Yeast as a Bioremediation Nanoparticle Agent in Piggery-Digested Wastewater Treatment

The opportunity to produce algal biofuel cost-effectively from waste materials, such as piggery-digested waste, drives research to optimize piggery waste effluent as an algal growth medium. Therefore, the aim of this study was to investigate the potential of newly isolated wastewater-born yeast to optimize growth parameters and maximize pollutant degradation in digested wastewater bioremediation. One isolate was identified as Galactomyces geotrichum through morphological observation and DNA sequencing. Growth parameters regarding pH, temperature, and inoculum amount were optimized by orthogonal design to maximize pollutant removal. Results showed that optimal growth conditions were pH 6, 25°C, and 2.5 g mycelium pellet moisture weight. Chemical oxygen demand (COD) reached 60% and total phosphorus (TP) reduction reached 45% under these conditions. Our observations demonstrate that pH had an overall significant effect on COD and TP reduction. More importantly, results suggested that pretreatment with locally isolated yeast is a nontoxic and ecofriendly method when compared to chemical reagents in preparing piggery waste as a medium for algal growth. This study provides a new microbial resource for removal of pollutants from piggery-digested wastewater. In this study, for the first time, algal biofuel feedstock was prepared by yeast pretreatment of undiluted and unsterilized piggery-digested waste, cost-effectively answering both energy needs and environmental concerns with a renewable resource.