Effects And Promotion Of Earthworm On Municipal Sewage Sludge Degradation

There are several techniques available for dealing with the municipal sewage sludge received during waste water treatment.Since municipal sewage sludge is a waste with high organic load generated in large quantities,a biological approach such as vermicomposting that uses Earthworms to degrade and partially digest the waste sludge was studied.To determine the effects and promotion of earthworms on degradation of municipal sewage sludge,obtaining a stable product with a high agronomic value by mineralize the essential nutrients like nitrogen,phosphorus and potassium from the sludge and reduce its risk to the environment.It is well established that many organic wastes can be ingested by earthworms and egested as peat like material termed as vermicompost,reduce the pathogens to safe levels(by devouring them and by discharge of antibacterial coelomic fluid)and toxic bioaccumulation by ingestion of the heavy metals through their intestine as well as through their skin.Sludge is an inevitable,hazardous and odorous by-product from conventional water and waste-water treatment plants which eventually requires safe disposal either in landfills or by incineration incurring heavy cost.When sludge is dewatered and dried,the residue is termed�biosolids'.Management of biosolids remains problematic due to the high cost of installing sewage sludge stabilization reactors and dehydration systems.Sewage sludge is a potential health hazard as it contains high numbers of cysts of protozoa,parasitic ova,fecal pathogens like Salmonella spp.,Shigella spp.and Escherichia coli and heavy metals such as zinc,cadmium,mercury and copper.In addition,sludge contains organic molecules and essential plant nutrients like nitrogen,phosphorus,potassium and various trace elements.Where in such setting of excess sludge as the byproduct of biological wastewater treatment process which can be costly and slow upon handling such residual byproduct.With the new wave of industrialization and energy based intensive agriculture,chemical pathways for raw materials conversion became predominant with extensive use of agrochemicals.The damaging long-term environmental impacts and resource depletion indicate un-sustainability of the current methods.There is an impetus to develop a low-cost approach to promote municipal sludge degradation and to fasten the rated its stabilization.It is an increasing knowledge that vermicomposting is a promising technology for the safe,effective,and sustainable treatment of organic wastes.Its final product-vermicompost is regarded as a gold bio-organic fertilizer because it contains a higher content of water-soluble nutrients and a wider richness of microbial community diversity relative to composting product(Earthworms feed readily upon the sludge components,rapidly converting them into vermicompost,reduce the pathogens to safe levels and ingest the heavy metals.Volume is significantly reduced from 1 m~3 of wet sludge(80%moisture)to 0.5 m~3 of vermicompost(30%moisture;This study evidences that earthworms can facilitate the stabilization of PDS through modifying microbial activity and number and community during vermicomposting.