Wastewater treatment is crucial for maintaining public health, protecting the environment, recovering valuable resource, and ensuring sustainable water use. Petroleum refinery wastewater poses significant challenges for treatment and has severe environmental implications if not managed properly. Some of the concerns associated are complex chemical composition, high chemical oxygen demand (COD) and biochemical oxygen demand (BOD), oil and grease, salinity, and pH imbalance thereby making them highly toxic. Advanced technologies, viz., integrated strategies, membrane filtration, and advanced oxidation processes (AOPs), may be utilized to treat complex and recalcitrant wastewater. But, to prevent ecosystem disruption, biological methods using specialized microbes or their components are preferred over physical or chemical methods. Bioflocculants are natural, biodegradable polymers produced by microorganisms such as bacteria, fungi, and algae. These substances promote the aggregation or flocculation of suspended particles in wastewater, facilitating their removal. Unlike chemical flocculants, bioflocculants are environmentally friendly and pose fewer health risks, making them an attractive alternative for wastewater treatment. Bioflocculants have shown significant promise in addressing the complex challenges posed by petroleum refinery wastewater, viz., suspended solids and oil removal, heavy metal removal, reduction of COD and BOD, and enhanced biodegradability. Apart from these merits, challenges such as production costs, performance consistency, regulatory approvals and public acceptance, and integration with existing treatment systems will be addressed in this book chapter.
