Effluent

About: Effluent is a research topic. Over the lifetime, 32668 publications have been published within this topic receiving 533991 citations.

Fate of silica nanoparticles in simulated primary wastewater treatment.

Abstract: Through novel application of small-angle neutron scattering, we examined the fate of silica nanoparticles (SiO2NPs) during simulated primary wastewater treatment, by measuring, in real time, the colloidal behavior of SiO2NPs in wastewater (sewage). We examined the effects of surface functionality on SiO2NP fate in wastewater, by comparing both unfunctionalized (uncoated or “bare”) SiO2NPs and SiO2NPs functionalized with a thin coating of a nonionic surfactant (Tween 20), which is widely used in personal care and household product formulations containing engineered oxide nanoparticles. Our results show new evidence that the surface functionality of SiO2NPs plays a crucial role in their flocculation and sedimentation behavior in wastewater, and thus the likely efficacy of their removal from the effluent stream during primary wastewater treatment. Uncoated SiO2NPs did not flocculate in wastewater over typical residence times for primary treatment. Conversely, surface-functionalized (Tween-coated) SiO2NPs und...

Regrowth of Potential Opportunistic Pathogens and Algae in Reclaimed-Water Distribution Systems

Abstract: A study of the quality of reclaimed water in treated effluent, after storage, and at three points in the distribution system of four plants in California, Florida, Massachusetts, and New York was conducted for 1 year. The plants had different treatment processes (conventional versus membrane bioreactor), production capacities, and methods for storage of the water, and the intended end uses of the water were different. The analysis focused on the occurrence of indicator bacteria (heterotrophic bacteria, coliforms, Escherichia coli, and enterococci) and opportunistic pathogens (Aeromonas spp., enteropathogenic E. coli O157:H7, Legionella spp., Mycobacterium spp., and Pseudomonas spp.), as well as algae. Using immunological methods, E. coli O157:H7 was detected in the effluent of only one system, but it was not detected at the sampling points, suggesting that its survival in the system was poor. Although all of the treatment systems effectively reduced the levels of bacteria in the effluent, bacteria regrew in the reservoir and distribution systems because of the loss of residual disinfectant and high assimilable organic carbon levels. In the systems with open reservoirs, algal growth reduced the water quality by increasing the turbidity and accumulating at the end of the distribution system. Opportunistic pathogens, notably Aeromonas, Legionella, Mycobacterium, and Pseudomonas, occurred more frequently than indicator bacteria (enterococci, coliforms, and E. coli). The Mycobacterium spp. were very diverse and occurred most frequently in membrane bioreactor systems, and Mycobacterium cookii was identified more often than the other species. The public health risk associated with these opportunistic pathogens in reclaimed water is unknown. Collectively, our results show the need to develop best management practices for reclaimed water to control bacterial regrowth and degradation of water before it is utilized at the point of use.

Recycling of wastewaters of textile dyeing industries using advanced treatment technology and cost analysis—Case studies

Abstract: Textile dyeing industries in Tirupur and Karur of Tamil Nadu (India) usually discharge effluents ranging between 80 and 200 m3/t of production. Dyeing is performed either by conventional winch process or by advanced soft flow reactor process. Hypochlorite, the commonly used bleaching chemical is being gradually phased out by alkaline hydrogen peroxide solution that generates less effluent and fewer solids in the effluents. Coloring of yarn/cloth takes place in the presence of high concentration of sodium chloride or sodium sulphate (25–75 kg/m3) in dye solutions. Dye bath wastewaters and wash waters are the process effluents of dyeing industry which are collected separately or together and follow the advanced treatment for maximum recycling of recovered waters. Dye bath water after treating by sand and nanofiltrations (NF), the permeate is used in process for dye bath preparation and the reject of about 20–30% is sent to multi effect evaporator (MEE)/solar evaporation pond (SEP). Wash waters treated using a sequence of physicochemical and biological unit processes are passed into two stages reverse osmosis (RO) membrane systems and then the permeate is reused in the processes. The rejects about 15–20% of the inlet volume is subject either to nanofiltration for salt recovery or sent to evaporators. The final rejects from nanofilter systems is directed to multi effect evaporator system where condensed waters are recovered. The removal of total dissolved solids (TDS), chemical oxygen demand (COD), chloride and sodium are in the range of 80–97%, 91–97%, 76–97% and 96%, respectively. Multiple effect evaporators out flows of about 2–3% of the effluent volume are allowed for solar evaporation and the solids are disposed off. The cost of operation of MEE is about INR 400/m3 of the rejects. The cost of water recovery is about INR 60–80/m3 including commissioning and maintenance whereas price of raw-water in Tirupur is about INR 100/m3.