| 1. |
- Beal, Jacob, et al.
(författare)
-
Robust estimation of bacterial cell count from optical density
- 2020
-
Ingår i: Communications Biology. - : Springer Science and Business Media LLC. - 2399-3642. ; 3:1
-
Tidskriftsartikel (refereegranskat)abstract
- Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data.
|
|
| 2. |
- Cameron, Lachlan, et al.
(författare)
-
NAMAs and INDCs : Interactions and opportunities
- 2015
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Countries representing more than 90 percent of global greenhouse gas emissions and population have submitted intendednationally determined contributions (INDCs) in anticipation of the 21st COP in Paris. In parallel, developing countries are designing at least 152 nationally appropriate mitigation actions (NAMAs) and 13 have secured implementation funding. Connecting these two concepts, more than a third of developing countries communicate a role for NAMAs in their INDCs. It is therefore vital to understand the potential role of NAMAs (here understood as specific actions) with respect to INDCs (which are often broader targets) and vice versa. This paper explores the links between NAMAs and INDCs with regard to various elements central to their implementation, including: access to finance; stakeholder engagement; sustainable development impacts; measurement, reporting and verification (MRV); and institutional frameworks.To avoid delaying mitigation action any further, it is important to keep momentum behind NAMAs. They represent one of the few tools at our disposal for countries to undertake mitigation actions, be recognised for these efforts, and mobilise climate finance and investment. The skills and learning on NAMA development can be seen more fundamentally as capacity for the design of bottom-up actions. Attention should be paid now to ensure that this capacity is maintained in the future. To do this, continued attention must be paid to NAMAs in Paris, as a key implementation tool for INDCs and, therefore, a key element of the success of a new global climate agreement.
|
|
| 3. |
- Diener, Silvia, et al.
(författare)
-
Accelerated carbonation of ashes and steel slags in a landfill cover construction
- 2008
-
Ingår i: Proceedings of Second International Conference on Accelerated Carbonation for Environmental and Materials Engineering. - : University of Rome "La Sapienza". ; , s. 389-400
-
Konferensbidrag (refereegranskat)abstract
- Fly ash from biofuel incineration and slags from steel production were used in two full scale applications of cover constructions on municipal solid waste (MSW) landfills. The long-term stability of the cover materials is studied in a designed laboratory experiment. The impact of six environmental factors on accelerated carbonation is investigated over a period of three years. Leaching behaviour, acid neutralization capacity, mineral composition (XRD) and thermo gravimetrical behaviour (TG) are tested after different periods of ageing under different conditions. By now samples were taken after three and ten months of ageing. Multivariate data analysis was used for data evaluation. The results indicate the factors material, ageing time and carbon dioxide content of the atmosphere to be most relevant.
|
|
| 4. |
- Diener, Silvia, et al.
(författare)
-
Accelerated carbonation of steel slags in a landfill cover construction
- 2010
-
Ingår i: Waste Management. - : Elsevier BV. - 0956-053X .- 1879-2456. ; 30:1, s. 132-139
-
Tidskriftsartikel (refereegranskat)abstract
- Steel slags from high-alloyed tool steel production were used in a full scale cover construction of a municipal solid waste (MSW) landfill. In order to study the long-term stability of the steel slags within the final cover, a laboratory experiment was performed. The effect on the ageing process, due to i.e. carbonation, exerted by five different factors resembling both the material characteristics and the environmental conditions is investigated. Leaching behaviour, acid neutralization capacity and mineralogy (evaluated by means of X-ray diffraction, XRD, and thermogravimetry/differential thermal analysis, TG/DTA) are tested after different periods of ageing under different conditions.Samples aged for 3 and 10 months were evaluated in this paper. Multivariate data analysis was used for data evaluation. The results indicate that among the investigated factors, ageing time and carbon dioxide content of the atmosphere were able to exert the most relevant effect. However, further investigations are required in order to clarify the role of the temperature.
|
|
| 5. |
|
|
| 6. |
- Diener, Silvia, et al.
(författare)
-
Mineral transformations in steel slag used as landfill cover liner material
- 2007
-
Ingår i: SARDINIA 2007. - Cagliari : CISA, Environmental Sanitary Engineering Centre. - 9788862650038
-
Konferensbidrag (refereegranskat)abstract
- In Europe, 15.2 million tonnes of steel slags have been generated in 2004 (Euroslag, 2006) out if which almost 6 million tonnes came from electric arc furnace (EAF) steelmaking and secondary metallurgical processes. In the presented project from Luleå University of Technology, two types of EAF slag and one slag originating from secondary metallurgical processes named ladle slag are investigated. The chemical and physical properties of these slags have been studied in detail (Herrmann, 2006; Andreas et al., 2005). For utilising steel slags in the liner of a landfill cover the long-term stability of the minerals is of great importance. Therefore, the ageing of steel slag minerals is evaluated with the help of a laboratory experiment. Particularly, the research questions, the experimental set-up and the methodology are presented. The present paper is part of a research project of the Division of Waste Science and Technology at Luleå University of Technology, Sweden in cooperation with Uddeholm Tooling AB, Hagfors municipality and MiMeR (Mineral and Metal Recycling Research Centre). It is investigated if steel slags are stable as a landfill cover liner material. The long-term stability is evaluated by determining the factors influencing the mineralogy of the slags and possible mineral transformations through ageing under the environmental conditions in a liner. The experiment includes two similar types of EAF slag and one ladle slag. Each steel slag sample is made by mixing 50% EAF slag and 50% ladle slag, addition of water and compaction. The specimens are stored in boxes under different atmospheric conditions. A reduced multivariate design has been chosen to determine the impact of different factors on the slag mineralogy. The factors that are varied in the experiment are relative humidity, carbon dioxide and temperature of the atmosphere surrounding the slag material as well as ageing time and the quality of the water used for sample making (see table 1). Table 1. Factorial design for ageing experiment of steel slagsLowMiddleHighRelative humidity30% -100%Carbon dioxide content0.036 (air)20 % * 100 %Temperature5 °C30 °C60 °CTime 1 month6 months1 yearWater quality destilled water -LeachateThe ageing of minerals is expected to initiate mineral transformations in steel slags. Primary phases will alter into secondary mineral phases. Changes in mineralogy can influence the stability of the liner. To evaluate mineralogy and properties of the aged steel slag, different analyses will be performed after the storage time of the specimens. X-ray diffraction and scanning electron microscopy as well as shear strength, acid neutralisation capacity and cation exchange capacity will be included. A possible mineral transformation for an alkaline material as steel slags can be the reaction of calcium ions from calcium silicates with the carbon dioxide resulting in the precipitation of calcium carbonate. Through this carbonation reaction, the transport of carbon dioxide into the bulk of the specimen could be hindered by the reaction products. Therefore, surface morphology can influence mineral transformations. First results and evaluations will be presented at the conference. REFERENCES Andreas L., Herrmann I., Lidstrom-Larsson M. & Lagerkvist A. (2005) Physical properties of steel slag to be reused in a landfill cover, Sardinia 2005, Tenth International Waste Management and Landfill Symposium, S. Margherita di Pula, Cagliari, Italy; 3 - 7 October 2005Euroslag (2006) Legal status of Slags. Position Paper. January 2006. The European Slag Association - EUROSLAG. Duisburg, Germany.Herrmann I. (2006). Use of Secondary Construction Material in Landfill Cover Liners. Licentiate Thesis. Luleå University of Technology, Sweden.
|
|
| 7. |
|
|
| 8. |
|
|
| 9. |
- Hamisi, Rajabu, 1978-, et al.
