Department of Chemical and Process Systems Engineering
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Item Treatment of Piggery Wastewater using an Acti-zyme (Biocatalyst) and Paper mill Biochar Compound Co-capturing Biogas(5 th Anniversary of ANSOLE (2011-2016): International Conference on Renewable Energy (INCORE2016), 2016-02-03) Manyuchi, Musaida Mercy; Guvavaa, Grace N.; Ikhu-Omoregbe, Daniel I. O; Oyekola, Oluwaseun O.The world is facing formidable challenges in meeting rising demands of clean water as the available supplies are depleting due to extended droughts, population growth, more stringent health based regulations and competing demands from a variety of users. At the same time, wastewater treatment plants are using energy from the national grid rather than generating their own energy. Piggery farms and paper mills make use of a lot of water and thus contribute towards water shortage. The piggery farms produce a significant amount of wastewater which water can be effectively treated via anaerobic routes to harness biogas. On the other hand, paper mills are generate excessive amounts of sludge during paper making process. Secondary treatment of wastewater can therefore be used to make sludge based activated biochar which can be used in wastewater treatment. This work assessed the feasibility of using a compound from activated carbon from paper mill sludge (PMS) and Acti-zyme (a digestion bio-catalyst) to treat piggery wastewater anaerobically and co-capturing the biogas produced for energy usage. A piggery wastewater treatment plant generating 6000 m3 /day of wastewater was considered and the change in the wastewater physicochemical properties was determined using standard methods. The amount of biogas produced was determined using a water displacement method for retention periods of 30 days at 37 °C. The use of Acti-zyme and PMS biochar compound at 50 g/m3 reduced the piggery wastewater contaminants properties such as total solids, colour, pH and BOD5 by >70%. The treated effluent met the set standards for effluent water disposal. Biogas was produced at a rate of 2.3 m3 /m3 .day with a bio-methane composition of about 78%Item Biosorbents for the removal of synthetic organics and emerging pollutants: Opportunities and challenges for developing countries(Environmental Development, 2016-05-23) Chaukura, Nhamo; Gwenzi, Willis; Tavengwa, Nikita; Manyuchi, Musaida MercyContamination of aquatic systems by synthetic organic contaminants and emerging pollutants poses significant public and environmental health risks in developing countries. These contaminants mainly originate from textile, agrochemical, and pharmaceutical industries. The removal of such contaminants is problematic in developing countries because advanced water treatment methods are still lacking in developing countries due to their high costs. The application of biosorption for removal of organic contaminants in developing countries is attractive for three reasons; (1) large quantities of biomaterials for use as biosorbents are readily available; (2) lack of advanced water and wastewater treatment systems for removal of organic contaminants; and (3) the technology is relatively cheap compared to advanced methods (e.g. membrane filtration) often used in developed countries. Overall, this has the potential to remove organic contaminants from aqueous systems while simultaneously reducing the public health and environmental impacts associated with the disposal of such biowastes. However, large-scale application of biosorption faces potential challenges including lack of funding, poor mechanical properties of biosorbants, complex adsorption mechanisms involved, and poor regeneration capacity. In addition, spent biosorbents present an environmental risk and their disposal is problematic due to the potential of contaminating surface and ground water. Possible disposal methods for spent biosorbent include use as a filler in road surfacing, as a soil amendment, and in phytoremediation cells where the organics are absorbed and broken down by plants. Overall, biosorption is a potentially viable alternative, but further research on its ability to remove pollutants from multi-component systems, its regeneration capacity, and plant design parameters is required before the benefits of the technology are realised in developing countries.Item Biogas Production from Saw dust using Acti-zyme as Digestion Catalyst and its Upgrading to Bio methane using Chemical Absorption(World Energy Council Congress, 2016-01-01) Manyuchi, Musaida Mercy; Bobo, Arthur. E.; Ikhu-Omoregbe, Daniel I. O; Oyekola, Oluwaseun O.Zimbabwe has one of the largest deposits of timber in Southern Africa (about 500 000 tons per annum) such that most entrepreneurs venture into timber processing. The venture results in generation of a lot of sawdust dumps that are of no economic use if they are left lying around. There is 10000 metric tons that go to waste each year which when bio-converted can result in biogas. This paper therefore presents the potential for biogas production from saw dust bio-catalysed by Acti-zyme a biocatalyst to enhance the digestion hence biogas yield. This paper