Characteristics Of Sludge And Treatment Strategies In An Economic City In East China

The treatment of sewage and sludge,the products of sewage disposal,are two systems which are of equal importance and close relationship.The treatment of sludge guarantees the final implement of sewage treatment.At present,there is a lack of attention to the sewage sludge pollution and its disposal in China,due to the limited development of environmental protection,less awareness of us,underdeveloped techniques and facilities of environmental protection and imperfection of relevant laws.This paper carries out the research the sludge from 18 sewage plants in an economic county,KS,in East China.The research will report the physical and chemical properties and disposal methods of the sludge in these plants,analyze the advantages and disadvantages of the disposal techniques and evaluate relevant potential techniques which are beneficial to the disposal of the sludge in KS.The analysis aims at providing a basis for the future sludge management strategies in China.The main findings of this research include:1.The 18 sewage plants involved in this research mainly dispose domestic wastewater in KS.The volume of wastewater treatment is 240,000 tons·d-1 and the generation of the sludge is 175 tons·d-1.2.Most of the sewage plants use amendments(flocculants)to regulate the sludge.The dehydration methods are belt filter pressing,frame filter pressing,centrifugal dewatering,the first two of which are the main methods.3.The moisture content of the sludge lies between 66.78%?89.18%.The organic content of the sludge in half of the sewage plants reaches to more than 40%.The content of C,H,N,P in the sludge discharged from the sewage plants is relatively high.The heavy metal content of the sludge is generally high.The main heavy metals are As,Zn,Cu and Ni,among which the times of ultra standard of Cu is more than 100.4.The heat value of the sludge in all the sewage plants can't meet the requirement of direct combustion,so dehydration pretreatment need to be conducted.After dehydrating,the sludge mainly goes to thermal drying process,the rest of which is used to feed earthworm to make fertile.The expense of the sludge's disposal,expense of transport and disposal included,ranges from 300 to 400 yuan.ton-1,which is about 10%of the total sewage plant sewage treatment fee.