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1.
Bioresour Technol ; 301: 122672, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31945681

RESUMO

The objective of this study was to evaluate the performance of an outdoor membrane-coupled high-rate algal pond equipped with industrial-scale membranes for treating urban wastewater. Decoupling biomass retention time (BRT) and hydraulic retention time (HRT) by membrane filtration resulted in improved process efficiencies, with higher biomass productivities and nutrient removal rates when operating at low HRTs. At 6 days of BRT, biomass productivity increased from 30 to 66 and to 95 g·m-3·d-1 when operating at HRTs of 6, 4 and 2.5 days, respectively. The corresponding nitrogen removal rates were 4, 8 and 11 g N·m-3·d-1 and the phosphorous removal rates were 0.5, 1.3 and 1.6 g P·m-3·d-1. The system was operated keeping moderate specific air demands (0.25 m3·m-2·h-1), resulting in reasonable operating and maintenance costs (€0.04 per m3) and energy requirements (0.29 kWh per m3). The produced water was free of pathogens and could be directly used for reusing purposes.


Assuntos
Águas Residuárias , Purificação da Água , Biomassa , Nitrogênio , Tanques , Eliminação de Resíduos Líquidos
2.
J Environ Manage ; 258: 110039, 2020 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-31929073

RESUMO

Water scarcity is a global issue that is threatening social and economic development. One approach to alleviating scarcity is the incorporation of new water sources into supply systems, including desalinated seawater for industrial and municipal use. In Chile, large volumes of water are used in water-scarce regions where mining takes place, alongside agriculture and small communities. This situation has driven a debate around policies to increase the use of seawater to satisfy the water demand of the mining industry. The economic, social and environmental implications of such a policy, however, are poorly understood and the current regulatory framework to address concerns and uncertainties is inadequate. This paper presents a technical, legal, economic and environmental appraisal of such a policy and considers options to improve outcomes. The appraisal suggests that clear regulations derived from economic, social and environmental analysis must be generated to provide legal certainty and reduce risks. Alternative or complementary water supply options should be allowed where mining operations can demonstrate negligible hydrological and social impacts or use innovative solutions such as stakeholder water rights swaps and water efficiency technologies. We provide insight that will help to drive a better policymaking process aimed at tackling water scarcity in Chile and in similar areas of the world.


Assuntos
Purificação da Água , Água , Chile , Política Pública , Abastecimento de Água
3.
Water Res ; 171: 115472, 2020 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-31931379

RESUMO

Microbial extracellular polymeric substances (EPS) have gained increasing attention for various water treatment applications. In this study, EPS produced from nitrogen-limited glycerol/ethanol-rich wastewater were used to recover Cu2+ and Pb2+ from aqueous solutions. Continuous flow-through tests were conducted on a column packed with silica gel coated with polyethyleneimine, to which EPS were irreversibly attached as shown by optical reflectometry. These immobilised EPS excellently adsorbed Cu2+ and Pb2+, with 99.9% of influent metal adsorbed before the breakthrough points. Metal desorption was achieved with 0.1M HCl, with an average recovery of 86% for Cu2+ and 90% recovery for Pb2+. For the first time, we successfully showed the possibility to regenerate and reuse the immobilised EPS for five adsorption-desorption cycles (using Cu2+ as an example) with no reduction in the adsorbed amount at the breakthrough point (qbp). Based on the mass balance of the associated metal ions participating in the adsorption process, ion exchange was identified as the major mechanism responsible for Cu2+ and Pb2+ adsorption by EPS. The results demonstrate the potential of wastewater-produced EPS as an attractive and perhaps, cost-effective biosorbent for heavy metal removal (to trace effluent concentrations) and recovery (86-99%).


