Wastewater in petrochemical processes and produced water from oil and gas production remain a challenge for the industry to minimize their impact on the environment. Recent research and development of treatment technologies for petrochemical wastewater and produced water from oil and gas industries published in 2018 were summarized in this annual review. Great efforts and progresses were made in various treatment options, including membrane processes, advanced oxidation, biological systems, adsorption, coagulation, and combined processes.Practitioner points Treatment technologies for petrochemical wastewater are reviewed. Research development in produced water from oil and gas industries is summarized. Reviewed technologies include traditional, advanced, and innovative processes.

In this study, two auxiliary collectors (methyl naphthalene and naphthalene) of molybdenite and the traditional collector (kerosene) were mixed for molybdenite flotation, respectively. According to the selection and analysis of the auxiliary collector, it was found that the surface energy (γC= 4.50 mJ/m2) of the polycyclic aromatic hydrocarbons is very close to that (γS= 42.55 mJ/m2) of the molybdenite {100} surface. Therefore, it can be physically adsorbed onto the molybdenite {100} surface according to the principle of similar compatibility. Batch flotation was conducted on actual ore with the mixed collector, compared with kerosene alone. Batch flotation results showed that the mixed collector at a mass ratio of 95:5 of main collector to auxiliary collector at pH 11.0 improved molybdenite flotation, that is, the Mo recovery was increased by 3–4%. The practical application feasibility of the auxiliary collector was analyzed by the filtration speed of the flotation concentrate and the crystal resolution characteristics of the auxiliary collector. The results show that solid naphthalene (Nap) is easy to crystallize at low temperature and adhere to the surface of the flotation concentrate, resulting in a decrease of filtration velocity, while liquid methylnaphthalene (MNap) does not crystallize at low temperature. These results imply that the mixed collector Kerosene/MNap can generate a superior synergistic effect and achieve better collecting capacity than kerosene alone, resulting in the increase of flotation recovery by 3–4 percentage points. Moreover, the addition of MNap has little negative impact on the subsequent treatment of the product.

In this study, a flotation collector N-(carboxymethyl)-N-tetradecylglycine (NCNT) was introduced for the purpose of energy-saving, and its adsorption ability on a fluorapatite (001) surface was investigated by density functional theory calculation. The results of frontier molecular orbital analysis of NCNT and adsorption energy between NCNT and fluorapatite (FAp) showed that NCNT possessed better activity and stronger interactions in the reagent–FAp system than oleic acid (OA). A simulation model revealed that the adsorption positions of NCNT on the fluorapatite surface are calcium atoms, at which NCNT chemisorbed on (001) fluorapatite surface via a bidentate geometry involving the formation of two Ca–O bonds. Flotation experiments verified that NCNT had a good recovery of 92.27% on FAp at pH 3.5, which was slightly lower than OA. Moreover, NCNT was used at 16 °C, which was much lower than the OA’s service condition (25 °C).

This review provides a snapshot of papers published in 2015 relevant to the topic of mine drainage generation and control options. The review is broken into 3 sections: Generation, Prediction and Prevention, and Treatment Options. The first section, mine drainage generation, focuses on the characterization of mine drainage and the environmental impacts. As such, it is broken into three subsections focused on microbiological characterization, physiochemical characterization, and environmental impacts. The second section of the review is divided into two subsections focused on either the prediction or prevention of acid mine drainage. The final section focuses on treatment options for mine drainage and waste sludge. The third section contains subsections on passive treatment, biological treatment, physiochemical treatment, and a new subsection on beneficial uses for mine drainage and treatment wastes.