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1.
J Environ Qual ; 49(3): 545-556, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-33016384

RESUMO

Water reuse is believed to be a sustainable solution to overcome the scarcity of freshwater. Aerobic and anaerobic membrane bioreactors are becoming an effective technology for wastewater treatment and reuse. Aerobic membrane bioreactors show good nutrient removal, whereas those that are anaerobic have nutrient-rich effluent, enabling the direct agricultural use of the effluent. As a result, the end use will dictate the potential environmental impacts of the bioreactor's application. Therefore, with the consideration of the end use (i.e., discharge or reuse) of the effluent, this study aimed to compare the environmental and economic impacts associated with full-scale aerobic and anaerobic membrane bioreactors for municipal wastewater treatment under different end use scenarios using life cycle assessment and cost analysis. The results of these analyses show that anaerobic bioreactors have greater environmental impacts and life cycle cost than aerobic bioreactors in the discharge scenario due to the incorporation of a biological nutrient removal system. In the reuse scenario, anaerobic membrane bioreactors have lower impacts that are attributable to the offset of the nutrients required for crops, and the potential benefits vary depending on the types of crops receiving the reclaimed water. Integrating anaerobic membrane bioreactors with agricultural fertigation resulted in effluent water nitrate concentrations (after crop uptake and soil treatment) of <2 mg L-1 in most U.S. states. This indicated that the use of the anaerobic membrane bioreactors effluent for fertigation could be a win-win solution to both irrigation water shortage and high environmental impact associated with nutrient removal.


Assuntos
Purificação da Água , Anaerobiose , Reatores Biológicos , Água Doce , Águas Residuárias
2.
J Environ Qual ; 49(3): 517-533, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-33016389

RESUMO

Nutrient pollution is considered a wicked problem because of its many significant economic, social, and environmental impacts that are caused by multiple pollutants originating from a variety of sources and pathways that exist across different temporal and spatial scales. Further adding to the difficulty in managing nutrient pollution is that it is a global, rural, and urban problem. A systems approach can improve nutrient management by incorporating technological, environmental, and societal considerations. This approach can consider valuation of monetized and nonmonetized co-benefits and the inherent consequences that make up a nutrient management program. In this introduction to a special collection of papers on nutrient pollution, we describe several systems frameworks that can be used to support nutrient management and evaluation of system performance as it relates to impacts, then highlight several attributes and barriers of nutrient management that point to the need for a systems framework, and conclude with thoughts on implementing systems approaches to nutrient management with effective community engagement and use of new technologies. This special collection presents results from a USEPA Science to Achieve Results (STAR) initiative to advance solutions to nutrient pollution through innovative and sustainable research and demonstration projects for nutrient management based on a systems approach. These studies evaluate several promising nutrient control technologies for stormwater or domestic wastewater, investigate the effects of agricultural conservation practices and stream restoration strategies on nutrient loads, and discuss several challenges and opportunities-social, policy, institutional, and financial considerations-that can accelerate adoption of reliable technologies to achieve system-level outcomes.


Assuntos
Nutrientes , Rios , Agricultura , Análise de Sistemas , Águas Residuárias
3.
J Environ Qual ; 49(3): 534-544, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-33016405

RESUMO

Many states are adopting more stringent nutrient load restrictions, requiring utilities to invest in costly improvements. To date, substantial research has been done to independently assess the nutrient removal efficacy of wastewater treatment technologies and stormwater control measures. The analysis presented here provides a unique assessment by evaluating combinations of nutrient load reduction strategies across water supply, wastewater, and stormwater sectors. A demonstration study was conducted evaluating 7812 cross-sector removal strategies in the urban water system using empirical models to quantify efficacy of common wastewater treatment, water management, and stormwater control measures (SCMs). Pareto optimal solutions were evaluated to identify the most cost-effective strategies. To meet stringent nutrient requirements, wastewater treatment facilities (WWTFs) will likely require advanced biological nutrient removal with carbon and ferric addition. Even with these technologies, WWTFs may still be unable to obtain target nutrient requirements. In addition, municipalities can consider water management practices and SCMs to further reduce nutrient loading or provide a more cost-effective nutrient removal strategy. For water management practices, source separation and effluent reuse were frequently identified as part of the most effective nutrient strategies but face engineering, political, and social adoption barriers. Similarly, SCMs were frequently part of effective nutrient removal strategies compared to only adopting nutrient removal practices at WWTFs. This research provides the framework and demonstrates the value in using an urban water system approach to identify optimal nutrient removal strategies that can be easily applied to other urban areas.