(författare)
-
Reactive transport modelling of long-term phosphorus dynamic in the compact constructed wetland using COMSOL Multiphysics
-
Ingår i: Ecological Engineering Journal.
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- A three-dimensional reactive transport model (RETRAP-3D) was developed by this study in the COMSOL Multiphysics®software to evaluate the long-term sorption capacity and mechanisms of dissolved reactive phosphorus removal in reactive adsorbent. The model coupledphysics interfaces for water flow, transport of reactive species, reaction kinetics for chemical compositions and biofilm development. Simulations were conducted for Polonite®, Filtralite P®, and Blast Furnace Slag mediaat fully saturated media, equilibrium miscible solution and isothermal heat transfer conditions. The model was validated using column experimental data ofsimilar media for application in constructed filter beds. The general modelling results showed good agreement with the measured breakthrough data. The most significant DIP retention capacity (P < 0.02) and longest residence time(1250 days) has been found for Polonite® and the most insignificant DIP retention for blast furnace slag (P > 0.54). The DIP removal was significantly correlated to factors of pH change, media characteristics, hydraulic dosage and retention times. These results demonstrate the reliability of the model as aflexible tool to predict the long-term performance of filter media and better understand processes within the system under various operational, weather and wastewater conditions.
|
|
| 10. |
- Herrmann, Björn, et al.
(författare)
-
Emergence and Spread of Chlamydia trachomatis Variant, Sweden
- 2008
-
Ingår i: Emerging Infectious Diseases. - : Centers for Disease Control and Prevention (CDC). - 1080-6040 .- 1080-6059. ; 14:9, s. 1462-1465
-
Tidskriftsartikel (refereegranskat)abstract
- A variant of Chlamydia trachomatis that had escaped detection by commonly used systems was discovered in Sweden in 2006. In a nationwide study, we found that it is now prevalent across Sweden, irrespective of the detection system used. Genetic analysis by multilocus sequence typing identified a predominant variant, suggesting recent emergence.
|
|
| 11. |
|
|
| 12. |
- Herrmann, Inga, 1978-, et al.
(författare)
-
Discharge of indicator bacteria from on-site wastewater treatment systems
- 2017
-
Ingår i: Desalination and Water Treatment. - : Desalination Publications. - 1944-3994 .- 1944-3986. ; 91, s. 365-373
-
Tidskriftsartikel (refereegranskat)abstract
- Small-scale on-site wastewater treatment facilities present the risk of microbial pollution of groundwaterused for drinking water and surface water used for recreational purposes. This study assessedthe discharge of indicator bacteria, total coliform, Escherichia coli, intestinal enterococci and Clostridiumperfringens, by flow-proportional sampling from 12 full-scale on-site treatment systems featuringbiological treatment units (mainly sand filters) and alkaline filter beds for phosphorus treatment(P-filters). Correlations of effluent bacterial concentrations with pH, total and dissolved organic carbon,filter age and hydraulic load were evaluated. The bacterial concentrations in the effluents ofthe sand filters were considerable. The concentrations for excellent bathing water quality set in theEU bathing water directive, 200 and 500 colony forming units (cfu)/100 mL for intestinal enterococciand E. coli, respectively, were exceeded in three (intestinal enterococci) and one (E. coli) of the eightinvestigated sand filters. In one of the sand filters, effluent E. coli concentrations were high althoughno obvious malfunction of the filter was observed. In the effluent from the other investigated biologicaltreatment units (a trickling fibre filter, two units with attached growth treatment and one aeratedactivated sludge technique), bacterial concentrations were very high (75,000 cfu/100 mL of Clostridiumperfringens and 85,000 cfu per 100 mL of total coliform), possibly because of a shorter retention time ofthe wastewater in these facilities, missing aeration and little time between start-up and measurements.Three and four of the nine investigated P-filters exceeded excellent bathing water quality in coastalwaters as stipulated by the EU bathing water directive in respect of E. coli and intestinal enterococci,respectively.
|
|
| 13. |
- Herrmann, Inga, et al.
(författare)
-
Effect of temperature on the performance of laboratory-scale phosphorus-removing filter beds in on-site wastewater treatment
- 2014
-
Ingår i: Chemosphere. - : Elsevier BV. - 0045-6535 .- 1879-1298. ; 117, s. 360-366
-
Tidskriftsartikel (refereegranskat)abstract
- P-sorbing filter beds appear to be viable options for treating wastewater to reduce P discharges and recover this non-renewable resource. However, greater knowledge of filters’ responses to temperature variations is required to assess their likely performance in full-scale applications and facilitate the transfer of laboratory results to the field. Thus, in the present study two filter materials (Top16 and Polonite) were characterized physicochemically and effects of temperature on their performance were investigated under controlled laboratory conditions. Using a 22 factorial design and secondary wastewater eight filter columns were tested at temperatures of 4.3 °C and 16.5 °C. Temperature significantly (α = 0.05) and strongly affected the P binding capacity of both materials, as it was 1.2- and 1.5-fold higher at 16.5 °C than at 4.3 °C for Top16 and Polonite, respectively. This is probably due to the enhanced precipitation of calcium phosphates at higher temperature. Observed reductions in total organic carbon content in the wastewater were also positively correlated with temperature, while the pH and reduction of dissolved organic carbon remained unaffected. The physicochemical analyses indicated that several calcium phases dissolved from the filter materials, primarily gypsum and bassanite from Top16 and Portlandite from Polonite. No clear evidence of any crystalline calcium phosphates was observed in the used materials. The results clearly show that temperature strongly influences the retention of P in filters and its effects should be carefully considered before using candidate filters in full-scale applications.
|
|
| 14. |
- Herrmann, Inga, et al.
