Pretreatment of Methane Fermentation Effluent by Physico-chemical Processes before applied to Soil Trench System

In this study, ammonia stripping and magnesium ammonium phosphate hexahydrate O H 6 PO MgNH 2 4 4 ⋅ method (MAP) were evaluated for pretreating methane fermentation effluent before applied to soil trench system. For ammonia stripping, the optimal calcium hydroxide dosage was searched systematically. The results shown that the overdosing of calcium hydroxide, 27.5/l wastewater, achieved not only higher ammonia but higher phosphorus, COD, SS and Turbidity removal efficiency. In addition, the volume and settling rate of precipitation was also relative optimal. As expected, ammonia stripping performance was highly dependent on air/water ratio; however, from the point of view of engineering application, air flow rate as 5 l/min for 1 l wastewater should be optimal. For MAP, the optimal pH was about 9 based on