| 1. |
- 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
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In: Water Research. - Oxford, United Kingdom : Elsevier BV. - 0043-1354 .- 1879-2448. ; 47:14, s. 5165-5175
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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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| 2. |
- Blum, Kristin M., 1989-, et al.
(author)
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Comprehensive assessment of organic contaminant removal from on-site sewage treatment facility effluent by char-fortified filter beds
- 2019
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In: Journal of Hazardous Materials. - : Elsevier. - 0304-3894 .- 1873-3336. ; 361, s. 111-122
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Journal article (other academic/artistic)abstract
- The removal of organic contaminants from wastewater using cost-efficient and easily accessible methods have been increasingly studied in recent years. Most studies have focused on municipal sewage treatment plants; however, our study investigated treatment with char-fortified filter beds for on-site sewage treatment facilities (OSSFs). OSSFs are commonly used in rural and semi-urban areas all over the world to treat wastewater to reduce eutrophication and water-related diseases. To screen for a wide range of organic contaminants in order to improve the understanding of wastewater treatment efficiency and molecular properties, samples were taken from an OSSF field study site that used three filter types: sand, char-fortified sand, and char-fortified gas concrete. First, we screened for organic contaminants with state-of-the-art gas chromatography and liquid chromatography mass spectrometry-based targeted and untargeted analysis and then we developed quantitative structure-property relationship models to find the key molecular features responsible for the removal of organic contaminants. We identified 74 compounds, of which 24 were confirmed with reference standards. Amongst these 74 compounds were plasticizers, UV stabilizers, fragrances, pesticides, surfactant and polymer impurities, pharmaceuticals and their metabolites, and many biogenic compounds. Sand filters that are sometimes used as a last treatment step in OSSFs can remove hydrophobic contaminants. The addition of biochar significantly increases the removal of these and a few hydrophilic compounds (Wilcoxon signed-rank test, α = 0.05). Gas concrete did not appear to be suitable for the removal of organic contaminants. This study showed that, besides hydrophobic effects, biodegradation is the most important removal pathway in long-term field applications. However, further improvements are necessary to remove very hydrophilic contaminants as they were not removed with sand and biochar-fortified sand.
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| 3. |
- Gros Calvo, Meritxell, et al.
(author)
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Screening and prioritization of micropollutants in wastewaters from on-site sewage treatment facilities
- 2017
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In: Journal of Hazardous Materials. - : Elsevier. - 0304-3894 .- 1873-3336. ; 328, s. 37-45
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Journal article (peer-reviewed)abstract
- A comprehensive screening of micropollutants was performed in wastewaters from on-site sewage treatment facilities (OSSFs) and urban wastewater treatment plants (WWTPs) in Sweden. A suspect screening approach, using high resolution mass spectrometry, was developed and used in combination with target analysis. With this strategy, a total number of 79 micropollutants were successfully identified, which belong to the groups of per- and polyfluoroalkyl substances (PFASs), pesticides, phosphorus-containing flame retardants (PFRs) and pharmaceuticals and personal care products (PPCPs). Results from this screening indicate that concentrations of micropollutants are similar in influents and effluents of OSSFs and WWTPs, respectively. Removal efficiencies of micropollutants were assessed in the OSSFs and compared with those observed in WWTPs. In general, removal of PFASs and PFRs was higher in package treatment OSSFs, which are based on biological treatments, while removal of PPCPs was more efficient in soil bed OSSFs. A novel comprehensive prioritization strategy was then developed to identify OSSF specific chemicals of environmental relevance. The strategy was based on the compound concentrations in the wastewater, removal efficiency, frequency of detection in OSSFs and on in silico based data for toxicity, persistency and bioaccumulation potential.
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| 4. |
- Hamisi, Rajabu, et al.
(author)
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Modelling phosphorus sorption kinetics and the longevity of reactive filter materials used for on-sitewastewater treatment
- 2019
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In: Water. - : MDPI AG. - 2073-4441. ; 11:4
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Journal article (peer-reviewed)abstract
- Use of reactive filter media (RFM) is an emerging technology in small-scale wastewater treatment to improve phosphorus (P) removal and filter material longevity for making this technology sustainable. In this study, long-term sorption kinetics and the spatial dynamics of sorbed P distribution were simulated in replaceable P-filter bags filled with 700 L of reactive material and used in real on-site treatment systems. The input data for model calibration were obtained in laboratory trials with Filtralite P®, Polonite® and Top16. The P concentration breakthrough threshold value was set at an effluent/influent (C/C 0 ) ratio of 1 and simulations were performed with P concentrations varying from 1 to 25 mg L -1 . The simulation results showed that influent P concentration was important for the breakthrough and longevity, and that Polonite performed best, followed by Top16 and Filtralite P. A 100-day break in simulated intermittent flow allowed the materials to recover, which for Polonite involved slight retardation of P saturation. The simulated spatial distribution of P accumulated in the filter bags showed large differences between the filter materials. The modelling insights from this study can be applied in design and operation of on-site treatment systems using reactive filter materials.
