The Research On Flocculant For Treatment Of Wastewater Containing Cadmium

Heavy water is a great environment and human health hazards of pollution, as people's increasing attention to environmental protection, heavy metal wastewater treatment requirements become more stringent. In the flocculation precipitation of heavy metals in wastewater treatment, microbial flocculant is a class generated by the microbial activity of a flocculating polymer flocculant, which has a readily biodegradable, harmless to the environment and human characteristics. At present our country in terms of the Wastewater Treatment with flocculant-depth study yet, which was mainly due to high production costs, high concentrations of heavy metals in wastewater flocculation rate is low and other reasons. This paper focuses on the object of heavy metals from contaminated soil samples screened flocculant producing strains with high resistance to its growing conditions, the medium component optimization, flocculation of heavy metals in wastewater in terms of factors and actual applications.The subject of conventional screening, separation, purification, water from the Industrial Zone, Zhuzhou Shifeng Xia Xiang Wan,Port river sludge heavy metal contaminated area was isolated eight strains producing flocculant, a second screening from two genetic stability and high flocculating activity of microbial flocculant, namedⅡ3 andⅡ8. StrainⅡ3 andⅡ8 to pH, temperature on the growth of experimental and picture their growth curve. It was found that bacteriaⅡ3 andⅡ8 of the optimal growth temperature was 30℃,35℃, bacteria 113 optimal growth pH is 7, andⅡ8 to 9,Ⅱ3 andⅡ8 growth reached the maximum time was 48h and 42h.Determined by single factor experiments andⅡ8 bacteriaⅡ3 best C source, N source and inorganic elements. Bacteria 113 of the best C source is glucose, N source was urea, inorganic salts as CaCl2; bacteriaⅡ8 is the best source of sucrose, C, N source is peptone, inorganic salts as CaCl2. Of bacteria 113 orthogonal experiments conducted studies to determine the strain 113 produced the best composition ratio of flocculant best medium composition ratio (p/gL-1) scheme: glucose25, urea0.5, CaCl20.5, FeSO40.01.Conducted on the bacteria 113 flocculant dosage, coagulation system, coagulant concentration, dynamic mixing effects on flocculation were studied. Flocculant producing bacteria 113 found that the optimal dosage of kaolin suspension were 1.2mL/100mL; flocculation system coagulant concentration (1%CaCl2 solution) when the addition is 5mL/100mL MBFⅡ3 flocculation best; flocculation conditions in the best mixing speed 300r/min after 30s, 100r/min stirring 2min, to achieve optimum flocculation. At the same time the nature of MBFⅡ3 initial identification, found that the main active ingredients flocculation secretions present in the extracellular species, its good thermal stability, obtained after an initial identification of the main active ingredient of the flocculant and a small amount of protein to polysaccharide.With MBFⅡ3 of heavy metal Cd2+ solution treated under various conditions, experimentally derived:MBFⅡ3 of heavy metal removal of Cd2+ the best solution pH=7.0, dosage of 20mL, processing 20min, they can reach the maximum removal efficiency of 68.2%. Combined Removal of the two metals during the experiment, we found that Cd2+ and Pb2+ synergies, while the role of the two metal ions when the volume will increase.