Indigenous Bacillus Sp. Mediated Bioremediation of Sugar Industrial Wastewater: Optimization of Hydraulic Retention Time and Subsrate Concentration for Enhanced Pollutant Removal and Regulatory Compliance

The sugar industry plays an important role in driving economic growth and creating jobs in Indonesia. However, it also produces large amounts of wastewater during production and maintenance, which can pose serious environmental risks if not properly treated. Aim: This study analyzed the effects of hydraulic retention time (HRT) and wastewater concentration on contaminant removal efficiency via bioremediation using indigenous Bacillus sp. bacteria. Methodology and results: The methods involved collecting and analyzing wastewater samples, along with laboratory experiments using a reactor system. Both 50% diluted and raw/undiluted wastewater were tested at HRT of 2, 4, and 6 days. Samples taken from a sugar factory were analyzed for BOD, COD, and TSS, and the results were compared with applicable effluent standards. Multiple linear regression assessed variable impacts, revealing all treatments effectively removed contaminants from sugar industry wastewater. Conclusion, Significance, and Impact: The results showed that HRT and wastewater concentration significantly influenced bacterial pollutant removal (p < 0.05), confirming their importance as key operational parameters in bioremediation systems. Under optimal conditions the system achieved 75% to 95% reductions in TSS, BOD, and COD. These findings provide a practical, low-cost approach to bioremediation for treating wastewater from the sugar industry. They help reduce the impact of effluent discharge on aquatic ecosystems while supporting compliance with standards such as Indonesia’s PP No. 22/2021. In addition, they promote sustainable environmental management, align with circular economy principles, and offer a scalable solution for regions with limited resources.