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1.
J Environ Qual ; 49(3): 593-602, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-33016395

RESUMO

Emerging technologies and practices allow wastewater treatment facilities to recover valuable resources such as nutrients, energy, and recycled water during the wastewater treatment process. The ability to recover resources from wastewater introduces new tradeoffs in both water quality and quantity management. In particular, the fact that communities can obtain revenue from the sale of resources that are recovered from wastewater may help internalize the externalities of insufficient wastewater treatment. In this paper, we develop a theoretical model to characterize these tradeoffs within a hydroeconomic framework of optimal wastewater treatment with resource recovery, which is particularly well suited for applications in nutrient management. We use this model to derive analytical results that describe the economically optimal level of deployment, accounting for the fact that the technology or practice is costly and it generates benefits in the form of revenue from the recovered resource, as well as other societal benefits, such as improvements in human and ecosystem health. In addition, we present two examples using specific functional forms for treatment costs to demonstrate how the model can be applied to obtain general principles regarding societally optimal deployment. Our hydroeconomic framework can be used to explore the socioeconomic implications of strategies that target deployment of wastewater treatment with resource recovery, especially nutrients, at multiple scales.


Assuntos
Águas Residuárias , Purificação da Água , Ecossistema , Humanos , Eliminação de Resíduos Líquidos , Qualidade da Água
2.
J Environ Qual ; 49(4): 1011-1019, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-33016487

RESUMO

The pharmaceutical compound carbamazepine (CBZ) is a contaminant of emerging concern. Wastewater irrigation can be a long-term, frequent source of CBZ; therefore, understanding the fate and transport of CBZ as a result of wastewater reuse practices has important environmental implications. The objective of this study was to estimate long-term soil transport of CBZ originating from treated wastewater irrigation on plots under different land uses. Field data from a previous study comparing CBZ concentrations in soil under different land uses were used in numerical modeling with HYDRUS-2D for the estimation of CBZ soil transport during 20 yr of irrigation with treated wastewater. This study showed high CBZ retention in soil under all investigated land uses. Adequate modeling results were obtained by using soil organic carbon-water partitioning coefficient (Koc ) for the CBZ linear sorption coefficient (Kd ) estimation, yet an underestimation of CBZ concentration in soil was still noted. Thus, results suggest that, although highly important, organic carbon content is probably not the only soil property governing CBZ sorption at this site, indicating the potential research perspective. Modeling results showed wastewater irrigation containing CBZ for 20 yr increased the CBZ concentration in the soil profile and its vertical movement, with the slowest vertical transport rate occurring on the forested plots. Overall results suggest that a beneficial management practice could be to increase soil organic carbon (e.g., compost addition) when using treated wastewater for irrigation in order to retain CBZ in the surface soil and thus limit its leaching through the soil profile.


Assuntos
Poluentes do Solo/análise , Águas Residuárias , Carbamazepina/análise , Carbono , Solo , Eliminação de Resíduos Líquidos
3.
Water Sci Technol ; 82(5): 799-828, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-33031062

RESUMO

Since it is difficult to analyze the components of organic matter in complex effluent matrices individually, the use of more collective, but at the same time, specific wastewater characterization methods would be more appropriate to evaluate changes in effluent characteristics during wastewater treatment. For this purpose, size distribution and structural (resin) fractionation tools have recently been proposed to categorize wastewater. There are several case studies available in the scientific literature being devoted to the application of these fractionation methods. This paper aimed to review the most relevant studies dealing with the evaluation of changes in wastewater characteristics using size distribution and structural (resin) fractionation tools. According to these studies, sequential filtration-ultrafiltration procedures, as well as XAD resins, are frequently employed for size and structural fractionations, respectively. This review focuses on the most relevant publications including biological treatment processes, as well as chemical treatment methods such as coagulation-flocculation, electrocoagulation, the Fenton's reagent and ozonation. This study aims at providing an insight into the possible treatment mechanisms and details the understanding what structural features of wastewater components enabled or prevented efficient treatment (removal) or targeted pollutants.


