| 1. |
- Andersson Chan, Anneli, 1971-, et al.
(författare)
-
Increased nitrogen removal in existing volumes at Sundet wastewater treatment plant, Växjö
- 2014
-
Ingår i: Water practice and technology. - : IWA Publishing. - 1751-231X. ; 9:2, s. 215-224
-
Tidskriftsartikel (refereegranskat)abstract
- Many wastewater treatment plants need to improve their nitrogen removal due to stricter requirements and increasing loads. This often means larger bioreactor volumes, which can be very expensive and is sometimes impossible if space is limited. Therefore, there is a need for compact hybrid solutions that can increase capacity within existing volumes. Two full-scale demonstration projects using moving bed biofilm reactor (MBBR) technology has proven to be an efficient way to treat nitrogen in existing volumes at Sundet wastewater treatment plant in Växjö. Increased nitrification and denitrification capacity in parts of the main stream were demonstrated through the Hybas™ process, a combination of MBBR and activated sludge using the integrated fixed-film activated sludge technology. The ANITA™ Mox process, using autotrophic N-removal through anaerobic ammonium oxidation (anammox), provided high nitrogen removal for the sludge liquor. Data collected on-site for over a year are analyzed and compared with the performance of conventional treatment systems. These two full-scale demonstration projects have been a successful learning experience in identifying and correcting both process and operational issues, which may not have arisen at pilot scale. The set objectives in terms of nitrogen removal were met for both processes and design modifications have been identified that will improve future operation at Sundet WWTP.
|
|
| 2. |
- Andersson, S., et al.
(författare)
-
Extension of two large wastewater treatment plants in Stockholm using membrane technology
- 2016
-
Ingår i: Water Practice and Technology. - : IWA Publishing. - 1751-231X. ; 11:4, s. 744-753
-
Tidskriftsartikel (refereegranskat)abstract
- Like many other large cities, Stockholm is facing increased urbanization with densification of infrastructure as a result. At the same time, implementation of the Baltic Sea Action Plan and the EU Water Framework Directive is expected to result in more stringent effluent quality demands. The current situation gives rise to new challenges for the municipal wastewater treatment plants (WWTPs). This paper describes how two of Sweden’s largest municipal water organizations; Stockholm Vatten and Syvab, will face these challenges using ultrafiltration (UF) membrane bioreactor (MBR) technology. The effluent requirements for the rehabilitated plants are expected to be tightened to 6 mg/l and 0.2 mg/l for total nitrogen (TN) and total phosphorus (TP), respectively.
|
|
| 3. |
- Benavente, Martha, et al.
(författare)
-
Speciation and Removal of Arsenic in column packed with chitosan
- 2006
-
Ingår i: Water Practice & Technology. - : International Water Association (IWA). - 1751-231X. ; 1:4, s. 2006-89
-
Tidskriftsartikel (refereegranskat)abstract
- The arsenic speciation and arsenic removal in chitosan packed column were studied. Arsenic removal experiments were carried out with an arsenic standard solution (1.0 mg/l) and drilled well water samples from Limon Mine Community at different pH, water flowrate, and volume of adsorbent material. The simulation of arsenic speciation was carried out at a pH range from 0 to 12, a temperature of 25ºC, a pE equal to 4, and a total arsenic concentration of 1.34 x 10-5 mol kg-1. According to speciation calculations arsenic is found mainly in oxidized form in the conditions of Limon Mine’s drilled well waters, dihydrogen arsenate ion (H2AsO4-), and hydrogen arsenate ion (HAsO42-) being the major species. The experiments showed that arsenic adsorption depends mainly on the pH as well as the activity of functional groups that compose the chitosan structure. At pH 3 and volume of adsorbent material of 337.8 cm3 an adsorption of 94% was obtained from arsenic standard solution, and the arsenic present in the Limon Community’s water was almost totally removed at pH 3 and 7. The use of the results for designing purposes demands the breakthrough curves for chitosan to be determined.
|
|
| 4. |
- Desa, L., et al.
(författare)
-
Improving and upgrading an existing activated sludge with a compact MBBR - disc filters parallel line for municipal wastewater treatment in touristic alpine areas.
