Enhancing domestic wastewater treatment: Integrating vermifiltration and biochar for heavy metal and microplastic reduction and by-product utilization

Abstract

Water pollution, particularly from domestic wastewater contaminated with microplastics and heavy metals, poses significant threats to human health and ecosystems. The aim of this study was to assess the potential of vermifiltration combined with biochar to treat domestic wastewater using earthworm, Eisenia foetida. The objectives of this research were to monitor the change in water quality parameter (BOD, COD, TDS, TSS, Phosphate and Nitrate). Experiments were conducted using a Completely Randomized Design (CRD) with four treatments: Geofilter (Gf), Vermifilter (Vf), Geofilter + Biochar (Gf + Bi), and Vermifilter + Biochar (Vf + Bi). The result showed that using vermifiltration combined with biochar could reduce the biological oxygen demand (BOD), chemical oxygen demand (COD), total suspended solids (TSS) in domestic wastewater treatment highest followed by vermifiltrater, geofilter with biochar and geofilter, respectively. The results demonstrated the percentage removal of BOD (94.28 %), COD (89.82 %), TDS (88.35 %) and TSS (95.30 %). The Vf + Bi system showed high efficiency in heavy metal reduction: Mn (99.37 %), Zn (100 %), Cu (100 %), Pb (44.00 %), and As (100 %). Microplastic contamination was reduced most effectively by Vf + Bi (88.64 %), followed by Gf + Bi (86.36 %), Vf (77.27 %), and Gf (75.00 %). Post-treatment vermibed analysis revealed increases in Nitrogen, Phosphorus, Potassium, and organic carbon content in bedding. This study concludes that the integration of vermifiltration and biochar could be the eco-solution for nutrient recovery, water resource recycles and minimize pollution and efficient wastewater treatment and generating valuable by-products such as biofertilizer.