Bioaugmentation of microalgae for anaerobic co-digestion of paddy straw
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Date
2021
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Punjab Agricultural University, Ludhiana
Abstract
Present study was aimed at bioaugmentation of microalgae by co-culturing with nitrogen fixing bacteria co-digestion of bioaugmented microalgal biomass with paddy straw (PS) to enhance biogas production. All five microalgal strains (Spirulina subsalsa, Anabena sp., Chlorosarcinopsis eremi, Chlorella sp. and Scenedesmus MKB) were co-cultured with Rhizobium bacteria for enhancing biomass productivity. Maximum increase of 5.84% was found inChlorosarcenopsis eremi showed followed by Spirullina subsalsa. Chlorosarcenopsis eremi was further co-cultured with different bacterial strains (Rhizobium sp., Pseudomonas sp., Pseudomonas gessardii A-13 and Pseudomonas aeruginosa A-14) at 5% and 10% (v/v) concentrations. Highest biomass productivity was observed in Chlorosarcenopsis eremi co-cultured with 10% Rhizobium which showed 20% increase in biomass followed by co-culturing with 10% Pseudomonas sp.(increase of 18.9%). Co-cultured biomass of microalgae was co-digested with chopped paddy straw. Feedstock was analyzed for its proximate and chemical composition before and after anaerobic digestion. The biogas potential of co-cultured microalgae under ambient conditions (32°C-42°C) revealed that PS co-digested with co-cultured biomass of Rhizobium and Chlorosarcinopsis eremi in presence of poultry dropping yielded highest biogas (156.80 l/kg PS) which was 20.2% more than control followed by PS supplemented with Rhizobium broth showing an increase of 5.9% (148.50 l/kg PS). Co-cultured biomass resulted in more biogas production in short period of time as maximum harvested biogas (155% increase) was found in case of PS co-digested with co-cultured biomass of Rhizobium and Spirullina subsalsa in one month only. Proximate and chemical analysis showed decrease in total solids, volatile solids, total organic carbon, feedstock consumed while increase in ash, lignin, silica and nitrogen content. Seed germination studies were also conducted to analyze the effect of monocultured microalgae, co-cultured microalgae and Rhizobium broth on growth parameters of moong seeds. Seed germination parameters were improved in range of 1.74%- 40.6%. Highest enhancement of 40.6% in germination parameters was observed with soaking of seeds in co-cultured broth of (Rhizobium and Spirulina subsalsa). Hence, co-culturing of microalgae with bacteria has tremendous potential in increasing biomass productivity which can be further used for paddy straw management through biogas production.
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Saldi, Sejal (2021). Bioaugmentation of microalgae for anaerobic co-digestion of paddy straw (Unpublished M.Sc. thesis). Punjab Agricultural University, Ludhiana, Punjab, India.