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Pyrolysis is one promising outlets in disposal of sewage sludge. In the current review paper, some key influent factors on sludge pyrolysis technology and all products were discussed. How the main factors including pyrolysis final temperature, residence time, heating rate and way, the raw sludge characteristics and catalyst, etc influent the products were discussed. Thereafter, another important issue of sludge pyrolysis is the characters and application of the products as well as the key factors affected sludge pyrolysis. The mainly composition, characters and applied prospect were discussed. An important aspect of sewage sludge pyrolysis is how to utilize the pyrolysis oil. Some of the properties and processing of pyrolysis oil were detailedly discussed.

Sludge pyrolysis oil has the potential to substitute for refinery petroleum products for its similar characters with petroleum. In this study, the diesel-like fraction, with high heating value and low sulfur content compared with sludge pyrolysis oil, was obtained from sludge pyrolysis oil which was processed by two-step distillation to remove volatile component and compounds with high boiling points. The chemical composition of diesel-like fraction was investigated by Gas Chromatograph / Mass Spectrometer. The results indicated that this part comprises compounds containing N and O element 48.3% and hydrocarbons 51.7%, the hydrocarbon chain length of the alkanes and alkenes distributes across the C10~C20 mass range in the latter which was close to that of diesel. The sulfur content of diesel-like fraction is 10 times higher than that of diesel, and other fuel characters were similar with that of diesel, which indicated that diesel-like fraction was promising to substitute for diesel. After adding 10% diesel-like fraction into 5 # diesel, the fuel characters of diesel changed so little that it did not influence the application of diesel, which would be significant to alleviate the shortage of petroleum.