Preparation Of Bioflocculant And Its Performance Research

Bioflocculant is one kind of metabolic product produced by the living cell, which has the flocculating activity. Its characteristics include the broad flocculating scope, non-toxic to human and biodegradable, etc. One of factors that limit bioflocculants application is the excessively high cost. The objective of this study is to look for the low-cost culture medium and prepare harmless and no secondary pollution bioflocculants. Waste water treatment application research has been carried with the bioflocculants.Flocculant-producing bacteria were isolated mainly from the air and activated sludge. After secondary screening, two strains that had higher and stable flocculating activity were obtained and they were named as M-1, M-2, respectively. M-1 strain was identified as Bacillus and M-2 strain was identified as Micrococcus Cohn. Brewage wastewater was used as low-cost medium to culture mixed bacterium M1-2. The influence of factors of external carbon source, nitrogen source, medium pH value, culture time etc. on strain flocculation effect was investigated and its culture conditions were optimized. The flocculating rate of kaolin suspension was up to 95.0% under the conditions as that the carbon and nitrogen sources was not needed to add, cultivating temperature 30℃, initial pH of culture medium 8.5, cultivating time 48 h and shaking speed 160 rpm, which shows that the brewery wastewater contained rich nutrient which can provide abundant carbon and nitrogen sources for flocculant-producing bacteria species M1-2 and it is feasible to take advantage of distillery wastewater to culture the mixed M1-2, so that the culture cost could be reduced greatly. The bioflocculant that produces by brewery wastewater has better flocculating activity.The crude flocculant performance was studied in the oil wastewater from Daqing some chemical plant. The effects of hydraulic mixing time, flocculant volume, the volume of CaCl2 solution and pH values factors on coagulation were studied. The best treatment conditions were determined by orthogonal test and some water quality index were monitored to evaluate the flocculant effect in these wastewater treatment processes. Mixed bacterium bioflocculant was studied in chemical plant. In the condition of pH value of 9, the flocculants volume of 6mL, the CaCl2 solution (1%) volume of 5mL, the flocculation rate was 90.5%, the removal rate of COD was 68.7%, and the removal ammonia-nitrogen was more than 95%. The results indicate that oil wastewater treatment with the bioflocculant is feasible.