Search

This work describes a comprehensive assessment of operating parameters of a bench-scale electrodialysis (ED) plant for nutrient concentration from an Anaerobic Membrane BioReactor (AnMBR) effluent. The ED bench-scale plant serves a dual purpose. Firstly, to generate a concentrated stream with a high nutrient content, and secondly, to produce high-quality reclaimed water in the diluted stream, both sourced from real wastewater coming from the effluent of an AnMBR. Two sets of experiments were conducted: 1) short-term experiments to study the effect of some parameters such as the applied current and the type of anionic exchange membrane (AEM), among others, and 2) a long-term experiment to verify the feasibility of the process using the selected parameters. The results showed that ED produced concentrated ammonium and phosphate streams using a 10-cell pair stack with 64 cm2 of unitary effective membrane area, working in galvanostatic mode at 0.24 A, and operating with an Acid-100-OT anionic exchange membrane. Concentrations up to 740 mg/L and 50 mg/L for NH 4 –N and PO 4 –P, respectively, were achieved in the concentrated stream along with removal efficiencies of 70% for ammonium and 60% for phosphate in the diluted stream. The average energy consumption was around 0.47 kWh·m−3. [Display omitted] • ED can effectively concentrate NH 4 -N and PO 4 -P from AnMBR real effluent. • Lower current values are preferable when working with real urban wastewater. • Selecting an adequate AEM is crucial due to low PO 4 -P recovery efficiencies. • Increasing the number of cell pairs in the ED stack enhances recovery and removal efficiencies. • Determining the most suitable parameters is critical for reducing energy consumption. [ABSTRACT FROM AUTHOR]

The destruction of the herbicide chloramben in 0.050 M Na 2 SO 4 solutions at natural pH has been studied by photoelectro-Fenton with UVA light (PEF). The trials were carried out in a cell equipped with an air-diffusion cathode for H 2 O 2 generation and different electrocatalytic anodes, namely active IrO 2 -based and RuO 2 -based electrodes and non-active boron-doped diamond (BDD) and PbO 2 ones. Similar removal rates were found regardless of the anode nature because the herbicide was mainly oxidized by OH formed from Fenton's reaction, which was enhanced by UVA-induced photo-Fenton reaction. The use of an IrO 2 -based anode led to almost total mineralization at high current density, as also occurred with the powerful BDD anode, since photoactive intermediates originated from OH-mediated oxidation were degraded under irradiation with UVA light. The good performance of the IrO 2 -based anode in PEF was confirmed at different current densities and herbicide concentrations. The presence of Cl − in the medium caused a slight deceleration of herbicide removal as well as mineralization inhibition, owing to the production of active chlorine with consequent formation of persistent chloroderivatives. Seven aromatic products along with oxalic and oxamic acids were identified in sulfate medium. Five aromatic derivatives were detected in Cl − -containing matrix, corroborating the generation of organochlorine compounds. In secondary effluent, larger mineralization was achieved by PEF with a BDD anode due to its high oxidation ability to destroy the chloroderivatives, although an acceptable performance was also obtained using an IrO 2 -based anode. [ABSTRACT FROM AUTHOR]

Antibiotic resistance genes (ARGs) and antibiotic amount increased within close proximity to human dominated ecosystems. However, few studies assessed the distribution of antibiotics and ARGs in multiple ecosystems especially the different urban wastewater. In this study, the spatial distribution of ARGs and antibiotics across the urban wastewater included domestic, livestock, hospital, pharmaceutical wastewater, influent of the wastewater treatment plant (WWTP) in Northeast China. The q-PCR results showed that ARGs were most abundant in community wastewater and followed by WWTP influent, livestock wastewater, pharmaceutical wastewater and hospital wastewater. The ARG composition differed among the five ecotypes with qnr S was the dominant ARG subtypes in WWTP influent and community wastewater, while sul 2 dominant in livestock, hospital, pharmaceutical wastewater. The concentration of antibiotics was closely related to the antibiotic usage and consumption data. In addition to the high concentration of azithromycin at all sampling points, more than half of the antibiotics in livestock wastewater were veterinary antibiotics. However, antibiotics that closely related to humankind such as roxithromycin and sulfamethoxazole accounted for a higher proportion in hospital wastewater (13.6%) and domestic sewage (33.6%), respectively. The ambiguous correlation between ARGs and their corresponding antibiotics was detected. However, antibiotics that exhibited high ecotoxic effects were closely and positively correlated with ARGs and the class 1 integrons (intI 1), which indicated that high ecotoxic compounds might affect antimicrobial resistance of bacteria by mediating horizontal gene transfer of ARGs. The coupling mechanism between the ecological risk of antibiotics and bacterial resistance needed to be further studied, and thereby provided a new insight to study the impact of environmental pollutants on ARGs in various ecotypes. [Display omitted] • Total ARG abundance was highest in community wastewater. • Qnr S dominant in INF and CM samples, while sul 2 dominant in other ecotypes. • The spatial distribution of antibiotics related to the production and usage volumes. • Chronic toxicity presented high risk for AZI, ROX and SD. • Coupling mechanism occurred between bacterial resistance and ecological risk. [ABSTRACT FROM AUTHOR]

