Huang, H; Nie, Z; Meng, B; Yue, B; Wang, D; Wu, N; Huang, Q
In order to explore the effect of different treatment processes on shale gas drilling cuttings, the water-based residues and oil-based residues generated from the treatment of shale gas drilling cuttings in Chongqing were sampled, the residual levels and the change rule of characteristic pollutants (heavy metals, PAHs and petroleum hydrocarbons) of drilling cuttings before and after different treatments processes were systematically analyzed. The results show that the combination process of thermal desorption and rotary kiln incineration has better effect on the removal of heavy metals from oil-based drilling cuttings, the combination of thermal desorption and rotary kiln incineration, single thermal desorption process, thermal desorption and electrolytic combination process can effectively remove 2-4 ring PAHs in oil-based drilling cuttings and light components of petroleum hydrocarbons, the removal rates of PAHs in drilling cuttings by the three processes were 72.5%, 95.3%, and 93.0% respectively, and the removal rates of petroleum hydrocarbons were 90.0%, 93.9%, and 93.2% respectively. Treatment of water-based drilling cuttings with solid-liquid separation and pressure filtration dehydration resulted in the accumulation of heavy metals (Cr, Ni, Cu, Zn, Pb, As) and 2-4 ring PAHs in water-based residues. After treatment, the contens of heavy metals, PAHs and petroleum hydrocarbons in the water-based residues and oil-based residues did not exceed the limits of the Identification Standards for Hazardous Wastes-Identification for Toxic Substance Content (GB 5085.6-2007), heavy metals and PAHs contents met the requirements of Soil Environmental Quality-Risk Control Standard for Soil Contamination of Development Land (GB 36600-2018). The research shows that the characteristic pollutants in the drilling cuttings can be effectively removed by thermal desorption as main treatment process, which has a good potential for resource utilization. © 2020, Editorial Board, Research of Environmental Sciences. All right reserved.