Pollution characteristics of organic contaminant in sludge from wastewater treatment plants and sludge ocean dumping disposal in China

Thirteen sludge samples from cities of Guangzhou,Shanghai and Dalian were collected and contents of organochlorine pesticides( OCPs),poly-aromatic hydrocarbons( PAHs),polychlorinated biphenyls( PCBs) and petroleum hydrocarbons were determined by chromatography and fluorometric spectrophotometry method. The results indicated that industrial sludge was more seriously polluted than domestic sludge in terms of PAHs,PCBs and petroleum hydrocarbons. Contents of the four detected organic contaminants in sludge from Shanghai were higher than those from Guangzhou and Dalian except for oil. It was also indicated that oil is the typical organic pollutant in sludge samples and 8% sludge samples exceeded its standard for the third kind of marine sediment beside oil. Furthermore,none of the collected sludge samples satisfied the qualifications of dumping to the ocean. The results also indicated that 92%sludge samples were under the limited standards for fertilization of sludge in terms of PAHs and PCBs,while only one sample fit with the relative standard in terms of petroleum hydrocarbons. Based on the above results,it was shown that most of the sludge could be disposed by land application rather than dumping to the ocean if oil concentration in the sludge was decreased to less than the relative limit.