Study On Production Of Bio-Oils From Sewage Sludge By Microwave Assisted High Temperature Pyrolysis

Along with the rise of wastewater treatment ratio, the sludge output is increasing all over the world., and the pollution of sewage sludge become more and more serious. Sewage sludge which is resemble with various organic waste contain a great deal of volatilizable organic matter. Pyrolysis could release energy as fuel or special chemicals.It is Pyrolysisi that sewage sludge convert into oil, aqueous, NGG and char by carbonization and decomposing in anaerobic atmosphere. Because of the similarity with lower distillation of petroleum in refinery, the oil fraction has huge potential in utilization.The characteristics of oil from sewage sludge pyrolysis was studied on the basis of screening different microwave absorbers. Condition of oil obtained from sewage sludge pyrolysis was optimized by the analysis of composition, harmful compounds and LHV. Furthermore the feasibility of recycle as fuel or chemical material was discussed. And mechanism of oil formation with different absorbers mixed was also analysised. Advantage in capability and safety of oil was displayed by comparing to traditional pyrolysis. It is just the superiority of microwave pyrolysis. So it has important meaning that sewage sludge could be converted into useful resource by microwave pyrolysis facing with the increasing amount of sewage sludge.The study show that temperature up to 900℃of sewage sluge was achieved during microwave treatment, and yield of oil fraction is lower than yield of gas. In order to compare with microwave, the max temperature of muffle was setted on 900℃. It is concluded that microwave has the advantage of short heating time and excellent effect in decomposion.The distribution of different classes of compounds is analysised. The ratio of aliphatic hydrocarbons is up to 33%~56%, and its LHV is 32MJ/kg~37MJ/kg. it can be used as substitute of lower distillation of petroleum. Oil obtained from microwave pyrolysis contain PAHs, but percent of harmful compounds only is 0.42% which is lower 1% than traditional pyrolysis. Many monoaromatic Hydrocarbons such as toluene, dimethylbenzene, cinnamene and phenol are all important chemical material.Although Oil obtained from muffle have higher LHV, content of aliphatic hydrocarbons of it is down to 8%, at the same time content of aromatic hydrocarbons is up to 50.3% which is double to oil obtained from microwave. If harmful PAHs form during burning, it is not safe.If char which is resident of microwave pyrolysis was recycled as microwave absorber, yield of char will decrease and amount of absorber needed decrease too. Because of concentration, the more recycle time is the more content of Si, Al and Ca is. This result in the increasing of light compound. It is propitious to reuse as fuel.