presents the bio-catalysed digestion of 4000 metric tons of saw dust per year to produce biogas using Acti-zyme. The generated biogas is then upgraded using chemical absorption for removal of carbon dioxide so as to increase the bio methane energy efficiency. Biogas produced was approximately 24 m 3 per day and was upgraded to 97% from 72% bio-methane composition per day using chemical scrubbing technique in an absorption column. The absorption column design considerations are also presented as well as its process control and the hazard analysis. These are essential in the optimal upgrading of the biogas. Purified bio methane has a higher calorific value of 99 % relative to the 77 % of raw biogas. An economic analysis showed that a 2 year payback period with a return on investment of 48% and break even sales at $331 580.00 with the upgraded bio methane being sold at $2.50/kg. The conversion and upgrading of biogas produced by anaerobic digestion using Acti-zyme is technologically, economically and environmentally feasible.Item TECHNO-ECONOMIC ANALYSIS FOR VIRGIN PAPER PRODUCTION FROM BAGASSE(8 th Zimbabwe Institute of Engineers Congress, 2014-09-14) Manyuchi, Musaida Mercy; Chiwanga, Auxilliah. T.; Nkomoc, D. J.The pulp and paper manufacturing industry relies heavily on importing waste paper as its raw material from neighbouring countries such as South Africa. At the same time, the available local resource is wood and cutting this results in environmental problems. As a measure to foster value addition and beneficiation as well as reduce deforestation, there is need to use alternative raw materials such as bagasse which is readily available at sugar plantations. This study involved the processing of 40 tons per day of virgin paper from bagasse as an alternative option using the Kraft process with a conversion yield of 35%. Optimum operating pressure and temperature were found to be 9.6 atmospheres and 200oC respectively and a detailed process design was done considering the process safety issues. After an environmental impact assessment the bagasse to virgin paper plant was recommended for siting in Chiredzi. An economic analysis carried out indicated a return on investment of 45% and a payback period of 2.2 years. The net present value was found to be $757 792 with the virgin paper selling price set at $108/ton. Henceforth the project is both technically and economically feasible.Item Women in Engineering for Economy Recovery in Zimbabwe(Asian Journal of Business and Management, 2013-08-03) Manyuchi, Musaida MercyEngineering is the application of scientific and mathematical knowledge as well as creativity for the development of solutions as well as for technology advancement. Previously the engineering field has been male dominated but of late women are taking up this discipline although the rate is still as low as 25%. The low uptake of these engineering fields by women therefore affects the output of women engineers into the society and consequently therefore failure to meet the engineering demands of our country. However, due to the women friendly policy implementation in Zimbabwe, involvement by women in engineering is increasing. Women engineers are helping ease problems of special skills shortage as well as lowering the gender imbalance that has existed in this field. Furthermore, participation by women engineers minimizes the employment shortage as well as re-boosting the economy in all fields such as academia, industry and entrepreneurship. Women engineers on the ground are working hard participating in the economic recovery of Zimbabwe but, there is need for more for an effective change. This is achievable through awareness campaigns and implementation of policies crafted to empower women.Item Vermifiltration of Sewage Wastewater for Potential Use in Irrigation Purposes Using Eisenia fetida Earthworms(World Academy of Science, Engineering and Technology, 2013-02-05) Manyuchi, Musaida Mercy; Boka, Simbarashe; Kadzungura, Luckmore—Vermifiltration was used for treatment of sewage wastewater using the Eisenia fetida earthworm species. The earthworms’ gut acted as a bioreactor and they reduced the sewage wastewater solid and liquid organic wastes through ingestion and expelling these as vermicompost. 500 earthworms were used in the vermifilter over a 5 period of days. The treated water pH increased from being acidic to neutral. The sewage wastewater biological oxygen demand (BOD5), chemical oxygen demand (COD), total dissolved and soluble solids (TDSS) and turbidity decreased by 98%, 70%, 95% and 98% respectively through vermifiltration. Vermifiltration significantly decreased the sewage water physicochemical parameters compared to an ordinary bio-filter without earthworms. The vermi-treated sewage water compared well with the set standards for irrigation water. Vermifiltration technology can therefore be applied as an environmentally friendly technique for sewage water treatment for irrigation purposesItem Vermicomposting in Solid Waste Management: A Review(International Journal of Scientific Engineering and Technology, 2013-12-01) Manyuchi, Musaida Mercy; Phiri, AnthonyVermicomposting is a bio-conversion process