- 2020
-
Ingår i: Water Practice and Technology. - : IWA Publishing. - 1751-231X. ; 15:2, s. 515-527
-
Tidskriftsartikel (refereegranskat)abstract
- Many wastewater treatment plants (WWTP) in touristic areas struggle to achieve the effluent requirements due to seasonal variations in population. In alpine areas, the climate also determines a low wastewater temperature, which implies long sludge retention time (SRT) needed for the growth of nitrifying biomass in conventional activated sludge (CAS). Moreover, combined sewers generate high flow and dilution. The present study shows how the treatment efficiency of an existing CAS plant with tertiary treatment can be upgraded by adding a compact line in parallel, consisting of a Moving Bed Biofilm Reactor (MBBR)-coagulation-flocculation-disc filtration. This allows the treatment of influent variations in the MBBR and a constant flow supply to the activated sludge. The performance of the new 2-step process was comparable to that of the improved existing one. Regardless significant variations in flow (10,000-25,000 m(3)/d) and total suspended solids (TSS) (50-300 mg/L after primary treatment) the effluent qualityfulfilled the discharge requirements. Based on yearly average effluent data, TSS were 11 mg/L, chemical oxygen demand (COD) 27 mg/L and total phosphorus (TP) 0.8 mg/L. After the upgrade, ammonium nitrogen (NH4-N) dropped from 4.9 mg/L to 1.3 mg/L and the chemical consumption for phosphorus removal was reduced.
|
|
| 5. |
- Gemeda, Shibabaw Tadesse, et al.
(författare)
-
Enterotoxins as a molecular marker of water quality
- 2022
-
Ingår i: Water practice and technology. - : IWA Publishing. - 1751-231X. ; 17:2, s. 623-636
-
Tidskriftsartikel (refereegranskat)abstract
- Safety of improved water supplies using enterotoxins as a molecular marker is evaluated. Water samples were collected from 248 households and tested for enterotoxins using polymerase chain reaction (PCR). The relationships between the presence of at least one enterotoxin and independent variables were investigated using Chi-square (chi 2), Fisher's exact test and binary logistic regression. Some 156 enterotoxin biomarkers were detected, 39% of samples had at least one, and 17% had multiple varieties. EAST1 was detected in the highest proportion of samples 33% and Sta in the lowest 2%. Shallow groundwater sources yielded 18% less enterotoxins than water from piped systems, a statistically significant result (P=0.031). A lower proportion of enterotoxins was detected in relation to those who did not know and use cloth filters than those with knowledge of them, and the negative association is statistically significant (P=0.017). It was shown that water samples in which TC colonies were detected were more likely to contain enterotoxins than those without (P=0.001). It is concluded that enterotoxin molecular markers can be used to monitor water safety.
|
|
| 6. |
- Gillblad, Thomas, et al.
(författare)
-
Integrating local solar energy and water recovery : Operating experiences of a systemic approach
- 2023
-
Ingår i: Water Practice and Technology. - 1751-231X. ; 18:12, s. 3291-3298
-
Tidskriftsartikel (refereegranskat)abstract
- The key message is the importance of a systemic approach to handling water and energy together, both in design and in oper-ation. The paper demonstrates how renewable energy, solar photovoltaic (PV) and solar thermal, in combination with a small nutrient removal plant, provides a reliable solution for small-scale decentralized water recovery operations. The system is automated and can operate outside the power grid and is designed to be a fully circular system in terms of both energy and water. The system has been installed on an island in the archipelago outside Stockholm, Sweden, to replace an old-fashioned septic tank. The effluent must satisfy rather strict effluent quality criteria for the Baltic Sea. The paper describes design considerations, instrumentation aspects, automation features, and operation experiences.
|
|
| 7. |
- Haghighatafshar, Salar, et al.
(författare)
-
An Innovative Method for Estimating Settling Velocity of Particles in Stormwater Using Absorbance Measurements and Modeling
- 2024
-
Ingår i: Water Practice and Technology. - 1751-231X. ; 19:5, s. 1810-1821
-
Tidskriftsartikel (refereegranskat)abstract
- The purpose of the study was to develop a simple and rapid method for measuring the average settling velocity of particles in stormwater ponds. Water samples with suspended particles were collected from the bottom of a stormwater pond in Lund, Sweden. The absorbance in various samples was measured over 24 hours (at 600 nm wavelength) and then translated into total solids concentrations. A one-dimensional model based on the Mason-Weaver equation was coded in Python and solved. The absorbance measurements were used to calibrate the model, thereby quantifying settling velocities and dispersion coefficients for samples from different zones of the stormwater pond. The quantified settling velocities ranged from 40 to 200 mm/h for fast-settling particles and from 2 to 8 mm/h for slow-settling particles. The developed methodology provided a mass estimate of the two modeled particle groups (i.e., fast- and slow-settling particles). Based on the model estimates, fast-settling particles dominated all samples, constituting 70–90% of the total solid mass. Due to its simplicity and inexpensiveness, this methodology is a potential alternative to more demanding and complicated methodologies used for measuring particle velocities in sedimentation systems.
|
|
| 8. |
- Hall, Ashley, et al.
