Innovative Biogas and Bio-solids generation from anaerobic sewage sludge digestion using acti-zyme as biocatalyst as a sustainable measure for developing countries

Abstract

Sewage sludge was anaerobically digested using Acti-zyme, a biocatalyst for generation of biogas and bio-solids as an innovative strategy for obtaining biogas. Acti-zyme loadings of 35-50 g/m3 was employed for sewage sludge loading of 5-10 g/L. day in 250 mL reactors emanating the digesters. The agitation in the digesters was maintained at 60 rpm, at a mesophillic temperature of 37 °C for a period of 40 days. The biogas quantity produced was measured using the water displacement method daily. Samples of the biogas were collected and analyzed for bio-methane (CH4 ), carbon dioxide (CO2 ) and traces gases composition using gas chromatography. The bio-solids obtained were dewatered for destruction of pathogens and tested for nitrogen, phosphorous and potassium (NPK) content using uv-vis spectrophotometry. Optimum biogas quantity was produced at a sewage sludge loading of 7.5 g/L. day and Acti-zyme loading of 50 g/m3 with 78% CH4 unlike in Acti-zyme free digesters were a maximum of 65% CH4 was obtained. High nitrogen content bio-solids with 8.17 %, 5.84 % and 1.34 % of NPK respectively were produced. Acti-zyme is therefore an attractive bio-catalyst for sustainable sewage treatment for co-generation of biogas and bio-solids.