Effects of Different Bulking Agents on Nitrogen Transformation During Sewage Sludge Composting

Bulking agents,including rice straw,sawdust and tree leaves,were used to investigate the changes of temperature,TN,NH+4-N and NO-3-N during the sewage sludge composting by artificial turnover protocol.The results showed that using rice straw or rice straw plus sawdust as the bulking agents was beneficial for killing the pathogens and accelerating the speed of composting due to faster temperature increase and a longer duration of the high temperature period.Water-soluble NH+4-N was the highest on the 14th day of composting,which was followed by a rapid decline,while NO-3-N increased on the 14th day of composting.The contents of soluble NH+4-N and NO-3-N in the pile with sawdust or tree leaves were lower than the piles with rice straw or rice straw plus sawdust.The content of TN of the pile decreased during the process of composting due to NH 3 loss through volatilization,which occurred during the first 28 days of composting.Compost pile with rice straw resulted in a higher N loss,while sawdust decreased N loss.