Effectiveness of vermifiltration systems in wastewater bioremediation: a sustainable and cost-effective approach

Abstract In areas with limited access to conventional sanitation systems, as in rural areas, there is an imperative for sustainable alternatives for wastewater treatment. This study aims to demonstrate the efficiency of a domestic scale vermifilter system containing Eisenia foetida worms and coconut fibre as a substrate in reducing wastewater pollutants. The study evaluated 3 configurations: a filter without worms (control), a vermifilter with 15 cm of coconut fibre and another with 30 cm of coconut fibre. The last one was installed in a house in Baños district of Cuenca, Ecuador. The results showed that the vermifilter with 30 cm of coconut fiber showed the optimal efficiency, achieving removals of 55.8% for COD, 56.4% for BOD5, 39.97% for nitrates, 59.65% for ammoniacal nitrogen, and 48.06% for total nitrogen. Furthermore, the system exhibited a remarkable efficacy in eliminating pathogenic amoeba, achieving up to 70.42% removal, and coliforms, with a removal rate of 60%. However, an increase in parameters such as dissolved oxygen, electrical conductivity, total dissolved solids and phosphates was also observed. To achieve the required disinfection, tertiary treatments were evaluated: activated carbon filters, which achieved 62% removal of amoebas and 35% of coliforms, and a subsurface constructed wetland, which reached 100% elimination of amoebas and 40% of coliforms. These findings demonstrate that the thickness of the coconut fibre and the inclusion of worms directly influence the removal of contaminants and microorganisms. This positions the vermifilter as a promising solution for sanitation in rural areas. However, it is recommended to complement this system with disinfection or tertiary technologies to guarantee the quality of treated water