| 1. |
- Bengtsson, Simon, 1977, et al.
(författare)
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A comparison of aerobic granular sludge with conventional and compact biological treatment technologies
- 2019
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Ingår i: Environmental Technology (United Kingdom). - : Informa UK Limited. - 1479-487X .- 0959-3330. ; 40:21, s. 2769-2778
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Tidskriftsartikel (refereegranskat)abstract
- The aerobic granular sludge (AGS) technology is growing towards becoming a mature option for new municipal wastewater treatment plants and capacity extensions. A process based on AGS was compared to conventional activated sludge processes (with and without enhanced biological phosphorus removal), an integrated fixed-film activated sludge (IFAS) process and a membrane bioreactor (MBR) by estimating the land area demand (footprint), electricity demand and chemicals’ consumption. The process alternatives compared included pre-settling, sludge digestion and necessary post-treatment to achieve effluent concentrations of 8 mg/L nitrogen and 0.2 mg/L phosphorus at 7°C. The alternative based on AGS was estimated to have a 40–50% smaller footprint and 23% less electricity requirement than conventional activated sludge. In relation to the other compact treatment options IFAS and MBR, the AGS process had an estimated electricity usage that was 35–70% lower. This suggests a favourable potential for processes based on AGS although more available experience of AGS operation and performance at full scale is desired.
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| 2. |
- Björklund, Karin, 1979, et al.
(författare)
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Sorption of organic pollutants frequently detected in stormwater: evaluation of five potential sorbents
- 2018
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Ingår i: Environmental Technology (United Kingdom). - : Informa UK Limited. - 1479-487X .- 0959-3330. ; 39:18, s. 2335-2345
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Tidskriftsartikel (refereegranskat)abstract
- Adsorption filtration is one of the most promising techniques for removal of dissolved, colloidal and particulate pollutants from stormwater. The aim of this study was to compare the capacity of five filter materials – cellulose, chitosan, chitosan-covered bark, pine bark and polypropylene/polyethylene (PP/PE) fibres – to sorb organic pollutants frequently detected in stormwater, including polycyclic aromatic hydrocarbons (PAHs), alkylphenols and phthalates. In batch tests, synthetic stormwater spiked with a mixture of the organic compounds was contacted with the materials for up to 24 h. The compounds were then liquid–liquid extracted and analysed using GC-MS. Cellulose and chitosan showed very low sorption capacity for the organic contaminants, whereas >70% of the initial concentration of most tested compounds was removed using PP/PE fibres, and >80% with pine bark and chitosan-covered bark. The highest adsorption capacity was found for PAHs (up to 44 μg/g) using PP/PE fibres and bark. For all tested compounds, maximum sorption was approached within 30 min using these materials.
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| 3. |
- Cossio Grageda, Claudia, 1974, et al.
(författare)
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Wastewater management in small towns - understanding the failure of small treatment plants in Bolivia
- 2018
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Ingår i: Environmental Technology (United Kingdom). - : Informa UK Limited. - 1479-487X .- 0959-3330. ; 39:11, s. 1393-1403
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Tidskriftsartikel (refereegranskat)abstract
- Wastewater management in developing countries is a challenge, especially in small towns with rapid population growth. This study aims at assessing the performance and management of five treatment plants (TPs) in rural areas of Cochabamba, Bolivia. Pollutants’ concentrations, wastewater flows, hydraulic and organic loads and hydraulic retention times were determined in three small treatment plants (2000–10,000 population equivalent [p.e.]; flow > 432 m3/d) and two very small treatment plants (<2000 p.e.; flow < 432 m3/d). The performance assessment was based on operational parameters, treatment efficiency and effluent quality. Management data were collected through semi-structured interviews with managers of local water associations. The results support that the poor performance of the TPs is due to lack of operational expertise and financial resources for adequate operation and maintenance (O&M). Additionally, effective treatment was affected by the type of technology used and whether the plant design included plans for O&M with available resources. This study contributes to a better understanding of actual operating conditions of wastewater TPs in small towns, thus providing needed information regarding technology selection, design, implementation and operation.
