Utilizing Recycled Pumice and Oyster Shell Waste for Cost-Effective Treatment to Mitigate Pollutants and Toxicity in Swine Wastewater

Abstract

Despite the abundant nutrients that could be reutilized in swine wastewater, inadequate wastewater management leads to excessive metals and organic matter, causing ecological impacts on aquatic and terrestrial ecosystems. In this study, we devised a filtration system using waste pumice and oyster shells for the cost-effective treatment and reclamation of swine wastewater. The toxicity of the treated wastewater was assessed using soil nematode Caenorhabditis elegans and Chinese cabbage Brassica rapa chinensis. Our findings revealed significant removal of suspended solids (SS), biochemical oxygen demand (BOD), chemical oxygen demand (COD), total phosphorus (TP), and heavy metals (arsenic, copper, nickel, and zinc) from the swine wastewater after treatment with pumice and oyster shells. Moreover, untreated wastewater significantly inhibited the germination of Chinese cabbage, a trend 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-h exposure, whereas treated wastewater showed notably reduced toxicity. Phytotoxicity assays on Chinese cabbage revealed no toxicity in recycled pumice and oyster shells as fertilizer additives, with significant growth induction observed. These results suggest that recycled pumice and oyster shell waste can effectively enhance water quality and reduce environmental toxicity in raw swine wastewater, offering a cost-effective wastewater treatment solution for small-scale pig farms.

Keywords: Livestock wastewater, marine waste, phytotoxicity, soil nematode