| 1. |
- Amneklev, Jennie, et al.
(författare)
-
Upstream silver source mapping - a case study in Stockholm, Sweden
- 2014
-
Ingår i: Water Science and Technology. - : IWA Publishing. - 0273-1223 .- 1996-9732. ; 69:2, s. 392-397
-
Tidskriftsartikel (refereegranskat)abstract
- Silver (Ag) can be a problem for wastewater treatment plants (WWTP) and their capability to use sewage sludge as a soil fertilizer. Due to a high accumulation rate in soils, the levels of Ag in the incoming water at the WWTP must be reduced. This study aims to identify major diffuse emission sources in the technosphere through a comprehensive substance flow analysis of Ag in Stockholm, Sweden. Large inflows and stocks of Ag were present in electrical and electronic goods and appliances as well as in jewellery and silverware. The total inflow was 3.2 tonnes (4.2 g/person), the total stock was 100 tonnes (140 g/person) and the total outflow was 330 kg (430 mg/person). Major identified Ag sources with emissions ending up in the WWTP (total 26 kg, 34 mg/person) were food, amalgam and beauty products (via urine and faeces, 12 mg/person or 11% of incoming amount), and textiles (via washing, 17 mg/person or 16% of incoming amount). This study explains approximately 35% of the total 80 kg Ag in the incoming water at Henriksdal WWTP in Stockholm. Plastic, photography and beauty products were identified as possible sources of Ag that need to be examined further.
|
|
| 2. |
- Bakyayita Kizito, Grace, et al.
(författare)
-
Kinetic studies of Cd (II) and Pb (II) ions biosorption from aqueous media using untreated and chemically treated biosorbents
- 2014
-
Ingår i: Water Science and Technology. - : IWA Publishing. - 1606-9749 .- 1607-0798 .- 0273-1223 .- 1996-9732. ; 69:11, s. 2230-2236
-
Tidskriftsartikel (refereegranskat)abstract
- Untreated and chemically treated Albizia coriaria, Erythrina abyssinica and Musa spp were studied in batch for uptake of Cd2+ and Pb2+ ions at pH 2.0–9.0 and agitation time; 30–390 min. Optimum biosorption conditions were; pH 4 for Pb2+ ions and pH 5 for Cd2+ ions, contact time was 3.5 hours at 24 ± 1 °C for 10 mg/L biosorbent dosage and initial metal ions concentration of 20 mg/L. Chemical treatment had a 10–17% biosorption efficiency enhancement for Cd2+ ions and a 1.6–2.3% reduction effect for Pb2+ ions. The sorption capacities for Cd2+ and Pb2+ ions for treated biosorbents were between 1.760–1.738 mg g−1 compared to 1.415–1.539 mg g−1 for untreated materials. The pseudo second order model suitably fitted the Cd2+ and Pb2+ ions biosorption data with regression coefficients (R2) between 0.9784–0.9999. Fitting of the Ho model to the experimental data showed that the biosorption mechanism for both metal ions studied was mainly a chemisorption process. Therefore, treated A. coriaria, E. abyssinica and Musa spp were potential biosorbents for remediation of Cd2+ ions and the untreated materials suitable for removing Pb2+ ions from contaminated aqueous media.
|
|
| 3. |
- Björklund, Karin, 1979, et al.
(författare)
-
Screening of Organic Contaminants in Urban Snow
- 2011
-
Ingår i: Water Science and Technology. - : IWA Publishing. - 0273-1223 .- 1996-9732. ; 64:1, s. 206-213
-
Tidskriftsartikel (refereegranskat)abstract
- Snowmelt is known to cause peak concentrations of pollutants, which may adversely affectreceiving water quality. High concentrations of metals and suspended solids in snow have beenreported, whereas studies on organic pollutants are rare. This study aims at investigating theoccurrence of anthropogenic organic compounds in urban snow in Gothenburg (Sweden). The mostfrequently detected organic pollutants in the collected snow samples were polycyclic aromatichydrocarbons (PAHs), high molecular-weight phthalates, 4-nonylphenol and 4-t-octylphenol.Brominated flame retardants and chlorinated paraffins were only sporadically detected. In severalsnow samples, the concentrations of specific PAHs, alkylphenols and phthalates were higher thanreported stormwater concentrations and European water quality standards. Pollutant sourceidentification and sustainable management of snow are important instruments for the mitigation oforganic contaminants in the urban environment.
|
|
| 4. |
- Björklund, Karin, 1979, et al.
