Membrane - The Biological Reactor In Nonylphenol Ethoxylates Removal And Relocation Of Translational Research

Nonylphenol polyethoxylates (NP_nEO) is able to disrupt the endocrine system of wildlife, since they are called Endocrine Disrupting Chemicals (EDCs). Due to the production and usage pattern, great amount of NP are released into WWTPs. NPnEO were removed to some extent in the sewage treatment plants, large NP_nEO molecules with longer ethylene oxide (EO) chain were biodegraded efficiently, however not mineralized to CO₂ but to middle metabolites, such as small NP_nEO with short chain or nonylphenol (NP). These metabolites are of higher toxicity than their parent compounds, and exhibit endocrine disrupting activity. The process of wastewater treatment does not lead to a reduced risk but lead to an elevated risk, becoming the main source of these small NP_nEO metabolites in the environment.Elimination of Nonylphenol ethoxylates (NP_nEO, n=1-4) and their degradation products (Nonylphenols and Nonylphenoxy carboxylates), as well as their transfer and transform, was studied in a pilot plant membrane bioreactor (MBR) working in parallel to a full-scale wastewater treatment plant (WWTP) using conventional activated sludge reactor (CASR) without sludge discharge. After the experiment, for the purpose of enhancing NP_nEO removal in MBR, MBR-NF was proposed. The MLSS in the MBR was 8000mg/L, and in the CASR was 3000mg/L. The elimination of NP_nEO and rejection mechanism in MBR-NF was studied and the feasibility was analyzed. The following results were obtained:The two plants were not influenced by NP_nEO in the experiment. Under the three experiment conditions, the COD removal rate in MBR was 87.24%, and the NH₃-N removal rate was 99.97%. The COD removal rate in CASR was 83.98%, and the NH₃-N removal rate was 98.35%.Under the three different NP_nEO-sludge loading conditions, the effluent concentrations of NP_nEO from MBR were lower than those from conventional activated sludge reactor (CASR), the results showed that MBR could remove NP_nEO more effectively than CASR. The average NP_nEO removal rate in MBR was 99.4%, 98.7%, 95.6%, and the average removal rate in CASR was 97.5%, 96.8%, 91.8% ,respectively.By the determination of the NP_nEO in the activated sludge, the sludge had a good capacity of adsorption of NP_nEO and could accumulate in a long time. The adsorption of sludge in MBR and CASR composed a little proportion in the NP_nEO elimination. only 0.6% and 0.8%, respectively.By the determination of oxygen uptake rate (OUR) and ammonia uptake rate (AUR), the activated sludge was depressed by NP_nEO to some extent. After domesticated a few days, the sludge activity was enhanced 23% and 14% than ever.In the MBR-NF process, the nanofiltration membrane had a good rejection effect in the small module organism, the rejection rate of NP_nEO was 66.3%. The concentrated water was circumfluenced to the MBR reactor, the biodegradation of NP_nEO was intensified.