(författare)
-
Enhancing the reliability of laboratory phosphorus filter tests: effect of influent properties and interpretation of effluent parameters
- 2014
-
Ingår i: Water, Air and Soil Pollution. - : Springer Science and Business Media LLC. - 0049-6979 .- 1573-2932. ; 225:1
-
Tidskriftsartikel (refereegranskat)abstract
- Filtration can be a convenient technique for removing phosphorus (P) at on-site wastewater treatment facilities to recycle this non-renewable element. When testing potentially suitable materials for these filters, the properties of the influent and the method used to analyse measured effluent concentrations both affect the P binding capacity determined in filter tests and therewith filter longevity predictions. At present, there is a lack of robust methods for material investigation and filter test interpretation. This study was conducted to investigate the effect of inflow PO4-P concentrations (concentration) and hydraulic surface load (load) on P binding capacity and to analyse possible interpretations of laboratory filter tests. A 22 factorial experiment with replicates was performed on the calcium-based filter material Filtra P. The investigated concentrations ranged from 12 to 50 mg L-1 and loads from 419 to 1,023 L m-2 day-1. P binding capacity (calculated by mass balance including data until PO4-P breakthrough point) was negatively affected by concentration and positively affected by load, with the effect of concentration being slightly greater. Depending on the factors' settings and on the method of evaluation (i.e. analysing all pre-saturation data or considering only pre-breakthrough results), the total measured P binding capacity varied between 2.2 and 9.0 g kg-1. The part of the breakthrough curve between the breakthrough point and saturation contributed significantly to the measured P binding capacity, and it took about three times longer for the filters to become saturated than to reach breakthrough. Furthermore, a considerable amount of P that had reacted with the filter material was washed out of the filters as particle-bound P. This indicates that it is important to determine both the PO4-P and the particle-bound P phases in the filter effluent
|
|
| 15. |
- Herrmann, Inga
(författare)
-
Filter beds for on-site wastewater treatment : Towards more reliable estimations of phosphorus retention
- 2014
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Phosphorus (P) is an important plant nutrient and essential for life. However, thephosphate rock used for fertilizer production is a non-renewable resource and itsproduction is expected to peak. At the same time, the discharge of P into naturalwaters is causing eutrophication, a severe problem in areas such as the Baltic Sea. Onsitewastewater treatment facilities in Sweden contribute substantially to this discharge because of their inadequate retention of P. Filter beds are a potentially useful technique to capture P in on-site facilities. However, many variables need to be considered when the P retention of potential filter materials is estimated in laboratory tests prior to designing full-scale filters. The overall aim of this thesis was therefore to increase the reliability of forecasting P retention in full-scale filters by increasing the understanding of P retention in P filters under varying conditions and by identifying measures that could lead to more reliable methods of testing filter materials at laboratory scale.The effects of influent type, influent P concentration, loading rate and ambienttemperature on the filter materials Filtra P, Filtralite P, Top16 and Polonite wereinvestigated in filter column experiments using 22 factorial designs. Furthermore, the P binding mechanism was studied using mineral phase investigations and by determining the reaction time of the P in the filter. In addition, filter performance was estimated by means of hydro-geochemical transport modelling.The investigated factors significantly (Į = 0.05) affected the retention of P in the filter materials showing that it is important to consider those factors when designing laboratory filter experiments and full-scale filters. Using secondary wastewater as an influent instead of P solution decreased the P binding capacity of Filtralite P, probably due to organic compounds contained in the wastewater. Increasing influent P concentration decreased the number of bed volumes treated before breakthrough in Filtra P by 82%. The loading rate was shown to be an important design parameter. Increasing the loading rate, something commonly done in the laboratory to accelerate the testing, significantly increased the amount of washed-out particulate P in Filtra P and Filtralite P. However, the residence time was also shown to be important; it should be maximised in filter tests as far as practical constraints allow. Increasing the temperature from 4.3 to 16.5°C increased the P binding capacity in both Top16 and Polonite which was attributed to an enhanced precipitation of calcium phosphates. This indicates that results obtained from experimental filters at room temperature might overestimate filter performance in the field where the temperature can be lower. In addition, full-scale filters might function better in warm rather than cool climates. The results further showed that it is crucial to measure both the concentration of dissolved P and particulate P in the filter effluent, as P-containing particles were observed to escape from the experimental filters in this study. Hydroxylapatite was detected in the outflow hose of the Filtra P columns indicating that this mineral phase may form in the filters under certain conditions. The geochemical models, however, indicated that the only precipitated calcium phosphate compound was amorphous tricalcium phosphate.Two hydro-geochemical transport models were developed that satisfactorily described the experimentally derived P breakthrough curves and effluent pH of the filter columns with Filtralite P. The simulations suggested that calcium oxide, calcite and the calcium-silicate phase wollastonite supplied the Ca2+ and OH- ions required for the precipitation of phosphate.
|
|
| 16. |
|
|
| 17. |
- Herrmann, Inga, et al.
(författare)
-
Hydraulic conductivity of fly ash : sewage sludge mixes for use in landfill cover liners
- 2009
-
Ingår i: Water Research. - : Elsevier BV. - 0043-1354 .- 1879-2448. ; 43:14, s. 3541-3547
-
Tidskriftsartikel (refereegranskat)abstract
- Secondary materials could help meeting the increasing demand of landfill cover liner materials. In this study, the effect of compaction energy, water content, ash ratio, freezing, drying and biological activity on the hydraulic conductivity of two fly ash - sewage sludge mixes was investigated using a 27-1 fractional factorial design. The aim was to identify the factors that influence hydraulic conductivity, to quantify their effects and to assess how a sufficiently low hydraulic conductivity can be achieved. The factors compaction energy and drying, as well as the factor interactions material×ash ratio and ash ratio×compaction energy affected hydraulic conductivity significantly (α = 0.05). Freezing on 5 freeze-thaw cycles did not affect hydraulic conductivity. Water content affected hydraulic conductivity only initially. The hydraulic conductivity data were modelled using multiple linear regression. The derived models were reliable as indicated by R2adjusted values between 0.75 and 0.86. Independent on the ash ratio and the material, hydraulic conductivity was predicted to be between 1.7 × 10-11 m s-1 and 8.9 × 10-10 m s-1 if the compaction energy was 2.4 J cm-3, the ash ratio between 20 and 75 % and drying did not occur. Thus, the investigated materials met the limit value for non-hazardous waste landfills of 10-9 m s-1.
|
|
| 18. |
- Herrmann, Inga, 1978-, et al.
(författare)
-
Markbaserad rening - design, funktion och bedömningkriterier vid tillsyn
- 2021
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Markbaserade reningsanläggningar för avloppsvatten har använts länge i Sverige och anses som en robust och driftsäker reningsmetod. Kommunerna som ansvarar för tillsynen har vid inspektionsbesök av anläggningar observerat olika brister i sådana markbaserade anläggningar, t.ex. förhöjd slamförekomst i slamavskiljare, fördelningsbrunn, spridarledningar och/eller luftningsrör, för höga vattennivåer i delar av anläggningen och/eller problem med ventilation. Dessa problem har också uppmärksammats i olika projekt. Det är dock generellt svårt att bedöma huruvida dessa brister har en negativ påverkan på reningsanläggningens funktion. Det finns ett behov av ökad kunskap om när en markbaserad anläggning fungerar eller inte och hur detta ska bedömas, både för att en anläggning inte ska dömas ut i onödan och för att en anläggning som inte fungerar tillfredsställande får rätt typ av åtgärd.I detta projekt undersöktes design-, funktions- och tillsynsprinciper för markbaserade anläggningar med hjälp av litteraturstudier och intervjuer. Syftet var att bidra till utformning av relevanta bedömningskriterier för markbaserade reningsanläggningar som kan användas vid prövning och tillsyn. Målen var att:- granska litteraturen inom markbaserad rening för att lista viktiga faktorer som påverkar funktionen,- jämföra svenska dimensioneringskriterier för slamavskiljare och infiltrationer med kriterier som används i andra länder (Norge och USA),- beskriva hur tillsyn av markbaserade anläggningar genomförs hos kommuner som är aktiva inom tillsyn,- belysa hur olika kommuner resonerar angående bedömningen av olika typer av brister (i detta mål ingår att bedöma hur allvarliga olika typer av brister är – det vill säga om bristerna kräver en uppföljning i form av föreläggande eller förbud eller om det räcker med information eller enklare uppföljning – och hur pass stor samstämmighet som finns mellan olika kommuner vid bedömning av bristers allvarlighet),- uppmärksamma svårigheter med att bedöma funktionen i markbaserade anläggningar och peka ut framtida områden som behöver vidare arbete, samt att- sammanfatta hur tillsyn bedrivs i andra länder och resonera kring vilka lärdomar som kan dras därur.
|
|
| 19. |
|
|
| 20. |
- Herrmann, Inga, et al.
