Combined Ozonation-ultrafiltration Process For Removing Typical Endocrine Disrupting Chemicals From Secondary Effluent

Wastewater treatment and reuse is a useful solution for heavy water pollution andwater shortage. Secondary effluent, owing to its huge and stable quantity as well asfavorable quality, is an ideal source for wastewater reclamation and reuse. However,endocrine disrupting chemicals (EDCs), ubiquitous in secondary effluent, may threatenthe safety of the reclaimed water. Presently, study on removal technologies of EDCs isinadequate, so it is urgent to develop effective and efficient removal processes toremove EDCs.Based on the optimization of EDCs analysis method, this paper mainlyinvestigated the degradation characteristics and kinetics of EDCs by ozonation, studiedthe rejection characteristics and mechanism of EDCs by ultrafiltration, established andoptimized a combined ozonation and ultrafiltration (O3-UF) process, and furthermoreexamined its performance in removing EDCs from secondary effluent duringcontinuous operation.Parameters of the Ultra-performance liquid chromatography tandem massspectrometry (UPLC-MSMS) method were optimized. The simultaneousquantification method for detection of five selected EDCs: estrone (E1),17β-estradiol (E2), estriol(E3),17α-ethynyl estradiol (EE2) and bisphenol A(BPA) was established, whose quantification limit was0.1ng/L. Secondaryeffluent from G wastewater treatment plant (WWTP) of Beijing was determined to berepresentative in terms of its quality and was utilized in this research. EDCsconcentration and estrogenic activity of G secondary effluent were2.4-162.7ng/Land251.33ng/L E2equivalent concentration (EEQC) respectively. Protein,polysaccharide and humic substances were the main dissolved organic matters of GWWTP secondary effluent.Ozonation of EDCs obeyed the pseudo-first order reaction kinetics model,with reaction rate constants of0.0532-0.0973min-1. Degradation efficiency ofEDCs was affected by O3concentration (CO3) and contact time (tO3). Under thesame CO3tO3value, higher O3concentration resulted in larger EDCs degradationefficiency. Organic matters inhibited EDCs degradation and promoted the decay of dissolved O3.Suspended solid and organic matter formed membrane fouling enhancedEDCs interception by ultrafiltration membrane. Ultrafiltration process ofdifferent organic matter synthesized secondary effluents and secondary effluentof G WWTP accorded with cake filtration law. Average removal efficiency offive targeted EDCs by clean membrane and secondary effluent of G WWTPfouled membrane was (19.4±9.7)%and (32.1±22.3)%respectively under50kPa.Rejection of EDCs by clean membrane was mainly results of physical andcharged surface adsorption, while fouled membrane removed EDCs via physicaland charged surface adsorption as well as size exclusion.Combined O3and UF process with UF unit acting after O3unit produced betterreclaimed water and formed weaker membrane fouling during the treatment ofsecondary effluent. Optimized parameters for O3-UF process were: O3concentration6.1mg/L, contact time7min and membrane flux23LMH. During continuous operation,O3-UF process exhibited good EDCs removal performance with EDCs concentrationlower than0.7μg/L and EEQC less than0.1μg/L in effluent when EDCs concentrationwas adjusted to50μg/L in the influent.