Study On The Sludge Composting Technology Of The Surplus Activated Sludge In Villages And Towns

The rural sewage plants in our country produces much surplus sludge during processing.Based on the facts on all aspects,the application of sludge composting in agriculture seems to be the best method in sludge disposal according to our national situation.Hence we conducted experiments and research on the effect of different ways of ventilation,additive amount of different weight ratio conditioner and different volume ratio conditioner on the sludge composting and analyzed the change of rules of the features of appearance,temperature,water content,p H and organic matter content.In the study of the effects of different ventilation ways on the sludge composting,we conducted a comparative test between intermittent forced ventilation and natural ventilation,during which the testing method we adopted are all regulated in the “ The Sludge Disposal of Urban Sewage Plant for Agricultural Use”(CJ-T309-2009).Both of the water content and organic matter content of the two composting piles decreased gradually and the water content became lower than the standard limitation of 60% at the end.The way of intermittent forced ventilation performed better than the other.In the study of the effects of the conditioner of different weight ratio on the sludge composting,three piles were set to a make a comparison.After aeration composting above 30 days,the weight ratio(sludge: saw dust)10:1 outperformed.During this process,the water content and organic matter content reduced overtly;the temperature maintained at the medium for fermentation and the p H changed within a reasonable range.They all meet the requirements of the sludge composting.When it's over,the water content of the three piles were 41.29%,43.23% and 54.56%,the p H were 7.12,7.21 and 7.26,respectively which was apparently lower than the standard 60%.Therefore it's unnecessary to dry the matured composting samples.The total nutrient content of the three piles were4.88 %,5.47% and 4.89 %,respectively.It could provide the nutrition needed for the growth of crops and other plants.Totally,the No.1 composting piles owned higher maturity,good composting performance and could be utilized in agriculture,besides,the composting outcome conformed to the standards of“ the Standards of Pollutant Control in the Sludge Used in Agriculture ”(GB4284-84).In the study of the effects of the conditioner of different volume ratio on the sludge composting,the No.1 composting piles owned higher maturity,good composting performance,which met the Hygienic requirements for harmless disposal of night soil(GB7959-2012),and the composting piles stayed over40? for longer time,during this process,the water content and organic matter content reduced overtly;the temperature maintained at the medium for fermentation and the p H changed within a reasonable range.After composting,water content of the three composting piles were about 50%.The volume ratio(sludge: rice husk)1:1,After the completion of the compost products contain high nutritional elements,it could provide the nutrition needed for the growth ofcrops and other plants.So it's feasible to compost the surplus sludge from rural sludge plant.