Infusion of fruit-vegetable waste biomass into bakery sludge to enhance nutrient availability and vermicompost maturity using Eisenia fetida

Vermicomposting of bakery sludge (BS) was studied when amended with fruit-vegetable waste (FV) and cow dung (CD) with different proportions in vermi-units (VU): VU1((CD100)), VU2((CD75BS25)), VU3((CD50BS25FV25)), VU4((CD25BS25FV50)), and VU5((CD25 BS50FV25)). Results showed a reduction in pH and total organic carbon and an increase in electrical conductivity, ash content, nitrogen, phosphorus, and potassium after vermicomposting. Carbon/nitrogen decrease followed: VU3 > VU1 > VU4 > VU2 > VU5, whereas a maximum reduction in carbon/phosphorus (60.7%) was observed in VU3 and a minimum (44.8%) in VU5. Seed germination assay of Cicer arietinum was 71-138% with maximum in VU3. Respiration rates of 69-115 mgCO(2) kg(-1)VC48h(-1) were achieved signifying stability and non-toxic impact. The presence of FV waste in vermi-units enhanced earthworm population, biomass, growth rate, and cocoons. VU3 exhibited higher macro- and micronutrients as well as worm growth and fecundity over other vermi-units. Based on results, FV waste and CD amendment at 25% and 50%, respectively, are suggested as appropriate to produce enriched vermicompost from BS using Eisenia fetida.

Automated summary

Vermicomposting of bakery sludge with the addition of fruit-vegetable waste and cow dung improved the quality of the sludge. The pH decreased, total organic carbon decreased, and electrical conductivity, ash content, nitrogen, phosphorus, and potassium increased after vermicomposting. Among the different ratios of waste and dung, VU3 showed the best results, with the highest seed germination rate. The addition of fruit-vegetable waste also enhanced the population and growth rate of earthworms.