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EVALUATION OF BIOGAS YIELD AND MICROBIAL SPECIES FROM MULTI-BIOMASS FEEDSTOCKS
Published 2014-12Subjects: “…Biogas yield…”
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Livestock and poultry wastes management in Swaziland
Published 2006Subjects: “…biogas,…”
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Page will reload when a filter is selected or excluded.- A survey was carried out to assess the methods of livestock and poultry wastes management in Swaziland. The survey adopted the use of questionnaires which sought for information on the types of wastes generated, types of litter materials used, methods of wastes collection, predisposal wastes treatment, wastes utilization and possible effects of the wastes on the environment. Additional information was collected through personal communication and focused group discussions during the field trips while administering the questionnaires. Points of information gathering were commercial poultry and livestock farms, homesteads, dip tanks and feedlots. The data were analysed using percentages and frequencies, and the results presented in tables. Major solid wastes generated were from animal dung, poultry droppings and litters. Saw dust was the most popularly used litter material by about 38.7% of the large scale establishments while crushed corn cob was the least used by about 5.3%. Urine and spent water from washing in milking parlours and dip tanks constituted the liquid wastes. Waste collection was by manual scrapping with spades, sweeping and floor washing using water hoses, and use of mechanical scrappers. Manual scrapping was the most predominant method for solid wastes collection. It was used by about 60% and 95.8% of the large scale establishments and homesteads respectively. Mechanical scraping was mainly used in the large scale establishments. Solid wastes were either collected and taken directly to the field for application or temporarily stored in compost pits and refuse dumps to undergo further decomposition. Only 33.3% of the homesteads had temporary dump sites. In most homesteads, kraal manure is removed during land preparation which eliminates the need for storage. About 33.3% of the large scale establishments had dump sites, 17.4% had compost pits while 16% had a combination of dumpsites and compost pits. Liquid wastes were disposed off on strip fields or adjacent streams. About 75.0% of the homesteads and 33.3% of the large scale establishments conveyed their wastes using wheel barrows while 4.2% and 26.7% respectively made use of a combination of wheel barrows and tractor trailers. All the homesteads and about 72.0% of the large scale establishments used solid wastes as fertilizers on their own farms. Liquid effluent was used for irrigation by about 5.3% of the large scale establishments. The ministry of agriculture and cooperatives is emphasizing the use of livestock wastes in fish farming while the biogas plants which were established to utilize some of the wastes have been abandoned. Respondents admitted awareness of the dangers inherent in poor livestock and poultry wastes management but only a few admitted that their management techniques constituted any hazards to the environment. Solid wastes as presently generated, collected and utilized constitute no environmental threat but the liquid discharged to streams and wet cattle that wade through streams immediately after dipping are considered potential sources of pollution. Wastes are a potential source of biogas which is being effectively utilized in many countries. The abandoned biogas pilot schemes should be reactivated. Water quality assessment should be carried out on streams to which wastes are discharged and appropriate steps taken to prevent pollution. Oxidation ponds should be constructed near dip tanks and milking parlours. More extension work is required to educate the rural populace on the use of livestock wastes for fish farming. 1 results 1
- Anaerobic digestion 1 results 1
- Biogas yield 1 results 1
- Multi-feedstock 1 results 1
- Renewable energy 1 results 1
- Swaziland 1 results 1
- Virtually all countries, especially the developing nations, are being confronted with the twin problems of waste management and energy deficit. This development has led to the search for renewable energy sources. Although pig dung, water hyacinth and maize cob have been identified as good feedstocks for biogas production, studies utilising their mixtures have not been fully explored. This study was therefore designed to evaluate the biogas yield and microbial species from mixtures of biomass feedstocks. The feedstocks utilised for this study comprised Pig Dung (PD), Water Hyacinth (WH), and Maize Cob (MC). The PD and WH were sourced from University of Ibadan Teaching and Research Farm while MC was sourced from refuse bins in Oje Market. Six feedstock groups were selected namely PD, WH, MC, PD:MC (PM), PD:WH (PW), and PD:MC:WH (PMW). Each mixture was made in equal proportion on dry weight basis. A simple biogas digester was fabricated from a 10-litre plastic keg for feedstock biodegradation. Each feedstock sample to be digested was prepared by mixing 0.75 kg dry feedstock with 8.25 litres of water in the ratio of 1:11 (w/v) to form slurry. The slurry was fed into the corresponding digester, and kept for 35 days for anaerobic digestion while samples of the effluent were taken at seven days interval for five weeks for laboratory analyses. Parameters including temperature, pH, carbon, nitrogen, carbon to nitrogen (C-N) ratio, potassium, phosphorus, and microbial identification characteristics were determined using standard methods. Gas generated was estimated based on Archimedes’ Principle. Data were analyzed using descriptive statistics and ANOVA at p ˂ 0.05. Temperature and pH of all slurries ranged from 25.75±0.4oC to 28.75±0.4oC and 5.80±0.0 to 7.85±0.1 respectively. There was a significant difference in percentage nitrogen, phosphorus and potassium of the various slurries. Mean C-N ratio of the various slurries decreased from day 0 to day 35 as follows: 20.05±2.1 to 16.27±1.1, 23.28±0.1 to 12.95±1.2, 97.54±3.3 to 47.70±1.3, 57.27±0.2 to 28.34±2.1, 28.52±4.2 to 24.19±2.0 and 49.86±2.9 to 37.24±2.4 for PD, WH, MC, PM, PW, and PWM respectively. Predominant organisms identified at day 35 were: Methanobacterium, Enterobacter and Aspergillus spp. The anaerobic, coliform and fungal counts ranged from 6.80×102 to 1.0×105cfu/g, 4.3×104 to 6.2×106cfu/g, and 9.1×103 to 6.3×106cfu/g respectively throughout the duration of the study. The highest anaerobic count (1.0×105±0.03×105cfu/g) was recorded in PW on day 28. Peak biogas production was observed on day 23 for PD (987.50±3.5mL); day 24 for PW (1095.00±7.1mL), and PM (732.50±17.7mL); day 25 for MC (560.00±7.1mL), day 26 for WH (635.00±7.1mL) and PMW (662.50±10.6mL). Group PW had the highest biogas yield of 6067.00±38.2mL for the entire duration of the study. There was a significant difference between the mean biogas yields of the various feed stock groups. Co-digestion of pig dung with water hyacinth had the highest number of anaerobes and biogas yield as compared to single feed stocks. Therefore, the use of multi-biomass feed stocks for biogas production as a source of alternative energy production should be fully optimised. 1 results 1
- beddings, 1 results 1
- biogas, 1 results 1
- dip tanks, 1 results 1
- kraal, 1 results 1
- livestock wastes, 1 results 1
- manure, 1 results 1
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