Characteristics And Trihalomethane Formation Reactivity Of Dissolved Organic Matter In Effluents From Membrane Bioreactors With And Without Filamentous Bulking

Water scarity is one of the most important factors that influence the global economical development.It has been the top three problems that human society have to overcome in the 50 years.Municipal wastewater reclamation and resue is an efficient method to improve the water resource usage,which can not only reduce the water pollution problem but also relieve the water scarity issue.In this study,synthetic wastewater was treated by two identical membrane bioreactors(MBRs):the normal sludge MBRand the bulking sludge MBR.Effects of filamentous bulking on the characteristics and trihalomethane(THMs)formation reactivity of MBR effluent dissolved organic matter(EfOM)were investigated.MBR performance,properties and trihalomethane(THMs)formation characteristics of extracellular polymeric substances(EPS),soluble microbial products(SMP)and MBR effluent dissolved organic matter(DOM)in MBR with filamentous bulking were investigated.Filamentous sludge bulking had no significant influence on the regulated MBR effluent water quality except NO2-N and NO3-N.Normal MBR effluent had more low molecular weight(LMW)(<5 kDa)EfOM(92.43%)than filamentous MBR(75.18%).About two-thirds of EfDM from filamentous MBR were hydrophilic substances.On the contrary,EfOM from normal MBR exhibited higher hydrophobicity.The ratio of polysaccharides and proteins in MBR effluents increased after filamentous bulking.There were more protein-like materials,fulvic acid-like and humic acid-like in the other EfOM.The THM formation reactivity of filamentous MBR EfOM was 30.15%of normal MBR EfOM,whereas filamentous MBR EfOM exhibited higher formation reactivity of bromine containing species.MBR effluent DOM was mostly composed of slow reacting substances.The majority of fluorescence organics in MBR effluent,EPS and SMP were soluble microbial-like products.MBR effluent DOM was mostly composed of hydrophilic substance(HiS).Among the hydrophobic materials,hydrophobic acids(HoA)were the most abundant composition,and had the highest THMs formation potential(THMFP).In addition,compared with EPS,SMP exhibited higher THMFP,and was easier to produce bromine-containing THMs,which were more toxic than chloro-THMs.