Study On Removal Of Cu²⁺ From Wastewater By Immobilized Pseudomonas Fragi. YB2

In this paper,the adsorption of copper containing wastewater with immobilized cold-adapted bacteria was studied.Mainly include the screening of cold-resistant strains,study on the adsorption of Cu²⁺ by free cells,the choice of the method of immobilization,the study on the adsorption of Cu²⁺ by immobilized cells.As well as the simulation experiment of sequencing batch reactor and internal-circulation reactor.The main results as follows:?1?The source of water was cold water fish ponds of Yanji Helong,selected six advantage cold-resistant strains,three strains of bacteria were named as YB1,YB2 and YB3,and other three strains of fungi were named as Z-6,Z-7 and Z-10;Then comprehensive consideration the solid plate with 50 mg/L Cu²⁺ screening and MIC value.Finally,the most advantages cold-resistant strain YB2 was selected,and identified as Pseudomonas fragi.?2?The influencing factors of the adsorption of Cu²⁺ by free cells were investigated:pH value 5.0,Free cell dosage 2.0 g/L,Cu²⁺ initial concentration 50.0 mg/L,Adsorption time 120 min,the maximum adsorption rate was 40.1%,the adsorption amount was 9.2 mg/g.SEM analysis showed that Cu²⁺ had a destructive effect on the cell;EDS showed the occurrence of adsorption Cu²⁺.The equilibrium adsorption data of free cells was in accordance with the Langmuir and Freundlich isotherm model.The kinetics of the adsorption followed pseudo-second-order rate expressio.?3?By examining the mechanical strength,mass transfer performance and the adsorption efficiency of Cu²⁺,finally selected sodium alginate as the immobilized material and carried the following experiments.The influencing factors of the adsorption of Cu²⁺ by immobilized cells were investigated: Immobilized time 60 min,immobilized bacteria amount 0.8 g/L,pH value 5.0,Cu²⁺ initial concentration 50mg/L,adsorption time 0-300 min,the maximum adsorption rate was 98.12%,and adsorption capacity was 13.84 mg/g.Compared with the adsorption properties of Cu²⁺ adsorption of free cells,adsorption efficiency increased 58.02%,adsorption capacity increased 4.64mg/g.Therefore,immobilized cells of Cu²⁺ adsorption is obviously better than that of free cells and selected the immobilized cells for further trials.The immobilized cells were used for the analysis and re-adsorption.The adsorption efficiency was still more than 80% after the immobilized cells were reused for three times.SEM showed that the surface of the immobilized carrier was rough with voids,which could provide attachment and growth space for the cells;EDS energy spectrum showed the occurrence of adsorption Cu²⁺.The equilibrium adsorption data of immobilized cells was in accordance with the Langmuir and Freundlich isotherm model.The kinetics of the adsorption followed pseudo-second-order rate expression.?4?The experimental device simulation for the treatment of copper containing wastewater with sequencing batch reactor and internal-circulation reactor.three influencing factors of sequencing batch reactor were hydraulic retention time?1,3,5 h?,Aeration rate?4.15,8.20,10.48 L/min?and the amount of immobilized cells?1.75,3.5,7.0 g/L?.Finally,choice the hydraulic retention time was 3 h,the aeration rate was 8.20 L/min and the immobilized cell dosage was 3.5 g/L.The system was carried out for eight hours,after two hours to reach stability,the maximum adsorption efficiency was 90.29%,the adsorption amount was 12.23 mg/g.In internal-circulation reactor simulation test,the Cu²⁺ initial concentration was 50 mg/L,immobilized cell investment plus the amount of 3.5 g/L,aeration 8.0 L/min,dissolved oxygen 6.14 mg/L,15?for simulation of containing copper wastewater treatment,after 120 min the adsorption efficiency of Cu²⁺ reached 95%.