Sludge Vermicomposting

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 ‘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, faecal pathogens and also 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. When stabilized through a composting process, it can become a good source of organic fertilizer and soil additive, free of chemicals and pathogens.

Vermicomposting is an innovative technology for the treatment of wastewater sludge. Earthworms have real potential both to increase the rate of aerobic decomposition and composting of organic matter and also to stabilize the organic residues in the sludge – removing the harmful pathogens and heavy metals (by bio-accumulation). They also mineralize the essential nutrients nitrogen, phosphorus and potassium from the sludge. It may not be possible to remove toxic substances completely, but at least change the ‘chemical make-up’ of the sludge to make it harmless to the soil and enable its use as a nutritive organic fertilizer. This method has been found to comply with grade A standards for sludge stabilization.

Concept Biotech has been using this technology as it has advantageous factors in minimizing the degradable organic matter and to use the same as a bio-resource for organic manure production.

Sludge from pharmaceuticals, food industries and sewage treatment plants has been successfully vermicomposted into manure which is in turn used for managing industrial green zone.