which is widely being used for solid waste management. In this bio-conversion process, earthworms feed on the organic waste to produce more earthworms, vermicompost and vermiwash as products. Earthworms which include Megascolex Mauritii, Eisenia Fetida, Eudrilus Eugeniae, Perionnyx Excavatus, Lampito Mauritii, Eisenia Andrei, Lampito Rubellus and Drawida Willis have been widely used for vermicomposting. Vermicomposting has been done for various wastes including animal, plant, pharmaceutical, food waste and sewage waste over vermicomposting periods ranging from 28-120 days using these earthworms. The process conditions during vermicomposting ranged from 18- 67°C for temperature, pH 5.9-8.3 and moisture content 10.6-80%. Vermicompost yields of 30-50% have been achieved for various organic wastes and composting periods. The vermicompost and vermiwash produced were rich in nitrogen,phosphorous and potassium (NPK). The vermicompost obtained had NPK compositions ranging from 0.3-4.19%, 0.2- 1.6% and 0.2-6.18% respectively. The vermiwash obtained had NPK composition ranging from 0.14-1.58%, 0.05-7.53% and 0.47-1.26% respectively. Vermicompost and vermiwash have been applied on cow pea, soy bean, maize and marigold as bio-fertilizers. Vermicomposting can be used for solid waste management and the production of bio-fertilizersItem Pilot Scale Studies for Vermifiltration of 1000m3 /day of Sewage Wastewater(Asian Journal of Engineering and Technology, 2013-03-01) Manyuchi, Musaida Mercy; Kadzungura, Luckmore; Boka, SandraVermifiltration is a technology in which the combined action of earthworms’ activity and theabsorption properties of soil, sand and gravel particles on the organic pollutants are applied for wastewater treatment. Vermifiltration was used in sewage wastewater treatment as a cheaper and enviro-friendly technology. 1000m3 /day of sewage wastewater was treated in a four layered vermifilter at an Eisenia fetida earthworm density of 8 000 earthworms/m2 in a 3.6m2 soil bed. The vermifilter bed layers comprised of 4-8mm garden soil particles, 8-12mm mixed sand and gravel particles, 30-50mm small aggregates and 70-80mm large aggregates respectively. A vermifilter bed porosity of 0.96 was used. The vermifilter had a hydraulic retention time of 0.082days and a hydraulic loadingrate of 0.93m3/m2.day. The vermifilter design effectively resulted in over 90% reduction in BOD, COD, TDSS andturbidity as well as neutralized pH in the sewage wastewater. Proper vermifilter design ensures optimum sewage wastewater treatment for potential use in irrigationItem Impact of Vermicompost on Lettuce Cultivated Soil(International Journal of Inventive Engineering and Sciences (IJIES), 2013-10-02) Manyuchi, Musaida Mercy; Mudamburi, T; Phiri, Anthony; Muredzi, Perkins— Vermicomposting is an environmentally friendly technique that is used for organic solid waste management. Waste corn pulp blended with cow dung and office paper was vermicomposted over 30 days to produce vermicompost which is a bio-fertilizer. The vermicompost was applied to soil cultivated with lettuce at the planting and after every four weeks. The impact of vermicompost on the soil was quantified. Application of vermicompost resulted in a 5%, 21.7%, 16.9% and 4.92% increase in soil pH, nitrogen, phosphorous and manganese content respectively. Application of the vermicompost also resulted in a 9.41% and 3.77% decrease in soil electrical conductivity and potassium content respectively. However, application of vermicompost did not alter the copper and zinc content of the lettuce cultivated soil. The lettuce showed vigor and vitality during the period of growth. Vermicompost can be used for sustainable agriculture practicesItem Effective Separation of Vermicasts fromEarthworms Using a Cylindrical Rotary Trommel Separator(International Journal of Innovative Research in Science, Engineering and Technology, 2013-08-02) Manyuchi, Musaida Mercy; Phiri, AnthonyVermicomposting technology is widely being used worldwide as a solid waste management strategy. During vermicomposting Eisenia fetida earthworms ingest the solid organic waste and after a bioconversion process it is expelled as vermicasts. These vermicasts can be used as solid bio-fertilizers; however there are challenges of separating the earthworms from the vermicasts after vermicomposting. Pilot studies were therefore done using a cylindrical rotary trommel screen separator prototype to efficiently separate the earthworms from the vermicasts. The vermicasts were obtained from vermicomposting waste corn pulp mixed with cow dung manure and waste office paper. The cylindrical rotary screen had a mesh size of 4 mm, length of 250 mm and diameter of 90 mm. A throughput of 1.3 m3 /hr comprising of vermicasts and earthworms with a moisture content of 40-60% was separated trommel screen rotational speeds of 30-70rpm. The vermicasts separation efficient was around 80-95% but optimum separation of 95% was achieved at 40% moisture content and trommel screen rotational speed of 50rpm. Using a mechanical trommel screen separator increased the separation of vermicasts and earthworms, hence making the vermicomposting technology ideal.