Vermistabilization of fecal sludge with organic enriched substrates for compost production using two earthworm species (Eisenia foetida and Eudrilus eugeniae)

Abstract

Developing countries are facing high generation of fecal sludge without adequate systems for proper treatment, leading to detrimental effects on the environment from its disposal. An emerging and innovative option in curbing this problem is the use of epigeic earthworm species to stabilize the waste into vermicompost, a value‐added resource. Substrate enrichment techniques can be applied to promote the sustainability and effectiveness of the vermicomposting process. This study was therefore carried out to determine the potential of two epigeic earthworm species (Eisenia foetida and Eudrilus eugeniae) to transform and stabilize fecal sludge into vermicompost using organic enriched substrates. Enriched substrates were prepared with 160 g of coconut coir, 120 g of fecal matter (65–70% dry matter) and 80 g of organic black soil. Three treatments of the vermibed substrates were prepared which were labelled T1, T2 and T3, with T1 containing Eisenia foetida, T2 containing Eudrilus eugeniae and T3, the control treatment, containing no earthworm. Treatments were triplicated and about 3‐week‐old 20 clitellated, E. fetida (live weight ∼255–275 mg) were introduced into the vermibeds for vermicomposting over a duration of 12 weeks. Physicochemical parameters such as pH, organic carbon (Corg), total nitrogen (Ntot), available phosphorus (Pavail), exchangeable calcium (Caexch), iron (Fe), lead (Pb), and aluminium (Al) changes in the setups at the beginning and end of the vermicomposting period were evaluated. Eisenia foetida demonstrated a higher Corg mineralization (67.59%) compared to Eudrilus eugeniae, which attained 67.22%. Eisenia foetida also showed 5% more mortality than Eudrilus eugeniae. The study revealed that the two epigeic earthworm species for the vermicomposting of fecal waste in the enriched substrates played significant role in stabilizing the waste into vermicompost that was rich in nutrients, with lower levels of metals, higher levels of microbial biomass and higher levels of enzyme concentration.

Performance evaluation of developed macrophyte-assisted vermifiltration system designed with varied macrophytes and earthworm species for domestic wastewater treatment

“…Results of earthworm mortality recorded in the treatments are lower than that recorded in previous studies [ 9 , 16 , 17 ] and this could be due to the aerobic conditions caused by the presence of the macrophytes. Anaerobic and anoxic conditions are major sources of worm mortality Results from this study demonstrated that the vermibed in the MAV systems did not only facilitate the wastewater treatment process but also maintained the earthworm mortality below 10%.…”

“…In the treated effluents, TDS, TSS, chlorides, turbidity and DOC were consistently reduced over the sampling period and this could be attributed to the actions of the macrophytes and earthworms. Macrophyte roots and vermibeds are capable of trapping the organic and inorganic solids where they are biologically processed by earthworms and microbes [ 16 , 17 ]. Macrophyte roots houses denitrifying bacteria and other microorganisms that assimilate organic matter using C as an electron donor [ 36 ].…”

“…[ 29 ] reported that earthworms devour on the pathogens and promote the production of antibiotics that kill the pathogenic organisms. Thus, earthworms predate the pathogens which get filtered into the vermibed [ 16 ]. BOD and COD removal from the vermifiltration process also creates unsuitable physico-chemical environment for pathogens to thrive and thus makes them more susceptible to die-off in the filter bed [ 48 ].…”

“…Vermifiltration, which integrates earthworm and microbes, is one of the filtration techniques gaining much attention in wastewater treatment due to its low energy consumption, less operation, less maintenance costs and chemical-free treatment process [13]. The earthworm species commonly used in vermifiltration processes are Eisenia fetida and Eudrilus eugeniae [14][15][16]. The resulting treated wastewater are potential sources for reuse such as irrigation [17].…”

Influence of vermifiltered wastewater on the morphological, physiological and biochemical developments of Zea mays, Triticum aestivum and Sorghum bicolor seed germination

“…12,13,14 In vermifiltration, contaminants are removed by filtration and a microbial layer formed on the filter bed contributes to their degradation. 15,16 The contaminants are retained on the filter beds in the form of solids and they are consumed and converted into humus by the earthworms. 14,17 Aeration is increased in the filter bed by the borrowing action of earthworms.…”