Preparation Of Microbial Flocculant And Treatment Of Heavy Metal Wastewater

In recent years, with the rapid development of economy, a lot of industrial wastewater emissions lead to more heavy metal accumulation in the soil and water, seriously polluted the environment and endanger the health of humans and other creatures. So the in-depth study of heavy metal wastewater treatment technology is imperative. Flocculation precipitation is a method of water treatment generally used at home and abroad. Flocculants plays an important role in the process of water treatment. Microbial flocculant (MBF) as a new type of water treatment agent, highly effective, non-toxic, no secondary pollution and application field of advantages, has been paid more and more attention, and its potential applications in the field of water treatment is highlighted.In this paper, based on the microbial flocculant MBFA9 as the research object, by optimizing the cultivative and productive conditions of flocculant bacteria, to improve its flocculate properties, and carries on the component analysis of flocculating agent, mainly studies the MBFA9’s effect on treatment of wastewater containing Pb2+, optimize the processing conditions and analysis its reaction mechanism. The results show that:(1) The optimum culture and flocculation conditions as follows:the temperature of 30℃, table speed of 150 r/min, inoculation amount of 3%(V/V), under the condition of pH of 7-8 train 72 h in fermentation medium, the fermented liquid dosage is 0.1%(V/V), stirring speed of 200 r/min quick stir 1 min, then stir 5 min to 80 r/min slower, the flocculating rate of 97.8%.(2) MBFA9 has stability of acid and high temperature, through the infrared spectrum analysis, determine the flocculant flocculation role of the material is a macromolecular polysaccharide with thermal stability, and the flocculation mechanism mainly for adsorption bridging role.(3) MBFA9 has the characteristics of removaling Pb2+, optimized through the influence of MBFA9 on the capture of Pb2+:the best shock time of MBFA9 capture Pb2+ is 30min, the optimum pH is 4-6, the optimum dosage is 5%(V/V), the optimum temperature is 25℃-35℃. The removal rate can be as high as 98.85%. Study on Dynamics:trapping behavior of quasi two level dynamic model can better describe the MBFA9 of Pb2+ in wastewater, the theoretical maximum trapping volume was 196.08mg/g, the adsorption rate constant K2 was 0.0186 g/mg/min. Thermodynamic aspects of Langmuir isothermal adsorption model can fit MBFA9 better Pb2+ trapping, correlation coefficient R.2=0.9603.(4) Compare and analysis the IR spectra of MBFA9 capturing Pb2+ shows that the main component of MBFA9 is polysaccharides, and combine with SEM and EDS presume that the reaction mechanism is that functional groups on the surface of flocculant and Pb2+ formed chelate by chelation, It occurs chemical reaction between hydroxyl, amido, carboxyl and Pb2+ in the trapping process, there is also a floc of sweep function, so MBFA9 has better removal effect on Pb2+.