(författare)
-
Modeling phosphate transport and removal in a compact bed filled with a mineral-based sorbent for domestic wastewater treatment
- 2013
-
Ingår i: Journal of Contaminant Hydrology. - : Elsevier BV. - 0169-7722 .- 1873-6009. ; 154, s. 70-77
-
Tidskriftsartikel (refereegranskat)abstract
- Phosphorus filter units containing mineral-based sorbents with a high phosphate (PO4) binding capacity have been shown to be appropriate for removing PO4 in the treatment of domestic wastewater in on-site facilities. However, a better understanding of their PO4 removal mechanisms, and reactions that could lead to the formation of PO4 compounds, is required to evaluate the potential utility of candidate sorbents. Models based on data obtained from laboratory-scale experiments with columns of selected materials can be valuable for acquiring such understanding. Thus, in this study the transport and removal of PO4 in experiments with a laboratory-scale column filled with a commercial silicate-based sorbent were modeled, using the hydro-geochemical transport code PHREEQC. The resulting models, that incorporated the dissolution of calcite, kinetic constrains for the dissolution of calcium oxide (CaO) and wollastonite (CaSiO3), and the precipitation of amorphous tricalcium phosphate, Ca3(PO 4)2, successfully simulated the removal of PO4 observed in the experiments.
|
|
| 21. |
- Herrmann, Inga, et al.
(författare)
-
Phosphorus binding to Filtra P in batch tests
- 2012
-
Ingår i: Environmental technology. - : Informa UK Limited. - 0959-3330 .- 1479-487X. ; 33:9, s. 1013-1019
-
Tidskriftsartikel (refereegranskat)abstract
- Recent guidelines from the Swedish Environmental Protection Agency recommend stricter regulations for phosphorus (P) reduction in small-scale wastewater treatment, which raises the need for additional and novel treatment steps in small-scale facilities. Following a biological pre-treatment, filter systems can be a convenient option. In this study, the P binding capacity of the filter material Filtra P was investigated in batch tests. The batch test method was evaluated with respect to the effects of liquid-to-solid ratio and particle size on P binding capacity. For initial concentrations (ci ) between 3 and 100 mg L−1, the P in the solution was completely and rapidly bound to the material, indicating that Filtra P was an efficient substrate for this process. The maximum amount of bound P was 4.3 ± 0.64 g kg−1 at c i = 300 mg L−1. P binding capacity and turbidity measured in the supernatant correlated positively. Turbidity was probably caused by calcium-P-precipitates suggesting precipitation was the major removal mechanism. Neither liquid-to-solid ratio, nor particle size, affected P binding capacity significantly (α = 0.05) at ci = 1000 mg L−1, confirming that the conditions used in the batch tests were appropriate. In full-scale applications, the precipitate formed may be at risk of being washed out of the filter, leading to low total P reduction and recovery.
|
|
| 22. |
- Herrmann, Inga, et al.
(författare)
-
Phosphorus fluxes and recovery options in the wastewater system of the city of Luleå, Northern Sweden
- 2012
-
Konferensbidrag (refereegranskat)abstract
- Phosphorus fluxes in Sweden’s municipal wastewater systems are barely known today and phosphorus recovery is poor in many systems. Further, there are about one million on-site treatment facilities, of which a majority has a low phosphorus capturing potential. There is a need to identify phosphorus losses and recovery options in the systems to increase phosphorus recovery both on centralised and decentralised level. This study focuses on the municipality of Luleå, northern Sweden. Luleå’s sanitary system is partly centralised (discharging to a WWTP with a moving bed biofilm reactor and chemical phosphorus precipitation) and partly decentralised (with several small-scale or on-site treatment facilities). The aim of this study is to identify and quantify phosphorus fluxes, including phosphorus recovery rates and losses, in the municipality’s existing sanitary system. Furthermore, alternative and innovative sanitary systems are analysed towards their phosphorus fluxes and recovery options. The study therefore contributes to more sustainable sanitation systems
|
|
| 23. |
|
|
| 24. |
|
|
| 25. |
- Herrmann, Inga, et al.
(författare)
-
Reuse of steel industry slag in a landfill top cover
- 2006
-
Ingår i: Abstract proceedings of the 4th Intercontinental Landfill Research Symposium, [June 14th to 16th 2006, Gällivare, Sweden]. - Luleå : Luleå tekniska universitet. ; , s. 88-89
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)
|
|
| 26. |
|
|
| 27. |
|
|
| 28. |
- Herrmann, Inga, 1978-, et al.
(författare)
-
Slutrapport av projekten "Fosforfällor för små avlopp - hur länge fungerar de?" och "Bakterieutsläpp från små avlopp"
- 2017
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Små enskilda avloppsanläggningar i Sverige består ofta av en slamavskiljare med markbädd eller infiltration. I områden med hög skyddsnivå har på senare år ett stort antal fosforfilter installerats. Syftet med denna studie var att undersöka markbäddars och fosforfilters förmåga att reducera halten bakterier och fosfor i avloppsvattnet. Avloppsanläggningar i Västerbotten, Norrbotten och Norrtälje kommun identifierades och inspekterades. Prover togs mellan september 2015 och september 2016 från tolv avloppsanläggningar, åtta markbäddar och nio fosforfilter. Provtagning skedde minst tre gånger vid varje anläggning, och varje provtagningstillfälle varade cirka 3–4 timmar då det togs två stickprover från slamavskiljarens tredje kammare alternativt från fördelningsbrunnen, samt två flödesproportionella samlingsprover efter den biologiska reningen (det vill säga efter markbädden eller biosteget i minireningsverket) och efter fosforfiltret. I proverna mättes pH, mängden suspenderat material, temperatur, indikatorbakterier (E. coli, totala koliforma, intestinala enterokocker och Clostridium perfringens/C. perfringens), halten löst och total fosfor, halten löst och totalt organiskt kol (DOC, TOC) samt BOD. Spårämnesförsök genomfördes i tre fosforfilter med färgen rhodamin. 22 av de 34 inspekterade avloppsanläggningarna (65 procent) lämpade sig inte för flödesproportionell provtagning, vilket visar på svårigheten med att kontrollera funktionen av små avloppsanläggningar med hjälp av provtagning. Nio av 21 inspekterade fosforfilter lämpade sig inte för provtagning på grund av att det inte fanns något vattenflöde genom filtret, vilket indikerar att filtren inte fungerade som avsett. I utloppen från tre av de åtta undersökta markbäddarna var medelkoncentrationen intestinala enterokocker högre än badvattendirektivets gränsvärde för inlandsvatten med utmärkt vattenkvalitet. För E. coli-koncentrationer var detta fallet bara i en enda markbädd, men detta trots att det utgående vattnet var klart och hade TOC koncentrationer på en acceptabel nivå. Det här visar att bakteriekoncentrationer kan vara höga även om markbädden ser ut att fungera. Efter de nio undersökta fosforfiltren var bakteriekoncentrationen särskilt hög efter fosforfilter utan markbädd som förbehandlingssteg. I flera fall översteg koncentrationerna gränsvärdet för utmärkt badvattenkvalitet enligt badvattendirektivet; i tre fosforfilter med avseende på E. coli och i fyra fosforfilter med avseende på intestinala enterokocker. Medelkoncentrationen av E. coli-bakterier reducerades signifikant (p = 0,044) i fosforfiltren, vilket tyder på att fosforfilter kan tjäna som ett reningssteg som ytterligare reducerar bakterier. Detta kunde dock inte påvisas för intestinala enterokocker, totala koliforma eller C. perfringens. Koncentrationen av koliforma bakterier var