abstract
- The objective of the present study is synthesis of glycol chitosan coated selenium nanoparticles (GC-Se NPs) and evaluation of oxidative stress and ginsenoside accumulation in P. ginseng C. A. Meyer. We synthesized (Se NPs and GC-Se NPs) and characterized using various spectroscopic analyses. The highest concentration (20 mg L−1) of GC-Se NPs induced moderate ROS (O2[rad]− and H2O2) accumulation and upregulation of PgSOD and PgCAT showing good biocompatibility and less toxicity at the highest concentration. Furthermore, ginsenoside biosynthetic pathway genes (PgHMGR, PgSS, PgSE, PgDDS) also showed significant upregulation upon 20 mg L−1 GC-Se NPs treatment. At 20 mg L−1 GC-Se NPs treatment, ginsenoside accumulated upto 217.47 mg/mL and 169.86 mg/mL mainly due to the increased proportion of Rb1 and Re ginsenosides. Altogether, our results suggested that ecofriendly conjugation of GC with Se NPs could be used as a bio fortifier to enhance the ginsenoside profile and to increase the quality of ginseng roots.
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| 48. |
- Achermann, Stefan, et al.
(author)
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Trends in Micropollutant Biotransformation along a Solids Retention Time Gradient
- 2018
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In: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 52:20, s. 11601-11611
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Journal article (peer-reviewed)abstract
- For many polar organic micropollutants, biotransformation by activated sludge microorganisms is a major removal process during wastewater treatment. However, our current understanding of how wastewater treatment operations influence microbial communities and their micropollutant biotransformation potential is limited, leaving major parts of observed variability in biotransformation rates across treatment facilities unexplained. Here, we present biotransformation rate constants for 42 micropollutants belonging to different chemical classes along a gradient of solids retention time (SRT). The geometric mean of biomass-normalized first-order rate constants shows a clear increase between 3 and 15 d SRT by 160% and 87%, respectively, in two experiments. However, individual micropollutants show a variety of trends. Rate constants of oxidative biotransformation reactions mostly increased with SRT. Yet, nitrifying activity could be excluded as primary driver. For substances undergoing other than oxidative reactions, i.e., mostly substitution-type reactions, more diverse dependencies on SRT were observed. Most remarkably, characteristic trends were observed for groups of substances undergoing similar types of initial transformation reaction, suggesting that shared enzymes or enzyme systems that are conjointly regulated catalyze biotransformation reactions within such groups. These findings open up opportunities for correlating rate constants with measures of enzyme abundance such as genes or gene products, which in turn should help to identify enzymes associated with the respective biotransformation reactions.
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| 49. |
- Aggarwal, Ruchi, et al.
(author)
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Sunlight promoted removal of toxic hexavalent chromium by cellulose derived photoactive carbon dots
- 2022
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In: Chemosphere. - : Elsevier BV. - 0045-6535 .- 1879-1298. ; 287
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Journal article (peer-reviewed)abstract
- A scalable synthetic procedure for fabricating photoactive carbon dots (CD) from microcrystalline cellulose (MCC) is presented. The MCC was transformed into a photoactive nanosized CD by a one-step acid-assisted thermal-carbonization (~90 °C for 30 min). The efficiency of the obtained CD was determined by photo-removal of toxic hexavalent chromium (Cr(VI)) ions from wastewater. CD obtained from cellulose completely removed 20 ppm of Cr(VI) wastewater within ∼120 min under sunlight illumination. No Cr(VI) removal was observed in dark conditions and with control cellulose material as reference samples. The Cr(VI) removal follows pseudo-first-order kinetics along with a half-life of ∼26 min. Furthermore, the Cr(VI) removal from wastewater was supported via cyclic voltammetry analysis. Using a low-cost, naturally available cellulose material and sulfuric acid, the world's most-used chemical, creates techno-economic prerequisites for a scalable process of photoactive carbon dots.
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| 50. |
- Ahmad, Arslan, et al.
(author)
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Deep-dive into iron-based co-precipitation of arsenic : A review of mechanisms derived from synchrotron techniques and implications for groundwater treatment
- 2024
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In: Water Research. - : Elsevier Ltd. - 0043-1354 .- 1879-2448. ; 249
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Research review (peer-reviewed)abstract
- The co-precipitation of Fe(III) (oxyhydr)oxides with arsenic (As) is one of the most widespread approaches to treat As-contaminated groundwater in both low- and high-income settings. Fe-based co-precipitation of As occurs in a variety of conventional and decentralized treatment schemes, including aeration and sand filtration, ferric chloride addition and technologies based on controlled corrosion of Fe(0) (i.e., electrocoagulation). Despite its ease of deployment, Fe-based co-precipitation of As entails a complex series of chemical reactions that often occur simultaneously, including electron-transfer reactions, mineral nucleation, crystal growth, and As sorption. In recent years, the growing use of sophisticated synchrotron-based characterization techniques in water treatment research has generated new detailed and mechanistic insights into the reactions that govern As removal efficiency. The purpose of this critical review is to synthesize the current understanding of the molecular-scale reaction pathways of As co-precipitation with Fe(III), where the source of Fe(III) can be ferric chloride solutions or oxidized Fe(II) sourced from natural Fe(II) in groundwater, ferrous salts or controlled Fe(0) corrosion. We draw primarily on the mechanistic knowledge gained from spectroscopic and nano-scale investigations. We begin by describing the least complex reactions relevant in these conditions (Fe(II) oxidation, Fe(III) polymerization, As sorption in single-solute systems) and build to multi-solute systems containing common groundwater ions that can alter the pathways of As uptake during Fe(III) co-precipitation (Ca, Mg bivalent cations; P, Si oxyanions). We conclude the review by providing a perspective on critical knowledge gaps remaining in this field and new research directions that can further improve the understanding of As removal via Fe(III) co-precipitation.
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