Comparison of the removal of phthalates and other organic pollutants from industrial wastewaters in membrane bioreactor and conventional activated sludge treatment plants

摘要

In recent years greater attention has been paid to the presence of pollutants in wastewaterntreatment plants, mainly because of strict environmental regulations and the possibility of reusingntreated water in industrial processes. Since some organic pollutant compounds are not sufficientlynremoved in conventional activated sludge treatment (CAST) plants, new treatment processes havenbeen developed, such as membrane bioreactors (MBRs). In this study a submerged membranenbioreactor (MBR) was used to treat mixed industrial wastewaters in parallel with a CAST plant.nTwo hydraulic retention times (HRT) of wastewater were tested as one of the operationalnconditions of MBR and the quality of effluents of the two processes were studied and compared.nSeveral general quality parameters were analysed in wastewaters: chemical oxygen demandn(COD), pH, conductivity, nitrogen, phosphate, suspended solids (SS) and turbidity. The twonsystems reduced COD by around 90%. SS was reduced by around 81% in the CAST plant andnaround 90% in the MBR plant. The results for the other general parameters were similar or betternin the MBR process, which worked at a lower HRT. We also studied the removal of a group of sixnphthalates and bis(2-ethylhexyl)adipate ester by SPME/GC—MS in the two treatment plants. Mostnof these compounds were not completely removed in the two treatment plants and werenidentified at low mg l21 levels. We also tentatively identify some organic compounds in thenwastewaters. Most of the compounds we found in the influent, MBR effluent and CAST effluentnwere benzene derivates, styrene, naphthalene and naphthalene derivates, and phenol derivates.