Assuntos
Eliminação de Resíduos Líquidos , Águas Residuárias , Fracionamento Químico , Floculação , Ultrafiltração
4.
Water Sci Technol ; 82(5): 861-876, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-33031066

RESUMO

Salicylhydroxamic acid is an effective and selective collector for tungsten and molybdenum ores. However, the salicylhydroxamic acid flotation wastewater discharge may cause damage to the water environment for the residual processing reagents with poor biodegradability. Combined O3 and biological aerated filter (BAF) has a well-known potential for removing refractory or toxic organic pollutants. Combined process of O3 and BAF (O3-BAF) was applied to treat the simulated wastewater from W-Mo mineral processing in this study. Compared single ozonation to O3-BAF, various influencing factors were discussed like O3 dosage, reaction time, initial pH value, gas-water ratio and organic loading. Meanwhile, degradation mechanism of salicylhydroxamic acid was reduced. Under the optimal experiment conditions as pH value 8, O3 dosage 1.3 mg·L-1, reaction time 15 min, the five-day biochemical oxygen demand (BOD5)/chemical oxygen demand of potassium dichromate (CODCr) value increased to from 0.19 to 0.35. The effluent was pumped to the following BAF process, when the optimal experiment conditions was organic load = 0.82 kgCODCr (m-3·d-1), gas-water ratio = 6:1, CODCr concentration of effluent was 28.92 mg·L-1 and the removal ratio was 86.26%, while the removal ratio could higher to 91.12% for the O3-BAF combined process. The effluent could meet the discharge and reuse emission standards requirements in China. UV-vis absorption spectra and high performance liquid chromatography showed the degradation pathway of salicylhydroxamic acid by ozone oxidation was salicylhydroxamic acid → salicylic acid + hydroxylamine → catechol → maleic → small molecular organic acid → carbon dioxide + water.


Assuntos
Eliminação de Resíduos Líquidos , Águas Residuárias , China , Salicilamidas
5.
Water Sci Technol ; 82(5): 905-917, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-33031069

RESUMO

This study develops a novel design scheme based on engineering fluid mechanics for the single-pipe-type sludge drainage mechanism of sedimentation tanks in the wastewater treatment industry. A laboratory-scale clarifier is fabricated for experimental verification. Sludge drainage ratio and suspended solids (SS) of inflow are selected as two factors for laboratory experiments, and SS values are measured to evaluate the performance of the sludge drainage pipe. Experiment data show that the designed single sludge drainage pipe can successfully achieve the supposed task with a coefficient of variation (CV) of SS less than 8.5%. The variation scope of CV from 1.5% to 8.3% suggests that the sludge drainage performance is relatively steady. Nine sets of 3D computational fluid dynamic (CFD) simulations, which is based on the inhomogeneous Eulerian-Eulerian multiphase model, were conducted for a comprehensive exploration and assessment. Results reveal noticeable deviations of the characteristics of the fluid in the outermost orifice of the sludge drainage pipe from the designed value. Although the fluid velocity through each orifice is matched with the designed values, the mass flowrate differs with a maximum of four times the designed value and a standard deviation of 0.4 of hole among the nine simulations. This study also suggests some considerations in the design process and routine operation of the single-pipe-type sludge drainage system.


Assuntos
Esgotos , Águas Residuárias , Eliminação de Resíduos Líquidos
6.
J Environ Manage ; 263: 110368, 2020 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-32883474

RESUMO

Nowadays, alternative options to conventional wastewater treatment should be studied due to rising concerns emerged by the presence of pharmaceuticals compounds (PhCs) in the aquatic environment. In this work, a combined system including biological treatment by activated sludge plus adsorption with activated carbon is proposed to remove three selected drugs (acetaminophen (ACT), caffeine (CAF) and ibuprofen (IBU)) in a concentration of 2 mg L-1 of each one. For it three sequencing batch reactors (SBR) were operated. SBR-B treated a synthetic wastewater (SWW) without target drugs and SBR-PhC and SBR-PhC + AC operated with SWW doped with the three drugs, adding into SBR-PhC + AC 1.5 g L-1 of a mesoporous granular activated carbon. Results showed that the hybrid system SBR-activated carbon produced an effluent free of PhCs, which in addition had higher quality than that achieved in a conventional activated sludge treatment in terms of lower COD, turbidity and SMP concentrations. On the other hand, five possible routes of removal for target drugs during the biological treatment were studied. Hydrolysis, oxidation and volatilization pathways were negligible after 6 h of reaction time. Adsorption route only was significant for ACT, which was adsorbed completely after 5 h of reaction, while only 1.9% of CAF and 5.6% of IBU were adsorbed. IBU was the least biodegradable compound.


