Anaerobic Digestion of Tannery Solid Waste for Biogas Production: The case of Modjo Tannery, Modjo; Ethiopia

The present study characterized the physical property, total solids (TS), volatile solids (VS) and Carbon to Nitrogen ratio (C/N ratio) of tannery solid waste (TSW). Five different combinations with or without cow dung (CD) were assessed for their biogas production suitability in triplicate batch digesters (D-1, D-2, D-3, D-4, and D-5) with a total volume of 2.8L. The results showed that TS, VS and C/N ratio of wastes were 56.37%, 76.34% and 29.05%, respectively. The results also suggested that the highest volume of biogas (4,756 ml) with a methane content of 60.37% was produced by the digester containing 75% TSW and 25% CD and the lowest biogas (2,539 ml) with quality of 68.06% was produced by digester containing 100% CD. The average methane contents of different digesters were D-1 (100% TSW) 53.23%, D-2 (75% TSW: 25% CD) 60.37%, D-3 (50% TSW: 50% CD) 58.78%, D-4 (25% TSW: 75% CD) 57.66% and D-5 (100% CD) 67.31%. Total and volatile solid removal efficiency of all digesters was in the range of 42.27-76.34% and 47.16-79.23%. The study concluded that TSW is a good feedstock for biogas production by utilizing agro-industrial based organic solid waste for bioenergy production

Aerosols behaviour in sensitive areas of the northwestern Himalaya—A case of Kullu-Manali tourist complex, India

332-340Total suspended particulate (TSP) matter on fortnightly basis throughout the year and mass size distribution of aerosols as well as ultrafine aerosols on weekly basis in the months of May and June were monitored during 1996-2003 at different altitudinal locations of the Kullu-Manali tourist complex in the northwestern Himalaya. Concentration of TSP ranged from 35.8 (August 1996) to 207.3 μg m-3 (June 2003) at Mohal [1150 m from average sea level (ASL)] and from 31.7 (July 2003) to 239 μg m-3 (April 2001) at Manali (2050 m ASL). The mass size distribution of aerosols showed a bimodal distribution having one peak in the coarse size range (3.3-9 μm dia) and the other in the fine size range (0.08-2.1μm dia] at both the locations. Ultrafine aerosol (UA) (0.001-0.1 μ m radius) concentrations were found to be highest at the lowest experimental altitude site (Mohal) and vice versa. The diurnal variation of UA concentration for three years showed that the concentration ranges from 2640 (at 0500 hrs LT) to 5160 Number (N) cm-3 (at 1300 hrs LT) at Mohal and from 400 (at 0400 hrs LT) to 2190N cm-3 (at 1300 hrs LT) at Kothi. On an average, TSP crossed its permissible limit set by National Ambient Air Quality Standard (NAAQS) level in the sensitive areas such as Kullu-Manali hill spots. Bimodal nature mass size distribution indicates two important sources contributing in total aerosols-the fine mode, primarily due to anthropogenic activities and the coarse mode aerosols, mainly due to natural sources. Large number of concentration of ultrafine particles indicates the presence of air pollutants more low altitudes as compared to high altitudes