beroende av fosforfiltrets hydrauliska belastning, vilket tyder på att flödesregimen och vattnets uppehållstid i filtret är viktiga parametrar som påverkar bakteriereduktionen. Både för markbäddarna och för fosforfiltren fanns ett samband mellan koncentrationen av indikatorbakterierer och utloppskoncentrationen av TOC och DOC, vilket tyder på att en högre halt av organiskt kol i utgående vatten visar på en sämre bakteriereduktion. Två av de åtta undersökta markbäddarna visade på god fosforreduktion som uppgick till 70 procent (slamavskiljare exkluderad) vilket krävs vid normal skyddsnivå enligt nuvarande regelverk. Fosforreduktionen i tre andra markbäddar var lägre (21–29 procent). Övriga tre markbäddar kunde inte betraktas vara godtagbara reningsanläggningar eftersom det troligtvis skedde en betydande inströmning av vatten in i dessa markbäddar med utspädning som följd. Den högsta koncentrationen av fosfor i utgående vatten från en markbädd var omkring 15 mg/l. Dock var utgående fosforkoncentrationer från de undersökta markbäddarna endast i fyra av åtta fall så höga (>2mg/l) att ett efterföljande fosforfilter skulle vara meningsfullt. Därför är det viktigt att markbäddar med efterföljande rening i fosforfilter byggs med tätskikt för att undvika in- och exfiltration. Fem av de nio utvärderade fosforfiltren reducerade (tillsammans med den biologiska förbehandlingen) mer än 90 procent av den inkommande fosforn från slamavskiljaren. Det betyder att de klarade reningskravet för fosfor i områden med hög skyddsnivå. Två av filtren uppvisade utgående koncentrationer av totalfosfor på 1–3 mg/l och den högsta utgående medelkoncentrationen var 4,4 mg/l. I anläggningar med biologiska behandlingsenheter som inte var markbäddar stod fosforfiltren för merparten av fosforavskiljningen. Fosforreduktionen i fosforfiltren korrelerade med pH i utgående vatten från filtren, med en beräknad korrelationskoefficient på 74 procent, vilket indikerar att pH kan användas som indikator på filtrets funktion. Dock visade resultaten också att fosforfilter med liknande pH-värde (nära 9) kan skilja sig mycket med avseende på fosforreduktion. Koncentration av organiskt kol eller fosfor i inkommande vatten till fosforfiltren kunde inte korreleras till filtrens fosforreducerade förmåga. En hög hydraulisk belastning påverkade dock fosforfiltrens funktion negativt. Liknande effekt hade filtrets ålder, om än inte lika tydligt. De preliminära resultaten från spårämnesförsöken indikerar att de fosforfilter som hade längre uppehållstid också hade högre fosforavskiljning än filter med kortare uppehållstid.
|
|
| 29. |
|
|
| 30. |
- Herrmann, Inga, 1978-, et al.
(författare)
-
Steel slag used in landfill cover liners: laboratory and field tests
- 2010
-
Ingår i: Waste Management & Research. - 0734-242X .- 1096-3669. ; 28:12, s. 1114-1121
-
Tidskriftsartikel (refereegranskat)abstract
- Stricter rules for landfilling within the EU have led to the closure of many landfills and a need for large amounts of cover liner materials. Therefore, the potential utilization of mixtures of electric arc furnace slag (EAFS) and ladle slag (LS), which are currently deposited in landfills, as a material for use as landfill liner was investigated. Laboratory analyses showed the mixtures to have similar compression strength to that of high-strength concrete and low hydraulic conductivity (<10-11 m s-1 in some cases). However, both their hydraulic conductivity and compaction properties were strongly affected by the time between adding water to the mixtures and compacting them (tests showed that a delay of 24 h can lead to an increase in hydraulic conductivity, so it should be compacted as soon as possible after mixing the material with water). In addition, the performance of a cover liner constructed using EAFS and LS was studied in a 2-year field trial on a landfill for municipal solid waste, in which the average amount of leachate collected from ten lysimeters was only 27 L m-2 year-1, easily meeting Swedish criteria for the permeability of covers on non-hazardous waste landfills (≤50 L m-2 year-1). Thus, the material seems to have promising potential for use in barrier constructions.
|
|
| 31. |
|
|
| 32. |
- Herrmann, Inga, et al.
(författare)
-
The effect of hydraulic loading rate and influent source on the binding capacity of phosphorus filters
- 2013
-
Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 8:8
-
Tidskriftsartikel (refereegranskat)abstract
- Sorption by active filter media can be a convenient option for phosphorus (P) removal and recovery from wastewater for on-site treatment systems. There is a need for a robust laboratory method for the investigation of filter materials to enable a reliable estimation of their longevity. The objectives of this study were to (1) investigate and (2) quantify the effect of hydraulic loading rate and influent source (secondary wastewater and synthetic phosphate solution) on P binding capacity determined in laboratory column tests and (3) to study how much time is needed for the P to react with the filter material (reaction time). To study the effects of these factors, a 22 factorial experiment with 11 filter columns was performed. The reaction time was studied in a batch experiment. Both factors significantly (α = 0.05) affected the P binding capacity negatively, but the interaction of the two factors was not significant. Increasing the loading rate from 100 to 1200 L m-2 d-1 decreased P binding capacity from 1.152 to 0.070 g kg-1 for wastewater filters and from 1.382 to 0.300 g kg-1 for phosphate solution filters. At a loading rate of 100 L m-2 d-1, the average P binding capacity of wastewater filters was 1.152 g kg-1 as opposed to 1.382 g kg-1 for phosphate solution filters. Therefore, influent source or hydraulic loading rate should be carefully controlled in the laboratory. When phosphate solution and wastewater were used, the reaction times for the filters to remove P were determined to be 5 and 15 minutes, respectively, suggesting that a short residence time is required. However, breakthrough in this study occurred unexpectedly quickly, implying that more time is needed for the P that has reacted to be physically retained in the filter.
|
|
| 33. |
|
|
| 34. |
- Herrmann, Inga, 1978-, et al.
(författare)
-
Treatment of Phosphorus and Bacteria in Filters used for On-Site Sanitation in Cold Climate
- 2016
-
Konferensbidrag (refereegranskat)abstract
- Swedish rural on-site wastewater facilities need to reduce the phosphorus (P) concentrations in the wastewater to prevent eutrophication of the Baltic Sea, as well as the bacteria concentrations to comply with EU standards for bathing water quality. The aim of this study was to investigate two different on-site filter systems at full-scale, sand filters and (often subsequently used) alkaline P filters towards their performance to treat P and bacteria from domestic wastewater. Flow-proportional composite samples were taken from five sand filter beds and two P filters. Four of the five investigated sand filters considerably reduced the concentration of total P in the wastewater. However, infiltrating soil / ground water may have diluted the effluents. The investigated P filters varied in performance. While one of them treated P effectively, the other one performed poorly, probably due to old age and clogging. Low inlet P concentrations impeded the general assessment of the P filters’ efficiency. Concentrations of four indicator bacteria, intestinal enterococci, E. coli, total coliforms and C. perfringens, were considerably reduced in four of the five investigated sand filter beds. Bacteria removal in the two investigated P filters was difficult to assess because of low bacteria concentrations in the influents.
