Effect of bioaugmentation to the performance and microbial communities of slow sand filter treating culinary wastewater

Culinary wastewater is one of the sources of organic pollutant load in surface water if treated improperly. This study analyzed the performance of the slow sand filter (SSF) unit with the bioaugmentation of Bacillus cereus and Bacillus spp. compared to the non-bioaugmented system to treat culinary wastewater. A system consisting of the grease trap, roughing filter, and SSF was used to treat real culinary wastewater. Bioaugmentation was conducted before the SSF unit, while BOD, COD, and phosphate parameters were monitored for 21 days of operation. NGS was then used to analyze the microbial community structure in both bioaugmented and non-bioaugmented systems. The bioaugmented system achieved significantly higher BOD removal of 62.5 ± 11% compared to the non-bioaugmented system (55.56 ± 11.4%). The bioaugmented system achieved significantly higher COD removal (71.45 ± 1.55%) compared to the non-bioaugmented system (53.97 ± 7.36%). The bioaugmented system also significantly outperformed the non-bioaugmented system in phosphate removal, with a value of 73.64 ± 1.88%. Microbial community analysis showed that the bioaugmented sample had 2157 OTUs and 8,843 unique tags, while the non-bioaugmented sample had 2152 OTUs and 7409 unique tags. The most dominant genus was MM2 of the Proteobacteria phylum, with a relative abundance of 25.32% in the bioaugmented and 29.27% in the non-bioaugmented samples. Pseudomonas, with a relative abundance of 2.52%, was the least dominant genus in the non-bioaugmented sample. Some species of Bacillus, such as B. cereus, can reduce organic matter and grow with increased concentrations of hydrocarbon. Mycobacterium genus had the most dominant species identified, with M. fortuitum showing the capability in organics degradation with enhanced metabolism.