Feasibility of vermicomposting dairy biosolids using a modified system to avoid earthworm mortality

Earthworms and vermicompost: an eco-friendly approach for repaying nature's debt

The steady increase in the world's population has intensified the need for crop productivity, but the majority of the agricultural practices are associated with adverse effects on the environment. Such undesired environmental outcomes may be mitigated by utilizing biological agents as part of farming practice. The present review article summarizes the analyses of the current status of global agriculture and soil scenarios; a description of the role of earthworms and their products as better biofertilizer; and suggestions for the rejuvenation of such technology despite significant lapses and gaps in research and extension programs. By maintaining a close collaboration with farmers, we have recognized a shift in their attitude and renewed optimism toward nature-based green technology. Based on these relations, it is inferred that the application of earthworm-mediated vermitechnology increases sustainable development by strengthening the underlying economic, social and ecological framework.

Use of earthworms (Eisenia fetida) to reduce phytotoxicity and promote humification of pre-composted olive oil mill wastewater

BACKGROUND

Olive mill wastewaters (OMWW) contain a high recalcitrant organic load and an associated toxicity that make their treatment necessary before environmental application. The aim of this study was to evaluate the feasibility of promoting the valorization and reducing the phytotoxicity of OMWW through a pre-composting process together with straw-chip bulking materials followed by the application of earthworms (Eisenia fetida) in the presence of oat seedlings (Avena sativa L.) seedlings.

RESULTS

After 3 months, the pre-composted material showed properties similar to a partially digested compost with some significant amelioration of chemical-physical and biochemical properties. The application of earthworms permitted a significant decrease in chemical (total organic carbon, water-extractable organic carbon, total nitrogen) and biological parameters (dehydrogenase enzyme activity), and an increase in humic substances and available nitrogen forms. In the presence of plants a higher C/N ratio and a lower content of nitrates were observed. In addition, the reduction in phenolic compounds observed in treatments with earthworms caused a decrease in phytotoxicity by about 50% with respect to the pre-composted material, which results in an increase in germination index.

CONCLUSION

The utilization of earthworms, in particular in the presence of plants, may be an ecologically sound and economically feasible technology to obtain a non-toxic, high-value product useful for agricultural purposes.

Vermicomposting of source-separated human faeces for nutrient recycling

The present study examined the suitability of vermicomposting technology for processing source-separated human faeces. Since the earthworm species Eisenia fetida could not survive in fresh faeces, modification in the physical characteristics of faeces was necessary before earthworms could be introduced to faeces. A preliminary study with six different combinations of faeces, soil and bulking material (vermicompost) in different layers was conducted to find out the best condition for biomass growth and reproduction of earthworms. The results indicated that SVFV combination (soil, vermicompost, faeces and vermicompost - bottom to top layers) was the best for earthworm biomass growth indicating the positive role of soil layer in earthworm biomass growth. Further studies with SVFV and VFV combinations, however, showed that soil layer did not enhance vermicompost production rate. Year-long study conducted with VFV combination to assess the quality and quantity of vermicompost produced showed an average vermicompost production rate of 0.30kg-cast/kg-worm/day. The vermicompost produced was mature as indicated by low dissolved organic carbon (2.4+/-0.43mg/g) and low oxygen uptake rate (0.15+/-0.09mg O(2)/g VS/h). Complete inactivation of total coliforms was noted during the study, which is one of the important objectives of human faeces processing. Results of the study thus indicated the potential of vermicomposting for processing of source-separated human faeces.

Vermicomposting potential of Perionyx sansibaricus (Perrier) in different waste materials

The decomposition efficiency of Perionyx sansibaricus (Perrier) for vermicomposting was evaluated by using a variety of wastes such as agriculture waste, farm yard manure and urban solid waste. Vermicomposting resulted in significant increase in total N (80.8-142.3%), phosphorous (33.1-114.6%) and potassium (26.3-125.2%), whereas decrease in organic C (14.0-37.0%) as well as C:N ratio (52.4-69.8%) in different experimental beddings. P. sansibaricus showed maximum biomass production, growth rate (mg day(-1)), mean cocoon numbers, and reproduction rate (cocoon worm(-1)) in VLL (vegetable waste+leaf litter) as compared to other substrate materials. There was a consistent trend for earthworms' growth and reproduction rate, related to initial N-content of the substrate (P<0.05), but there was no clear effect of C:N ratio of the composted material on earthworm cocoon numbers and weight gain. Earthworm showed minimum total population mortality in VLL and maximum in HHCD (household waste+cow dung), after 150 days of experimentation. The increased level of plant metabolites in end product (vermicompost) and growth patterns of P. sansibaricus in different organic waste resources demonstrated the candidature of this species for wastes recycle operations at low-input basis.

Vermicomposting of winery wastes: a laboratory study

In Mediterranean countries, millions of tons of wastes from viticulture and winery industries are produced every year. This study describes the ability of the earthworm Eisenia andrei to compost different winery wastes (spent grape marc, vinasse biosolids, lees cakes, and vine shoots) into valuable agricultural products. The evolution of earthworm biomass and enzyme activities was tracked for 16 weeks of vermicomposting, on a laboratory scale. Increases in earthworm biomass for all winery wastes proved lower than in manure. Changes in hydrolytic enzymes and overall microbial activities during the vermicomposting process indicated the biodegradation of the winery wastes. Vermicomposting improved the agronomic value of the winery wastes by reducing the C:N ratio, conductivity and phytotoxicity, while increasing the humic materials, nutrient contents, and pH in all cases. Thus, winery wastes show potential as raw substrates in vermicomposting, although further research is needed to evaluate the feasibility of such wastes in large-scale vermicomposting systems.