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| 4. |
- Fredriksson, Johan, 1979, et al.
(författare)
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Long-term dynamics of the bacterial community in a Swedish full-scale wastewater treatment plant
- 2019
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Ingår i: Environmental Technology. - : Informa UK Limited. - 0959-3330 .- 1479-487X. ; 40:7, s. 912-928
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Tidskriftsartikel (refereegranskat)abstract
- The operational efficiency of activated sludge wastewater treatment plants depends to a large extent on the microbial community structure of the activated sludge. The aims of this paper are to describe the composition of the bacterial community in a Swedish full-scale activated sludge wastewater treatment plant, to describe the dynamics of the community and to elucidate possible causes for bacterial community composition changes. The bacterial community composition in the activated sludge was described using 16S rRNA gene libraries and monitored for 15 months by a terminal restriction fragment (T-RF) length polymorphism (T-RFLP) analysis of the 16S rRNA gene. Despite variable environmental conditions, a large fraction of the observed T-RFs were present at all times, making up at least 50% in all samples, possibly representing a relatively stable core fraction of the bacterial community. However, the proportions of the different T-RFs in this fraction as well as the T-RFs in the more variable fraction showed a significant variation over time and temperature. The difference in community composition between summer and winter coincided with observed differences in floc structure. These observations suggest a relationship between floc properties and bacterial community composition, although additional experiments are required to determine causality.
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| 5. |
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| 6. |
- Hagelqvist, Alina, 1980-, et al.
(författare)
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Co-digestion of manure with grass silage and pulp and paper mill sludge using nutrient additions
- 2016
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Ingår i: Environmental technology. - : Taylor & Francis Group. - 0959-3330 .- 1479-487X. ; 37:16, s. 2113-2123
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of this research is to evaluate how methane production is affected by the co-digestion of pig and dairy manure with grass silage and pulp and paper mill sludge at mesophilic conditions, and to assess whether methane production is affected by other factors than the now known ones, i.e., nutrient deficiency, low buffering capacity, inadequate dilution, and an insufficient activity and amount of microorganism culture. The season of grass silage and manure collection proved to be an important, previously unreported, factor affecting short-term (20 days) methane production.
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| 7. |
- Haghighatafshar, Salar, et al.
(författare)
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Laboratory-scale assessment of vacuum-degassed activated sludge for improved settling properties
- 2017
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Ingår i: Environmental Technology (United Kingdom). - : Informa UK Limited. - 1479-487X .- 0959-3330. ; 38:17, s. 2193-2201
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Tidskriftsartikel (refereegranskat)abstract
- Vacuum degassing of activated sludge was tested at eight different Swedish wastewater treatment plants with laboratory-scale equipment in batch mode in order to evaluate its efficiency on improvement of sludge compaction and settling properties. The results show that the efficiency of the degassing technique is mainly dependent on the initial sludge volume index (SVI) of the target sludge which was found to be related to its process configuration. Facilities with full activated sludge-based nitrogen removal processes, including both nitrification and denitrification, had high SVIs (>300 mL g(-1)) and were strongly affected by vacuum degassing with reduction of SVI up to 30%. Nitrogen removal facilities also including biological phosphorus removal showed better compaction and settling properties with relatively lower SVIs and were affected to a lesser extent by degassing with SVI reduction of 10-20%. Wastewater treatment plants without full biological nitrogen removal, lacking either nitrification or denitrification (or both) processes in the activated sludge had the lowest SVIs observed with almost no effect of vacuum degassing.
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| 8. |
- Hey, Tobias, et al.