(författare)
-
Simulating organic pollutant flows in urban stormwater: development and evaluation of a model for nonylphenols and phthalates
- 2011
-
Ingår i: Water Science and Technology. - : IWA Publishing. - 0273-1223 .- 1996-9732. ; 65:3, s. 508-515
-
Tidskriftsartikel (refereegranskat)abstract
- Stormwater-quality models can be useful tools for predicting pollutant loads and identifying sources of contamination. Most models in current use handle pollutants such as metals, nutrients and suspended solids, whereas models including emerging organic contaminants are rare.This study aims at developing and evaluating a model for simulating stormwater flows of two groups of organic pollutants; nonylphenols and phthalates. Sources, emission patterns and environmental fate were examined to create a model framework for the organic contaminants. The model was calibrated using field data from three urban catchments. The results show that the simulated pollutant concentrations are overestimated compared to the measured concentrations, which are often close to or below the analytical detection limit. The high uncertainty and the lowpredictive power of the model may be explained by factors such as incorrect catchment data, lack of knowledge on buildup, washoff and other processes involved in substance fate, and an underreporting of pollutant concentrations in stormwater. More data on release patterns and sewer fate are needed to adequately simulate stormwater concentrations of nonylphenols and phthalates. A conventional substance flow analysis based on bookkeeping, evaluated in parallel to the computer model, has proven to be useful for calculating fluxes of nonylphenols and phthalates in urban catchments.
|
|
| 5. |
- Björklund, Karin, 1979
(författare)
-
Substance flow analyses of phthalates and nonylphenols in stormwater
- 2010
-
Ingår i: Water Science and Technology. - : IWA Publishing. - 0273-1223 .- 1996-9732. ; 62:5, s. 1154-1160
-
Tidskriftsartikel (refereegranskat)abstract
- The occurrence of nonylphenol and several phthalates in water environments is highly undesired because of their negative effects on aquatic organisms. The objectives of this study were to identify emission sources of phthalates, nonylphenol and its ethoxylates (NP/EOs) in urban stormwater, and to quantify the substance fluxes from the source to the stormwater system, using the methodology of substance flow analysis (SFA). The SFA, applied on an urban motorway area, showed that phthalates are mainly emitted from vehicles and coated roofing material, whereas the major NP/EOs sources are vehicles and concrete. It was estimated that approximately 4.1 kg of four selected phthalates and more than 400 g of NP/EOs are emitted annually to stormwater in the studied area. The SFA approach presented in this study, using factors that express the emission rate of a specific substance from a specific source, could be applied in urban catchments of various character to estimate fluxes of water contaminants.
|
|
| 6. |
- Borris, Matthias, et al.
(författare)
-
Simulating future trends in urban stormwater quality for changing climate, urban land use and environmental controls
- 2013
-
Ingår i: Water Science and Technology. - : IWA Publishing. - 0273-1223 .- 1996-9732. ; 68:9, s. 2082-2089
-
Tidskriftsartikel (refereegranskat)abstract
- The effects of climatic changes, progressing urbanization and improved environmental controls on the simulated urban stormwater quality in a northern Sweden community were studied. Future scenarios accounting for those changes were developed and their effects simulated with the Storm Water Management Model (SWMM). It was observed that the simulated stormwater quality was highly sensitive to the scenarios, mimicking progressing urbanization with varying catchment imperviousness and area. Thus, land use change was identified as one of the most influential factors and in some scenarios, urban growth caused changes in runoff quantity and quality exceeding those caused by a changing climate. Adaptation measures, including the reduction of directly connected impervious surfaces (DCIS) through the integration of more green spaces into the urban landscape, or disconnection of DCIS were effective in reducing runoff volume and pollutant loads. Furthermore, pollutant source control measures, including material substitution, were effective in reducing pollutant loads and significantly improving stormwater quality
|
|
| 7. |
- Bürger, Raimund, et al.