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| 5. |
- Kårelid, Victor, 1989-
(author)
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Towards application of activated carbon treatment for pharmaceutical removal in municipal wastewater
- 2016
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Licentiate thesis (other academic/artistic)abstract
- Many pharmaceuticals are found in municipal wastewater effluents due to their persistence in the human body as well as in conventional wastewater treatment processes. This discharge to the environment can lead to adverse effects in aquatic species, such as feminization of male fish. During the past decade, these findings have spawned investigations and research into suitable treatment technologies that could severely limit the discharge. Adsorption onto activated carbon has been identified as one of the two main technologies for implementation of (future) full-scale treatment.Recent research has put a closer focus on adsorption with powdered activated carbon (PAC) than on granular activated carbon (GAC). Studies where both methods are compared in parallel operation are thus still scarce and such evaluation in pilot-scale was therefore a primary objective of this thesis. Furthermore, recirculation of PAC can be used to optimize the treatment regarding the carbon consumption. Such a setup was evaluated as a separate treatment stage to comply with Swedish wastewater convention. Additionally, variation of a set of process parameters was evaluated.During successive operation at three different wastewater treatment plants an overall pharmaceutical removal of 95% could consistently be achieved with both methods. Furthermore, treatment with GAC was sensitive to a degraded effluent quality, which severely reduced the hydraulic capacity. Both treatment methods showed efficient removal of previously highlighted substances, such as carbamazepine and diclofenac, however in general a lower adsorption capacity was observed for GAC. By varying the input of process parameters, such as the continuously added dose or the contact time, during PAC treatment, a responsive change of the pharmaceutical removal could be achieved. The work in this thesis contributes some valuable field experience towards wider application of these treatment technologies in full-scale.
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| 6. |
- Mc Conville, Jennifer R, 1978, et al.
(author)
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Bridging sanitation engineering and planning: theory and practice in Burkina Faso
- 2011
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In: Journal of Water Sanitation and Hygiene for Development. - : IWA Publishing. - 2043-9083 .- 2408-9362. ; 1:3, s. 205-212
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Journal article (peer-reviewed)abstract
- The global challenge of providing sanitation services to the un-served underlines a need to change the way in which sanitation planning and service provision is approached. This paper offers a framework for categorizing sanitation projects planning processes based on planning steps and procedural planning theory to help engineers and sanitation planners gain a deeper understanding of the dynamics of these processes. The analysis identifies and discusses trends in both guidelines and actual sanitation programs. The results show that contemporary sanitation planning guidelines and field projects utilize patchwork processes of different planning modes, although the step of designing options is dominated by an expert-driven, rational-comprehensive approach. The use of planning theory can help engineers to ask critical questions about the objectives of the planning process and to develop context-appropriate planning processes that will make a difference for improving sanitation service provision.
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| 7. |
- Nordström, Albin
(author)
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Biogeochemical Processes in Denitrifying Woodchip Bioreactors and their Application in the Mining Industry
- 2019
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Doctoral thesis (other academic/artistic)abstract
- This thesis evaluates passive denitrifying woodchip bioreactors (DWBs) for the removal of nitrate (NO3-) in neutral pH mine drainage, where water is passed through a carbon-rich porous matrix (e.g. woodchips) for the reduction of NO3- to nitrogen gas. DWBs have been used for the removal of NO3- from water in various settings and are expected to operate with little maintenance for at least a decade; however, the processes controlling the emission of greenhouse gases and other undesirable by-products, as well as the magnitude and variability in NO3- removal rates and how these develop over time, are not completely understood and were the focus of this thesis.Water treatment in DWBs was investigated in laboratory-scale column tests and in a pilot-scale bioreactor installed at the Kiruna iron ore mine, northern Sweden. Denitrification was the major pathway for NO3- removal in both experimental systems. Incoming NO3- concentrations (up to 30.0 mg N L-1) were removed to below detection limits at temperatures and hydraulic residence times (HRTs) between 5-22°C and ~1.9-2.6 days, respectively, without substantial production of nitrite or ammonium (NH4+). NO3- removal was incomplete in both systems when HRTs decreased to ~1 day, and/or as temperature decreased below 5°C in the pilot-scale bioreactor, under which conditions an increased production of nitrous oxide (N2O) and NH4+ was observed (relative to the NO3- reduced).In the column tests, non-ideal flow was detected and solute transport was described using a dual-porosity model. Stagnant zones not transmitting flow did not participate in NO3- removal and the fraction of immobile water increased with increases in the advection velocity, suggesting that bioreactor performance could be enhanced by emphasizing design with low advection velocities. The study demonstrated that dominating biogeochemical processes varied with time in the pilot-scale bioreactor. There was a decline in organic carbon export and increase in pH and alkalinity that, based on a stoichiometric mass-balance, was suggested to be the result of a change in fermentation end-products that provided a carbon source to the denitrifying community. The decline in NO3- removal rates and biogeochemical process diversity, and the preferential selection of denitrifiers with the genetic capacity for reduction to N2O, but not N2, are hypothesized to arise from the temporal development of syntrophic structures between fermenters and denitrifiers.
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| 8. |
- Renman, Gunno, et al.
