| 1. |
- Abed, Suhail N., et al.
(författare)
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Phytoremediation performance of floating treatment wetlands with pelletized mine water sludge for synthetic greywater treatment
- 2019
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Ingår i: Journal of Environmental Health Science & Engineering (Online). - : Springer Science and Business Media LLC. - 2052-336X. ; 17:2, s. 581-608
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: Buckets containing floating reed (Phragmites australis) simulated floating treatment wetlands (FTWs) and were used to improve the remediation performance of synthetic greywater (SGW). The aim of the study was to investigate the behaviour of FTWs for treatment of key contaminants within artificial greywater. Methods: Pelletized ochre based on acid mine water sludge was introduced to selected FTWs, because of its capability in sequestration phosphorus and other trace elements. The impact of the following four operational variables were tested in the experimental set-ups of the FTWs (four replicates each): pollutant strength (high- (HC) and low- (LC) concentrations), treatment time (2- or 7-days of hydraulic retention time (HRT)), presence or absence of macrophytes (P. australis) and cement-ochre pellets. Results: The results showed that 5 - day biochemical oxygen demand (BOD) and chemical oxygen demands (COD) were significantly (p < 0.05) reduced in all wetlands. Nitrate-nitrogen (NO3-N) concentrations were significantly (p < 0.05) higher, and those measurements for PO4-P were significantly (p < 0.05) lower than the corresponding ones determined for the influent. The existence of ochre pellets with P. australis significantly (p < 0.05) decreased B, Cd, Cr, Cu, Mg, Ni and Zn concentrations, but increased Al, Ca, Fe and K concentrations in the effluent, with the exception of sodium (Na). Conclusions: The FTW performances can be improved by utilising ochre-cement pellets to increase the pH of greywater. The presence of P. australis acts as a buffer to neutralise the pH of SGW. Rhizomes and biofilms mitigate increases in turbidity, TSS and colour values.
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| 2. |
- Almuktar, Suhad A.A.A.N., et al.
(författare)
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Wetlands for wastewater treatment and subsequent recycling of treated effluent : a review
- 2018
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Ingår i: Environmental Science and Pollution Research. - : Springer Science and Business Media LLC. - 0944-1344 .- 1614-7499. ; 25:24, s. 23595-23623
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Tidskriftsartikel (refereegranskat)abstract
- Due to water scarcity challenges around the world, it is essential to think about non-conventional water resources to address the increased demand in clean freshwater. Environmental and public health problems may result from insufficient provision of sanitation and wastewater disposal facilities. Because of this, wastewater treatment and recycling methods will be vital to provide sufficient freshwater in the coming decades, since water resources are limited and more than 70% of water are consumed for irrigation purposes. Therefore, the application of treated wastewater for agricultural irrigation has much potential, especially when incorporating the reuse of nutrients like nitrogen and phosphorous, which are essential for plant production. Among the current treatment technologies applied in urban wastewater reuse for irrigation, wetlands were concluded to be the one of the most suitable ones in terms of pollutant removal and have advantages due to both low maintenance costs and required energy. Wetland behavior and efficiency concerning wastewater treatment is mainly linked to macrophyte composition, substrate, hydrology, surface loading rate, influent feeding mode, microorganism availability, and temperature. Constructed wetlands are very effective in removing organics and suspended solids, whereas the removal of nitrogen is relatively low, but could be improved by using a combination of various types of constructed wetlands meeting the irrigation reuse standards. The removal of phosphorus is usually low, unless special media with high sorption capacity are used. Pathogen removal from wetland effluent to meet irrigation reuse standards is a challenge unless supplementary lagoons or hybrid wetland systems are used.
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| 3. |
- Hussein, Amjad, et al.
(författare)
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Treatment of artificial wastewater containing two azo textile dyes by vertical-flow constructed wetlands
- 2018
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Ingår i: Environmental Science and Pollution Research. - : Springer Science and Business Media LLC. - 0944-1344 .- 1614-7499. ; 25:7, s. 6870-6889
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Tidskriftsartikel (refereegranskat)abstract
- The release of untreated dye textile wastewater into receiving streams is unacceptable not only for aesthetic reasons and its negative impacts on aquatic life but also because numerous dyes are toxic and carcinogenic to humans. Strategies, as of now, used for treating textile wastewaters have technical and economical restrictions. The greater part of the physico-chemical methods, which are used to treat this kind of wastewater, are costly, produce large amounts of sludge and are wasteful concerning some soluble dyes. In contrast, biological treatments such as constructed wetlands are cheaper than the traditional methods, environmental friendly and do not produce large amounts of sludge. Synthetic wastewater containing Acid Blue 113 (AB113) and Basic Red 46 (BR46) has been added to laboratory-scale vertical-flow construction wetland systems, which have been planted with Phragmites australis (Cav.) Trin. ex Steud. (common reed). The concentrations 7 and 208 mg/l were applied for each dye at the hydraulic contact times of 48 and 96 h. Concerning the low concentrations of BR46 and AB113, the unplanted wetlands are associated with significant (ρ < 0.05) reduction performances, if compared with planted wetlands concerning the removal of dyes. For the high concentrations of AB113, BR46 and a mixture of both of them, wetlands with long contact times were significantly (ρ < 0.05) better than wetlands that had short contact times in terms of dye, colour and chemical oxygen demand reductions. Regarding nitrate nitrogen (NO3-N), the reduction percentage rates of AB113, BR46 and a mixture dye of both of them were between 85 and 100%. For low and high inflow dye concentrations, best removals were generally recorded for spring and summer, respectively.