(författare)
-
A consistent modelling methodology for secondary settling tanks: A reliable numerical method.
- 2013
-
Ingår i: Water Science and Technology. - : IWA Publishing. - 0273-1223 .- 1996-9732. ; 68:1, s. 192-208
-
Tidskriftsartikel (refereegranskat)abstract
- The consistent modelling methodology for secondary settling tanks (SSTs) leads to a partial differential equation (PDE) of nonlinear convection–diffusion type as a one-dimensional model for the solids concentration as a function of depth and time. This PDE includes a flux that depends discontinuously on spatial position modelling hindered settling and bulk flows, a singular source term describing the feed mechanism, a degenerating term accounting for sediment compressibility, and a dispersion term for turbulence. In addition, the solution itself is discontinuous. A consistent, reliable and robust numerical method that properly handles these difficulties is presented. Many constitutive relations for hindered settling, compression and dispersion can be used within the model, allowing the user to switch on and off effects of interest depending on the modelling goal as well as investigate the suitability of certain constitutive expressions. Simulations show the effect of the dispersion term on effluent suspended solids and total sludge mass in the SST. The focus is on correct implementation whereas calibration and validation are not pursued.
|
|
| 8. |
- Cema, Grzegorz, et al.
(författare)
-
Dissolved oxygen as a factor influencing nitrogen removal rates in a one-stage system with partial nitritation and Anammox process
- 2011
-
Ingår i: Water Science and Technology. - : IWA Publishing. - 0273-1223 .- 1996-9732. ; 64:5, s. 1009-1015
-
Tidskriftsartikel (refereegranskat)abstract
- A biofilm system with Kaldnes biofilm carrier was used in these studies to cultivate bacteria responsible for both partial nitritation and Anammox processes. Due to co-existence of oxygen and oxygen-free zones within the biofilm depth, both processes can occur in a single reactor. Oxygen that inhibits the Anammox process is consumed in the outer layer of the biofilm and in this way Anammox bacteria are protected from oxygen. The impact of oxygen concentration on nitrogen removal rates was investigated in the pilot plant (2.1 m(3)), supplied with reject water from the Himmerfjarden Waste Water Treatment Plant. The results of batch tests showed that the highest nitrogen removal rates were obtained for a dissolved oxygen (DO) concentration around 3 g O(2) m(-3). At a DO concentration of 4 g O(2) m(-3), an increase of nitrite and nitrate nitrogen concentrations in the batch reactor were observed. The average nitrogen removal rate in the pilot plant during a whole operating period oscillated around 1.3 g N m(-2)d(-1) (0.3 +/- 0.1 kg N m(-3)d(-1)) at the average dissolved oxygen concentration of 2.3 g O(2) m(-3). The maximum value of a nitrogen removal rate amounted to 1.9 g N m(-2)d(-1) (0.47 kg N m(-3)d(-1)) and was observed for a DO concentration equal to 2.5 g O(2) m(-3). It was observed that increase of biofilm thickness during the operational period, had no influence on nitrogen removal rates in the pilot plant.
|
|
| 9. |
- Christensson, Magnus, et al.
