Pyrolysis of wastewater treatment sludges for the production of oil and adsorbents.

摘要

Sewage sludge treatment is one of the most difficult problems in the field of wastewater treatment because of increasing expenses and environmental sensitivity. Pyrolysis to produce bio-oil and adsorbents from sewage sludge is a promising way, to not only improve economical value but also, reduce pollutants associated with sludge. The aim of this study was to evaluate the production of oil and adsorbents from raw, wasted activated and digested sludges. The pyrolysis was performed in a laboratory scale horizontal batch reactor. The operating temperature ranged from 250 to 500°C while a gas phase residence time of 20 minutes was maintained with 50 mL/min of nitrogen gas as a purge flow.; The maximum oil yield was achieved with primary sludge at 500°C. Temperature and volatile solids were the most important factors affecting the yield of oil and phenol adsorption capacity of the char, however sludge type also affected the both results. Pretreatment of sludge by either acid or base did not improve the quantity of the products, though it did affect the volatile solids fraction of the samples. The phenol adsorption capacity of the char was affected by pretreatment. The use of a catalyst (zeolite) reduced char recovery.