Study On Treatment Technology Of Potato Starch Processing Wastewater

Potato starch wastewater is a kind of high concentrated organic wastewater which isdifficult to be treated. In this thesis, the treatment process of “coagulation andsedimentation+UASB+contact oxidation” was used to treat potato starch wastewaterand the operation results indicated that this process was effective and efficient.When PAC was used for coagulation treatment of potato starch wastewater, theaverage removal rates of COD and SS were36.2%and71.0%, respectively.The start-up of UASB was realized at low organic concentration, high hydraulicloading and batch influent. During the stable continuous operation, the CODconcentrations of influent and effluent were9253～10797mg·L^-1and468～623mg·L^-1,respectively at the treatment capacity of500m³·d^-1. The corresponding COD removal rateand organic loading rate were84.5%and10.0kgCOD·（m³·d）^-1, respectively. When theorganic loading rate was3.0kgCOD·（m³·d）^-1in the UASB, the sludge bed was floc. Thegranular sludge appeared when the organic loading rate reached7.5kgCOD·（m³·d）^-1in theUASB. The sludge granulation was accomplished at the organic loading rate of10.0kgCOD·（m³·d）^-1.The contact oxidation bioreactor was started at batch influent. The qualities of theinfluent were: COD of488～547mg·L^-1，BOD₅of195～221mg·L^-1and SS of115～141mg·L^-1, and the DO was controlled at3～4mg·L^-1. The organic loading rate was increasedduring operation. At the end of operation, the removal rates of COD, BOD₅and SS were85.0%,91.8%and70.9%, respectively. The organic loading rate was0.85kgCOD·（m³·d）^-1. During whole operation of contact oxidation bioreactor, the sludge colorchanged from black at the beginning to yellowish brown finally. After the stable operation,the mount of nematodes reduced in the sludge and rotifers increased.These results indicated that it was reasonable, feasible and efficient to treat potatostarch wastewater by the treatment process of “coagulation and sedimentation+UASB+contact oxidation”, and significant economic and environmental benefits could beachieved.