Assuntos
Eliminação de Resíduos Líquidos , Águas Residuárias , Adsorção , Reatores Biológicos , Esgotos
7.
J Environ Manage ; 263: 110395, 2020 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-32883477

RESUMO

One of the main drawbacks of upflow anaerobic sludge blanket (UASB) reactors that treat low-strength sewage at room temperature is related to the low quality of their effluents in terms of dissolved methane, organic matter, and nitrogen content. The present study aims to evaluate the feasibility of using an integrated fixed-film activated sludge (IFAS) system as an alternative post-treatment technology to mitigate the environmental impact of such effluents. For this purpose, a pilot plant composed of a UASB (120 L) followed by an IFAS (66 L) system was operated for 407 days. Special attention was paid to the suspended biomass retention capacity and the dissolved methane and nitrogen removal potential of the IFAS post-treatment system. Furthermore, the role of carriers on denitrification and nitrification processes and the microbial communities present in the biofilm were also analyzed. Average total chemical oxygen demand (CODT) and ammonium removal efficiencies of 92 ± 3% and around 57 ± 16% were attained throughout the entire operation, respectively. During a first period in which biomass was maintained in both biofilms and suspension, and nitrite was the main electron acceptor, maximum nitrogen removal and methane removal efficiencies of 32.5 mg TN L-1 and 93% were observed in the IFAS system, respectively. However, throughout the second period, in which suspended biomass was completely washed out from the IFAS system, and nitrate became the main electron acceptor, these values decreased to 18 ± 4 mg TN Lfeed-1 and 77 ± 12%, respectively. Surprisingly, throughout the entire operation, it was observed that around 50 and 41% of the total nitrogen and methane removals observed in the IFAS system, respectively, were carried out in the aerobic compartment. Aerobic methane oxidizers and anammox were detected with significant relative abundances in the biofilm carriers used in the anoxic and aerobic compartments using 16S rRNA gene amplicon sequencing analysis. Therefore, the use of an IFAS system could be suited to diminish greenhouse gas emissions and nutrients concentration for those sewage treatment plants that used UASB systems, especially in countries with temperate and warm climates.


Assuntos
Nitrogênio , Esgotos , Anaerobiose , Reatores Biológicos , Metano , RNA Ribossômico 16S , Eliminação de Resíduos Líquidos
8.
Water Sci Technol ; 82(1): 97-106, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32910795

RESUMO

Domestic wastewater containing a high proportion of organic matter and nutrients is a serious pollution problem in developing countries. This study aimed to evaluate the performance of a novel attached-growth high rate algal pond (AG-HRAP) employing attached-growth media and artificial light sources for treating domestic wastewater and enhancing nutrient recovery. Light intensities in the range of 40-180 µmol/m2/s were used in the AG-HRAPs. The experimental results showed that the highest chemical oxygen demand (COD), total nitrogen (TN) and total phosphorus (TP) removal efficiencies of 88, 62 and 69%, respectively, were found at the hydraulic retention time (HRT) of 15 days and the average light intensity of 180 µmol/m2/s. Moreover, the effluent COD concentrations could meet Thailand's national discharge standard. The highest biomass and protein productivities of 54 ± 4 and 37 ± 8 g/m2/d, respectively, were found in the AG-HRAPs, which were higher than in previous studies of HRAPs. The Stover-Kincannon kinetic values for COD, TN and TP removals of the AG-HRAPs (R2 = 0.9) were higher than those of the conventional systems. Additionally, the novel AG-HRAP system could provide a highly cost-effective operation when compared to other microalgal systems.


Assuntos
Tanques , Águas Residuárias , Iluminação , Nutrientes , Tailândia , Eliminação de Resíduos Líquidos
9.
Water Sci Technol ; 82(1): 131-143, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32910798

RESUMO

Higher standards in the European Water Framework Directive and national directive demand advanced wastewater treatment for removal of nutrients and organic micropollutants before the discharge into water bodies. Systematic investigations regarding relative dosage and filtration processes for removal of flocculated solids are currently lacking. In this study, the performance of technologies for advanced removal of total phosphorus down to <100 µg/L with pile cloth-filtration (CF) and membrane filtration was verified and synergy effects for the removal of other contaminants were identified. The results show that an over-stoichiometric addition of coagulants of >5 mol Me3+/mol sRP was necessary to achieve soluble reactive phosphorus (sRP) concentrations of <50 µg/L in the effluent. After the coupled process of tertiary phosphorus removal and solids removal, the soluble non-reactive phosphorus (sNRP) concentration regulates the lowest total phosphorus effluent concentration. sNRP is also partially, but not completely, removed by the use of coagulants. CF has proven to be an alternative technology for the removal of phosphorus and total suspended solids below the detection limit.