|
|
| 35. |
- Herrmann, Inga
(författare)
-
Use of sedondary construction material in landfill cover liners
- 2006
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The applicability of fly ash - sewage sludge and steel slag mixtures in landfill cover liners was investigated putting special emphasis on the hydraulic conductivity (HC) of the materials. The objective was to identify the factors significantly affecting the HC of the materials and to quantify their effects using multiple linear regression (MLR). It was discussed what impact low-HC liners might have on the landfill system and the environment. Although mainly affected by the COMPACTION ENERGY used, the HC of the fly ash - sewage sludge samples were also affected by DRYING and the factor interactions MATERIAL×ASH RATIO and ASH RATIO×COMPACTION ENERGY. The models derived using multiple linear regression could be used to predict an HC between 1.7×10-11 m s-1 and 9.5×10-10 m s-1, if a compaction energy of 2.4 J cm-3 was applied and no drying occurred. TIME between the addition of water and compaction mainly affected the HC of the steel slag samples. The HC of the steel slag mixtures was between 10-8 and 10-12 m s-1 if they were compacted immediately after water addition. The HC showed a decreasing trend during the measurement period of 53±1 days. It was suspected that cement reactions in the material influenced HC. Low-HC liners are a potential environmental hazard. Monitoring of landfill emissions is prescribed for about 30 years though contaminated landfill leachate is generated for at least one human generation. As the failing of the liner can go along with a sudden increase of leachate release from the landfill and thus with severe environmental pollution, the concept of applying low-HC liners needs to be reconsidered.
|
|
| 36. |
- Isaksson, Frida, et al.
(författare)
-
Greywater reuse for different purposes in Sweden : A literature review
- 2023
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Globally, water demands are increasing as a result of e.g., population growth and a warmer climate; at the same time freshwater supplies are becoming scarcer. Also in parts of Sweden where water shortage historically has not been a concern, the availability of freshwater for potable water use is declining, especially in the summer. As a result, alternative water management strategies are receiving increased attention in an effort to reduce the pressure on potable water sources. One strategy is the treatment, recirculation and re-use of greywater, a type of water that can be collected in source-separating wastewater systems. Hence, the aim of this literature review was to provide knowledge necessary to understand how greywater can be treated, recycled and re-used in the society, with an emphasis on reuse in Sweden. The review covers different aspects including greywater characteristics, greywater treatment processes, legal frameworks and guidelines on greywater re-use, global examples as well as summary of findings from sustainability analyses conducted on greywater re-use systems.Greywater makes up 75–90% of the total domestic wastewater volume and thereby represents an important source for water reuse in systems with source-separating wastewater systems. Data of the quantity of greywater produced in households globally and in Sweden vary. According to Swedish studies, one person may produce between 66 to 150 l/d. Additionally, research indicates that greywater contains less pathogens and nutrients compared to mix wastewater due to the separation of greywater from blackwater, which in turn contains the human excreta. However, the concentrations of measured parameters vary significantly between different areas. Therefore, in order to ensure the quality of greywater, site-specific measures are necessary.Studies have been conducted on different greywater treatment methods for non-potable re-use, with biological and filtration techniques receiving the most attention. However, it is challenging to make generalizations about the optimal treatment techniques based on the end-usage, due to the variation in greywater characteristics between sites. In addition, this review shows that there is a lack of legal guidance for greywater reuse, which makes it more challenging for practitioners to understand what levels of treatment that are required before the reclaimed water can be reused in used in society. The review also shows that further sustainability analyses should be conducted on greywater reuse systems, in order to understand their benefits more comprehensively.
|
|
| 37. |
- Jourak, Amir, et al.
(författare)
-
Longitudinal dispersion coefficient : effects of particle-size distribution
- 2013
-
Ingår i: Transport in Porous Media. - : Springer Science and Business Media LLC. - 0169-3913 .- 1573-1634. ; 99:1, s. 1-16
-
Tidskriftsartikel (refereegranskat)abstract
- The effects of particle-size distribution on the longitudinal dispersion coefficient (DL) in packed beds of spherical particles are studied by simulating a tracer column experiment. The packed-bed models consist of uniform and different-sized spherical particles with a ratio of maximum to minimum particle diameter in the range of 1–4. The modified version of Euclidian Voronoi diagrams is used to discretize the system of particles into cells that each contains one sphere. The local flow distribution is derived with the use of Laurent series. The flow pattern at low particle Reynolds number is then obtained by minimization of dissipation rate of energy for the dual stream function. The value of DL is obtained by comparing the effluent curve from large discrete systems of spherical particles to the solution of the one-dimensional advection-dispersion equation. Main results are that at Peclet numbers above 1, increasing the width of the particle-size distribution increases the values of DL in the packed bed. At Peclet numbers below 1, increasing the width of the particle-size distribution slightly lowers DL.
|
|
| 38. |
- Jourak, Amir, et al.
(författare)
-
Modeling of phosphate removal by fitra P in fixed-bed columns
- 2011
-
Ingår i: 2nd International Conference on Environmental Science and Technology , ICEST 2011. - China. - 9781424492619 ; , s. 241-248
-
Konferensbidrag (refereegranskat)abstract
- Hydropower still faces complex scientific and technical challenges in order to secure the availability and reliability of the power plants despite more than a century of development. The main challenge is due to new market constrains such as electrical market deregulation and introduction of renewable sources of energy. The major problem is related to the dynamic of the rotor involving several fields: hydraulics, power engineering and mechanics. On the other side, the large and growing hydropower world market represents an opportunity for technically advanced companies offering better efficiency. The difficulty to scale rigorously any technical advance makes full-scale experiment a necessity. World unique facilities are available at Porjus, Sweden, for this purpose. The Porjus Hydropower Centre is composed of a Francis (U8) and a Kaplan (U9) turbine of 10 MW, each exclusively dedicated to education, research and development. In order to further investigate specific issues related to availability and reliability, a project was initiated in 2006. The main objective is to make U9 a full-scale hydropower laboratory able firstly to furnish the necessary data for the development of rotor-dynamic models but also turbines and bearings. To this purposes more than 200 sensors have been installed to measure displacements, forces, pressure, film thickness, strains... The work presents an overview of the newly upgrade facility as well as some of the problems faced during the instrumentation of the machine.
|
|
| 39. |
|
|
| 40. |
|
|
| 41. |
|
|
| 42. |
- Jourak, Amir, et al.
(författare)
-
The calculations of dispersion coefficients inside two-dimensional randomly packed beds of circular particles
- 2013
-
Ingår i: AIChE Journal. - : Wiley. - 0001-1541 .- 1547-5905. ; 59:3, s. 1002-1011
-
Tidskriftsartikel (refereegranskat)abstract
- The longitudinal (DL) and transverse (DT) dispersion coefficients in two-dimensional (2D) randomly packed beds of circular particles in a laminar flow regime are derived. A 2D discrete system of particles is divided into cells using modified Voronoi diagrams. The relationship between the variation of the stream function and the averaged vortictiy is obtained from Computational Fluid Dynamics simulations. The whole flow pattern is then obtained by using the principle of energy dissipation rate minimization. The obtained values of DL agree well with 3D experimental data for all velocities investigated. At very high velocities, DT in 2D appears to be higher than 3D experimental data. In addition, the effects of particle size distribution, packing structure, and porosity on the DL and DT were studied. One result was that an increase in the width of the particle size distribution resulted in higher values of DL and DT at high velocities.
|
|
| 43. |
- Kaykhaii, Saida, 1989-, et al.