Assuntos
Metais Pesados , Poluentes Químicos da Água , Purificação da Água , Adsorção , Concentração de Íons de Hidrogênio , Polímeros
4.
J Environ Manage ; 256: 109740, 2020 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-31989972

RESUMO

Among hazardous pollutants, 2,4-Dinitrophenol (2,4-DNP) is considered highly toxic and possesses a remarkable resistance to degradation. Therefore, investigation of the possible mechanisms for removal of such pollutants is important. Laccase enzyme can decompose phenolics despite the fact that its application has been limited due to lack of possibility to reuse it. Immobilization can overcome this problem. In this paper, laccase complexes with montmorillonite K10 and zeolite were used to decompose 2,4-DNP with concentrations of 1.5 mg l-1 and 50 mg kg-1 in synthetic wastewater and soil, respectively. The maximum removal of pollutant from wastewater in samples containing laccase-zeolite and laccase-montmorillonite complexes were 99 and 93.3%, respectively, which occurred at 4 h incubation compared with 6 h for free laccase. The maximum removal of pollutant from soil was observed for all treatments after 16 h of incubation. The maximum removal for samples containing free laccase, laccase-zeolite, and laccase-montmorillonite complexes were 98.5%, 98.6%, and 90.4%, respectively. Control sample also showed maximum removal of 35.8%. In general, application of laccase-zeolite complexes in aqueous environment, and these complexes and free laccases in soil was found very effective in degradation of 2,4-DNP. Hence, the use of laccase, especially immobilized laccases, for removal of 2,4-DNP from environment is promising.


Assuntos
Lacase , Purificação da Água , 2,4-Dinitrofenol , Enzimas Imobilizadas , Solo , Águas Residuárias
5.
J Environ Manage ; 256: 109943, 2020 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-31989978

RESUMO

Magnetic graphene oxide-titanate composites (MGO@TNs) were synthesized via growing titanate nanosheets on the graphene oxide sheets with magnetite nanoparticles anchored on. The as-prepared MGO@TNs showed a hierarchical structure and large specific surface area (193.4 m2/g), which were suitable for rapid and effective adsorption of Pb(II) from wastewater. Moreover, the loaded magnetite nanoparticles guaranteed the effective magnetic separation of MGO@TNs, avoiding secondary pollution. The adsorption mechanism were illuminated to be ion exchange and surface complexation. Batch adsorption experiments showed the maximum adsorption capacity of MGO@TNs reached 322.7 mg/g for Pb(II) removal. The removal efficiency retained 89.6% after six adsorption-desorption cycles. In addition, the efficiency reached up to 99.8% when applying MGO@TNs for removal of Pb(II) from simulated realistic battery wastewater, ensuring the safe discharge of treated water. The good adsorption performance, recyclability and easy magnetic separation ability made sure that the MGO@TNs has great potential for purification of Pb(II) contaminated wastewater.


Assuntos
Poluentes Químicos da Água , Purificação da Água , Adsorção , Grafite , Cinética , Chumbo , Fenômenos Magnéticos , Águas Residuárias
6.
J Environ Manage ; 256: 109964, 2020 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-31989983

RESUMO

The contamination of water resources by nitrate is a global problem. Indeed, traditional treatment technologies are not able to remove this ion from water. Alternatively, biological denitrification is a useful technique for natural water nitrate removal. This study aimed to evaluate the use of glycerol as a carbon source for drinking water nitrate removal via denitrification in a reactor using microorganisms from natural biomass. The experiment was carried out in a continuous fixed bed reactor using immobilised microorganisms from the vegetal Phyllostachys aurea. The tests were started in batch mode to provide cells growth and further immobilisation on the support. Then, the treatment experiments were accomplished in an up-flow continuous reactor. Ethanol was used as the primary carbon source, and it was gradually replaced by glycerol. The C:N (carbon to nitrogen) ratio and the hydraulic residence time (HRT) were evaluated. It was possible to remove 98.14% of nitrate using a C:N ratio and HRT of 3:1 and 1.51 days, respectively. The results have demonstrated that glycerol is a potential carbon source for denitrification in a continuous reactor using immobilised cells from natural biomass.


Assuntos
Água Potável , Purificação da Água , Biomassa , Reatores Biológicos , Carbono , Desnitrificação , Glicerol , Nitratos , Nitrogênio
7.
J Environ Manage ; 256: 109969, 2020 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-31989986

RESUMO

This study reports a new inorganic-organic composite membrane fabricated by an electrostatic self-assembling method. The low-cost and eco-friendly porous geopolymer (PG) was chosen as a support, on which chitosan (CS), a "green" biomaterial, was used to form an active layer. With optimum dosage of CS (2.0 mL of 1.0% CS solution), the obtained CS/PG membrane exhibited a high porosity of 50.97% with an average pore diameter of 13.93 nm as well as a high water flux of 1663.82 ± 22.46 L/m2·h·bar. The effects of initial concentration, pH, flow rate and temperature of the feed solution on crystal violet (CV) removal by the CS/PG were evaluated in a continuous mode. The results indicated ~95% CV could be removed from water during continuous treating of 14 h. The effectiveness in CV removal by the CS/PG membrane was attributed to the synergistic effect of rejection and adsorption. Furthermore, the composite membrane could be easily regenerated for prolonged use. Overall, this work opens a new possibility of building cost-saving and eco-friendly composite membranes for practical applications in water purification.


