Sequential Biological and Photochemical Processes For Greywater Treatment

Abstract

Greywater reuse is an attractive solution to meet the rising demand for water. newlineGreywater is the wastewater generated from washbasins, laundries, kitchen sinks and newlinebathrooms, excluding wastewater from toilets. The greywater includes 50 to 70% of newlinethe total wastewater produced from households. Greywater mainly consists of newlinedifferent contaminants, including organics, suspended solids, nutrients, surfactants and newlineemerging contaminants (ECs). Disposal of untreated greywater to water and other newlineenvironmental bodies might pose health hazards and environmental risks. Treatment newlineand reuse of greywater can solve the disposal problem and meet various non-potable newlinewater demands such as toilet flushing, floor cleaning, car washing, industrial cooling newlinewater and landscape irrigation. It requires a comprehensive and appropriate treatment newlineapproach to meet the reuse standards. newlineIn past decades, many greywater treatment methods such as physical (filtration, newlineadsorption), chemical (coagulation, flocculation, ion-exchange resin system), newlinebiological (rotating biological contactor (RBC), sequencing batch reactor (SBR), newlinemoving bed biofilm membrane bioreactor (MBBMR), up-flow anaerobic sludge newlineblanket (UASB) reactor) and advanced oxidation processes (AOPs) (UV- and ozonebased newlineAOPs, TiO2-based AOPs) were adopted. Although these conventional newlinegreywater treatments displayed promising process efficiency for various contaminants, newlinesome drawbacks are associated with these methods, such as fouling (filtration), high newlinecost of adsorbent and disposal problems (adsorption), high chemical requirement newline(coagulation, flocculation), large footprint and longer operational time (RBC, newlineMBBMR, UASB reactor) and high energy requirements (UV- and ozone-based newlineAOPs). Since a single conventional treatment method is inefficient in removing all newlinecontaminants from greywater, coupling physicochemical and biological methods can newlinebe a suitable alternative. newline