Release characteristics of PAHs in oil-based drilling cuttings solidified body

An effective way to further dispose and utilize resources is to make oil-based drilling cuttings into blocky solidified body. However, when solidified body is used, PAHs may leach out. The release characteristics of 5 kinds of polycyclic aromatic hydrocarbons (PAHs) in solidified body, including naphthalene, anthracene, fluoranthene, benzo (b) fluoranthene and benzo (a) pyrene (BaP), were studied by using the test method of effective amount of inorganic components in solid (NEN7371) and the diffusion test method of inorganic components in bulk materials (NEN7375) and to assess their leaching release risks. The results showed that the effective release rates of the 5 kinds of PAHs were all below 2%. The effective release amount of BaP exceeded the limiting value of Category Ⅲ in Groundwater Quality Standard (GB/T 14848-2017). In static immersion release characteristic experiments, 5 kinds of PAHs released at the early stage, and their accumulated release amount at the previous 16 days accounted for more than 78% of the cumulative total release amount of 64 days. The release mechanism of the 5 kinds of PAHs included diffusion control, dissolution release, delayed release, depletion and surface wash-off. Different PAHs in solidified body had different release characteristics, but in general, they were mainly released in the way of diffusion control. In the later stage, they mainly released in the form of depletion mechanism.