Assuntos
Quitosana , Poluentes Químicos da Água , Purificação da Água , Adsorção , Concentração de Íons de Hidrogênio , Cinética
8.
Chemosphere ; 242: 125268, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31896175

RESUMO

This study investigated chlorinated transformation products (TPs) and their parent micropollutants, aromatic pharmaceuticals and personal care products (PPCPs) in the urban water bodies of two metropolitan cities. Nine PPCPs and 16 TPs were quantitatively or semi-quantitatively determined using isotope dilution techniques and liquid chromatography-tandem mass spectrometry. TPs and most PPCPs were effectively removed by conventional wastewater treatments in a wastewater treatment plant (WWTP). Chlorinated parabens and all PPCPs (at concentrations below 1000 ng/L) were present in the waters receiving treated wastewater. By contrast, the waters receiving untreated wastewater contained higher levels of PPCPs (up to 9400 ng/L) and more species of chlorinated TPs including chlorinated parabens, triclosan, diclofenac, and bisphenol A. The very different chemical profiles between the water bodies of the two cities of similar geographical and climatic properties may be attributed to their respective uses of chemicals and policies of wastewater management. No apparent increase in the number of species or abundances of TPs was observed in either the chlorinated wastewater or the seawater rich in halogens. This is the first study to elucidate and compare the profiles of multiple TPs and their parent PPCPs in the water bodies of coastal cities from tropical islands. Our findings suggest that chlorinated derivatives of bisphenol A, diclofenac, triclosan, and parabens in the surface water originate from sources other than wastewater disinfection or marine chlorination. Although further studies are needed to identify the origins, conventional wastewater treatments may protect natural water bodies against contamination by those chlorinated substances.


Assuntos
Desinfecção/métodos , Monitoramento Ambiental/métodos , Água do Mar/química , Águas Residuárias/química , Poluentes Químicos da Água/análise , Purificação da Água/métodos , Cromatografia Líquida , Cidades , Cosméticos/análise , Halogenação , Preparações Farmacêuticas/análise , Taiwan
9.
Chemosphere ; 242: 125259, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31896176

RESUMO

Activated carbon (AC), prepared from dried loofah sponge, was supported on nickel foam to fabricate AC/Ni electrodes. The characteristics of ammonium electrosorption on AC/Ni electrodes was studied. Results showed that AC prepared in one-step activation (without pre-pyrolysis), i.e., OAC, had relatively low crystallinity, high mesoporosity, and high specific capacitance compared to those made in two-step carbonation followed by activation. Adsorption and desorption density of NH4+ were measured at constant potential of -1.0 V (vs. Hg/HgO) and +0.1 V (vs. Hg/HgO), respectively. Non-faradaic charging contributed to the electrochemical storage and adsorption of ammonium ions on the AC surface with a maximal charge efficiency of 80%, at an applied potential of -1.0 V (vs. Hg/HgO). Multiple-layer adsorption isotherm better described the electrosorption of ammonium ion on OAC/Ni electrodes yielding a maximum adsorption capacity of 6 mg-N g-1, which was comparable with other similar systems. Overall, results clearly demonstrated the effect of synthesis strategy on the capacitive charging behaviors of AC/Ni electrodes and its relationship to NH4+ electrosorption.


Assuntos
Compostos de Amônio/análise , Carvão Vegetal/química , Luffa/química , Níquel/química , Poluentes Químicos da Água/análise , Purificação da Água/métodos , Adsorção , Capacitância Elétrica , Eletrodos , Íons , Modelos Teóricos , Propriedades de Superfície
10.
Chemosphere ; 242: 125287, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31896200

