Research On Typical PPCPs Removal Effect And Mechanism By Manganese Ore Columnar Reactor In Anaerobic Condition

Various pharmaceuticals and personal care products?PPCPs? in the aquatic environment have attracted increasing concern during the last decade, because they were continuously discharging to the aquatic environment and had been frequently detected in water bodies. Although at trace concentrations?ranging from ng.L-1 to ug.L-1?, they still can cause adverse effects in the aquatic ecological system over the long term. What ' s more, their biological toxicity impacts is difficult to predict.Conventional wastewater treatment plants?WWTPs? often fail to remove PPCPs completely and efficiently, therefore many of them have been ubiquitously detected in WWTP effluents. Advanced oxidation process and membrane separation technology were proved to be good ways to PPCPs removal, but it costs too much. Therefore, it's better to find anther process with low cost and high efficiency.Manganese ore reserves are abundant in the earth. Meanwhile, it has good adsorption, catalysis and oxidation performance, so it has huge potential and research prospects in PPCPs removal and degradation. Dissimilatory metal reduction bacteria could use metal oxide as electron acceptor and organics as electron donor to reducing metal, so it has potential to degrade PPCPs.Therefore, in this research, manganese ore and dissimilatory metal reduction bacteria was combined in a reactor that aiming to degrade PPCPs.Among PPCPs in the aquatic environment, Diclofenac and carbamazepine were detected at the highest frequency, and they are both hard to disposal and degrade, so they were selected as representatives of pharmaceuticals in this research. Two cylindrical reactors were set up: one with manganese ore and anaerobic sludge, another only with manganese ore. They all run under anaerobic conditions. The feeding water is domestic wastewater with 0.5mg.L-1 diclofenac and carbamazepine.The hydraulic retention time is 2 days. Based on this two reactors, this research aims to study the removal effect and mechanism of diclofenac and carbamazepine. In the end of the research, we try to select diclofenac degrading bacteria and study its mechanism of action. Some conclusions are obtained:?1? Carbamazepine is hard to disposal and degrade in our anaerobic manganese columns. Diclofenac is easily degradable comparing with Carbamazepine. Diclofenac degradation rate is 21.82% in column 1 and 67.37% in column 2. The degradation of diclofenac has little change over time in column 1, while it gradually reduces in column 2.?2? Through the study on the removal mechanism of diclofenac, it was found that catalytic and oxidation reaction of manganese ore plays the main role in degrading diclofenac, while bacteria contribution rate is less.?3? In the study of the by-products of diclofenac, two main by-products were found:5OH-DCF and DCF-2,5-IQ. The degradation way is likely to be this: diclofenac adsorbed to the surface of manganese ore, with the catalysis and hydroxylation reaction,it turns to be 5OH-DCF,and then was oxidized to be DCF-2,5-IQ. Besides the main way, found five minor degradation pathway and the degradation of 11 kinds of diclofenac by-products were found as well.?4? By the research on diclofenac degradation bacteria,two kinds of bacteria were found with good degradation efficiency on diclofenac. Bacteria DM1-2 has been identified as Burkholderia sp.,and bacteria DM1-2 has been identified as Pseudomonas sp.. DM1-2 and DM2-1 grow under anaerobic conditions that need MnO₂ and Fe₂O₃ as electron acceptor to obtain energy through degradation of diclofenac?This process is similar to dissimilar metal reducing bacteria growth process.