Study On Optimization For Sludge High Temperature Aerobic Composting Process

Excess sludge production increase with the increasing of urban sewage treatment, disposal of the sludge has become a very urgent environment problem. Compost can transfer sludge to valuable composting product, and have the advantage of low running cost for broad prospect of application. But currently sludge composting exist some problems such as composting cycle long, odorous gases, large dosage of conditioner et al. Therefore, this topic is based on the multi-scale regulation theory, respectively from the graining biological conditioner, compound microbial agents, positive and negative pressure coupling ventilation to optimize the high temperature sludge aerobic composting process, the results are as follows:1.A granular biological conditioners dosing quantity optimization. In the high temperature aerobic composting process of sludge, the optimal dosing quantity of granular biological conditioner is 20%, under this dosing quantity condition, pile body heated up rapidly, at day 2 close to 50℃ high temperature, maintain the longest high temperature period to eight days; Organic matter degradation rate is the highest, from the initial 59.8% to 47.4%; Compost dehumidification effect is good, the final moisture content of sludge composting products is 48.4%; Keep nitrogen effect, can keep the ammonia of pile body under 500 ppm; C/N ratio of final sludge composting product is greater than the C/N ratio of the initial sludge; The pile body oxygen content is high, is not easy to generate H2 S. Changes in the pH of the pile body material is not large.2.Determine compound microbial agents vaccination ratio. The optimum inoculation of compound microbial agents in high temperature aerobic sludge composting process is 5%, under this condition of the inoculation ratio, pile body heated up rapidly, at day 3 has reached to 59℃ high temperature, maintain the longer high temperature period to 6 days; Sludge organic matter degradation quickly, from the original 59.2% to the final 51.7%;Compost dehumidification effect is good, the final moisture content of sludge composting products was 58.3%, conditioner final moisture content was 36.2%;Ammonia remain below 500 ppm in the pile body; Final C/N ratio of sludge composting product is significantly lower than the C/N ratio of initial sludge; The oxygen content of pile body first decline then rising, the hydrogen sulfide and oxygen content in negative correlation. But there is little effect on the pH change of the pile body material.3.The choice of ventilation. The best ventilation way of high temperature aerobic sludge composting was first negative pressure ventilation then positive pressure way, under this condition of the ventilation mode, the early stage of the pile body heated up faster, the highest temperature is high 6℃ than the positive pressure ventilation; It is advantageous to the middle and later periods of the pile body to remove moisture and final moisture content is low for 53.5%, the final moisture content of conditioner is lowest for 35.4%;It is favorable for the biodegradation of the pile body organic matter, its ultimate organic matter content is the lowest for 40.4%;The release of ammonia concentration is low; The final composting sludge C/N ratio high than the original sludge C/N ratio. But there is little effect on the pH change of the pile body material.