Assuntos
Fósforo , Eliminação de Resíduos Líquidos , Filtração , Floculação , Águas Residuárias
10.
Sci Total Environ ; 741: 140480, 2020 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-32886969

RESUMO

The co-treatment of two synthetic faecal sludges (FS-1 and FS-2) with municipal synthetic wastewater (WW) was evaluated in an aerobic granular sludge (AGS) reactor. After characterisation, FS-1 showed the following concentrations, representative for medium-strength FS: 12,180 mg TSS L-1, 24,300 mg total COD L-1, 93.8 mg PO3-P L-1, and 325 mg NH4-N L-1. The NO3-N concentration was relatively high (300 mg L-1). For FS-2, the main difference with FS-1 was a lower nitrate concentration (18 mg L-1). The recipes were added consecutively, together with the WW, to an AGS reactor. In the case of FS-1, the system was fed with 7.2 kg total COD m-3d-1 and 0.5 kg Nitrogen m-3d-1. Undesired denitrification occurred during feeding and settling resulting in floating sludge and wash-out. In the case of FS-2, the system was fed with 8.0 kg total COD m-3d-1 and 0.3 kg Nitrogen m-3d-1. The lower NO3-N concentration in FS-2 resulted in less floating sludge, a more stabilised granular bed and better effluent concentrations. To enhance the hydrolysis of the slowly biodegradable particulates from the synthetic FS, an anaerobic stand-by period was added and the aeration period was increased. Overall, when compared to a control AGS reactor, a lower COD consumption (from 87 to 35 mg g-1 VSS h-1), P-uptake rates (from 6.0 to 2.0 mg P g VSS-1 h-1) and NH4-N removal (from 2.5 to 1.4 mg NH4-N g VSS-1 h-1) were registered after introducing the synthetic FS. Approximately 40% of the granular bed became flocculent at the end of the study, and a reduction of the granular size accompanied by higher solids accumulation in the reactor was observed. A considerable protozoa Vorticella spp. bloom attached to the granules and the accumulated particles occurred; potentially contributing to the removal of the suspended solids which were part of the FS recipe.


Assuntos
Esgotos , Águas Residuárias , Reatores Biológicos , Nitrogênio , Eliminação de Resíduos Líquidos
11.
Environ Monit Assess ; 192(10): 625, 2020 Sep 08.
Artigo em Inglês | MEDLINE | ID: mdl-32897491

RESUMO

Donnybrook Waste Stabilization Ponds (WSP) are overloaded and water hyacinth plants have infested the ponds. The study assessed the feasibility of integrating the problematic water hyacinth plants into the current treatment process. Grab samples of influent and effluent for each pond were collected between 28 March and 23 April 2019 and the analysis was done following standard APHA methods. Parameters considered include pH, turbidity, TDS, TSS, TN, TP, BOD, and COD. The raw sewage mean pH, turbidity, TDS, TSS, TN, TP, BOD, and COD were 8.08, 580 NTU, 1639 mg/L, 1294 mg/L, 78 mg/L, 8.16 mg/L, 287 mg/L, and 887 mg/L. The mean pH, turbidity, TDS, TSS, TN, TP, BOD, and COD in the effluent from the existing maturation pond, control pilot pond, and water hyacinth pilot pond were 7.7, 7.7, and 7.3; 75, 67, and 47 NTU; 861, 758, and 668 mg/L; 276, 172, and 82 mg/L; 27, 28, and 17 mg/L; 4, 5.28, and 4 mg/L; 114, 52, and 30 mg/L; and 243, 122, and 81 mg/L. It was concluded that the water hyacinth may be integrated into the WSP system to enhance contaminant removal. The water hyacinth in the ponds should be harvested periodically to avoid secondary organic and nutrient loading from dead plants.


