Release Characteristics Of Harmful Substances During Co-processing Sewage Sludge In Cement Kilns

With the acceleration of urbanization and sewage treatment rate, the large numberof sludge has become an important factor restricting urban development. Sludgetreatments have many ways in the current, but those ways will bring serious secondarypollution which is not widely used. Cement kiln co-processing of sludge technologyprovides a new way of thinking for the disposal of sludge. Having the advantages thatother technologies do not have, it is expected to solve the problem of secondarypollution, which is the key to get wet sludge dry in low-temperature. The article studiesrelease characteristics of harmful substances during co-processing sewage sludge incement kilns, in order to provide a theoretical basis for the development andoptimization of co-processing sludge in cement kilns technology.Using GC-MS system to study the changes in the composition of sludge afterrising drying at different temperatures, analyzing the situation rising drying during thereleasing hazardous gases. The results showed that: the sludge contains up to90kindsof organic compounds in which the nitrogen and sulfur is a major source of harmfulorganic substances. With the increase of drying temperature the odor organic matter inthe sludge has increaseddry as well as the stench releasing in processing of sludge.The distribution features of the nitrogen and sulfur in sludge was studied andanalysised the migration process of the two elements illustrating their migrationmechanism.The results showed that: the form of sulfur in the sludge mainly exsits in organicsulfur.At a certain temperature it transferred into the acid, finally mainly relasing in theform of dimethyl trisulfide, H2S and SO2gases Nitrogen in sewage sludge mainly exists in the form of organic nitrogen, and finally in the form of NH3, HCN and otherinorganic gases released into the environment.The effect of oxygen content on the drying and combustion process of sludge isstudied using TG-FTIR system.and the results showed that the presence of oxygen isadvantageous to the decomposition of organic matter in sludge, and with the increaseof oxygen concentration, the decomposition rate is higher. At the range of0~300℃temperature under the atmosphere of12.5%oxygen concentration of sludge pyrolysisis to produce the least amount of gas.Using TG-FTIR system to study the effect of the cement kiln ash absorbs harmfulgases from sludge deposal, analyzing ash sludge inhibition of the releaseed harmfulgases.The results showed that: the cement preheater of fly ash on the sludge of releaseof gas species would not be a big impact But the ash can inhibit the production of gaswhen the mass ratio of sludge and fly ash greatly1:1, the amount of gas released fromthe drying and burning of sludge is at least.By orthogonal test method to determine the optimal digestion method to use ICPdetection of heavy metal content in sludge and studied several kinds of heavy metals indifferent drying temperature of heavy metal content of the study The results showedthat with the increase of drying temperature, the quantity of heavy metals releaseincreases too, including arsenic volatilizing quantity at range of200~300℃itsvolatilizing quantity up to32.13mg/kg. The minimum amount of volatile is lead at300℃when only5.16mg/kg volatilizing...