(författare)
-
Applicability of using sedimentation and membrane filtration for stormwater treatment
- 2021
-
Konferensbidrag (refereegranskat)abstract
- Stormwater runoff is one of the most important contributor of pollutants to natural waters. Therefore, separation of pollutants from stormwater runoff before entering the receiving waters is an important issue. Nitrogen (ammonium, nitrite, nitrate, total nitrogen), phosphorus (organic and inorganic), metals (Fe, Cd, Zn, Pb, As, Al, metalloid arsenic, Cr, Cu, Ni in total, dissolved and truly dissolved form) are main compounds that are contained in various concentrations in the runoff and should be separated. Various methods have been used for stormwater treatment. Membrane technology has shown acceptable treatment ability in water and wastewater industries1, but is not yet used for treatment of stormwater. Ceramic, polymeric and metallic membranes have been used in other research studies in order to optimise removal efficiency for separation of particulate, colloidal and dissolved substances in runoff. To prevent fouling, which is the major problem in membranes and to decrease the operational cost, use of a proper pre-treatment is helpful 2–4, as is periodical cleaning of membrane surface 5,6. This process can be further assisted by using membranes with larger pore size (microfiltration, ultrafiltration) than nanofiltration and reverse osmosis membranes which have smaller pore size but higher removal efficiency. In this study, sedimentation was used as a pre-treatment method and a membrane process with different pore sizes and pulsatile flow (fluid flow with periodical variation) were evaluated with respect to separation of pollutants from a snowmelt mixture. For the aim of this research work, polyether sulfone nanofiltration and ultrafiltration membranes (PES NF, UF membrane) were used to assess the ability of the overall process to postpone fouling and treat the snowmelt mixture. The variation of pulse frequency was chosen between 0 and 2 Hz. A peristaltic pump with a constant rotational velocity of 220 rpm was used in all the experiments. Sedimentation as pre-treatment method was investigated in pre-experiments and it was shown that a variation in sedimentation time between 0.5-1 hours did not affect the treatment ability of the process. Therefore, 0.5 hour of sedimentation time was chosen in order to reduce the experimental run time. The experimental runs will be carried out during the winter period Feb-April 2021. The concentration of TSS, pH, total and dissolved metals and chloride, as well as the particle size distribution, turbidity and volume of clean water achieved in each experimental run is measured. The results from these experiments will give valuable information about treatment efficiency, if pulsatile flow increases the treatment performance as well as knowledge about the clogging process of the filter.
|
|
| 44. |
- Kaykhaii, Saida, 1989-, et al.
(författare)
-
Enhancing stormwater treatment through ultrafiltration: impact of cleaning chemicals and backwash duration on membrane efficiency
- 2023
-
Ingår i: Water Reuse. - : IWA Publishing. - 2709-6092 .- 2709-6106. ; 13:4, s. 634-646
-
Tidskriftsartikel (refereegranskat)abstract
- The effect of chemical cleaning and regular backwashing on the efficiency of an ultrafiltration membrane fouled during stormwater treatment was studied. Increasing backwash time from 30 to 60 s resulted in an increase in productivity by 20%. However, the productivity was highest when a backwash time of 45 s was used (3% higher than using 60 s). Chemical cleaning was carried out using an alkaline solution (NaOH with or without NaOCl) followed by acid washing with HCl. The addition of NaOCl to the cleaning chemical did not significantly increase the efficiency of chemical cleaning, and the average pure water permeability increase was 97 ± 13 LMH bar−1 after chemical cleaning with NaOH followed by HCl and 117 ± 15 LMH bar−1 after chemical cleaning with NaOH + NaOCl followed by HCl, on average. In addition, reversibility after chemical cleaning was 96 ± 67%, on average. The result from scanning electron microscopy showed that at the end of the experiments, inorganic foulants existed in both the inner layer (feed side) and the outer layer (permeate side) of the membrane.
|
|
| 45. |
- Kaykhaii, Saida, 1989-, et al.
(författare)
-
Stormwater treatment using an ultrafiltration membrane and pulsatile fluid flow
- 2023
-
Ingår i: Urban Water Journal. - : Taylor & Francis. - 1573-062X .- 1744-9006.
-
Tidskriftsartikel (refereegranskat)abstract
- A polymeric ultrafiltration (UF) membrane was used for stormwater treatment, with the focus on evaluating the increase in the membrane process productivity by adding pulsatile fluid flow to UF membrane treatment. Sedimentation and sieving were used as pre-treatment. The result showed that increasing the pulse frequency from 0 to 4 Hz increased productivity from -6.6 to 82 LMH. UF membrane removed suspended solids, oil and turbidity below detection limit. The UF membrane also separated total coliforms, E. coli and P. aeruginosa below detection limit. Total organic carbon (TOC) was reduced by between 70 and 91%. In addition, the UF membrane was able to reduce BOD7 and COD to below 7 mg/L in the permeate. According to the US EPA, WHO, and national regulations in Canada, Japan, and South Korea, treated stormwater can be used for flushing toilets and streets irrigation and agricultural use.
|
|
| 46. |
- Kaykhaii, Saida, 1989-, et al.
(författare)
-
Stormwater treatment using membrane filtration with pulsatile fluid flow
- 2021
-
Konferensbidrag (refereegranskat)abstract
- Stormwater runoff is one of the most important contributor of pollutants to natural waters. Therefore, separation of pollutants from stormwater runoff before entering the receiving waters is an important issue. Nitrogen (ammonium, nitrite, nitrate, total nitrogen), phosphorus (organic and inorganic), metals (Fe, Cd, Zn, Pb, As, Al, metalloid As, Cr, Cu, Ni in total, dissolved and truly dissolved form) are main compounds that are contained in various concentrations in the runoff and should be separated. Various methods have been used for stormwater treatment. Membrane technology is applied in water and wastewater industries1, but is not yet used for treatment of stormwater. Ceramic, polymeric and metallic membranes have been used in other research studies in order to optimise removal efficiency for separation of particulate, colloidal and dissolved substances in runoff. To prevent fouling, which is the major problem in membranes and to decrease the operational cost, use of a proper pre-treatment is helpful 2–4, as is periodical cleaning of the membrane surface 5,6. This process can be further assisted by using membranes with larger pore size (microfiltration, ultrafiltration) than nanofiltration and reverse osmosis membranes which have smaller pore size but higher removal efficiency. In this study, sedimentation was used as a pre-treatment method and an ultrafiltration membrane process and pulsatile flow were evaluated with respect to separation of pollutants from snowmelt mixture. A bench-scale membrane unit was used with a polyether sulfone ultrafiltration membrane (PES/PVP UF membrane) to assess the efficiency of the process and to evaluate if pulsatile flow at different pulse frequencies (0 and 4 Hz) can postpone fouling. The feed and permeate was sampled and analysed on the concentration of TSS, pH, total and dissolved metals and chloride content, as well as the particle size distribution, TOC, turbidity and oil index. The volume of permeate achieved in each experimental run was monitored. The results from these experiments showed that by increasing pulse frequency from 0 to 4 Hz, the productivity of membrane increased from 13.5% to 65.5%. In addition, TOC removal increased from 70% to 87%. Regardless of pulse frequency the ultrafiltration membrane set-up removed TSS, particles and oil fractions completely. Dissolved As, Cd, Cu, Cr, Ni, Pb and P were reduced by 16, 12.6, 11.8, 23.5, 21, 44 and 73.1%, respectively.
|
|
| 47. |
- Kaykhaii, Saida, 1989-, et al.