Assuntos
Eichhornia , Purificação da Água , Monitoramento Ambiental , Tanques , Esgotos , Eliminação de Resíduos Líquidos , Águas Residuárias , Zimbábue
12.
Bioresour Technol ; 317: 124049, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-32871330

RESUMO

Using vertical flow constructed wetlands (VFCWs) with different influent wastewater volumes and feeding modes, this study aimed to identify the optimal operation strategy for dry seasons under wastewater deficiency. Using half the influent wastewater volume (HIWV) did not necessarily improve the removal efficiency (RE) of the chemical oxygen demand (COD), NH4+-N, NO3--N and total nitrogen. In the HIWV treatments, intermittent resting did not result in significantly different pollutant REs, whereas strategies involving partial saturation and prolongation of the hydraulic retention time (HRT) slightly decreased the pollutant REs compared with those obtained in the constant feeding mode. Of the three HIWV strategies, the intermittent resting mode achieved the highest anaerobic ammoxidation, the dominant pathway for nitrogen removal in the systems, and thus stimulated nitrogen transformation. The intermittent resting mode forms part of the recommended operation strategy for VFCWs in dry seasons with wastewater deficiency.


Assuntos
Águas Residuárias , Áreas Alagadas , Análise da Demanda Biológica de Oxigênio , Desnitrificação , Nitrogênio/análise , Estações do Ano , Eliminação de Resíduos Líquidos
13.
Chemosphere ; 258: 127213, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32947655

RESUMO

Worldwide, the aquatic environment is contaminated by micro-pollutants, such as ingredients of personal care products, pesticides and pharmaceuticals. This contamination is one of the major environmental issues of global concern. Adsorption is one of approach, which has been most extensively discussed within recent years for the reduction of the input of micro-pollutants into the environment. In the present study, the natural clay classified as Na-montmorillonite, was characterized and tested for its potential to remove four model compounds representing different polarity and ionizability: i) diatrizoic acid (DAT), ii) iopamidol (IOP), iii) metformin (MTF), and iv) carbamazepine (CBZ). The adsorption efficiency of clay was evaluated by initial compound concentration, effect of pH, contact time and temperature. The results indicated that clay was able to remove the pharmaceuticals from aqueous medium with an efficiency of 70% for CBZ and MTF. In contrast, clay showed a lower removal of 30% for DAT and no removal for IOP. The results indicate that clay could rapidly and efficiently reduce the concentration of CBZ and MTF, which could provide a solution to remove some substances, without undesirable by-product generation. However, this study clearly demonstrated that removal rates strongly depend on the compound. Albeit chemical structure may play a role for the different degree of removal, this study could not completely explain the sorption mechanism between sorbent-sorbate interactions.


Assuntos
Bentonita/química , Eliminação de Resíduos Líquidos/métodos , Poluentes Químicos da Água/análise , Adsorção , Carbamazepina , Argila , Concentração de Íons de Hidrogênio , Temperatura , Águas Residuárias
14.
Ecotoxicol Environ Saf ; 203: 110984, 2020 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-32888605

RESUMO

The use of water for drinking and agriculture requires knowledge of its toxicity. In this study, we compared the use of genetically modified bioluminescent (GMB) bacteria whose luminescence increases in the presence of toxicants and Chinese Hamster Ovary (CHO) cells for the characterization of the toxicity of water samples collected from a lake and streams, hydroponic and aquaponic farms, and a wastewater treatment plant. GMB bacteria were used to probe genotoxicity, cytotoxicity and reactive oxygen species-induced effects in the whole water samples. Unlike GMB bacteria, the use of CHO cells requires XAD resin-based pre-concentration of toxic material present in water samples for the subsequent cytotoxicity assay. In addition to the examination of the toxicity of the water from the different sources, the GMB bacteria were also used to test the XAD extracts diluted to the concentrations causing 50% growth inhibition of the CHO cells. The two biomonitoring tools provided different results when they were used to test the above-mentioned diluted XAD extracts. A pre-concentration procedure based on adsorption by XAD resins with subsequent elution was not sufficient to represent the material responsible for the toxicity of the whole water samples toward the GMB bacteria. Therefore, the use of XAD resin extracts may lead to major underestimates of the toxicity of water samples. Although the toxicity findings obtained using the GMB bacteria and CHO cells may not correlate with each another, the GMB bacteria assay did provide a mechanism-specific biomonitoring tool to probe the toxicity of water samples without a need for the pre-concentration step.