Assuntos
Nutrientes , Água , Cidades , Análise Custo-Benefício , Águas Residuárias
4.
J Environ Qual ; 49(5): 1322-1333, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-33016441

RESUMO

Antibiotics and estrogens are recognized as emerging contaminants in the water environment because of their potentially adverse effects on aquatic ecosystems. The concentrations of four steroid estrogens (17α-estradiol, 17ß-estradiol, estrone, and estriol) and eight antibiotics (norfloxacin, levofloxacin, ciprofloxacin, enrofloxacin, metronidazole, sulfapyridine, doxycycline, and sulfamethoxazole) in the Chaohu Lake basin in Anhui province, China, were analyzed along with adjacent wastewater. The levels of the target antibiotics and estrogens were below detection limits (not detected [nd])-89.86 and nd-118.09 ng L-1 , respectively, in the lake water. All of the target antibiotics and estrogens were detected in sediment, and the concentrations ranged widely (nd-35,544 and nd-16,344 ng kg-1 , respectively). Antibiotics and estrogens varied spatially in the study area and mostly came from untreated wastewater. Antibiotics and estrogens were associated with water parameters such as pH and total nitrogen. A significant positive correlation was observed between estriol and levofloxacin concentrations (r = .65; p < .01), indicating that levofloxacin from the same source might have inhibited the microbiological degradation of estriol in the surface water. Overall, the estrogens pose a more severe risk than antibiotics to the Chaohu Lake system. However, co-occurrence of antibiotics may affect the fate of estrogens in the same lake media. More attention should be given to estrogens than to antibiotics in wastewater-affected lake systems.


Assuntos
Águas Residuárias , Poluentes Químicos da Água/análise , Antibacterianos/análise , China , Ecossistema , Monitoramento Ambiental , Estrogênios/análise , Lagos/análise
5.
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
6.
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
7.
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
8.
Water Sci Technol ; 82(5): 829-842, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-33031063

RESUMO

A high-surface-area and inexpensive activated carbon has been produced from lemon peel using chemical activation with H3PO4 at 500 °C in a N2 atmosphere. Afterwards, the synthesized cobalt nanoparticles using coprecipitation method were adsorbed on the activated carbon surface, and as a result magnetic activated carbon was obtained. Sample characterization has been assessed via X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, X-ray photoelectron spectroscopy, nitrogen adsorption-desorption and magnetic properties. It was found that magnetic activated carbon-cobalt nanoparticles (MAC/Co) synthesized had a high saturation magnetization. The MAC/Co revealed super-paramagnetic behaviors at room temperature, and have been readily isolated from solution by using an exterior magnet. Next, adsorption behavior of malachite green and Pb(II) onto the generated MAC/Co has been examined. Sorption kinetics and equilibrium have been studied using batch procedure. The kinetic and isothermal adsorption results were matched completely with the Elovich and Langmuir models, respectively. Based on the Langmuir model, the highest adsorption capacities of malachite green dye and Pb(II) ion respectively were 263.2 and 312.5 mg g-1 at room temperature. Based on the results, the MAC/Co is a probable economic and effective adsorbent that can be employed as a new adsorbent to remove malachite green dye and Pb(II) from wastewater.


Assuntos
Nanopartículas , Poluentes Químicos da Água , Carvão Vegetal , Cobalto , Chumbo , Fenômenos Magnéticos , Corantes de Rosanilina , Águas Residuárias , Poluentes Químicos da Água/análise
9.
Water Sci Technol ; 82(5): 851-860, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-33031065

RESUMO

The microalgae treatment system is an economically and environmentally friendly option for wastewater treatment. However, the effects of heavy metal toxicity on microalgae cells can limit the use of microalgae in the treatment of industrial effluents rich in heavy metals. In this work, we studied the effect of Ni, Cu, Al, Hg and Pb, added as single-metal solutions to the microalgae culture medium, on the growth of 20 indigenous strains belonging to a wide variety of microalgae genera. Ni and Cu were the most toxic to the strains tested. A highly tolerant strain of the Phacus genera was selected. We determined the effect of multiple combinations of Ni, Al and Pb on the cell growth of the selected strain and on the removal capacity of each metal from the microalgae culture medium. Phacus was able to grow in the multi-metal solution (Ni, 5.00 mg/L; Al, 9.94 mg/L and Pb 1.00 mg/L) and to efficiently remove the metals, with removal capacities of 8.82 ±0.16 mg/g for Ni, 2.09 ± 0.05 mg/g for Pb and 16.90 ± 0.53 mg/g for Al. The reductions of Ni, Al and Pb concentrations were 66.67, 64.28 and 79.17% respectively.


