A State of Art Review on Marine Oily Wastewater Treatment and Management

Abstract

The chronic discharge of marine oily wastewater, mainly including bilge water, offshore produced water and ballast water, has been referred to as a major contributor to marine oil pollution. Its unregulated discharge may cause serious, long-term damage to local industries such as fishery and tourism, coastal communities, and the environment. Petroleum hydrocarbons, organic acids, heavy metals, radionuclides, production chemicals, and many other contaminants in oily wastewater have led to the adoption of stringent regional, national, and international environmental standards, regulations, and management practices. To date, onboard treatment has been most often used to remove unwanted substances from oily wastewater. A number of physical, chemical, and biological methods, such as gravity separation, air flotation, coagulation, membrane filtration, absorption, adsorption, and biological treatment have been investigated. However, they are either ineffective on dispersed/free oil or not applicable for onboard treatment due to safety, space and cost concerns. Particularly, many dissolved organics such as polycyclic aromatic hydrocarbons (PAHs) may stay unaffected and raise serious environmental concerns. UV and advanced oxidation processes, on the other hand, have been gaining significant attention because of their small footprint, ability of complete mineralization of contaminants, ease of operation, low cost and risk, and high efficiency. However, as emerging technologies, the lack of understanding of reaction mechanisms and performance prediction in the marine environment may affect their applicability.