Study On Recovery Technology Of Starch From Cassava Starch Waste Water

This article firstly summarized the main methods and development prospects of starch water’s resource utilization at home and abroad, and then introduced what have done specifically. In this article, secondary separation wastewater fetched from a starch factory in Nanning, Guangxi was used as study object, methods of natural precipitation, coagulation experiment method, enzyme method and microbial method were used to recover starch from the waste water.Natural precipitation method are widely used in most of starch factory, in this article, natural precipitation method was used without adding anything, just place secondary separation wastewater naturally for8hours, then separated the supernatant and sediment then measure the starch amount in sediment. Aluminum sulfate, ferric chloride, polyacrylamide and polymeric aluminum sulfate were used in coagulation experiment method, the best dosage amount and PH value was determined by measuring the COD removal rate and turbidity. Trypsin used in enzyme method, trypsin dosage amount, temperature, time and pH value were altered to get the optimal condition. The microbial method was that adding anaerobic wastewater into secondary separation wastewater, bacteria in anaerobic wasterwater decomposited organic matters without starch so as to improve starch precipitation.Through the experiment research the following conclusions can be obtained:1. Organics such as such as starch, protein and amino acids were abundant in secondary separation wastewater, among which the content of starch was very high, through natural precipitation method,7.04g/L starch can be recovered.2. After treatment with organic and inorganic flocculants, turbidity of wastewater is low, remove ratio of COD was also relatively good,8.02g/L starch can be recovered.3. Recover starch from secondary separation wastewater with the help of trypsin, and study the recovery conditions based on orthogonal design, the result showed that recover amount of starch was8.72g/L, but the shortcoming was that the cost of this method was high.4. Recover starch from secondary separation wastewater with microbial method, the amount of starch recovered can reach to9.58g/L, the effect of recovery is obvious, and the cost is low.All in all, it is of great significance to recover residual starch from cassava secondary wastewater, and it has boarder application prospects to improve the currently feasible recovery technology.