Research On Flocculant Produced By Aspergillus Niger And Its Flocculation

In China, the annual production of starch is about 1 million tons, and the waste generated in the production process of starch has caused serious environmental pollution. Microbial flocculation is an effective way to deal with waste and reduce environmental pollution. This research is for the solid-liquid separation stage during the fermentation process, the use of Aspergillus niger to treat potato residue after fermentation. After flocculation, sediment is added to animal feed to make full use of organic nutrients in waste to create economic value, and reduce the pollution of waste materials and reduce the cost of wastewater treatment.With kaolin suspension as the experimental agent, the flocculation effect of the five strains were compared, and the flocculation rate of Aspergillus niger was 83.9%, so the Aspergillus niger was determined as the experimental strain. The distribution of the flocculant produced by Aspergillus niger was analyzed, and the activity of the flocculant was found in the supernatant of the fermentation culture of Aspergillus niger, which was an extracellular substance produced by Aspergillus niger,The p H value, flocculation rate and dry weight of mycelium were monitored during the fermentation of Aspergillus niger, and the optimum fermentation time was 72 h. To study the influencing factors of the production of flocculant from Aspergillus niger, the research showed that the strain generated the most flocculation product when the carbon source of the medium was sucrose, nitrogen source was sodium nitrate, the p H value was 7, the culture temperature was 30. Extraction and qualitative analysis of the substance produced by Aspergillus niger showed that we have discovered a white powder soluble in water,which contains a large amount of polysaccharide and trace amounts of protein, in order to lay a foundation for further research on the flocculation mechanism of microorganisms.With COD removal rate as a measure, we use PB experiment to determine three significant factors which affect the flocculation, and the flocculating co nditions were optimized by response surface method.Result of fermentation culture of Aspergillus niger flocculation processing potato starch waste fermentation product showed that: p H was 7.0, the dosage of coagulant was 5.45%, the coagulant dosage was 869 mg/L, the removal rate of COD was 75.74%, which was consistent with the theoretical value of 76.1%. Experiments show that has good flocculating effect by fermentation of Aspergillus niger flocculation of potato residue.