Based On The Cohesive Cohesive Nutrient Source Srb Sludge Immobilized Carbon Source And Handling Of Waste Water Containing Cadmium Study

A novel technology, which can provide a reticular structure for SRB sludge to resist outer rigorous environment and gain high removal rate, has been put forward for treating heavy metal wastewater by immobilized SRB sludge beads with inner cohesive nutrient source, which has the advantage of high heavy metal removal rate and full utilization of nutrition without the problem on high effluent COD_Cr.The adsorption behavior of granule active carbon milled for 30min (C-30) was performed through batch experiments, including pH value of solution, temperature and rotary speeds. The best pH value was 7.0, and the effect of temperature range of 20～40℃and rotary speeds range of 60～140r/min upon adsorption capacity were little, which was good for engineering applications. The optimal desorption condition was similar to the adsorption process except the distinct effect under high temperature. In the regenerative experiment, pure water was suitable for desorption with 4 times recycling.The adsorption isotherms were analyzed and regression analysis of the data showed that the adsorption behaviors of sodium lactate can be well described with the Freundlich equation. The distribution coefficient K_d indicated that the low concentration of sodium lactae was propitious to adsorption. It took about 10 minutes for adsorption process of milled granule active carbon C-30 to reach its equilibrium. The pseudo-first-order kinetic model can successfully describe the process. At the same time, the Freundlich equation can depict the adsorption behaviors of sodium lactate on enabled SRB beads. As far as the optimized immobilized beads with unenabled SRB sludge were concerned from the regenerative kinetic experiment, the adsorption processes belonged to the model of film diffusion limiting in the first adsorption time, but then they belonged to the model intraparticle diffusion limiting both in the second adorption time and the third adorption time. When the concentration of Cd²⁺ was 100mg/L, the enabled SRB beads can regenerate once in effect. The adsorption capacity of optimized immobilized SRB sludge beads which were added in 15% Polyvinyl Alcohol (PVA), 6% C-30, 40% SRB sludge, reached the peak (6.1mg/g) with equilibrium time of 3.5h. And the optimal conditions were 30g/L sodium lactate, pH7.0, 30℃, and 100r/min. In the desorption experiments, the desorption capacity of optimized immobilized SRB sludge beads was 0.4mg/g with equilibrium time of 10h. Not only the COD_Cr of solution reached the national secondary discharge standard, but also the optimal desorption conditions were 10h equilibrium time, pH7.0, 30℃, and 100r/min.In the discontinuous experiments, the factors including Cd²⁺ concentration, initial pH, temperatures and the rotary speeds were investigated in the treatment process of Cd(II)-bearing wastewater. The results showed that when the concentration of Cd²⁺ was less than 900mg/L, the removal ratio can exceed 90%. And the immobilized SRB sludge beads with inner cohesive nutrient source were able to efficiently remove 98.5% Cd²⁺ in 100mg/L under the conditions of 30℃and initial pH=5～8, with effluent COD_Cr up to par. The removal rate of SO₄^2- was close to 95%. The rotary speeds which was less than 140r/min made few effect on the removal of Cd(II)-bearing wastewater.The last results inferred that SO₄^2- was reduced to S^2- by SRB inside, and Cd²⁺ was precipitated outside beads in the way of S^2- atmosphere on the surface of immobilized beads through the analysis of SEM, XRD and EDX data.