RESUMO

A novel electrospun dual-responsive polyethersulfone-poly(dimethyl amino) ethyl methacrylate nanofibrous adsorbent was fabricated via electrospinning for the removal of Cu (II) from aqueous solution. Morphological, chemical, and dual-responsiveness of the composite nanofibrous adsorbent were characterized using scanning electron microscope equipped with energy dispersive x-ray, Fourier transform infrared, and UV-VIS spectrophotometer, respectively. The obtained uniform and bead-free nanofibers were then used for the removal of Cu (II) from aqueous solution. Results showed that the temperature-responsiveness of the nanofibers is dependent on the pH of the solution, as indicated by the decreasing lower critical solution temperature with increasing pH level. Temperature and pH offer a synergistic effect on the adsorption of Cu (II), with maximum adsorption observed at pH 6.5 at 55 °C. Kinetic, thermodynamic, and isotherm studies indicate that the adsorption of copper ions follows chemisorption and is thermodynamically favored at increasing temperature. From the Langmuir isotherm model, the obtained maximum adsorption capacity, qm, was 161.30 mg g-1 at 55 °C. From the desorption studies, results showed that the maximum desorption was observed at pH 3 at 25 °C. In conclusion, PES-PDMAEMA has the capability to adsorb and desorb Cu (II) by adjusting both pH and temperature, hence it can be considered as an efficient and economical adsorbent for heavy metals such Cu (II).


Assuntos
Cobre/análise , Metacrilatos/química , Nanofibras/química , Nylons/química , Polímeros/química , Sulfonas/química , Poluentes Químicos da Água/análise , Purificação da Água/métodos , Adsorção , Concentração de Íons de Hidrogênio , Íons , Cinética , Propriedades de Superfície , Temperatura Ambiente , Termodinâmica
11.
Environ Technol ; 41(4): 440-449, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30010517

RESUMO

A lab-scale electrodialysis (ED) which consisted of 11 pieces of cation-exchange membranes and 10 pieces of anion-exchange membranes was used to treat concentrated brine of Reverse osmosis (RO) membrane. The effect of operating parameters such as applied voltage, flowrate, and operating mode was investigated to measure the performance of a lab-scale ED. Three different voltages (5, 10, and 15 V) and flowrates (20, 30, and 40 L/h) were applied in order to optimize the operating conditions of the ED system. The maximum TDS removal efficiencies were 85%, 97%, and 98% for 5, 10, and 15 V, respectively. It was concluded that the desalination efficiencies were almost the same at flowrates values of 20, 30 and 40 L/h. The TDS concentration of the treated brine in the concentrate compartment rises to the highest value of 25,400 mg/L with desalination rate of 92.5% after five cycle operation. Moreover, the desalinated brine can be used as fresh water.


Assuntos
Purificação da Água , Ânions , Filtração , Membranas Artificiais , Osmose
12.
Environ Technol ; 41(3): 287-295, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-29974822

RESUMO

In this study, the flocculation properties of FucoPol, a bacterial extracellular polysaccharide, were investigated. FucoPol is a high molecular weight polymer and negatively charged due to the presence of glucuronic acid and the acyl groups succinyl and pyruvyl. High flocculation rate values (>70%) were achieved with a low bioflocculant dosage of 1 mg/L, for pH values in the range 3-5 and temperature within 15-20°C. The bioflocculant was also shown to be stable after freezing/thawing and heating up to 100°C. Given the polymer's anionic character, the size of flocs formed and their surface profile, bridging seems to be the main flocculation mechanism of FucoPol. This study demonstrated that FucoPol is a promising natural, biodegradable and biocompatible alternative to the currently used synthetic or inorganic hazardous products, with potential to be used as a novel flocculation agent in several applications, such as water treatment, food or mining. Further studies will involve evaluating the reduction of cation dosage on flocculation efficiency, as well as testing the applicability of FucoPol to flocculate different types of suspended solids, such as, for example, activated carbons, soil solids or yeast cells.


Assuntos
Caulim , Purificação da Água , Floculação , Concentração de Íons de Hidrogênio , Polissacarídeos Bacterianos , Suspensões
13.
Environ Technol ; 41(5): 577-585, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-30074439