(författare)
-
Stormwater treatment using ultrafiltration – Effect of cleaning chemical and backwash time on membrane efficiency
- 2022
-
Konferensbidrag (refereegranskat)abstract
- Stormwater runoff is known as one of the main contributors of pollutants which is often discharged untreated to the water bodies and causes environmental risk [1]. Membrane treatment may be a good option for treatment of heavily polluted stormwater as it can also remove small particles and colloids that are not normally captured in typical stormwater facilities such as ponds, wetlands, etc. However, fouling in membranes is challenging to control. Application of a pre-treatment prior to the membrane process might help to postpone fouling [2]. In addition, a proper combination of backwash and chemical cleaning for the membrane is essential but this has not yet been studied specifically for stormwater runoff treatment with membranes. In this study, a combination of ultrafiltration PVP/PES membrane with pulsatile fluid flow was used for separation of pollutants from stormwater. Sieving was considered as pre-treatment. In addition, a combination of backwash and chemical cleaning was used to assess reversibility, flux recovery and productivity of the membrane. The results showed that by increasing backwash time from 30 to 60 s, the reversibility and flux recovery increased from 26% to 75% and 55% to 87%, on average and also resulted in 20% increase in productivity. Cleaning chemically with alkaline solution (NaOH, pH=12), followed by acidic solution (HCl, pH=2), had a good impact on removing foulants from membrane surface. According to the experiments, addition of NaOCl to the alkaline solution did not have significant effect on pure water flux recovery. From environmental point of view, using NaOCl is not recommended [3].
|
|
| 48. |
- Kaykhaii, Saida, 1989-, et al.
(författare)
-
Stormwater treatment with ultrafiltration: Characterisation of backwash water : [Traitement des eaux pluviales par ultrafiltration: Caractérisation deseaux de rétrolavage]
- 2023
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Backwash water is an integral part of membrane treatment, normally making up between 2 and 10 % of the clean water production which constitutes a large volume on an industrial scale. To identify suitable treatment or disposal methods for backwash water, it is important to understand the characteristics of the backwash water and what contaminants it contains. In this study, the backwash water from an ultrafiltration membrane process for stormwater treatment was analysed. Concentrations of TSS and TOC were 2.4 and 24 times higher in the backwash water than the influent stormwater. The concentration of particulate and dissolved (<0.45µm) metals in the backwash water was high, for example, the average concentration of total Cu and Cr was 742 ± 215 and 737 ± 243 µg/L. In addition, the average concentration factors for Cu and Cr were 29 ± 9 and 41 ± 15.9. Methods such as coagulation, electrocoagulation and evaporation could be used to further treat backwash water. The residue fraction would contain high concentrations of metals that need to be disposed or could potentially be a good resource for metal recovery in the future.
|
|
| 49. |
- Kaykhaii, Saida, 1989-
(författare)
-
Urban Stormwater Treatment with Ultrafiltration and Pulsatile Fluid Flow
- 2023
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Stormwater can be a potential water resource if it is treated, and the quality meets the demand, depending on the application. Various nutrients and pollutants, for example microorganisms can enter stormwater and can vary depending on time and place, as the contaminants come from different sources. Sometimes the quality of stormwater can also deteriorate during its collection and storage. Therefore, the treatment of stormwater could be necessary before reuse and before discharge into the environment. Various treatment methods exist for this purpose. Ponds, wetlands, and bioretention systems are used in various countries to remove pollutants from stormwater. In addition to these methods, the use of membranes for stormwater treatment has become of interest.The application of membrane technology in new areas such as stormwater treatment requires a great deal of research to evaluate the potential opportunities and challenges. Research has been conducted to separate one or a few pollutants from stormwater using membranes. However, more research is needed to evaluate the applicability of using membranes for stormwater treatment, and their challenges and advantages. For this purpose, three experimental studies have been carried out. Polluted snow along a road was collected and treated using an ultrafiltration membrane. To prevent any damages to the membrane, a pretreatment step was included before the membrane process. It was of interest to evaluate the membrane process ability for treating snowmelt and to evaluate the potential for water reuse depending on regulations in different countries. Another objective was to investigate the productivity of the membrane process and try to improve it by adding pulsatile fluid flow to the experimental set-up. To investigate membrane cleaning, backwashing was carried out at regular intervals, and different backwash times and two chemical cleaning combinations were used. In addition, the fouling layer on the membrane was studied using a scanning electron microscope. Afterwards, the quality of the backwash water from the membrane cleaning was analyzed, which may be helpful in the future when looking for a suitable method to recycle the backwash water.When evaluating pulsatile fluid flow, the productivity of the membrane process increased significantly as the frequency of pulses increased (from -6.6 to 82 L/m2/h). The treated snowmelt mixture was of high quality and could be used for various applications, such as wetland maintenance, toilet flushing, and other municipal use. If the treated stormwater is disinfected, it can also be reused as drinking water. In this study, the optimal backwash duration was found to be 45 s in relation to productivity, although the backwash efficiency and permeability were higher with a backwash time of 60 s. The use of chemicals (NaOH with or without NaOCl followed by HCl) could restore the pure water permeability of the membrane to 107 L/m2/h/bar-1, in average. The pure water reversibility after chemical cleaning was 96% on average. Analysis of the backwash water showed that it is a concentrated solution of stormwater pollutants. TOC concentration was 24 times higher than pretreated stormwater. In addition, the backwash water contained significant concentrations of particulate metals and the concentration factor for various metals varied between 15 to 40.
|
|
| 50. |
- Kinnunen, Juho, et al.
(författare)
-
Factors affecting effluent quality in on-site wastewater treatment systems in the cold climates of Finland and Sweden
- 2023
-
Ingår i: Journal of Cleaner Production. - : Elsevier. - 0959-6526 .- 1879-1786. ; 404
-
Tidskriftsartikel (refereegranskat)abstract
- Decentralized sanitation facilities serving single households to small communities can offer a more flexible way of improving global sanitation. In Nordic countries, on-site wastewater treatment systems (OWTS) are mostly used in sparsely populated areas and are regulated for the removal of phosphorus (Tot-P), organic matter (biological oxygen demand, (BOD7)) and total nitrogen (Tot-N). However, available reports, albeit commonly using small data sets, call attention to often low and variable treatment performance. In this work, a statistical analysis of 1301 samples from 395 units reported in 10 studies from Finland and Sweden was conducted. The objective was to increase knowledge regarding the effluent water quality of OWTS and their compliance with regulations. In addition, the goal was to identify possible factors affecting contaminant concentrations. Overall, compliance with base-level BOD7 removal requirements was met by most units while 10% of units exceeded Tot-N and >25% exceeded Tot-P limits. Non-compliance rates were high, especially for Tot-P, considering the studied data set was composed mostly of semi-new units (median 3.8 years). Neither weather (air temperature, precipitation, and snowmelt), age or load factors were found to strongly explain the data variability in either soil-based systems (SBS) or package plants (PP). Tot-N and Tot-P effluent concentrations of the two systems were not significantly different. Effluent BOD7 concentrations were lower in SBS (median 3.0 mg/L) when compared to PP (median 7.7 mg/L). Units with P-sorbing filters (median 0.69 mg/L) and chemical precipitation (median 1.54 mg/L), presented lower Tot-P effluent concentrations in contrast to traditional sand filters (median 4.0 mg/L). The biological process used in PP had a measurable effect on effluent BOD7 concentrations, with attached growth units presenting higher values (median 8.1 mg/L) than suspended growth units (median 7.1 mg/L). Although the data set utilized was large, its analysis revealed intrinsic bias in data collection, especially regarding system types and sampling seasonality with colder winter periods sampling underrepresented. There is a need for data collection to improve to allow conclusive treatment efficiency assessment including possible effects of climate and process-related factors.
|
|
