Dewatering and low-temperature pyrolysis of oily sludge in the presence of various agricultural biomasses

ABSTRACT

Pyrolysis is potentially an effective treatment of waste oil residues for recovery of petroleum hydrocarbons, and the addition of biomass is expected to improve its dewatering and pyrolysis behavior. In this study, the dewatering and low-temperature co-pyrolysis of oil-containing sludge in the presence of various agricultural biomasses, such as rice husk, walnut shell, sawdust, and apricot shell, were explored. As a result, the water content gradually decreases with the increase of biomass addition within 0–1.0 wt % in original oily sludge. Comparatively, the dewatering efficiency of sludge in the presence of four types of biomasses follows the order of apricot shell > walnut shell > rice husk > sawdust. On the other hand, rice husk and sawdust are relatively more efficient in the recovery of petroleum hydrocarbons compared with walnut shell and apricot shell. The recovery efficiency generally increased with the increase in the biomass content in the range of 0–0.2 wt %, then exhibited a gradually decreasing trend with the increase in the biomass content from 0.2 to 1.0 wt %. The results suggest that optimum amount of biomass plays an important role in the recovery efficiency. In addition, the addition of biomass (such as rice husk) also promotes the formation of C_xH_y and CO, increasing the calorific value of pyrolysis residue, and controlled the pollution components of the exhaust gas discharged from residue incineration. The present work implies that biomass as addictive holds great potential in the industrial dewatering and pyrolysis of oil-containing sludge.

KEYWORDS:

• Oily sludge
• dewatering
• pyrolysis
• biomass
• oil recovery

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the West Light Foundation of Chinese Academy of Sciences  [grant number 2015-XBQN-A-03]; the Xinjiang Program of Introducing High-Level Talents [grant number Y539031601], National Natural Science Foundation of China [grant number 41571446]; CAS Youth Innovation Promotion Association [grant number 2016380].