Study On The Preparation Of Dewatered Sludge By Microwave Alkaline Solution And Magnesium Ammonium Phosphate

In the two stage biochemical treatment system of city sewage,water phosphorus and nitrogen in the part of more than 90%were absorbed by activated sludge,but the nitrogen and phosphorus in sludge dewatering sludge occupies dry weight content of up to 4%and 9%,if not treated sludge for sea or landfill,which contains nitrogen and phosphorus will the consequences of the two serious environmental pollution,and the sewage treatment,nearly 40%of the phosphorus and nitrogen after most residual sludge dewatering liquid return processing system.If you can extract the sludge contained nitrogen and phosphorus,you can get some of the phosphorus resources for the preparation of fertilizer.This subject will take the form of struvite was microwave alkali solution of dehydrated sludge release of orthophosphate and ammonia,because want to get a better lytic effect,thus adding microwave technology,discusses the microwave alkali solution best operating conditions;secondly it discusses Mg/P(n(Mg2+/PO43+)),and the reaction time on the effect of pH the formation of struvite and nitrogen and phosphorus recovery.Experimental conclusion:(1)the pH value in the 12.5 to 13 range,the release effect of TP and phosphate best;subsequent reaction time on nitrogen and phosphorus release effect is not obvious,1H can obtain better orthophosphate and ammonia nitrogen releasing rate.(2)by Microwave-alkali hydrolysis process by the orthogonal test can get the best release conditions,the best pH taking into account the subsequent preparation of magnesium ammonium phosphate is 9.7-10.5 and the effluent pH,the experimental conditions of microwave alkali solution ultimately control the release of phosphorus and nitrogen in the sludge was pH12.6,the microwave heating rate of 14.23 DEG/min and subsequent reaction time for 4h,the final dewatered sludge microwave alkali solution of orthophosphate and ammonia release rate were 46.19%and 59.6%,the supernatant pH 11.5?12.6.(3)magnesium ammonium phosphate precipitation method of alkali recovery in the supernatant solution of phosphorus and nitrogen,ammonia nitrogen and orthophosphate is excessive,limiting factors;recovery of total phosphorus,orthophosphate and ammonia ratio with the magnesium phosphorus ratio increases in magnesium phosphorus ratio reached 1.4,phosphate recovery rate in the platform;Ph in the 9.5?10.5 range,the recovery rate of phosphate is best;stirring time is on the recovery effect of phosphate and ammonia nitrogen was not affected,10 minutes to form struvite precipitation.Under the Mg/P 1.4,pH10.5,the reaction 10min,the positive phosphate recovery rate is 98.47%,the ammonia nitrogen recovery rate is 86.54%.