Process Design Of UASB Combined With CASS Treatment Of Soybean Wastewater

Soybean wastewater is a kind of high concentration organic wastewater,which is complex and difficult to deal with.It is of great significance for the environmental protection and the development of soybean industry to seek a reasonable and effective treatment technology with a lower cost of management.This study aimed at the treatment of wastewater discharged from a bean product factory in Hebei.Through careful research,detailed analysis of water quality characteristics of soybean wastewater,comprehensive comparison of predecessors' Soybean wastewater treatment techniques and treatment process,and combined with the specific strength,scale and emission of the factory,initially identified the treatment process of “precipitation A/O(UASB and CASS combination)”.The experiment and design of the wastewater discharged from the soybean product factory were carried out.The flocculants with the best treatment effect were screened from four kinds of flocculants such as anionic polyacrylamide(APAM),cationic polyacrylamide(CPAM),sodium polyacrylate(PAAS)and polyaluminium chloride(PAC).The COD removal rate was 32.5% when the optimum dosage was 15.5l /(1L wastewater)with the mass fraction of 0.1%.The process of "precipitation-A / O" process is simulated by laboratory to deal with the waste water of the plant,which proves that the process design is feasible.Finally,according to the relevant design specifications and standards,the specific parameters of each process link is calculated.Waste water treatment capacity is designed to be 600t/d.The settling tank is designed with a rectangular shape of 8.0×5.0×3.0,the hydraulic retention time is 4.8h;the sedimentation tank is designed to have a rectangular shape of 10.8×2.3×2.3,the aspect ratio is 4.70?4,the settling time is 1.5h;the UASB reactor is designed with a cylinder shape of ?7.2×8.89,the ratio of height to diameter is 1.23>1,the hydraulic retention time is 14h;the CASS pool is designed with a rectangular structure of 13.4×5×5,the aeration time is 3.7h,the sedimentation time is 1.7h,the hydraulic retention time is 6h.The total COD removal rate of the whole process was designed to be around 98.5%.Finally,the water quality monitoring report shows that the effluent meets the water quality standard of "farmland irrigation water quality standard",thus confirming the good effect of the process design.