Study Of Effect Of Processing Conditions On Nitrogen Loss During Aerobic Composting Of Sewage Sludge

Sewage sludge is the byproducts during the treatment process of the municipal wastewater, so it is imperative to treat and dispose the sewage sludge in order to avoid the secondary pollution. Aerobic composting is one of the technology of the sewage sludge treatment. Unfortunately, the nitrogen loss during the sewage sludge composting is usually upon 40%, which reduces the agricultural value of product seriously. So it is necessary to study the effects of different factors on nitrogen loss during the composting to optimize the process. The purpose of this article is to study the effect of composting processing conditions on nitrogen loss, and provide a theoretical basis for the actual operation of aerobic composting of sewage sludge.In this paper, the study of the effect of processing conditions on nitrogen loss during the sewage sludge composting was divided into four aspects: the dewatering way of sludge, the bioleaching, the particle size of sludge, and the clinker reflux. Firstly, the effect of processing conditions on physicochemical characteristics of sludge and the degradation rate of organic matter during the composting was studied. Secondly, the transformation regulations between different nitrogen forms was analysised. In the end, studied the effect of the dewatering way of sludge, the bioleaching, the particle size of sludge, and the clinker reflux on nitrogen loss according to the cumulative emssion of ammonia and nitrous, and the nitrogen content during composting.The results showed that the moisture of the conventional dewatered sludge was 85.01%.The emission of carbon dioxide, methane, and nitrous oxide was mainly occurred during mesophilic stage, while the ammonia emission was mainly released in the thermophilic stage. In the end, the cumulative amount of ammonia was 114.95mg/kg, the cumulative of nitrous oxide was 7.66mg/kg, and the nitrogen loss was 2.31g/kg.The techonelogy of thermal drying treatment enhanced the value of p H, accelerated the volatilization of ammonia, and the cumulative amount of ammonia was 324.46mg/kg. At the same time, the thchonelogy of thermal drying treatment reduced the content of nitrate and nitrite, and reduced the mineralization rate of organic matter and the the release of nitrous oxide. The cumulative amount of nitrous oxide was 3.78mg/kg and the nitrogen loss was 3.91g/kg in the end of the composting.The bioleaching treatment could decreased the value of p H, and the cumulative amount of ammonia decreased to 190.30mg/kg. Non-addition of bulking agent during composting could shorten the thermophilic stage and increase the moisture of sludge and value of p H. At the same time, non-addition of bulking agent could decrease the rate of oxidation and decomposition of carbon resource, reduce the cumulative amount of nitrous oxide to 2.87mg/kg, and reduce the nitrogen loss from 41.82% to 46.77%.Reducing the particle size of sludge could promote the evaporation of moisture, decrease the value of p H, and decrease the cumulative amount of ammonia to 1099.52mg/kg. Reducing the particle size of sludge could improve the rate of degradation of organic matter, reduce the concentration of methane, and reduce the cumulative amount of nitrous oxide from 6.03mg/kg to 4.05mg/kg. In the end, the nitrogen loss was reduced to 28.13%.Clinker reflux could increase the moisture of sludge, extend the thermophilic stage, and promote the degradation of organic matter.The cumulative amount of ammonia decreased from 507.03mg/kg to 410.53mg/kg. What’s more, clinker reflux could increase the cumulative amount of nitrous oxide, and ruduce the nitrogen loss from 17.68% to 11.70%.