Assuntos
Bactérias , Monitoramento Biológico/métodos , Água Potável/análise , Lagos/análise , Rios , Águas Residuárias/análise , Animais , Bactérias/genética , Células CHO , Cricetulus , Hidroponia , Luminescência , Microrganismos Geneticamente Modificados/genética , Eliminação de Resíduos Líquidos
15.
Water Sci Technol ; 82(2): 281-291, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32941170

RESUMO

Biofilters based on earthworms-microorganisms represent, particularly in developing countries, an interesting alternative for domestic wastewater treatment due to their easy operation and low cost. However, there are several operational aspects that should be better understood in order to improve their performance. This paper studies the effect of using intermittent hydraulic loading rates to improve organic matter and nutrient removal from domestic wastewater using these biofilters. Three laboratory-scale columns, operating at a 2.5 m3 m-2day-1 hydraulic loading rate, were used. The B1-24 h, B2-8 h, B3-4 h column loading rates indicate that the columns were operated continuously for 24, 8 and 4 h, respectively. Each column (biomass biofilm/earthworms, redox potential, and head loss) and its corresponding operational performance parameters (TCOD, NH4+, NO3-, NO2-, TP) were monitored. The results showed that the B2-8 h intermittent hydraulic loading rate results in the best global performance, with 74%, 57%, and 20% average removal efficiencies for TCOD, nitrogen, and phosphorus, respectively. Moreover, it showed the best biomass growth (biofilm and earthworms), activity (as redox potential changes) and the lowest clogging effects (up to -1.0 cm). The intermittent operation influences the behavior of the earthworm-microorganism biofilters and offers the possibility of optimizing its global performance and achieving a resilient technology.


Assuntos
Oligoquetos , Águas Residuárias , Animais , Reatores Biológicos , Filtração , Nitrogênio/análise , Nutrientes , Fósforo , Eliminação de Resíduos Líquidos
16.
Water Sci Technol ; 82(2): 292-302, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32941171

RESUMO

Duckweed biomass production in a duckweed pond fed with three differently treated sewage (i.e. sewage treated by primary sedimentation (PS); conventional activated sludge process (CAS); and downflow hanging sponge process (DHS)) was evaluated in order to assess the effects of water quality on biomass yield. Higher and stable biomass production was observed when the duckweed pond was fed with PS or DHS-effluent than with CAS-effluent, evidently due to the difference in nutrient loads. Availability of nutrients, especially phosphorus, affected the biomass production rate: higher the nutrient, faster the production. Microbial community analysis revealed that the members of Rhizobiales were likely to contribute to stable and high biomass growth. From the results of the study, a sewage treatment system consisting of a primary sedimentation followed by a duckweed pond and a tertiary treatment unit can be proposed to maximize biomass production without compromising treatment objectives. Size and operational parameters of the duckweed pond should be determined primarily based on the nutrient availability in the influent water to maximize duckweed growth.


Assuntos
Araceae , Microbiota , Biomassa , Tanques , Esgotos , Eliminação de Resíduos Líquidos
17.
Water Sci Technol ; 82(2): 303-314, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32941172

RESUMO

The first full-scale semi-centralized wastewater treatment and resource recovery system based on source separation was implemented from 2014. To assess the operation performance, operating costs and resolve the problems faced in this system, the latest operation data from April 2017 to September 2018 was investigated. The results show that greywater and blackwater modules exhibited good removal performance for organics and nutrients, although misconnection between pipelines existed and influent loading rates fluctuated. The effluent could meet reuse standards. The biogas production rates of raw sludge could reach 7.27-10.9 m3 gas·per cubic raw sludge. The specific cost of treated water was higher than in a conventional treatment system. Power consumption made a major contribution to the total cost with a proportion of 55.3-94.2%. After optimizing and considering the comprehensive efficiencies, the costs would be affordable. The dewatered sludge of the anaerobic digestion module has been applied to agricultural and landscaping soil. It is suggested that organics in blackwater could be recovered as volatile fatty acids with high-efficiency anaerobic fermentation and used as an external carbon source for short-cut biological nitrogen removal. In conclusion, the semi-centralized system will be a feasible and sustainable alternative for conventional treatment systems in future.


