Biological Treatment of Cafeteria Wastewater Using Microbial Cultures: A Case Study at Kasetsart University

Abstract

This study aimed to evaluate the effectiveness of microbial augmentation using Bacillus spp. and lipase-producing microorganisms in enhancing the performance of an activated sludge system for cafeteria wastewater treatment at the Faculty of Science, Kasetsart University, Bangkhen Campus. The study was conducted over a 22-week period from June 13 to November 27, 2023. Influent and effluent wastewater qualities were monitored using biochemical oxygen demand (BOD₅), oil and grease (FOG), total dissolved solids (TDS), sulfide, and pH as the primary parameters. The treatment performance was compared with the Thai effluent standards for Category C buildings.

The results demonstrated that microbial augmentation combined with operational improvements significantly enhanced wastewater treatment efficiency. At the end of the experimental period, BOD₅ decreased from 1,255 to 7.40 mg/L, achieving a removal efficiency of 99.41%. FOG decreased from 617 to 5.60 mg/L with a removal efficiency of 99.09%, while TDS decreased from 1,043 to 200 mg/L, corresponding to an 80.82% reduction. Sulfide concentrations decreased from 4.12 mg S²⁻/L to non-detectable levels. The effluent pH ranged from 6.49 to 7.46, indicating suitable conditions for microbial activity and compliance with regulatory standards. However, system instability was observed during the initial operational phase, highlighting the importance of appropriate control of organic loading, aeration, and microbial dosing.

The findings suggest that microbial augmentation effectively improves cafeteria wastewater treatment performance by enhancing the removal of biodegradable organic matter, fats, oils, grease, and odor-causing compounds. Furthermore, this approach supports Green University initiatives by promoting sustainable wastewater management and minimizing environmental impacts.