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Surfactants are among the main chemical contaminants in greywater (GW) and can cause severe health issues in humans and aquatic organisms. We assessed the performance of a multistage constructed wetland system (EvaTAC) for GW treatment and capacity of the microbial community in linear alkyl benzene sulfonate (LAS) biodegradation. Physicochemical analyses were performed over 497 d, and biomass samples were collected for high-throughput DNA sequencing. The system was predominated by anaerobic conditions and received an average chemical oxygen demand (COD) and LAS of 374 and 32 mg·L−1, with removal rates of 66% and 43%, respectively. A positive correlation between COD and LAS suggested COD as a design parameter for LAS removal. We identified microbial genera participating in hydrolysis, fermentation, syntrophy, acetogenesis, methanogenesis, surfactant degradation, and sulphate reduction. Among the 15 surfactant-degrading genera, Pseudomonas was predominant. Community richness and diversity indices were comparable between subsystems, with a slight decrease in diversity observed towards the outlet. Among the LAS degraders, Rhodopseudomonas palustris had the highest relative abundance of operational taxonomic unit (OTU)s in all samples and the highest richness in the anaerobic chamber. The patterns in microbial community composition and environmental conditions suggest that LAS biodegradation occurred throughout the EvaTAC system. [ABSTRACT FROM AUTHOR]

Greywater presents great potential for reuse; if treated correctly and efficiently, it can be used for several residential uses. The objective of this work was to test advanced oxidation for greywater disinfection through UV/TiO2, UV/TiO2/H2O2, photo-Fenton, UV/H2O2 and photolysis (UV) processes, using Pseudomonas aeruginosa as an alternative indicator. In general, the processes with hydrogen peroxide (150 mg.L-1) mixed in the pretreated greywater and exposed to solar radiation or artificial radiation from UV lamps were the most efficient in the disinfection experiments, with total inactivation of P. aeruginosa. These processes (UV/H2O2 and photo-Fenton) were better fitted to the log-linear/caudal decay model with remaining microorganism for the hydrogen peroxide concentration of 25 mg.L-1. The use of P. aeruginosa as an alternative indicator for the greywater disinfection was very promising due to its high resistance and high natural concentration in the effluent used in the experiments. The treatment applied with the UV/H2O2 process with the hydrogen peroxide concentration at 150 mg.L-1 was the only one that showed acute toxicity, even though it removed a good part of the surfactant concentration from the pre-treated greywater. [ABSTRACT FROM AUTHOR]

Microalgal-bacterial processes represent a sustainable and cost-effective biotechnology able to promote efficient wastewater treatment, including natural pathogen removal (disinfection), as well as being able to perform CO2 uptake and biogas upgrading. In this context, the influence of CO2 supply from a synthetic gas mixture (30% v/v CO2) on the removal of pathogens (Pseudomonas, enterococci, and Escherichia coli) and total coliforms during secondary domestic wastewater treatment by a microalgal-bacterial symbiosis in a 180-L high-rate algal pond (HRAP) was investigated. The supply of CO2 in the HRAP positively influenced the Pseudomonas aeruginosa removal, with the removal efficiency increasing from 97.4% (1.6 log) to 99.6% (2.5 log) without and with CO2 supply, respectively. Likewise, the total coliform removal efficiency rose from 88.7% (1.1 log) to 99.4% (2.8 log). On the other hand, the effect of CO2 supply on enterococci (99.7% and 2.6 log) and Escherichia coli (98.6% and 2.2 log) removal was negligible. [ABSTRACT FROM AUTHOR]

Zero-discharge constructed wetland environments are more prone to the accumulation of pollutants. The relationship between filter media and microbial communities in this type of environment is still poorly known. We conducted bench-scale studies of different filter media (polyurethane foam, blast-furnace slag, and loofah) in these systems by simulating the batch operation with light greywater for 433 days. Physicochemical and microbiological analyses (scanning electron microscopy and polymerase chain reaction electrophoresis denaturing gradient gel) were used. In all systems, anoxic environments prevailed. These environments were crucial for methanogenesis and sulfidogenesis processes, which are primarily responsible for organic material conversion. The chemical oxygen demand/sulfate (COD/SO42−) ratio was the limiting factor in the competition of microorganisms involved in these processes. This condition, combined with the neutral-alkaline pH, also allowed Chloroflexi phylum bacteria to oxidize sulfide to sulfate and elemental sulfur in all studied media. The results showed strong evidence supporting that the microbial community formed in the present study is more related to operational/environmental conditions than to the different tested filter media. Thus, this demonstrates that the control of interactive effects between pH, redox potential, and the COD/SO42−ratio can prevent the accumulation and/or release of sulfide in anoxic environments. [ABSTRACT FROM PUBLISHER]

The intensive use and irregular disposal of pesticides in agriculture has caused serious environmental and health problems. In this work was evaluated the efficiency of UV and some advanced oxidation processes involving photo-Fenton reaction, O3 and O3/UV for the treatment of aqueous solutions containing commercial and standard pesticides. The results showed that the combination of UV radiation in alkaline means with O3 significantly increased the efficiency of the process of degradation and the photo-Fenton system is a promising alternative for the treatment of effluents containing pesticides. [ABSTRACT FROM AUTHOR]