(författare)
-
Experience from start-ups of the first ANITA Mox Plants
- 2013
-
Ingår i: Water Science and Technology. - : IWA Publishing. - 0273-1223 .- 1996-9732. ; 67:12, s. 2677-2684
-
Tidskriftsartikel (refereegranskat)abstract
- ANITA (TM) Mox is a new one-stage deammonification Moving-Bed Biofilm Reactor (MBBR) developed for partial nitrification to nitrite and autotrophic N-removal from N-rich effluents. This deammonification process offers many advantages such as dramatically reduced oxygen requirements, no chemical oxygen demand requirement, lower sludge production, no pre-treatment or requirement of chemicals and thereby being an energy and cost efficient nitrogen removal process. An innovative seeding strategy, the 'BioFarm concept', has been developed in order to decrease the start-up time of new ANITA Moxinstallations. New ANITA Mox installations are started with typically 3-15% of the added carriers being from the 'BioFarm', with already established anammox biofilm, the rest being new carriers. The first ANITA Mox plant, started up in 2010 at Sjolunda wastewater treatment plant (WWTP) in Malmo, Sweden, proved this seeding concept, reaching an ammonium removal rate of 1.2 kgN/m(3) d and approximately 90% ammonia removal within 4 months from start-up. Thisfirst ANITA Mox plant is also the BioFarm used for forthcoming installations. Typical features of this first installation were low energy consumption, 1.5 kW/NH4-N-removed, low N2O emissions, <1% of the reduced nitrogen and a very stable and robust process towards variations in loads and process conditions. The second ANITA Mox plant, started up at Sundets WWTP in Vaxjo, Sweden, reached full capacity with more than 90% ammonia removal within 2 months from start-up. By applying a nitrogen loading strategy to the reactor that matches the capacity of the seeding carriers, more than 80% nitrogen removal could be obtained throughout the start-up period.
|
|
| 10. |
- Corso, Carlos Renato, et al.
(författare)
-
Bioremediation of direct dyes in simulated textile effluents by a paramorphogenic form of Aspergillus oryzae
- 2012
-
Ingår i: Water Science and Technology. - : IWA Publishing. - 0273-1223 .- 1996-9732. ; 65:8, s. 1490-1495
-
Tidskriftsartikel (refereegranskat)abstract
- Azo dyes are extensively used for coloring textiles, paper, food, leather, drinks, pharmaceutical products, cosmetics and inks. The textile industry consumes the largest amount of azo dyes, and it is estimated that approximately 10–15% of dyes used for coloring textiles may be lost in waste streams. Almost all azo dyes are synthetic and resist biodegradation, however, they can readily be reduced by a number of chemical and biological reducing systems. Biological treatment has advantages over physical and chemical methods due to lower costs and minimal environmental effect. This research focuses on the utilization of Aspergillus oryzae to remove some types of azo dyes from aqueous solutions. The fungus, physically induced in its paramorphogenic form (called ‘pellets’), was used in the dye biosorption studies with both non-autoclaved and autoclaved hyphae, at different pH values. The goals were the removal of dyes by biosorption and the decrease of their toxicity. The dyes used were Direct Red 23 and Direct Violet 51. Their spectral stability (325–700 nm) was analyzed at different pH values (2.50, 4.50 and 6.50). The best biosorptive pH value and the toxicity limit, (which is given by the lethal concentration (LC100), were then determined. Each dye showed the same spectrum at different pH values. The best biosorptive pH was 2.50, for both non- autoclaved and autoclaved hyphae of A. oryzae. The toxicity level of the dyes was determined using the Trimmed Spearman–Karber Method, with Daphnia similis in all bioassays. The Direct Violet 51 (LC100 400 mg · mL−1) was found to be the most toxic dye, followed by the Direct Red 23 (LC100 900 mg · mL−1). The toxicity bioassays for each dye have shown that it is possible to decrease the toxicity level to zero by adding a small quantity of biomass from A. oryzae in its paramorphogenic form. The autoclaved biomass had a higher biosorptive capacity for the dye than the non-autoclaved biomass. The results show that bioremediation occurs with A. oryzae in its paramorphogenic form, and it can be used as a biosorptive substrate for treatment of industrial waste water containing azo dyes.
|
|
