Composting treatments of chlorobenzenes(CBs) in municipal sludges

Eight composting treatments including manual turning, inoculating-manual turning, continuous aeration, and intermittent aeration for municipal sludge with rice straw, wood chip and maize stalk were carried out. Chlorobenzene (CBs) in different composts were determined by gas chromatograph/mass spectrograph(GC/MS). Total contents of five CBs compounds (ΣCBs) in composts ranged from 0.035 mg/kg to 5.608 mg/kg, which decreased in the order: Guangzhou sludge mixed with rice straw by manual turning(5.608 mg/kg)＞Guangzhou sludge mixed with rice straw by inoculating-manual turning(0.355 mg/kg)＞Guangzhou sludge mixed with rice straw by continuous aeration(0.280 mg/kg)＞Foshan sludge mixed with rice by manual turning(0.173 mg/kg)＞Guangzhou sludge mixed with rice straw by intermittent aeration(0.103 mg/kg)＞Foshan sludge mixed with wood chip by intermittent aeration(0.088 mg/kg)＞Xi'an sludge mixed with maize stalk by aeration (0.078 mg/kg)＞Foshan sludge mixed with wood chip by manual turning(0.035 mg/kg). The content of most individual CBs compounds in composts was lower than 0.10 mg/kg. Among various composting treatments, foshan sludge mixed with wood chip and aeration composting especially intermittent aeration composting treatment were more efficient to degrade CBs in municipal sludge. Suitable composting treatment for municipal sludge to reduce CBs and to ensure its safer application to agricultural land is practical.