In this investigation, a sustainable and low-cost method to capture CO 2 generated from the treatment of urban wastewater was evaluated. We studied the adsorption of CO 2 on olive pomace biochar. The experiments of degradation of synthetic wastewater mimicking effluents of municipal wastewater treatment plant (WWTP) with an initial Total Organic Carbon (TOC) concentration of 10 mg L−1 were conducted by using the UV-C/H 2 O 2 process in the absence or presence of biochar. The biochar was placed in a fixed bed column through which air from the UV reactor was circulated. First, the effects of different parameters such as H 2 O 2 initial concentration and pH on wastewater mineralization efficiency were determined. Total Organic Carbon (TOC) removal was 87% in 2 h under optimal degradation conditions. The maximal concentration of CO 2(gas) in air, in a closed system (air volume: 7.3 10−4 m3), after 11 h was 12,500 μmol mol−1 in the absence of biochar and only 150 μmol mol−1 when 10 g biochar were used. The results proved that by combining biochar with oxidative degradation of organic compounds, it is possible to mineralize organic compounds and reduce the requisite CO 2 emissions by about 99%. The experimental equilibrium results were fit well with both Langmuir and Freundlich isotherms models concluding that CO 2 adsorption on biochar followed both chemisorption and physisorption and both monolayer and multi-layer CO 2 adsorption could occur. The total desorption of CO 2 from biochar was reached in 120 min by simultaneously increasing the temperature to 150 °C and introducing a purge N 2(gas). [Display omitted] • Capture of CO 2 from urban wastewater mineralization. • Optimized UV/H 2 O 2 process was used for degradation. • Olive pomace biochar reduced CO 2 emission by 99%. • CO 2 adsorption on biochar was chemisorption and physisorption. • The desorption of CO 2 was reached at 150 °C and with N 2 purge. [ABSTRACT FROM AUTHOR]

Abstract: The worldwide fresh water scarcity is increasing the demand for non-conventional water resources. Despite the technology being available for application of treated wastewater in irrigation, the use of effluent in agriculture is not being properly managed in the majority of cases. Industrial countries, where financial resources are available but restricted, face difficulties in some cases related to the lack of a complete definition of irrigation water quality standards, as well as to the lack of monitoring components that determine if the effluent is suitable for such use. The present paper presents a critical review on urban reclamation technologies for irrigation. The technologies are presented by the four most important parameters for irrigation water quality: salinity, pathogens, nutrients and heavy metals. An overview is given of the current, on-going evaluation of different reclamation technologies for irrigation. [Copyright &y& Elsevier]

The application of Phragmites australis based constructed wetlands (CW) have been widely used in various climates and also used for secondary treatment of diverse wastewater and polluted water. This work compares the treatment performance of two Phragmites -based mesocosms: the first with surface horizontal flow (SF), and the other with subsurface horizontal flow (SSF), in the same conditions of feeding and climate. The results showed a significantly high mineral content of the effluent water exiting SSF-CW. The last one was significantly more efficient in terms of removal of Total Suspended Solids (TSS), Chemical Oxygen Demand (COD), Total Nitrogen (TN), ammonium (NH 4 –N), and Total Phosphorus (TP) compared to SF-CW, i.e. 26.3, 3.12, 1.59, and 0.62 g. m−2. day−1 in the same order. The microbiological load reduction is also significantly higher in SSF-CW. On the contrary, the other parameters of pollution monitored do not allow the identification of a significant difference between SF- and SSF-CW. The atmospheric evapotranspiration value was higher in SSF-CW by 24.8 ± 20 mm. d−1, corresponding also to a higher harvestable biomass of Phragmites of 58.2 t. ha−1. year−1. [Display omitted] [ABSTRACT FROM AUTHOR]

