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The main aim of this study was to evaluate the lab scale, microbe-enhanced biogas production from water hyacinth blended with poultry waste and cow dung. A mesophilic anaerobic two-stage continuous reactor was set up to study the co-digestion for enhanced biogas production. The optimized mixing ratio of cow dung, water hyacinth, and poultry litter (2:1:1; 4:3:1 and 5:2:1) was used along with the effective microbial solution in a two-stage continuous reactor. The biogas yield was maximum in the 2:1:1 blend than the blends with a mixing ratio of 4:3:1 and 5:2:1. The reactor-loading rate was 4 and 5 g.L-1.day-1 with a retention time of 30 and 60 days respectively. The two-stage anaerobic digestion helps in controlling toxicity by acidogenesis and enhances energy production, thereby proving to be a technology that prevents environmental deterioration and enhances energy recovery, both of which are twin issues that need scientific attention. Maximum specific biogas of 0.128 Nm.L.g-1 of Volatile solid reduction (VSR) in hydrolyzer and 0.205 Nm.L.g-1 of VSR in methanizer was obtained at an optimized Carbon/Nitrogen (C/N) ratio of 20.8. The co-digestion of protein-rich waste with a carbon-rich source offers a reduced acclimatization period in the hydrolyzer with an increased C/N ratio, thereby increasing the biogas yield as observed in the methanizer. Several other parameters including Ammonia level, Volatile Fatty Acids influenced by the reactor alkalinity also determine the biogas yield. With increased alkalinity, free ammonia increases and may be inhibitory for anaerobic fermentation and may be toxic for methanogenic bacteria, thereby contributing to the reduction in biogas yield. The present investigation has led to a novel biogas and power-producing clean development mechanism (CDM) for the first time from a heterogeneous mixture of animal excreta and plant waste (livestock droppings, cow dung, and water hyacinths). The waste samples have been collected from sewage and sullage polluted Kosavampatti Lake and Phoosur lake in Namakkal district of Tamilnadu, India therein ending up in a high quantity of CO2 mitigation. [ABSTRACT FROM AUTHOR]

There is a great need to implement low-cost and user-friendly methods for further propagation of biogas technology in India. Environment unfriendly disposal of floral waste causes serious environmental pollution. Literature shows a limited research work regarding the anaerobic digestion of floral waste for biogas generation. The present experimental work aims to propagate floral waste as a sustainable source of biogas energy in India. Using different techniques like novel alkaline pretreatment, solar heating of the digester and co-digestion with food waste give enhanced biogas production from floral waste. A novel alkaline pretreatment of the floral waste using sodium carbonate and sodium bicarbonate gives an improvement in biogas output by 106%, with a saving in the cost of chemical pretreatment up to 96%, compared to traditional sodium hydroxide pretreatment. Also, solar heating of the digester increases the biogas output by 122% as compared to digesters in ambient conditions. Co-digestion of the floral waste with food waste also improves biogas output by 32.6%. Raw biogas from floral waste contains over 57% methane, which is higher than the previous studies. Large-scale application of the techniques can benefit the society. [ABSTRACT FROM AUTHOR]

Tanneries in India face the twin problems of managing process solid waste and treatment of effluent plant sludge. The present study covered (i) significance of optimization of mix proportions of substrates i.e., fleshings (F) and the primary sludge (PS) and secondary sludge (SS) generated during treatment of tannery wastewater (ii) residence time during co-digestion for enhancement of biogas generation and (iii) digestate analysis. Maximum biogas generation of 385 mL/g of VS was observed for the mix proportion of 1.00:2.70:0.30 (F:PS:SS) and a residence time of 45 days during co-digestion of tannery solid wastes. Biogas generation was enhanced by increasing the proportion of PS to SS. After digestion, secondary metabolites i.e., primary, secondary, and tertiary alcohols, amino acids, methane, and ammonia were observed from FT-IR analysis. The exothermic reaction was observed at around 175 °C and when C/N ratio of digestate was around 8.0. [ABSTRACT FROM AUTHOR]

In rural India, unpleasant atmosphere, anthropogenic gas emission, air and soil pollution are caused due to disposal of livestock's wastes (cow dung and chicken waste) in open environment. This study provides zero emission concept for waste disposal and value addition of these wastes for renewable green energy production. In this study, biogas production was carried out with varying proportion of cow dung to chicken waste (1:0, 0:1, 1:1, 2:1, 1:2, 3:1 and 1:3) for duration of 40 days. Chlorella pyrenoidosa was cultivated from digestate water and used as co-substrate in digester in varying proportions (2:1:1, 2:1:2 and 2:1:3) to study its role on biogas distribution. The effect of pH, feedstock ratio, time and C/N ratio for biogas production were evaluated. The maximum methane and hydrogen yield was 68% (30th day) and 29% (10th day) for 2:1:2 ratio respectively. The slurry possessed nitrogen (1.7%), phosphate (0.8%) and potassium (0.4%) respectively. • Green energy from digestion of cow dung and chicken waste with zero discharge. • Methane yield was 68% on 30th day with density of 1.27 kg/m3 for 2:1:2 ratio. • Cow dung: chicken waste: algae (2:1:2) resulted 29% of hydrogen yield on 10th day. • Slurry can be used as bio-manure due to 1.7% of nitrogen and 0.8% of phosphate. [ABSTRACT FROM AUTHOR]

India is one among the Asia's newly industrialized countries, in which urban centres generate large amount of municipal solid wastes due to the rapid urbanization. To demonstrate urban waste potentials for biogas production by anaerobic digestion, a comprehensive analysis on the availability of organic waste hotspots and its biogas potential for the exemplary case of Chennai, India, was undertaken. The identified hotspots and their biogas potential were plotted with Geographical Information System as thematic maps. The results of biogas potential tests revealed strong variations in the biogas potentials of individual waste streams from 240.2 to 514.2 mL N /g oDM (organic dry matter) with oDM reduction in the range of 36.4-61.5 wt.-%. Major waste generation hotspots were identified from the surveyed urban bio-reserves and the biogas potentials within an effective area of 5 km radius surrounding the hotspot were estimated. It was found that the biogas potential of individual hotspots ranged between 38.0-5938.7 m 3 /day. Further results revealed that the biogas potential during anaerobic co-digestion, by considering nearby bio-reserves in the effective areas of major hotspots, with and without residential organic waste, ranged between 4110.4-18-106.1 m 3 /day and 253.2-5969.5 m 3 /day, originating from 144.0-620.0 tons and 3.1-170.5 tons, respectively. Despite variations in the composition of the wastes, the Carbon/Nitrogen ratio, oDM reduction, biogas production and substrate availability were improved during co-digestion of nearby bio-reserves within the major hotspots, thereby improving the prevailing barriers in substrate management during anaerobic digestion of wastes.