An Environment-Friendly and Cost-Effective Air Flotation Process Using Hybrid Coagulant/Flocculant System of Ferric Chloride and Chitosan For Oil/Water Separation

A substantial amount of oil-contaminated water is generated from oil and gas explorations, and it remains the largest waste stream in the industry. Dissolved air flotation (DAF) is a separation technology widely used in the industry that generally reduces oil concentrations in wastewater prior to environmental discharge and/or beneficial reuse applications. However, there are some issues for the existing DAF system, including the high chemical cost for its operation, environmental pollution by chemical residual in treated water and the large quantity of non-biodegradable sludge. In this study, an environment-friendly and cost-effective DAF process was proposed and tested for separating emulsified oil from water. In this process, a hybrid coagulant/flocculant system with ferric chloride as a coagulant and chitosan as a bio-degradable flocculant was used to enhance the efficiency of oil/water separation. Some of the advantages of implementing this process include a 37% reduction in chemical costs, a 50% reduction in footprint for the flocculation process, a 90% reduction in the use of non-biodegradable ferric chloride, a broader operating pH range between 5 and 9, and wider applicability for both fresh and high salinity water. In addition, the sludge generated by this process is less toxic and more eco-friendly due to the lower dosage of ferric chloride and the addition of biodegradable chitosan. The results from this study contribute to the wider, environment-friendly and cost-effective application of air flotation for oil/water separation