(author)
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Phosphorus removal by slag depends on its mineralogical composition: A comparative study of AOD and EAF slags
- 2018
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In: Journal of Water Process Engineering. - : Elsevier. - 2214-7144. ; 25, s. 105-112
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Journal article (peer-reviewed)abstract
- Electric arc furnace slag (EAF) and argon oxygen decarburization slag (AOD) were investigated in column experiments to determine the effect of mineralogical composition on their P removal performance and lifespan. Polyethylene glycol (PEG) and NaOH solutions were used for pretreatment of the slags to adjust their dissolution properties. The modified slags exhibited better P removal performance at the beginning of the experiment, but had shorter lifespan than the unmodified slags. AOD and EAF modified with PEG and NaOH achieved 100% P removal during the first 84 and 60 pore volumes, respectively, which were ≥20 pore volumes longer than virgin AOD and EAF. However, virgin EAF and AOD both had a P removal efficiency above 90% during the first 280 pore volumes. Possibly, soluble minerals such as free lime are lost during the modification step, causing a decreased long-term P removal capacity. The XRD results showed that the high P removal ability of AOD and EAF was attributed to the dissolution of beta dicalcium silicate (β-C2) and gamma dicalcium silicate (γ-C2S), which were dominant mineral phases in the slags. Results from SEM-EDS analysis revealed significant P accumulation on the slag surface. Cracks on the EAF slag surface contributed to its longer lifespan. Analysis with P K-edge XANES spectroscopy showed that the P retained on the slag surface was dominated by amorphous calcium phosphate, with a substantial amount of carbonate apatite (around 30%). Amorphous calcium phosphate was transformed to crystalline apatite as the slag aged with column operating time.
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| 9. |
- Rostvall, Ande, et al.
(author)
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Removal of pharmaceuticals, perfluoroalkyl substances and other micropollutants from wastewater using lignite, Xylit, sand, granular activated carbon (GAC) and GAC+Polonite® in column tests – Role of physicochemical properties
- 2018
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In: Water Research. - : Elsevier. - 0043-1354 .- 1879-2448. ; 137, s. 97-106
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Journal article (peer-reviewed)abstract
- This study evaluated the performance of five different sorbents (granular activated carbon (GAC), GAC + Polonite® (GAC + P), Xylit, lignite and sand) for a set of 83 micropollutants (MPs) (pharmaceuticals, perfluoroalkyl substances (PFASs), personal care products, artificial sweeteners, parabens, pesticide, stimulants), together representing a wide range of physicochemical properties. Treatment with GAC and GAC + P provided the highest removal efficiencies, with average values above 97%. Removal rates were generally lower for Xylit (on average 74%) and lignite (on average 68%), although they proved to be highly efficient for a few individual MPs. The average removal efficiency for sand was only 47%. It was observed that the MPs behaved differently depending on their physicochemical properties. The physicochemical properties of PFASs (i.e. molecular weight, topological molecular surface area, log octanol water partition coefficient (Kow) and distribution coefficient between octanol and water (log D)) were positively correlated to observed removal efficiency for the sorbents Xylit, lignite and sand (p < 0.05), indicating a strong influence of perfluorocarbon chain length and associated hydrophobic characteristics. In contrast, for the other MPs the ratio between apolar and polar surface area (SA/SP) was positively correlated with the removal efficiency, indicating that hydrophobic adsorption may be a key feature of their sorption mechanisms. GAC showed to be the most promising filter medium to improve the removal of MPs in on-site sewage treatment facilities. However, more studies are needed to evaluate the removal of MPs in field trials.
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| 10. |
- Zhang, Wen, et al.
(author)
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Evaluation of five filter media in column experiment on the removal of selected organic micropollutants and phosphorus from household wastewater
- 2019
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In: Journal of Environmental Management. - : ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD. - 0301-4797 .- 1095-8630. ; 246, s. 920-928
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Journal article (peer-reviewed)abstract
- A bench-scale column experiment was performed to study the removal of 31 selected organic micropollutants (MPs) and phosphorus by lignite, xyloid lignite (Xylit), granular activated carbon (GAC), Polonite (R) and sand over a period of 12 weeks. In total 29 out of the 31 MPs showed removal efficiency > 90% by GAC with an average removal of 97 +/- 6%. Xylit and lignite were less efficient with an average removal of 80 +/- 28% and 68 +/- 29%, respectively. The removal efficiency was found to be impacted by the characterization of the sorbents and physicochemical properties of the compounds, as well as the interaction between the sorbents and compounds. For instance, Xylit and lignite performed well for relatively hydrophobic (log octanol/water partition coefficient (K-ow) >= 3) MPs, while the removal efficiency of moderately hydrophilic, highly hydrophilic and negatively charged MPs were lower. The organic sorbents were found to have more functional groups at their surfaces, which might explain the higher adsorption of MPs to these sorbents. The removal of several MPs improved after four weeks in sand, Xylit, GAC and lignite which may be related to increased biological activity and biofilm development. GAC and sand had limited ability to remove phosphorus (12 +/- 27% and 14 +/- 2%, respectively), while the calcium-silicate material Polonite (R) precipitated phosphorus efficiently and increased the total phosphorus removal from 12% to 96% after the GAC filter.
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