Research On Producing Bioflocculant By Preprocessed Sludge

Microbial flocculants have been widely followed because of its own advantages and bottlenecks in the sewage treatment. T he high cost of matrix which training the flocculant bacteria is the most important reason that obstructing flocculant large-scale sewage treatment applied to the production practice and purifying waste water. In this study, we put forward new ideas about the high cost problem of flocculant producing bacteria fermentation cultivation, selecting sludge extract substitute flocculation bacterium as fermentation medium after treatment. Investigate the environmental factors of the fermentation process, finally, carried on the comprehensive benefit evaluation for this research.Through the different conditions of sludge(Different temperature, time, p H) pretreatment, analysising the TOC concentration, TN concentration and T P concentration of the extract, etc. We determined the optimum pretreatment conditions. The effect of flocculant bacteria LLin6 directly using sludge extract fermentation to produce flocculant is not ideal, so we change the proportion of sludge extract medium optimization. Through adjustment and adding material concentration, determine the sludge concentration at 20~25 g/L, then treatment 3h at p H12 alkali, after processing the sludge extract by centrifugal supernatant, adjust p H value to 7.0, add 8g/L glucose, 112℃sterilization for 30 m in, then accessing flocculant producing bacteria LLin6 in fermentation cultivation, the rate of flocculation can gain more than 85% after 24 h fermentation. By growth analysis, we found that the flocculation bacteria LLin6 can grow well in the flocculant sludge extract medium.We regard sludge extract as culture medium, then investigated flocculant bacteria LLin6 in the fermentation process. Base on four groups single factor tests, then using response surface method to forecast optimum fermentation conditions of flocculant bacteria LLin6: Fermentation temperature 24.7 ℃, medium initial p H 6.5, 6% inoculated quantity, fermentation time, 22 h, under the condition of this theory could get the flocculating rate was 87.14%. And the actual flocculating rate was 85.54%, close to optimal predictive value,it is said that response surface analysis method to get the fermentation conditions of high credibility, it can predict response values.Proposed flocculant producing bacteria LLin6 sludge extract as the substrate production technological process of microbial flocculant, analyses product cost of biological flocculating agent after treatment of excess sludge as the substrate preparation, 3.5 T liquid biological flocculating agent, could recycle excess sludge(concentration of 6 g/L) is about 14.6 T, biological flocculating agent material costs by reduced 404.5 yuan, saved more than 55%(730 yuan), greatly reduce the cost of raw materials. In addition to economic benefits, it also will bring social and environmental benefits.