Utilizing recycled pumice and oyster shell waste for cost-effective treatment to mitigate pollutants and toxicity in swine wastewater

Despite the abundant nutrients that could be reutilized in swine wastewater, inadequate wastewater management leads to excessive metals and organic matter, causing environmental impacts on aquatic and terrestrial ecosystems. In this study, we recycled waste pumice and oyster shells for the cost-effective treatment and reclamation of swine wastewater. The toxicity of the treated wastewater was assessed using the soil nematode Caenorhabditis elegans and Chinese cabbage Brassica rapa chinensis. Our findings showed significant removal of suspended solids, biochemical oxygen demand, chemical oxygen demand, total phosphorus, and heavy metals (As, Cu, Ni, and Zn) from the swine wastewater after treatment with pumice and oyster shells. Moreover, untreated wastewater significantly inhibited the germination of Chinese cabbage, a trend that was reversed in treated wastewater. Both treated and untreated swine wastewater stimulated the growth of Chinese cabbage. Additionally, untreated swine wastewater exhibited high toxicity to the growth and reproduction of C. elegans after 72 hours of exposure, whereas treated wastewater showed notably reduced toxicity. The recycled pumice and oyster shells significantly induced growth and showed no toxicity in Chinese cabbage. These results suggest that pumice and oyster shell waste can effectively reduce environmental toxicity in raw swine wastewater, offering a cost-effective wastewater treatment solution for small-scale pig farms.