Integrated sand and activated carbon-based filtration for decanted oily wastewater treatment during offshore oil spill response.

Decanted oily wastewater is the generated stream associated with vessel-based skimming operations during offshore oil spill response. It contains a large amount of persistent, bio-accumulative, carcinogenic, and mutagenic oil contaminants, so it is critical to find effective ways to treat it. This study targets the decanted oily wastewater treatment by developing an integrated sand and activated carbon-based filtration approach. Three activated carbons (AC-1, AC-2, AC-3) were evaluated for oil removal from the oil-water mixture. AC-1 demonstrated superior performance with the highest BET surface area (704 m²/g) and pore volume (0.231 cm³/g). Batch adsorption experiments with AC-1 examined the effects of activated carbon textural characteristics, adsorbent dosage, and contact time on the total oil concentration and removal efficiency of polycyclic aromatic hydrocarbons (PAHs). Column experiments with AC-1 further explored various parameters, including the flow rate, column bed height, oil type, and adsorbent media on the adsorption performance. The findings demonstrate that 34 ml/min flow rate, 4 cm column height, and a combination of sand and activated carbon as adsorbent media achieved the highest total crude oil (Tera-Nova) and PAH removal efficiency (both 99.9%). By integrating the sand with activated carbon in the filtration system, both dissolved and emulsified petroleum hydrocarbons can be effectively removed. This research provides valuable insights into optimizing activated carbon-based systems in oil-water separation, with practical applications in marine oil spill response and wastewater treatment.