Phosphorus/EfOM Removal From Municipal Effluent By HFO Nanocomnosite And Related Biotoxicity Reduction

Advanced treatment of municipal secondary effluent has been one of focus concerned for alleviating the adverse effect on natural environment.In this study,the hydrated ferric oxide nanocomposite(HFO-201)was applied for phosphorus and EfOM removal from municipal effluent treatment.The adsorption capacity for phosphorus and the variation of organic matter during adsorption and disinfection were studied in detail.Apart from the evaluation of removal efficiency,toxicity assessments including baceria toxicity,algae toxicity and cell toxicity were conducted to evaluate the mitigation of potential adverse effect on natural waters.The HFO-201 showed definite adsorption capacity for EfOM and more than 50%TOC was removed in batch experiment,and the HFO-201 had not much difference in adsorption capacity than D201 for EfOM.Matters such as low molecular weight and hydrophobic substances,aromatic substances,etc.showed higher tendency to be removed by adsorption.The disinfection treatment has definite effect for TOC removal,and pretreatment by HFO-201 could help reduce the precursors of disinfection by-products.The secondary effluent exhibited certain toxicity.Treatment by HFO-201 could reduce toxicity and disinfection leaded to higher toxicity.In the assessment of acute luminescence toxicity,the secondary effluent had a value of 0.091 mg Hg/L and reduced to 0.072 mg Hg/L after HFO-201 treatment.After disinfection,the acute toxicity of secondary effluent and HFO-201 treated water had improved to 0.101 mg Hg/L and 0.080 mg Hg/L,respectively.The toxicity of disinfectant secondary effluent decreased to 0.088 mg Hg/L after HFO-201 treatment.In the assessment of algae toxicity(10 times concentration),the cell viability of secondary effluent was 71%and improved to 93%after HFO-201 treatment.After disinfection,the cell viability of secondary effluent and HFO-201 treated water had reduced to 60%and 87%,respectively.The viability of disinfectant secondary effluent improved to 81%after HFO-201 treatment.In the assessment of HepG2 cell toxicity(100 times concentration),the cell viability of secondary effluent was 80%and improved to 99%after HFO-201 treatment.After disinfection,the cell viability of secondary effluent and HFO-201 treated water had decreased to 72%and 91%,respectively.The viability of disinfectant secondary effluent improved to 90%after HFO-201 treatment.In the assessment of cell oxidative stress(100 times concentration),the relative value of secondary effluent was 153%and reduced to 117%after HFO-201 treated.After disinfection,the relative value of secondary effluent and HFO-201 treated water had improved to 181%and 127%,respectively.The value of disinfectant secondary effluent decreased to 137%after HFO-201 treatment.For biotoxicity reduction,HFO-201 and D201 did not exhibited significant difference.For phosphorus removal,the adsorption capacity of HFO-201 was higher than 40 mg P/g and was 3 times higher than D201.But the toxicity assessments showed low concentration phosphorus(1-5 mg P/L)had little influence on the biotoxicity of municipal secondary effluent.The HFO-201 nanocomposite exhibited excellent phosphorus removal capacity,and certain amount of EfOM could be removal simultaneously.By the application of HFO-201,the toxicity of effluent could decrease apparently,and the toxicity improved by disinfection could be mitigated.The HFO-201 nanocomposite was feasible for advanced treatment of municipal secondary effluent.