Study On Treatment Of Potato Starch Wastewater

In recent years, the growing area of potato has been rapidly spread as the fourth worldfood crop under the guidance of local government in China due to the shortage of world food.Potato processing enterprises also increase rapidly and the starch industry has become animportant channel for farmers to increase income. However the problem of wastewater andsewage disposal has been becoming serious. It is urgent to improve the treatment of potatostarch wastewater in order to reduce the environmental pollution of starch wastewater.Potato starch wastewater contains a lot of soluble organic pollutants and suspendedsolids with different sizes. It is non-toxic and is easy to biodegrade. Currently, biochemicaltechnique is commonly used to treat potato starch wastewater. But the potato starchproduction is hold in later fall and in early winter each year. The temperature of starchwastewater is not suitable for biochemical treatment. Alternatively coagulation is an effectivetechnique to a majority of separate suspended solids and some organic pollutants from starchwastewater. It is easy to operate and economic in investment.Coagulation-adsorption technique is used to treat potato starch wastewater in order toexamine if coagulation is applicable to the treatment of potato starch wastewater with lowtemperature in winter in the northwestern China. These procedures provide a theoretical basisfor this type of starch wastewater with high concentration of organic pollutants.The thesis consists of four parts.In the first chapter, advances in starch wastewater treatment were reviewed based onsummary of the production situation and corresponding pollution of potato starch wastewater.In the second chapter, coagulation is used to treat potato starch wastewater. It has beenfound that the total removal rate of COD is close to 54.5%, the total removal rate of variousprotein 32.0% and the total removal rate of suspend solid 97.0% in the presence of 1000mg/Lpolyaluminium chloride and 30mg/L polyacrylamide.In the third chapter, bentonite was modified and employed to treat potato starchwastewater. The experimental results show that original bentonite is better than modified onefor the treatment of potato starch wastewater.In the forth chapter, the preliminary comprehensive utilization of potato starch wastewater was studied. The contents of protein and starch in various potato starch sedimentswere evaluated after coagulation and adsorption. The recycling use of potato starch residueswas proposed.