Assuntos
Metais Pesados , Microalgas , Biodegradação Ambiental , Chumbo/toxicidade , Metais Pesados/análise , Metais Pesados/toxicidade , Águas Residuárias
10.
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
11.
Water Sci Technol ; 82(5): 887-904, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-33031068

RESUMO

The effectiveness of two Azadirachta indica bark activated carbons (ABAC) for the removal of selected toxic metals from mining wastewater and the attendant challenge of multivariate factors in the process were enhanced through optimization studies. Experimental design was carried out using adsorbent dosage, agitation rate, contact time, grain size, pH and temperature as independent variables. Batch adsorption experiments were conducted using the experimental design result, then the experimental data obtained were optimized using Design-Expert software and the results validated. Optimum values for ABAC-NaOH adsorbent were 1.999 g of adsorbent dosage, 149.73 rpm agitation rate, 119.55 min contact time, 2 mm grain size, pH of 7 and 30 °C temperature; while for ABAC-HCl adsorbent the optimum values were 3.993 g of adsorbent dosage, 150 rpm agitation rate, 120 min contact time, 2 mm grain size, pH of 7.001 and 30 °C temperature. These resulted in 100% removal efficiencies for all the selected toxic metals with standard errors of between 0.02 and 2.72%. So the optimization process is a very useful tool in adsorption studies. It has the merits of being economical, energy and time saving, and is therefore strongly recommended for the biosorption of toxic metals from mining wastewater using Azadirachta indica adsorbent.


Assuntos
Azadirachta , Águas Residuárias , Concentração de Íons de Hidrogênio , Metais , Mineração , Casca de Planta
12.
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
13.
Water Sci Technol ; 82(5): 927-939, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-33031071

RESUMO

UV/Vis spectrometers are powerful tools for online monitoring of wastewater constituents and processes. However, most studies only focus on typical parameters such as chemical oxygen demand (COD) and total suspended solids. This work presents a multi-parameter approach for calibration of a UV/Vis spectrometer for online monitoring of sewer systems. Parameters studied include soluble and total COD, nitrate, ammonium, sulphate and orthophosphate, as well as total dissolved sulphide, bisulphide and hydrogen sulphide, because they are one of the main causes for odour and corrosion in sewer systems. Two calibration methods are compared: multiple linear regression included in the manufacturer's software, and partial least square (PLS) computed using the pls package of the R library. Performance of the methods is evaluated for calibration and validation data sets employing four different criteria: relative root mean square error (RMSErel), RMSE-observations standard deviation ratio, Nash-Sutcliffe efficiency and percentage bias. A method-parameter dependency was revealed during the calibration phase but, when predicting new data, the PLS method showed higher robustness for almost all parameters. Both methods were able to predict concentration trends associated with sewer processes, some of which are strongly correlated to the sulphide species.


Assuntos
Águas Residuárias , Análise da Demanda Biológica de Oxigênio , Calibragem , Análise dos Mínimos Quadrados , Espectrofotometria Ultravioleta
14.
Water Sci Technol ; 82(5): 967-983, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-33031074

RESUMO

An easy-to-use, pollution-free and reusable beaded NiOx(OH)y catalyst for improving hypochlorite oxidation was prepared by impregnating the mixture of persulfate and alkali over alumina and then reduced it with Ni2+. The effects of catalyst preparation conditions and reaction parameters on NaClO conversion rate and Ni2+ dissolution rate were studied. Impregnating the γ-Al2O3 beads in PS/OH- mixed solution with 0.59 M PS and PS/OH- molar ratio of 1.1, and then reducing with 0.8 M Ni2+ solution is the best condition for preparing catalyst. The catalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The best catalytic layer is characterized by high content of chemisorbed oxygen which can be converted into atomic oxygen. The hypochlorite conversion rate increased with the catalyst dosage and reuse times, and decreased with available chlorine, while pH of hypochlorite solution had little effect on the conversion rate. After running stably for 120 h in continuous flow test, the chemisorbed oxygen content in the optimal catalytic layer decreased slightly. Atomic oxygen plays an important role in the decolorization of dye solution by NaClO/NiOx(OH)y system. The oxidant consumption cost of this process is much cheaper than Fenton reagent. The prepared catalyst has great potential in hypochlorite decomposition and wastewater treatment.