(författare)
-
Treatment of greywater with nanofiltration for nutrient removal – 2-year experience from Helsingborg
- 2024
-
Ingår i: Water Practice and Technology. - 1751-231X. ; 19:3, s. 900-910
-
Tidskriftsartikel (refereegranskat)abstract
- Source-separated sanitation and greywater treatment have become an increasingly attractive alternative to traditional waste-water management systems in recent years due to their potential to combat water scarcity, ease resource recovery, and meet tightening effluent demands. In Helsingborg, Sweden, source-separated wastewater from the new city district of Oceanhamnen is being collected and treated in a new treatment plant (RecoLab) to test, among other issues, how efficient greywater treatment can be in achieving low discharge limits for pollutants. The greywater treatment consists of activated sludge treatment, drum filter micro-sieving, and nanofiltration. In the first two years of operation, the robustness of the treatment system during periods with extreme conditions, e.g., very low and very high organic matter concentrations, was tested. The combination of biological treatment and nanofiltration has achieved stable effluent concentrations below 10 mg/L chemical oxygen demand, 2 mg/L total nitrogen, and 0.2 mg/L total phosphorus as average values for 22 months of operation with an average flow of 43 m3/day. The treatment system for greywater treatment thus shows the possibility to achieve low discharge limits and meet the new proposed effluent demands of the EU Urban Wastewater Treatment Directive.
|
|
| 9. |
- Hallberg, Magnus, et al.
(författare)
-
Evaluation of a sand filter material for road runoff treatment- pilot-scale field trial focused on copper and zinc removal
- 2022
-
Ingår i: Water practice and technology. - : IWA Publishing. - 1751-231X. ; 17:8, s. 1652-1665
-
Tidskriftsartikel (refereegranskat)abstract
- The effects of stormwater discharges on receiving aquatic environments and the need for their purification were highlighted by an EU court in May 2020. The ruling stated the need for removal of dissolved pollutants, which justifies field studies for development of far-reaching methods for runoff treatment. In this study, a standard sand was used as medium for road runoff filtration and removal of dissolved and particle-bound (<0.45 mu m) zinc (Zn) and copper (Cu). Data included 24 road runoff events, mimicking the flow variations and pollutant emissions over a seven-month period. The findings showed that sand can be used to remove Zn and Cu from road runoff in a gravity fed treatment system at a surface load ranging from 16.8 to 201 L m(-2) h(-1). The removal of total Zn and Cu was 93 and 67%, respectively. Dissolved Zn was efficiently removed by the sand (87%), however not Cu (19%). The sand efficiently removed total suspended solids (TSS) from the maximum occurring 443 mg L-1 to below 5 mg L-1. No head loss due to the TSS loadings was observed. The sand's potential to remove the investigated metals was shown, but in the longer term, effluent concentrations may exceed permitted values.
|
|
| 10. |
- Jonsson, Lena Margareta, et al.
(författare)
-
Dynamic and initial head loss in full-scale wastewater filtration and measures to prevent long-term initial head loss
- 2022
-
Ingår i: Water practice and technology. - : IWA Publishing. - 1751-231X. ; 17:7, s. 1390-1405
-
Tidskriftsartikel (refereegranskat)abstract
- Dual media sand filters at Henriksdal WWTP began to show high head loss after five years of operation, especially during the fluidization for sorting the filter bed after backwashing. At that time, the filters were still clean and the dynamic head loss, due to clogging of the filters with suspended solids during a cycle of operation, had its lowest value. Dynamic head loss over the lower sand layer surface in the dual media sand filter was detected in some filter cycles of operation. The initial head loss in the filters has increased over the years. This type of head loss is constant during a cycle of operation and increases only slowly with time. It is due to different factors, as precipitation of ferric oxide hydroxide in the nozzle slots and on the grains in the filter bed, and accumulation of filter bed grains below the filter bottom. Different measures were tested to reduce or eliminate the initial head loss in the filters. Results from frequency diagrams showed that changing nozzles and removing of filter bed material from below the filter bottom were the most favourable actions. Backwashing more frequently and with more sequences also reduced the initial head loss.
|
|