RESUMO

The efficacy of electrocoagulation at a pilot-scale as an alternative drinking water treatment technology to conventional coagulation is explored. A novel reactor was integrated into a pilot plant at the surface water supply of a small, remote community. Using iron anodes, the effect of metal loading (ML), current density and inter-electrode gap on the reduction of natural organic matter (NOM) was studied. Dissolved organics were characterized by large fractions of low molecular weight (<750 Da) hydrophilic carbon structures with lower charge density. A greater reduction in UV254 was yielded compared to dissolved organic carbon, indicating better removal of larger molecular weight fractions of NOM. As ML dosages increased from 27.8 to 60.8 mg/L, specific ultraviolet absorbance decreased from 1.92 ± 0.14 to 1.60 ± 0.10 L/m•mg respectively, from an initial raw water value of 2.21 L/m•mg. No clear trend was observed for the effect of current density and inter-electrode gap for NOM, however ML was the primary variable dictating the process' effectiveness. Energy requirements were observed to vary greatly and were highly dependent on ML, current density and inter-electrode gap; variables that all effect the operating potential and resistance. In general, conditions that yielded the greatest reduction of NOM, a 1 mm gap and 4-cell configuration, had energy requirements between 0.480 and 0.602 kWh/m3 of water treated.


Assuntos
Ferro , Purificação da Água , Carbono , Eletrocoagulação , Abastecimento de Água
14.
Environ Technol ; 41(5): 658-668, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-30074861

RESUMO

Monolayers of N-(2-aminoethyl)-3-aminopropyltrimethoxysilane have been established on magnetite nanoparticles to develop a novel magnetic adsorbent for fast decontamination of hexavalent chromium (Cr(VI)) from water. Results indicated that monolayer adsorption of the silane from water took place at low concentrations (<300 mg/L) and around 100% surface coverage was obtained at temperatures ≥90°C. The hydrolysed silane was anchored to the magnetite surface through condensation reactions between its silanol groups and the surface hydroxyl groups of magnetite. The functional amine groups were protonated by acid treatment for adsorbing Cr(VI). The monolayer of the silane on magnetite (MSM) with approximately 100% surface coverage showed extremely rapid adsorption kinetics for Cr(VI), such that the process was complete within 1 min. This enables the treatment of large amounts of sewage per unit time. The adsorption capacity for Cr(VI) was 8.0 mg/g, as estimated from the Langmuir isotherm model. The saturation magnetization of the MSM reached 64.16 emu/g, allowing easy magnetic recovery from water. In the presence of up to 50-fold molar excesses of chloride and nitrate anions, little effect on Cr(VI) removal was seen, but moderate and large impacts were observed with sulphate and hydroxyl anions, respectively. Desorption of adsorbed Cr(VI) and regeneration of the MSM were successfully achieved by NaOH and HCl treatments to deprotonate and protonate the amine groups, respectively. By selecting a silane with suitable functional groups, the surface properties may be tailored for a particular pollutant.


Assuntos
Nanopartículas de Magnetita , Compostos de Organossilício , Minorias Sexuais e de Gênero , Poluentes Químicos da Água , Purificação da Água , Adsorção , Cromo , Homossexualidade Masculina , Humanos , Concentração de Íons de Hidrogênio , Cinética , Masculino , Água
15.
Water Res ; 170: 115328, 2020 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-31785559

RESUMO

Combined sewer overflows contain a highly variable, wide range of contaminants, both in particulate and soluble form, making conventional water treatment processes unable to offer adequate public health protection. In this study, an integrated treatment process designed to simultaneously remove typical combined sewer overflow pollutants (suspended solids, chemical oxygen depends, turbidity) in conjunction with nutrient (nitrogen and phosphorus), was developed. The removal of particulates as well as dissolved nitrogen and phosphorus was achieved by first adsorbing soluble pollutants on zeolite and powdered activated carbon, and subsequently applying filtration carried out by polymer-enhanced microsieving. Laboratory experiments were designed using design-of-experiment techniques and carried out to assess the effects of the various treatment variables (cationic polymer, zeolite, powder activated carbon and microsieve size) in the designed combinations. A response surface model was fitted to the experimental dataset in order to capture and describe the non-linear relationships between treatment variables and treatment objectives. Finally, an optimization study was carried out using Pareto analysis showing that cationic polymer, zeolite, and powdered activated carbon, followed by fine mesh microsieving, worked synergistically in the integrated treatment process. Several optimal process conditions emerged, in particular, a treatment combination consisting of 1.1 mg/L of the cationic polymer, 250 mg/L of zeolite, 5 mg/L of powdered activated carbon, and a 370 µm mesh size. Under this condition, expected performance would be reductions of 72%, 56%, 35%, and 75% for turbidity, total Kjeldahl nitrogen, total chemical oxygen demand, and total phosphorous, respectively. The findings presented in this paper demonstrate the possibility of achieving multiple treatment objectives in a single and integrated treatment step, hence providing municipalities with viable treatment options where the issues of combined sewer overflow and nutrient management are simultaneously tackled.


