A review on treatment of rice mill wastewater with emphasis on biological technologies

Due to its higher biochemical oxygen demand (BOD) and chemical oxygen demand (COD), the rice mill industry is considered a major polluting sector. The issue is becoming more serious due to the organic portions of the rice mill effluent, such as starch and other biodegradable constituents. The main objective of this review is to discuss the most commonly used methodologies (physico-chemical, phytoremediation, and biological) for treating rice mill effluent and highlight their effectiveness, with a greater emphasis on biological techniques. The study also included discussions on rice milling operations and the current status of rice mill effluent generation. The physico-chemical techniques effectively reduce BOD, COD, total suspended solids (TSS), and total dissolved solids (TDS) from the effluents. Still, it has limitations, such as the utilization of high-cost reagents and the requirement for external energy. Researchers have recognized biological techniques as the most economical choice for treating industrial effluents containing organic constituents. Phytoremediation ensures better aesthetics and a healthier environment while assisting industries to minimize toxic compounds and nutrients. The review also looked at the methodology, advantages, and limitations of the treatment technologies used in rice mill wastewater treatment. Furthermore, we update all of these treatment techniques with relevant data from the literature. At the end of the study, we include aspects related to the conclusions and future scope of the topic.