State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing, 100012, China; State Environmental Protection Key Laboratory of Hazardous Waste Identification and Risk Control, Chinese Research Academy of Environmental Sciences, Beijing, 100012, China.
Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technology Institution Physical and Chemistry, Chinese Academy of Sciences, Beijing, 100190, China.
J Environ Manage. 2022 Feb 15;304:114170. doi: 10.1016/j.jenvman.2021.114170. Epub 2021 Dec 1.
Oil-based drilling cuttings (OBDC) produced from shale gas development is a hazardous waste that have high calorific values and should be disposed of properly. Burning bricks with OBDC is a promising co-disposal method; however, organic pollutants emitted during this process have not received sufficient attention. In this study, the composition and combustion characteristics of OBDC were determined, and the emissions of typical organic pollutants when burning bricks with the addition of OBDC were investigated; these included benzene series compounds (BTEXs), non-methane total hydrocarbons (NMHC), polycyclic aromatic hydrocarbons (PAHs), and polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs). The results showed that OBDC comprised large amounts of alkanes and aromatic hydrocarbons, and combusted mainly in the temperature range of 145-450 °C with an ignition temperature of 145 °C. The co-processing 10% OBDC increased the concentrations of toluene, NMHC, and PAHs in the flue gases by ∼1000%, ∼500%, and 200%, respectively, compared to the control experiment; however, their emission concentrations were within the limits set by the Integrated emission standards of air pollutants of Chongqing. It is worth noting that 26.443 ng/Nm PCDD/Fs with a total toxicity of 0.709 ng I-TEQ/Nm was generated from the co-processing 10% OBDC, which was ascribed to the high content of chlorine and aromatic hydrocarbons in the OBDC-promoted PCDD/Fs formed during the burning and cooling processes. Though PCDD/Fs in flue gas exceeded the 0.5 ng I-TEQ/Nm limit prescribed in the Pollution control standard for hazardous wastes incineration of China, the realistic emission of PCDD/Fs is expected to meet with this emission limit after desulfurization treatment as PCDD/Fs can be absorbed by gypsum. It is recommended that a lower amount of OBDC is added to reduce PCDD/F formation at the source and to take more efficient air pollution control system in order to reach a stricter emission limit of 0.1 ng I-TEQ/Nm in EU and USA. Cycling flue gas may also be an effective method to reduce other organic pollutants. Under these conditions, co-processing OBDC in brick kilns can be achieved without serious environmental pollution, making it a potential method for disposal and utilization.
油基钻井岩屑（OBDC）是页岩气开发产生的危险废物，具有高热值，应妥善处理。用 OBDC 烧制砖块是一种很有前途的共处置方法；然而，在此过程中排放的有机污染物尚未得到足够重视。在这项研究中，我们确定了 OBDC 的组成和燃烧特性，并研究了添加 OBDC 烧制砖块时典型有机污染物的排放情况；这些污染物包括苯系化合物（BTEXs）、非甲烷总烃（NMHC）、多环芳烃（PAHs）和多氯二苯并对二恶英和多氯二苯并呋喃（PCDD/Fs）。结果表明，OBDC 含有大量的烷烃和芳烃，主要在 145-450°C 的温度范围内燃烧，起始燃烧温度为 145°C。与对照实验相比，共处理 10%的 OBDC 使烟道气中的甲苯、NMHC 和 PAHs 的浓度分别增加了约 1000%、500%和 200%；然而，它们的排放浓度仍在重庆市综合大气污染物排放标准规定的限值内。值得注意的是，从共处理 10%的 OBDC 中产生了 26.443ng/Nm 的 PCDD/Fs，总毒性为 0.709ng I-TEQ/Nm，这归因于 OBDC 中高含量的氯和芳烃在燃烧和冷却过程中促进了 PCDD/Fs 的形成。尽管烟道气中的 PCDD/Fs 超过了中国《危险废物焚烧污染控制标准》规定的 0.5ng I-TEQ/Nm 限值，但经过脱硫处理后，预计实际排放的 PCDD/Fs 将符合这一排放限值，因为 PCDD/Fs 可以被石膏吸收。建议添加较少的 OBDC，以减少源头的 PCDD/F 形成，并采取更有效的空气污染控制系统，以达到欧盟和美国更严格的 0.1ng I-TEQ/Nm 排放限值。循环烟道气也可能是减少其他有机污染物的有效方法。在这些条件下，在砖窑中共处理 OBDC 可以在没有严重环境污染的情况下实现，这是一种潜在的处置和利用方法。