(författare)
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Evaluation of direct membrane filtration and direct forward osmosis as concepts for compact and energy-positive municipal wastewater treatment
- 2018
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Ingår i: Environmental Technology. - : Informa UK Limited. - 0959-3330 .- 1479-487X. ; 39:3, s. 264-276
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Tidskriftsartikel (refereegranskat)abstract
- Municipal wastewater treatment commonly involves mechanical, biological and chemical treatment steps to protect humans and the environment from adverse effects. Membrane technology has gained increasing attention as an alternative to conventional wastewater treatment due to increased urbanization. Among the available membrane technologies, microfiltration (MF) and forward osmosis (FO) have been selected for this study due to their specific characteristics, such as compactness and efficient removal of particles. In this study, two treatment concepts were evaluated with regard to their specific electricity, energy and area demands. Both concepts would fulfil the Swedish discharge demands for small- and medium-sized wastewater treatment plants at full scale: (1) direct MF and (2) direct FO with seawater as the draw solution. The framework of this study is based on a combination of data obtained from bench- and pilot-scale experiments applying direct MF and FO, respectively. Additionally, available complementary data from a Swedish full-scale wastewater treatment plant and the literature were used to evaluate the concepts in depth. The results of this study indicate that both concepts are net positive with respect to electricity and energy, as more biogas can be produced compared to that using conventional wastewater treatment. Furthermore, the specific area demand is significantly reduced. This study demonstrates that municipal wastewater could be treated in a more energy- and area-efficient manner with techniques that are already commercially available and with future membrane technology.
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| 9. |
- Hey, Tobias, et al.
(författare)
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Influences of mechanical pretreatment on the non-biological treatment of municipal wastewater by forward osmosis
- 2017
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Ingår i: Environmental Technology. - : Informa UK Limited. - 0959-3330 .- 1479-487X. ; 38:18, s. 2295-2304
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Tidskriftsartikel (refereegranskat)abstract
- Municipal wastewater treatment involves mechanical, biological and chemical treatment steps for protecting the environment from adverse effects. The biological treatment step consumes the most energy and can create greenhouse gases. This study investigates municipal wastewater treatment without the biological treatment step, including the effects of different pretreatment configurations, for example, direct membrane filtration before forward osmosis. Forward osmosis was tested using raw wastewater and wastewater subjected to different types of mechanical pretreatment, for example, microsieving and microfiltration permeation, as a potential technology for municipal wastewater treatment. Forward osmosis was performed using Aquaporin Inside™ and Hydration Technologies Inc. (HTI) membranes with NaCl as the draw solution. Both types of forward osmosis membranes were tested in parallel for the different types of pretreated feed and evaluated in terms of water flux and solute rejection, that is, biochemical oxygen demand (BOD7) and total and soluble phosphorus contents. The Aquaporin and HTI membranes achieved a stable water flux with rejection rates of more than 96% for BOD7 and total and soluble phosphorus, regardless of the type of mechanical pretreated wastewater considered. This result indicates that forward osmosis membranes can tolerate exposure to municipal waste water and that the permeate can fulfil the Swedish discharge limits.
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| 10. |
- Hey, Tobias, et al.
(författare)
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Potential of combining mechanical and physicochemical municipal wastewater pre-treatment with direct membrane filtration
- 2017
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Ingår i: Environmental Technology. - : Informa UK Limited. - 0959-3330 .- 1479-487X. ; 38:1, s. 108-115
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Tidskriftsartikel (refereegranskat)abstract
- At a full-scale wastewater treatment plant, raw municipal wastewater from the sand trap outlet was mechanically and physicochemically pre-treated before microfiltration (MF) in a large pilot-scale study. MF was performed using a low transmembrane pressure (0.03 bar) without backflushing for up to 159 h (∼6.6 d). Pre-filtration ensured stable MF operation compared with the direct application of raw wastewater on the membrane. The combination of physicochemical pre-treatment, such as coagulation, flocculation, and microsieving, with MF meets the European and Swedish discharge limits for small- and medium-sized wastewater treatment plants (WWTPs). The specific electricity footprint was 0.3–0.4 kWh·m−3, which is an improvement compared to the median footprint of 0.75 kWh·m−3 found in 105 traditional Swedish WWTPs with sizes of 1500–10,000 person equivalents. Furthermore, the biological treatment step can be omitted, and the risk of releasing greenhouse gases was eliminated. The investigated wastewater treatment process required less space than conventional wastewater treatment processes, and more carbon was made available for biogas production.
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