Study On Pollutants Removal Of Laboratory Aerobic Composting Reactor

Bio-toilet is the name of a dry or composting toilet that uses sawdust as a bulky matrix for bioconversion of human excreta into compost which can be used either as organic fertilizer rich in N,P and K,or as a soil conditioner.Compared with conventional sanitary facilities,bio-toilet needs neither water nor sewage system,and can inactivate pathogenic organism.Thus,it is significantly meaningful to study bio-toilet.The purpose of the experiment is to examine the removing effect of the reactor on the condition of simulating natural ventilation.The temperature in reactors is controlled at about 50℃,and the water content is between 50%and 60%.The study quantified analyzes the removal rates of COD,TOC,nitrogen of the laboratory aerobic composting reactor.And the conclusions are as follows:(1)Under the condition of batch-fed skatole,in 27th August,the skatole content decreased from 0.712mg/g,0.335 mg/g to 0.051 mg/g,0.012 mg/g in the first six hours. And the removal rate is 93%.Then,its amount kept decreasing,and the removal rate exceeded 99%after twenty four hours.In 6th September,the skatole content decreased from0.735mg/g,0.303 mg/g to 0.074 mg/g,0.057 mg/g in the first six hours.And the removal rate is 89%,80.9%respectively after six hours.The removal rate exceeded 99%after twenty four hours.Under the condition of intermittent,in the first 12 hours,it decreased with high speed.The content decreased from 0.667mg/g,0.667mg/g,0.333mg/g,0.333mg/g to 0.168 mg/g,0.125 mg/g,0.058 mg/g,0.068 mg/g after 12 hours.The removal rate can reach 90%after 24 hours and 93%at the end of 48 hours.(2)The degradation of TOC is that in the first 2 days,the speed is high.The contents in No.1,2,3 reactors are from 3.309mg/g,2.922 mg/g,3.515 mg/g to 1.948 mg/g,1.354 mg/g,1.391 mg/g.And the removal rate can reach about 50%.Then the speed lowered down.At the end of the experiment,the removal rate of TOC is 71.83%,60.58%,69.32%respectively.The degradation of COD is that in the first 2 days,the speed is high.And the removal rate can exceed 60%.Then the speed lowered down.At the end of the experiment,the removal rate of TOC is 72.59%,74.14%,80.57%respectively.(3)The content of ammonia-N decreased rapidly in the first 6 days,and during these days,its value decreased from 0.919mg/g,0.919mg/g,1.073mg/g,0.983mg/g to 0.391 mg/g,0.289mg/g,0.246mg/g,0.212mg/g.The loss rate of ammonia-N is 66.37%,73.28%,77.65%,80.12%respectively after 10 days.The loss of TN is apparent,but the speed changed a little.The value of TN decreased from2.394mg/g,2.394 mg/g,2.396 mg/g,2.195 mg/g to 1.392 mg/g,1.487 mg/g,1.300 mg/g,1.156 mg/g.Then the value declined a little.The loss rate of TN is 45.73%,43.36%,51.49%,50.01%respectively at the end of experiment.The loss of organic N is that the content of organic N decreased from 1.437mg/g,1.172mg/g to 0.932mg/g,0.812mg/g.The loss rate is near 40%at the end of experiment.The degradation speed of nitrate N changed a little.The amounts of nitrate N decreased from 0.0384mg/g,0.0397 mg/g to 0.0115 mg/g,0.0129 mg/g.The loss rate is about 70%at the end of experiment.Denitrification bacterial disappeared quickly.And 7 days later,the amount of denitrification bacterial disappeared above 90%in reactor No.1 and the denitrification bacterial in reactor No.4 disappeared above 80%at the end of 3 days.The three morphologies of nitrogen loss to different extents,and ammonia-N loss mostly.Organic N loss to some extent under the degradation of organism.At high temperature,the metabolism of organism is constrained.It shows that,at the condition of simulating natural ventilation,the main reason for nitrogen loss is the volatile caused by high temperature.(4)Kinetics results:We get good effect using simulation.The reaction of degradation of TOC and COD is zero order at the beginning of 2 days,and after 2 days, the reaction is one order.The relative error of true value and fitting value is not big. And we forecast the value of TOC and COD between 20d—50d.The forecasted value shows that the TOC and COD will not change a lot.In the whole process,there is no flavor in the reactor and the sanitary condition is kept good.So,we can say that aerobic composting reactor is a feasible facility to remove feces.It can achieve the purpose of degrading organics and keeping fertilizer. In the area where water is not enough,it is a good sanitary and composting facility.