Assuntos
Ácido Hipocloroso , Águas Residuárias , Catálise , Oxirredução , Difração de Raios X
15.
Environ Monit Assess ; 192(11): 700, 2020 Oct 12.
Artigo em Inglês | MEDLINE | ID: mdl-33047214

RESUMO

To investigate the possible impact of the traffic flow of mountainous roads and the construction and operation of a long tunnel on the water quality of a reservoir, this study conducts statistical analysis on water quality, meteorological, and traffic data of the Feitsui Reservoir and its upstream tributaries over the last three decades. Results from statistical regression analysis indicate that in the upstream area where the traffic flow is low, water quality varies insignificantly with rainfall and traffic flow, providing as a background reference of natural environment. Water quality near a conventional highway on which many vehicles travel through the catchment area is significantly affected by both rainfall and traffic flow since the drainage system of a conventional highway sends its gathered water into adjacent rivers. Not only does traffic flow generate contaminants, but also the construction of the Hsuehshan Tunnel of the No. 5 Expressway, Taiwan, in the catchment area of the Feitsui Reservoir generates pollution. Drainage, silt settling and retarding basin, and wastewater treatment facilities near the construction site mitigate the impact of tunnel construction and traffic flow on the environment. The No. 5 Expressway makes good use of viaduct and tunnel structures, collecting water from pavements within the catchment area into sewage facilities, filtering it, and then emitting it outside the catchment area, forming a closed system over the Feitsui Reservoir. The Expressway now shortens travel time from two hours to 40 min and accommodates 7-13 times previous traffic flows, insignificant influencing water quality in the upstream tributaries of the reservoir, demonstrating the effectiveness of its environmental protection measures.


Assuntos
Monitoramento Ambiental , Qualidade da Água , Rios , Taiwan , Águas Residuárias
16.
Water Sci Technol ; 82(6): 1025-1030, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-33055393

RESUMO

Microalgae can synthesise the ozone depleting pollutant and greenhouse gas nitrous oxide (N2O). Consequently, significant N2O emissions have been recorded during real wastewater treatment in high rate algal ponds (HRAPs). While data scarcity and variability prevent meaningful assessment, the magnitude reported (0.13-0.57% of the influent nitrogen load) is within the range reported by the Intergovernmental Panel on Climate Change (IPCC) for direct N2O emissions during centralised aerobic wastewater treatment (0.016-4.5% of the influent nitrogen load). Critically, the ability of microalgae to synthesise N2O challenges the IPCC's broad view that bacterial denitrification and nitrification are the only major cause of N2O emissions from wastewater plants and aquatic environments receiving nitrogen from wastewater effluents. Significant N2O emissions have indeed been repeatedly detected from eutrophic water bodies and wastewater discharge contributes to eutrophication via the release of nitrogen and phosphorus. Considering the complex interplays between nitrogen and phosphorus supply, microalgal growth, and microalgal N2O synthesis, further research must urgently seek to better quantify N2O emissions from microalgae-based wastewater systems and eutrophic ecosystems receiving wastewater. This future research will ultimately improve the prediction of N2O emissions from wastewater treatment in national inventories and may therefore affect the prioritisation of mitigation strategies.


Assuntos
Gases de Efeito Estufa , Microalgas , Ecossistema , Óxido Nitroso/análise , Águas Residuárias/análise
17.
Water Sci Technol ; 82(6): 1031-1043, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-33055394

RESUMO

This study evaluated the capacity of a pilot-scale high-rate algal pond (HRAP) to remove pharmaceutical compounds (PCs) from domestic wastewater in the city of Santiago de Cali, Colombia. The compounds analyzed included antiepileptics, hypolipidemic drugs, tranquilizers and analgesics, and anti-inflammatory drugs. The HRAP operated under a continuous water flow of 0.2 m3d-1 and a 3-day hydraulic retention time (HRT). Removal efficiencies were high (>70%) for fenofibric acid, ibuprofen, and paracetamol; medium (30-70%) for gabapentin, lamotrigine, fenofibrate, gemfibrozil, diclofenac, ketoprofen, naproxen, and pentoxifylline; and low (<30%) for carbamazepine and its metabolite 10,11-Dihidro-10,11-dihidroxicarbamazepine (CBZ-Diol). The findings herein are similar to other studies, but were obtained with a shorter HRT. These results show that tropical environmental conditions favor photodegradation and contribute to the development of microalgae and the biodegradation process. Twenty microalgae species were identified, with the phylum Chlorophyta as the most abundant, particularly due to its natural introduction. The removal of the PCs also reflected a percentage reduction (>50%) in the ecological hazard posed by most of the compounds, although it is important to note that the hazard from gemfibrozil and ibuprofen remained high even after treatment, indicating the need for complementary treatment.


