A novel physical-biochemical treatment of refinery wastewater.

As of 2022, China has achieved a crude oil processing capacity of 918 million tons, leading to a notable escalation in the production of refinery wastewater. The composition of refinery wastewater is intricate and diverse, posing a substantial challenge to its treatment. In order to facilitate appropriate discharge or reuse, an exhaustive separation process is imperative for refinery wastewater. Conventional pre-treatment processes typically employ inclined plate separators and dissolved air flotation (DAF) for the removal of oil and suspended solids (SS), while sequencing batch reactor (SBR), oxidation ditch, or biological aerated filter (BAF) are employed for the biological treatment process. However, these approaches encounter challenges such as a large spatial footprint, suboptimal treatment efficiency, and high energy consumption. In response to these challenges, this study introduces a novel integrated apparatus consisting of a high-efficiency oil remover (HEOR), coalescence oil remover (COR), and an airlift-enhanced loop bioreactor (AELR). A pilot-scale test was conducted to evaluate the performance of this integrated system in practical field applications. The pilot-scale tests reveal that, without the addition of chemical agents, the petroleum removal efficiency of "HEOR + COR" system was 1.2 times that of DAF. Compared with the SBR system, AELR's volume loading was increased by 1.56 times. The effluent quality achieved in the pilot-scale tests attained parity with that the original process. The "HEOR + COR + AELR" system exhibited energy and carbon emissions reduction of 28% and 30% compared to the "DAF + SBR" system, respectively. Therefore, the operating costs was reduced by approximate 1 Chinese Yuan (CNY) per ton of treated water. This technological advancement serves as a valuable reference for the implementation of low-carbon treatment of refinery wastewater.

Fiber coalescence treatment of oily wastewater: A new theory and application.

Oil pollution from produced water in the offshore petroleum industry is one of the most serious marine pollutants worldwide, and efficient separation technology is crucial for the control of oil pollutant emission. Medium coalescence is an efficient oil-water separation technology, but its theory is lacking and the development is slow. In this work, the microscopic mechanism of fiber coalescence was revealed, and found that the effective collision positions were the three-phase contact line and the exposed fiber surface. Further, a theoretical model for calculating the separation performance of a fiber bed was established. For a given inlet droplet size distribution and bed geometric parameters, the outlet droplet size distribution and the total separation efficiency of the fiber bed can be predicted. Then, an Ω-shaped woven method composed of oil-wet fibers and oil-phobic fibers was designed and the separation performance of the fiber beds prepared by the method and the influence law of various parameters were clarified through macroscopic experiment. Finally, the novel technology achieved its first engineering application on an offshore platform, with the average oil content of the outlet was less than 25 mg/L, which could reform the current treatment process of produced water.

A review of treatment technologies for produced water in offshore oil and gas fields.

Offshore oil and gas production is increasingly growing popular globally. Produced water (PW), which is the largest byproduct of oil and gas production, is a complex mixture of dissolved and undissolved organic and inorganic substances. PW contributes considerably to oil pollution in the offshore petroleum and gas industry owing to the organic substances, which mainly include hydrocarbons; this is a major concern to researchers because of the long-term adverse effects on the ecosystem. Since the development of offshore petroleum and gas industry, the PW treatment process has been classified into pretreatment, standard-reaching treatment, and advanced purification treatment based on the characteristics of PW and has been coupled with the environmental, economic, and regulatory considerations. The mechanism, design principle, application, and development of conventional technologies for PW treatment, such as gravity and enhanced gravity sedimentation, hydrocyclone, gas flotation, and medium filtration, are summarized in this study. Novel methods for further application, such as tubular separation, combined fibers coalescence, and membrane separation, are also discussed. Enhancement of treatment with multiple physical fields and environmentally friendly chemical agents, coupled with information control technology, would be the preferred PW treatment approach in the future. Moreover, the PW treatment system should be green, efficient, secure, and intelligent to satisfy the large-scale, unmanned, and abyssal exploration of offshore oil and gas production in the future.