Study On The Removal Mechanism Of Similar Persistent Organic Pollutants From Dyeing Wastewater By Pseudomonas Sp. Bacteria

Dyeing wastewater is a typical biorefractory wastewater due to the similar persistent organic pollutants (POPs). Similar POPs are component complexity and species diversity. Up to now, the similar POPs removal mechanism by bacteria was still unclear, and the reinforcement methods for similar POPs removal were lacked. This study was mainly focused on the microbial strengthening removal of typical similar POPs in dyeing wastewater. The removal mechanism of different types of similar POPs by Pseudomonas sp. bacteria was systematically researched, and the strengthening methods were also discussed.Firstly, the biochemical removal of cationic dye methyl violet (MV) and nonionic pollutants acenaphthene (ACE) by Pseudomonas sp. bacteria was revealed. They could both be adsorption removal by bacteria. For the MV, the cell wall and membrane was the main part for adsorption, accounted for more than 80%, tightly adherent extracellular polymeric substances (TB-EPS) accounted for about 10%; However, for the ACE, the cell wall and membrane, accounted for more than 70%, and intracellular substances accounted for about 10-25%. This results indicated that cationic and nonionic POPs could be biosorption removed by Pseudomonas sp. bacteria. Furthermore, the protein played a main role on adsorption of MV, and the lipid played a main role on ACE adsorption.Secondly, in the coexisting pollutants system, both reactive blue 13 (RB13) and pentachlorophenol (PCP) could be degraded by Pseudomonas sp. bacteria. And biodecolorization RB13 could be inhibited by PCP. The microbial degradation process of RB13 could be described by Michaelis-Menten kinetics equation, the kinetic constant Fmax and Km were 4.2 mg/L·h and 90.82 mg/L in the absence of PCP, and 0.58 mg/L·h and 20.61 mg/L in 20 mg/L PCP system. The results shown that in coexisting pollutants system, the presence of electronic competition could affect the biodegradation process. For anionic similar POPs, biodegradation was the mainly biological removal mechanism;Finally, the strengthening methods were proposed to solve the problems of low efficiency removal rate of anionic similar POPs. For adsorption removal reinforcement, modified bacteria were prepared to improve the removal of RB13 and PCP in neutral and acidic conditions. The adsorption dynamics, thermodynamics and the possible adsorption mechanism were presented under different pH conditions; For degradation removal reinforcement, the Redox mediators was introduced and examined. In the presence of 10 mg/L PCP system, the optimized AQS dosing was 0.3 mmol/L, the biodecolorizing of RB13 and dechlorination of PCP were increased to 4 and 2 times respectively. Furthermore, the AQS-PVA beads were prepared, the beads could retain high catalytic activity after more than 10 runs reused. The biodecolorization rate could maintain above 95%. This results demonstrated that the AQS-PVA beads had a well adsorption capability and stability.