Browsing by Author "Richard, Edwin"

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Life cycle analysis of potential municipal solid wastes management scenarios in Tanzania: the case of Arusha City
(Springer Nature, 2021-01-07) Richard, Edwin; Hilonga, Askwar; Machunda, Revocatus; Njau, Karoli
The municipal solid wastes (MSW) management technologies in most cities of developing countries pose a continuous risk of contaminating the environment and affecting human health adversely; often because MSW technologies are not comprehensively analyzed before their implementation. For this purpose, the life cycle assessment methodology was applied to access the different MSW management scenarios in Arusha City, Tanzania. Three different scenarios of recycling and sanitary landfilling (RSL) were developed as the business as usual scenario (RSL) (SN-1), RSL combined with composting (SN-2), and RSL combined with anaerobic digestion (SN-3). Results obtained showed that no scenario performed better in all impact categories, however with the current focus on climate change and limited funds in developing countries, the best option would be SN-2. The SN-2 which is the combination of recycling, composting and the landfill had the least economic cost and environmental burdens in most categories when compared to the other scenarios. The sensitivity analysis results indicated that improving diesel consumptions, reducing methane emissions to air and increasing the recycling rate of papers and plastics would reduce the total environmental impacts on all scenarios.
A review on strategies to optimize metabolic stages of anaerobic digestion of municipal solid wastes towards enhanced resources recovery
(BMC, 2019) Richard, Edwin; Hilonga, Askwar; Machunda, Revocatus; Njau, Karoli
Recently, there are increased efforts by municipals and researchers to investigate the potential of utilizing municipal solid wastes (MSW) for resources recovery. In many parts of developing countries, MSW is mostly collected for disposal with little emphasis on resources recovery. However, the MSW has high organic and moisture contents, and are suitable substrates for anaerobic digestion (AD) process to recover biogas for energy and digestate which can be used as fertilizers or for soil amendments. Resources recovery from the AD process consists of four metabolic stages; hydrolysis, acidogenesis, acetogenesis, and methanogenesis. These metabolic stages can be affected by several factors such as the nature of substrates, accumulation of volatile fatty acids, and ammonia inhibition. In this review, different optimization strategies towards resources recoveries such as pre-treatment, co-digestion, trace elements supplementation, optimization of key parameters and the use of granular activated carbon are discussed. The review reveals that the currently employed optimization strategies fall short in several ways and proposes the need for improvements.
A review on strategies to optimize metabolic stages of anaerobic digestion of municipal solid wastes towards enhanced resources recovery
(BioMed Central Ltd, 2019-12-17) Richard, Edwin; Hilonga, Askwar; Machunda, Revocatus; Njau, Karoli
Recently, there are increased efforts by municipals and researchers to investigate the potential of utilizing municipal solid wastes (MSW) for resources recovery. In many parts of developing countries, MSW is mostly collected for disposal with little emphasis on resources recovery. However, the MSW has high organic and moisture contents, and are suitable substrates for anaerobic digestion (AD) process to recover biogas for energy and digestate which can be used as fertilizers or for soil amendments. Resources recovery from the AD process consists of four metabolic stages; hydrolysis, acidogenesis, acetogenesis, and methanogenesis. These metabolic stages can be affected by several factors such as the nature of substrates, accumulation of volatile fatty acids, and ammonia inhibition. In this review, different optimization strategies towards resources recoveries such as pre-treatment, co-digestion, trace elements supplementation, optimization of key parameters and the use of granular activated carbon are discussed. The review reveals that the currently employed optimization strategies fall short in several ways and proposes the need for improvements.
Strategies to improve anaerobic digestion and environ-economic analysis of municipal solid wastes management options
(NM-AIST, 2021-06) Richard, Edwin
Different strategies have widely been applied for improving the anaerobic digestion of the organic fraction of municipal solid wastes. However, because of the heterogeneous compositions of organic fraction of municipal solid wastes, studies on different strategies are still required. This thesis focused on examining methods to improve anaerobic digestion of organic fraction of municipal solid wastes and environ-economic analysis of municipal solid wastes management options. Firstly, the study examined the effects of fungal (Pleurotus ostreatus) treatment of the banana leaves wastes towards edible mushrooms and biogas recovery. Secondly, the study assessed the effectiveness of banana winery wastewater in digesting the banana leaves wastes to improve methane yield. Thirdly, the study examined the potential of edible clay soils towards improving the anaerobic digestion of food wastes for biogas recovery. Next, the study analyzed and compared the environmental impacts of anaerobic digestion and other municipal solid waste management scenarios in the Arusha City of Tanzania. Finally, the study assessed the economic feasibility of the biogas plants for treating food and banana leaves wastes in the Arusha City of Tanzania. All the anaerobic digestion experiments were carried out in batch reactors. The environmental impact was analyzed using a life cycle analysis methodology. Fungal treatment of banana leaves wastes prior to anaerobic digestion process resulted in the biogas yield of 282 mL g -1 VS -1 and production of 181 ± 19 g of edible mushrooms per 2 kg of banana leaves wastes. The cost analysis revealed that mushroom cultivation has a higher economic value and therefore favoured before the anaerobic digestion process. Banana winery wastewater pre-treatment of banana leaves waste resulted in increased methane yield by 193% compared to non-pretreated banana leaves waste. The edible clay soils supplementation in the anaerobic digestion process resulted in an increase of 26.9% methane yield in a reactor with edible clay soils supplementation. Evaluations on environmental impacts revealed that the anaerobic digestion process outranked the current management option (Landfill) with the least environmental burdens. The study also revealed it is economically viable to invests the biogas plants for treating food and banana leaves wastes in Arusha City of Tanzania.
Two-stage banana leaves wastes utilization towards mushroom growth and biogas production
(Springer Nature Switzerland AG., 2020-11-20) Richard, Edwin; Hilonga, Askwar; Machunda, Revocatus; Njau, Karoli
Banana leaves wastes (BL) were subjected to fungal treatment using Pleurotus ostreatus to produce edible mushrooms and biogas in the anaerobic digestion process. Effects of fungal treatment on mushrooms production, lignin degradation, trace elements compositions and biogas yield during the anaerobic digestion process were evaluated. Treatment with P.ostreatus for 36 d resulted in the production of 181 ± 19 g of edible mushrooms per 2 kg of BL with biological efficiency of 37 ± 4%. Lignin concentration in fungal treated BL decreased by 10% indicating an improvement on its digestibility. Important trace elements (Fe, Mn, Mo, Co and Ni) necessary for the improvement of the anaerobic digestion process were also significantly reduced (P < 0.05) during the fungal treatment process. The biogas yield for the fungal treated BL was 282 mL g−1 VS−1 of which this study suggests that could be improved through trace element supplementation during the anaerobic digestion process.