Evaluating Treatment Performance of a Small-Scale Vermifilter for Vermifiltration of Lafenwa Abattoir’s Effluent, Lafenwa, Ogun State, Nigeria

Abattoir waste can be detrimental to the environment if improperly managed. In Nigeria, such wastes are dump in the open or nearby stream/river course, causing high oxygen demand, becoming heavy breeders of pathogens and micro-organism as well as increasing the risks of zoonotic disease outbreak threatening the quality of life and public health. This study explored the use of vermifiltration; a low-cost, odorless and sustainable wastewater treatment method that uses earthworms and microorganisms to break down abattoir waste effluent. A bio-reactor (presence of earthworms) and a control reactor system (absence of earthworms) each consisting of a collection tank, vermifiltration bed and a fabricated treated water collection tank used to treat the abattoir wastewater by varying the flow rate and concentration of the effluent that entered the vermifiltration system. This was across four levels and three replicates with Hydraulic Retention Time of 42,011.49 sec (116.69hrs) and Hydraulic Loading Rate of 8.7x10-6 m/s. Physico-chemical properties of discharge from bio-reactor recorded 11.010±1.755NTU for turbidity, 24.228±6.319mg/L for dissolved oxygen, 7.562±3.402mg/L for total suspended solid, 51.27±14.00mg/L for total dissolved solid, 6.3562±0.2584 for pH, 250.0±101.1CFU/mL for total coli count and 1296±200CFU/mL for total bacteria count respectively as against results from the control reactor which had mean values of 36.351±3.993NTU for turbidity, 14.277±2.241mg/L for dissolved oxygen, 19.569±1.996mg/L for total suspended solid, 137.21±37.40mg/L for total dissolved solid, 5.0958±0.5596 for pH, 2500.0±522.7CFU/mL for total coli count and 6413±1725CFU/mL for total bacteria count. The vermifiltration process was thus able to greatly reduce and filter out the pathogens found in the influent through the combined action of the earthworms and the filter layer of fine sand and gravel to a high degree. Thus, confirming that vermifiltration system could achieve good performance in the treatment of abattoir waste water.