Assuntos
Reatores Biológicos , Águas Residuárias , Ácidos Graxos Voláteis , Nitrogênio , Esgotos , Eliminação de Resíduos Líquidos
18.
Water Sci Technol ; 82(2): 315-329, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32941173

RESUMO

Reuse of wastewater, as well as recovery of valuable, toxic or harmful products in industrial discharges, still represents an important issue, not only because it reduces the effect on receiving water bodies, but also because of the economic resources it represents for industry itself. In this research, in situ regeneration of Mn2SO4 is evaluated, for its reuse as the main raw material in the original process of a fungicide plant. The regeneration is evaluated by selective recovery of Mn2+, Zn2+ and SO4= present in the wastewater produced by the industrial plant, and utilizing nanofiltration, electro-electrodialysis and chemical precipitation as separation alternatives. Each alternative was designed and evaluated technically and economically through simulations in Aspen Plus®, with data and information of the real process supplied by the company. Because zinc concentration is relatively low, its selective recovery was not attractive. The resulting Mn2SO4 solution and treated water quality in conventional alternatives were significantly poor with high costs. In contrast, nanofiltration and electro-electrodialysis alternatives generate water and by-products of higher quality and reuse potential with significantly lower costs. However, their viability depends on the membrane performance. The results were satisfactory, but future experimental studies are required to optimize the alternatives and define the correct pretreatment process.


Assuntos
Praguicidas , Purificação da Água , Compostos de Manganês , Sulfatos , Eliminação de Resíduos Líquidos , Águas Residuárias
19.
Water Sci Technol ; 82(2): 339-350, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32941175

RESUMO

This paper presents the sensitivity and uncertainty analysis of a plant-wide mathematical model for wastewater treatment plants (WWTPs). The mathematical model assesses direct and indirect (due to the energy consumption) greenhouse gases (GHG) emissions from a WWTP employing a whole-plant approach. The model includes: (i) the kinetic/mass-balance based model regarding nitrogen; (ii) two-step nitrification process; (iii) N2O formation both during nitrification and denitrification (as dissolved and off-gas concentration). Important model factors have been selected by using the Extended-Fourier Amplitude Sensitivity Testing (FAST) global sensitivity analysis method. A scenario analysis has been performed in order to evaluate the uncertainty related to all selected important model factors (scenario 1), important model factors related to the influent features (scenario 2) and important model factors related to the operational conditions (scenario 3). The main objective of this paper was to analyse the key factors and sources of uncertainty at a plant-wide scale influencing the most relevant model outputs: direct and indirect (DIR,CO2eq and IND,CO2eq, respectively), effluent quality index (EQI), chemical oxygen demand (COD) and total nitrogen (TN) effluent concentration (CODOUT and TNOUT, respectively). Sensitivity analysis shows that model factors related to the influent wastewater and primary effluent COD fractionation exhibit a significant impact on direct, indirect and EQI model factors. Uncertainty analysis reveals that outflow TNOUT has the highest uncertainty in terms of relative uncertainty band for scenario 1 and scenario 2. Therefore, uncertainty of influential model factors and influent fractionation factors has a relevant role on total nitrogen prediction. Results of the uncertainty analysis show that the uncertainty of model prediction decreases after fixing stoichiometric/kinetic model factors.


Assuntos
Gases de Efeito Estufa , Águas Residuárias , Análise da Demanda Biológica de Oxigênio , Nitrogênio , Incerteza , Eliminação de Resíduos Líquidos
20.
Water Sci Technol ; 82(2): 364-372, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32941177

RESUMO

Aerobic granular sludge process as a promising biotechnology has been one of the research hotspots in the area of wastewater treatment during the last two decades. In our study, after around 60 days' operation, filamentous granular sludge (FGS) was formed under low aeration (SAV = 0.085 cm/s) and multi-feeding conditions. The characteristics of FGS and the performance of the FGS system for organic matter and nutrients removal were investigated. The results showed that chemical oxygen demand (COD) and total organic carbon (TOC) removal efficiencies were relatively stable, while COD removal efficiency increased from 82% to 94% in the presence of sulfamethoxazole (SMZ) at low concentration (1 mg/L). At the same time, the TP removal efficiency could be improved and maintained at around 75%, while TN removal efficiency was flocculated at around 50%. The analysis of microbial diversity showed that Thiothrix and Trichococcus as typical filamentous species were detected and dominant in the FGS system. The abundance of Thiothrix increased from 15% to 34%, while Trichococcus decreased from 23% to 3% in the presence of SMZ.


Assuntos
Esgotos , Eliminação de Resíduos Líquidos , Aerobiose , Análise da Demanda Biológica de Oxigênio , Reatores Biológicos , Nitrogênio , Águas Residuárias
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