A STUDY ON TWO-STEP ANAEROBIC DIGESTERS TO TREAT SOYLEAN PRODUCTS WASTEWATER

This paper gives the tentative results on treating soylean products wastewater on using two different kinds of two-step anaerolic digesters-one is the concentric circles of two pipes with fixed filling film as one unit and the other is the seperated two-step type. Each of them has the results of the biogas production rate at 3, 0 L / Ld. and 4.9L / Ld; COD loading rate at 5.7g COD / Ld and 10.7gCOD / Ld; while the hydraulic retention time of 38 hours and 28 hours respectively. Both of them have the maerial dismantled rate about 90% and approximately the same methane quantity. They also can help on running amormal pH value and forming a certain extent of granular sludges inside. The seperated two-step type digeste has the loading rate to 83 gCOD / Ld in its frist acidific stage, 3.4 hours of hydraulic retevtion time with the pH value at 4.8-5.0, and having higher contents of volatile fatty acids, in comparison with the data, it is known that the seperated two-step anaerobic digester has better results for treating the soybean products wastewater.