This paper presents a novel set of water quality indexes to identify the area potentially affected by point sources of bacterial pollution in coastal bathing waters. The indexes, developed in the framework of the CADEAU service, are evaluated on the results of a modelling system based on the integration of a high-resolution ocean model, remote sensing observations and in situ monitoring data for the northern Adriatic Sea. In particular, the system is a downscaling of the Mediterranean Copernicus Marine Environment Monitoring Service and exploits data produced within the Bathing Waters Directive, the Water Framework Directive and the Urban Waste Water Treatment Directive to create added value products. The aim of the proposed indexes is to support the identification of areas of influence for bathing waters by identifying the potential threat from point sources of bacterial pollution, both in standard conditions and peculiar events such as a total bypass of wastewater treatment plants. The results for the Chioggia Municipality case study show the potential of the indexes to significantly improve the geographical identification and quantitative evaluation of the impacts of bacterial pollution sources on bathing waters, facilitating the design of mitigation measures. The proposed methodology represents a new management approach to support local authorities in defining the area of influence within the water bathing profile through the proper characterization of the point sources of bacterial pollution. • Spatio-temporal variability of bacterial pollution from point sources is modelled. • The system takes advantage of in situ data from official monitoring protocols. • Indexes are presented for characterizing the area of influence of bathing water. • Impact from mean discharge and total bypasses from point sources is estimated. • The indexes may identify potential sources of short-term pollution events. [ABSTRACT FROM AUTHOR]

AnMBR technology is a promising alternative to achieve future energy-efficiency and environmental-friendly urban wastewater (UWW) treatment. However, the large amount of dissolved methane lost in the effluent represents a potential high environmental impact that hinder the feasibility of this technology for full-scale applications. The use of degassing membranes (DM) to capture the dissolved methane from AnMBR effluents can be considered as an interesting alternative to solve this problem although further research is required to assess the suitability of this emerging technology. The aim of this study was to assess the effect of operating temperature and hydrodynamics on the capture of dissolved methane from AnMBR effluents by DMs. To this aim, a commercial polydimethylsiloxane (PDMS) DM was coupled to an industrial prototype AnMBR (demonstration scale) treating UWW at ambient temperature. Different operating temperatures have been evaluated: 11, 18, 24 and 30 °C. Moreover, the DM was operated at different ratios of liquid flow rate to membrane area (Q L :A) ranging from 22 to 190 Lh−1m−2 in order to study the resistance of the system to methane permeation. Methane recovery was maximized when temperature raised and Q L :A was reduced, giving methane recovery efficiencies (MRE) of about 85% at a temperature of 30 °C and a Q L :A of 25 Lh−1m−2. The study showed that high Q L :A ratios hinder methane recovery by the perturbation of the DM fibers, being this effect intensified at lower temperatures probably due the higher liquid viscosities. Also, the performed fouling evaluation showed that not significant membrane fouling may be expected in the DM unit at the short-term when treating AnMBR effluents. A resistance-in-series model was proposed to predict the overall mass transfer of the system according to operating temperature and Q L :A, showing that methane capture was controlled by the liquid phase, which represented up to 80–90% of total mass transfer resistance. The energy and environmental evaluation performed in this study revealed that PDMS DMs would enhance energy recovery and environmental feasibility of AnMBR technology for UWW treatment, especially when operating at low temperatures. When MRE was maximized, the combination of AnMBR with DM achieved net energy productions and net greenhouse gas reductions of up to 0.87 kWh and 0.216 kg CO 2 –eq per m3 of treated water. • Dissolved methane can be captured by PDMS membranes even at low temperatures. • The membrane's methane capture resistance is mainly controlled by the liquid phase. • A resistance-in-series model is proposed to predict the membrane's resistance. • Energy and environmental impacts of sewage treatment can be reduced by this system. [ABSTRACT FROM AUTHOR]