Assuntos
Poluentes Químicos da Água , Purificação da Água , Cidades , Nutrientes , Esgotos , Eliminação de Resíduos Líquidos
16.
Water Res ; 170: 115316, 2020 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-31785561

RESUMO

To reduce the discharge of trace organic compounds into water bodies associated with potential toxic effects such as endocrine disruption, new advanced treatment methods are being investigated at several wastewater treatment plants (WWTPs). One of the most studied and already implemented technologies is ozonation. However, ozonation only partially oxidizes trace organic compounds (TrOC) and as a result, transformation products (TPs) with unknown properties can be formed. In order to minimise the risk of releasing unknown and potentially toxic TPs into surface water, it is recommended to install a biological post-treatment after ozonation. The aim of this study was to evaluate the efficiency of a moving bed reactor following ozonation in a full-scale plant. Different ozone dosages (zspec. = 0.3, 0.5, 0.7 mg O3/mgDOC) were investigated. To assess the biological activity of the post-treatment, the assimilable organic carbon (AOC) was determined in addition to the formed biomass. Furthermore, selected TrOC were analysed in parallel to monitor the ozonation efficiency at different ozone doses. In addition, estrogenic, androgenic as well as corresponding antagonistic effects were investigated after each treatment step using the A-YES and A-YAS assay. A non-target screening was performed to evaluate a trend analysis of formed TPs as well as their removal by the post-treatment procedure. The results proved the successful design of the biological post-treatment reactor by a constant biofilm development and reduction of the AOC. Endocrine effects were removed below the limit of detection (LOD) of 10 pg EEQ/L already after ozonation for all applied ozone doses. Antagonistic effects were not significantly reduced during ozonation and subsequent biological post-treatment. For this reason, further research is needed to evaluate different post-treatment technologies. The trend analysis from non-target screening data showed a reduction of about 95% of the number of formed TPs by the biological post-treatment. Consequently, an assessment of the biological activity and the elimination capacity of a certain biological post-treatment technique is thus possible by applying the AOC in combination with a non-target screening.


Assuntos
Ozônio , Poluentes Químicos da Água , Purificação da Água , Oxirredução , Águas Residuárias
17.
Water Res ; 170: 115323, 2020 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-31790888

RESUMO

In this work, we investigated the effect of bromide ion (Br-) on NDMA formation using model precursor compounds, wastewater effluents and surface waters. Previous studies showed that Br- reacts with chloramines and forms bromochloramine, a reactive compound responsible for NDMA formation enhancement. Some limitations of those studies were the highest Br- concentrations used, and the limited number of precursors considered. Here, we observed enhancement of NDMA formation from most of the model precursor compounds within the Br- range (0-1000 µg/L) but this effect was suppressed in the presence of NOM. Also, NDMA formation was favored at pH 8 in the presence of Br- compared to pH 6. Nevertheless, Br- suppressed NDMA formation in wastewater effluent samples at low monochloramine doses while no effects were observed in surface waters.


Assuntos
Poluentes Químicos da Água , Purificação da Água , Brometos , Cloraminas , Dimetilnitrosamina , Águas Residuárias
18.
Water Res ; 170: 115313, 2020 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-31770646

RESUMO

White rot fungi have been studied for the removal of micropollutants of emerging concern from wastewater during the last decade. However, several issues need to be overcome for its plausible implementation at full-scale installations such as the addition of supplementary substrates, the partial re-inoculation of fresh fungi or the use of extended hydraulic retention times. This work proposes the immobilization of Trametes versicolor on rotating biological contactors at bench scale (flowrates of 10 L/d and reactor capacity of 10 L) for the treatment of different urban wastewater. This type of bioreactor achieved remarkable reductions of the total organic carbon loading of the wastewater (70-75%) in a wide range of C:N and C:P ratios with limited addition of supplementary substrates, non-refreshment of the fungal biomass and only 1-day of hydraulic retention. The addition of gallic acid as quinone-like mediator and quelated iron and manganese complexes increased the removal of pharmaceutical micropollutants mediated by the so-called advanced bio-oxidation process. The immobilization of Trametes versicolor on rotating biological contactors also showed a remarkable stabilization of the fungi during the continuous treatment of different urban wastewater under non-sterile conditions. Thus, this system is a sound alternative for biological urban wastewater treatment with pharmaceutical removal because overcome all the problems usually associated with the water treatment technologies based on white rot fungi that makes difficult the scaling-up of the process and its implementation in full scale wastewater treatment plants.


