Heavy metal always has great influence on sludge treatment,sometimes even decides the technical route selection.Based on the content and output of extraction of heavy metal from the sludge of three municipal wastewater treatment plants in Xi'an,this paper analyzed the relevant standards about sewage sludge disposal and hazardous waste treatment.The results showed that the policy and standards for sludge disposal lacked adequate attention to transformation property of heavy metal.Further,a series of standard...