Climate change not only intensifies eutrophication and enhances the rainfall, but also elevates the contents of greenhouse gases, which can further increase the intensity and frequency of extreme precipitation events. The effectivity of phytoremediation of urban wastewaters by water hyacinths under an extreme rainfall event (up to 380 mm d−1) was investigated using self-designed fabrications with six flow rates (2–15 m3 d−1) in situ on pilot scale for 30 days. The results suggest that water hyacinths had high N and P removal capacities even under adverse conditions such as low dissolved oxygen concentrations (DO, <1 mg L−1) and high ammonium concentrations (NH 4 +-N, >7 mg L−1). Specifically, the highest removal yields of N and P were 13.14 ± 0.47 g N·m−2·d−1 and 2.12 ± 0.04 g P·m−2·d−1, respectively. The results indicate that water hyacinths can be used for water treatment to reduce the amounts of NH 4 +-N, dissolved organic nitrogen (DON) and phosphate (PO 4 3−) even during extreme precipitation events. Moreover, DO increased due to wet deposition, runoff and surface flows during the extreme rainfall event, resulting in shifts between nitrification and denitrification processes which significantly altered nitrogen forms in urban wastewater. Results of this study suggest that water hyacinths could be recommended as a cost-effective and eco-friendly technology for urban wastewater phytoremediation in areas suffering from frequent extreme precipitation events. Image 1 • Phytoremediation with water hyacinths proved to be effective. • DO increased after extreme precipitation. • Changes in DO resulted in shifts between nitrification and denitrification. • Up to 99% NH 4 +-N and DON were removed by water hyacinths. • Water hyacinths were also effective during extreme precipitation. [ABSTRACT FROM AUTHOR]

This study mainly focuses on the efficiency of anodic oxidation process (Ti/Sb-SnO 2 /PbO 2 as anode and stainless steel as the cathode) in treating two different streams of urban wastewater, one from the influent of sequence batch reactor (WW1) and other from the effluent of constructed wetland (WW2). The effect of different operational parameters such as current density, hydraulic retention time, exposed electrode surface area, phosphorous, ammonia-nitrogen, nitrates, and coliform bacteria was studied. For an optimized current density of 30 mA/cm2 and an electrode surface area of 30 cm2, almost complete removal of COD and ammonia-nitrogen were achieved with both wastewaters (WW1 & WW2), while in case of phosphorous, 50% and 98% removal efficiencies were observed. Electrode deposition was analyzed using SEM-EDS and XRD, which confirms the presence of calcium and magnesium phosphates on the surface on the anode, which attributes to the phosphate removal. Electrochemical disinfection studies showed that complete inactivation of bacteria takes place within 30 min for WW1 and 60 min for WW2, and the cell morphological changes were studied using SEM analysis. Degradation of different micropollutants present in the wastewaters was evaluated with the aid of GC-MS. ICP - MS analysis confirmed that there was no leaching of lead from the anode surface, and the lead which is already present in the wastewater gets reduced to a permissible level, which further increases the treatment efficiency. Hence cleaner and comprehensive treatment of real urban wastewaters through anodic oxidation process was successfully demonstrated in this work. Image 1 • One step comprehensive treatment of urban wastewaters by electrochemical oxidation. • ~99.9% COD, 98% phosphorous and 100% ammonia-nitrogen removal was achieved. • Phosphorous removal was by forming calcium and magnesium phosphates on the cathode. • Complete inactivation of coliforms within a short period with cell wall rupture. • 100% removal of certain emerging and micro pollutants was noted using GC-MS. [ABSTRACT FROM AUTHOR]

Bioflocculation phenomena for filamentous cyanobacteria were studied and analysed in two different cultivation systems (i.e. based on air-bubbling and on shaking) and for different initial biomass concentrations. Floc formation and biomass settling were monitored during batch cultivation tests according to an innovative protocol. Results showed that the two cultivation systems enhanced two different flocculation behaviours: air bubbling led to the formation of small and dense flocs, while the shaking table resulted in larger (14 mm 2 vs 4 mm 2 ) but mechanically weaker flocs. Floc analysis evidenced that the different mixing systems also affected the speciation of biomass. A mathematical model was developed to simulate and predict the settling performance during the bioflocculation process of filamentous cyanobacteria. Natural settling was examined at different phases of biomass growth. Optimal conditions were obtained at the end of the exponential growth phase, when 70% of the total cultivated biomass could be recovered., Competing Interests: Declaration of competing interest The authors report no declarations of interest., (Copyright © 2019 Elsevier Ltd. All rights reserved.)