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| 4. |
- Rahi, Muna A., et al.
(författare)
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Biochemical performance modelling of non-vegetated and vegetated vertical subsurface-flow constructed wetlands treating municipal wastewater in hot and dry climate
- 2020
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Ingår i: Journal of Water Process Engineering. - : Elsevier BV. - 2214-7144. ; 33
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Tidskriftsartikel (refereegranskat)abstract
- Wastewater treatment and subsequent effluent recycling for non-drinking purposes such as irrigation contributes to the mitigation of the pressure on freshwater resources. In this study, two vertical sub-surface flow constructed wetland (VSSF-CW) pilot plants were operated to treat municipal wastewater and their effluents were reused for irrigation purposes. One of the wetlands was vegetated with Phragmites australis (Cav.) Trin. ex Steud. (common reed) to compare its efficiency of pollutant removals with the non-vegetated system, which had the same design. COMSOL Multiphysics 3.5a was operated for the Activated Sludge Model 2 (ASM2) to predict the chemical oxygen demand (COD) and ammonia-nitrogen (NH4-N) concentrations. The effluent quality of both treatment systems was assessed for several parameters. Computer simulations show a good compliance between the measured and predicted values of COD and NH4-N for the vegetated system. The calibrated model could be effectively used to predict the behaviours of those parameters as a function of time. Moreover, the effluents of both vegetated (VFp) and non-vegetated (VF) VSSF-CW were significantly (p < 0.05) improved compared to influent. Significant (p < 0.05) effects due to the presence of P. australis were observed for removals of total suspended solids (TSS), 5-day biochemical oxygen demand (BOD5), COD, NH4-N and ortho-phosphate-phosphorus (PO4-P). However, significant increases (p < 0.05) were noted for electrical conductivity (EC), total dissolved solids (TDS), nitrate-nitrogen (NO3-N) and sulphate (SO4) of both effluents compared to the raw wastewater. Except for EC, NH4-N and SO4, all water quality parameters complied with irrigation water standards.
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| 5. |
- Ray, Sanak, et al.
(författare)
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Kinetics of carbon and nitrogen assimilation by heterotrophic microorganisms during wastewater treatment
- 2019
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Ingår i: Environmental Monitoring and Assessment. - : Springer Science and Business Media LLC. - 0167-6369 .- 1573-2959. ; 191:7
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Tidskriftsartikel (refereegranskat)abstract
- The present study highlights microbial assimilation of carbon (glucose) and nitrogen (NH3–N) from wastewater using heterotrophic bioconversion process. Experiments were conducted to study the role of heterotrophic microbes towards removal of carbon and nitrogen at varying initial concentrations of carbon (COD, 533 to 1600 mg/l) and nitrogen (NH3–N, 73 to 249 mg/l) keeping the initial biomass of microorganisms constant. Removal of COD and ammonia from wastewater represented a first-order rate reaction, upon analysis of kinetics, indicating that the rate of reaction is dependent on the initial concentration of nutrients available. Rate equations were developed using the Monod model, and the maximum specific consumption rate (k4) and half saturation constant (Ks) values for NH3–N and COD were found to be 2.59 mg/l/h and 64.13 mg/l/h and 38.46 mg/l and 2162.69 mg/l, respectively. Assimilation of NH3–N followed the Freundlich isotherm model. The mass transfer coefficient for COD and NH3–N were found to be 0.13 h−1 and 0.81 h−1 respectively. The NH3–N is converted to N2O during nitrification, and observed values of N2O coincided with the empirically predicted values indicating the activity of heterotrophic nitrifiers. The regeneration/doubling time of heterotrophic microbial biomass varied from 26 to 121 h. Statistical techniques, viz. analysis of variance, multi-linear regression analysis and principal component analysis, validated the results.
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| 6. |
- Yaseen, Dina A., et al.
(författare)
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Comparison of experimental ponds for the treatment of dye wastewater under controlled and semi-natural conditions
- 2017
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Ingår i: Environmental Science and Pollution Research. - : Springer Science and Business Media LLC. - 0944-1344 .- 1614-7499. ; 24:19, s. 16031-16040
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Tidskriftsartikel (refereegranskat)abstract
- This study compares the performance of simulated shallow ponds vegetated with Lemna minor L. under controlled and semi-natural conditions for the treatment of simulated wastewater containing textile dyes. The objectives were to assess the water quality outflow parameters, the potential of L. minor concerning the removal of chemical oxygen demand (COD) and four azo dyes (Acid blue 113, reactive blue 198, Direct Orange 46 and Basic Red 46) and the plants’ growth rate. Findings show that all mean outflow values of COD, total dissolved solids (TDS) and electrical conductivity (EC) were significantly (p < 0.05) lower within the outdoor compared to the indoor experiment except the dissolved oxygen (DO). The COD removal was low for both experiments. The outflow TDS values were acceptable for all ponds. The pond systems were able to reduce only BR46 significantly (p < 0.05) for the tested boundary conditions. Removals under laboratory conditions were better than those for semi-natural environments, indicating the suitability of operating the pond system as a polishing step in warmer regions. The mean outflow values of zinc and copper were below the thresholds set for drinking and irrigation waters and acceptable for L. minor. The dyes inhibited the growth of the L. minor.
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