Assuntos
Águas Residuárias , Poluentes Químicos da Água , Colômbia , Tanques , Clima Tropical , Eliminação de Resíduos Líquidos , Poluentes Químicos da Água/análise
18.
Water Sci Technol ; 82(6): 1044-1061, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-33055395

RESUMO

This study evaluates the feasibility of advanced biofilm microalgae cultivation in a twin layer (TL) system for nutrient removal (N and P) as the tertiary treatment in small wastewater treatment plants (WWTPs) located in sensitive areas. Furthermore, the potential valorisation of microalgae biomass as a component of bio-based fertilizers is assessed. Scenedesmus sp. was chosen among 33 microalgae strains for inoculation of TL due to its high growth rate and its nutrient uptake capacity. The tests carried out in the prototype were markedly efficient for total soluble and ammoniacal nitrogen removal (up to 66 and 94%, respectively). In terms of potential valorisation of microalgae, the nutrient content was 5.5% N (over 40% protein), 8.8% P2O5 and 1.5% K2O, high enzymatic activity, very low levels of heavy metals and no detectable pathogen presence. However, in the formulation of solid-state bio-based fertilizers, the microalgae proportions in blends of over 2% of microalgae led to negative effects on ryegrass (Lolium perenne L. ssp.) and barley (Hordeum vulgare ssp.). The obtained results demonstrate that TL represents a promising technology, which allows efficient tertiary treatment of urban wastewater and the production of high-quality bio-based fertilizer.


Assuntos
Microalgas , Scenedesmus , Biomassa , Nutrientes , Águas Residuárias
19.
Water Sci Technol ; 82(6): 1062-1069, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-33055396

RESUMO

High rate algal ponds (HRAPs) are shallow, mixed systems for wastewater treatment, which use sunlight exposure for disinfection. Little is known regarding the relationships between the bacteria and viruses within HRAP systems. Uniquely, flow cytometry permits the rapid identification of bacterial and viral populations in wastewater samples, separating populations based on genome and particle size. Treated wastewater samples were collected from an HRAP at Kingston on Murray, South Australia. Flow cytometry analysis detected bacterial populations and discriminated virus-like particles (VLP) and large VLP (LVLP). Rapid, short term, fluctuations in the abundance of all three populations were observed. Changes in the abundance of these populations was compared; wastewater composition was used as metadata for the comparisons. Linear regression determined relationships in abundances between bacteria and LVLP (R2 0.2985); LVLP and VLP (R2 0.5829) and bacteria and VLP (R2 0.5778) all with p-values of <0.001. Bacterial, LVLP and VLP abundance positively correlated with each other, indicating potential microbial interactions. Overall, the results suggest a parasitic relationship was occurring and driving the abundances of bacteria and viruses within the system.


Assuntos
Tanques , Eliminação de Resíduos Líquidos , Citometria de Fluxo , Austrália do Sul , Águas Residuárias
20.
Water Sci Technol ; 82(6): 1070-1080, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-33055397

RESUMO

A novel coupling process using an aerobic bacterial reactor with nitrification and sulfur-oxidization functions followed by a microalgal reactor was proposed for simultaneous biogas desulfurization and anaerobic digestion effluent (ADE) treatment. ADE nitrified by bacteria has a potential to be directly used as a culture medium for microalgae because ammonium nitrogen, including inhibitory free ammonia (NH3), has been converted to harmless NO3-. To demonstrate this hypothesis, Chlorella sorokiniana NIES-2173, which has ordinary NH3 tolerance; that is, 1.6 mM of EC50 compared with other species, was cultivated using untreated/treated ADE. Compared with the use of a synthetic medium, when using ADE with 1-10-fold dilutions, the specific growth rate and growth yield maximally decreased by 44% and 88%, respectively. In contrast, the algal growth using undiluted ADE treated by nitrification-desulfurization was almost the same as with using synthetic medium. It was also revealed that 50% of PO43- and most metal concentrations of ADE decreased following nitrification-desulfurization treatment. Moreover, upon NaOH addition for pH adjustment, the salinity increased to 0.66%. The decrease in metals mitigates the bioconcentration of toxic heavy metals from wastewater in microalgal biomass. Meanwhile, salt stress in microalgae and limiting nutrient supplementation, particularly for continuous cultivation, should be of concern.


Assuntos
Chlorella , Microalgas , Anaerobiose , Nitrificação , Águas Residuárias
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