Assuntos
Poluentes Químicos da Água , Purificação da Água , Biodegradação Ambiental , Reatores Biológicos , Oxirredução , Trametes , Águas Residuárias
19.
J Photochem Photobiol B ; 202: 111699, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31756585

RESUMO

In this work, we propose a novel application of ERIC-PCR technique to study DNA damage after ultraviolet radiation (UV) and peracetic acid (PAA) treatment for water disinfection purpose. The efficacy of both treatments on E. coli suspension was evaluated by two approaches: through monitoring of inactivation by conventional culture technique, and by analyzing DNA damage with ERIC-PCR. All the experiments were carried out in a batch reactor, using three intensities of UV-C radiation (10.5, 4.2 and 2.1 mW/cm2) and different PAA concentrations (4 to 16 ppm). Both treatments produced bacterial inactivation in a dose-response fashion. Based on the results of bacterial count we obtained an index of inactivation (INACI). For each sample, DNA extraction was performed and evaluated by ERIC-PCR. Qualitative modifications were observed in ERIC-PCR band patterns for all the UV-C radiation intensities used, but no changes were detected at any of the PAA concentrations. The banding pattern modifications observed are consequence of the interruption of Taq polymerase enzyme amplification-activity, caused by the presence of alterations on the DNA structure (dimer and hydrates formation). Furthermore, an index was proposed to measure DNA damage (DNADI) regarding the changes in the relative optical density values of the amplification products. A linear correlation was obtained with a high correspondence between the inactivation index (INACI) and the DNA damage index (DNADI), that was expressed as DNADI = 0.05881×INACI. This approach proves that ERIC-PCR is a feasible and valuable tool for detecting and quantifying DNA damage and it may provide a useful strategy for bacterial identification, tracking changes in DNA and providing reliable and reproducible data.


Assuntos
Dano ao DNA , Enterobacteriaceae/genética , Purificação da Água/métodos , Dano ao DNA/efeitos dos fármacos , Dano ao DNA/efeitos da radiação , DNA Bacteriano/química , DNA Bacteriano/metabolismo , Desinfecção/métodos , Ácido Peracético/farmacologia , Reação em Cadeia da Polimerase , Raios Ultravioleta
20.
Water Res ; 170: 115296, 2020 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-31760361

RESUMO

Increased frequency and severity of extreme weather events (i.e., floods and droughts) combined with higher temperatures can threaten surface water quality and downstream drinking water production. This study characterized the effects of extreme weather events on dissolved organic matter (DOM) washout from watershed soils and the corresponding contribution to disinfection by-product (DBP) precursors under simulated weather conditions. A laboratory simulation was performed to assess the effects of temperature, drought, rainfall intensity, sea level rise, and acid deposition on the amount of DOM released from soil samples. DBP formation potentials (DBPFPs) were obtained to assess the effect of extreme weather events on DBP formation and drinking water quality. The results demonstrated that the dissolved organic carbon (DOC) and carbonaceous DBP levels increased with increasing temperature in a dry (drought) scenario. Regardless of the watershed from which a soil sample was obtained and the incubation temperature during rewetting or chlorination processes, the DOC and carbonaceous DBP levels also increased with increasing temperature. Brominated DBP formation was increased when bromide was present during the rewetting of soil, indicating the effect of sea level rise. When bromide was present during the chlorination of water for DBPFP tests, only the level of brominated DBPs increased. Acid deposition had various effects under different weather conditions. The results of heavy rainfall simulations suggested that water quality deteriorates at the beginning of an extreme rainfall event. Abundant DOM was washed out of soil, leading to a peak in the DBPFP level. The level of DOM in seepage water was less than that of the surface runoff water during rainfall. The situation was more severe when the rainfall came after a long drought and the drought-rewetting cycle effect occurred.


Assuntos
Poluentes Químicos da Água , Purificação da Água , Desinfecção , Trialometanos , Qualidade da Água
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