Department of Chemical and Process Systems Engineering

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ACTI-ZYME BIOCHEMICAL PROPERTIES: POTENTIAL FOR USE IN ANAEROBIC SEWAGE TREATMENT CO-GENERATING BIOGAS
(Asian Journal of Science and Technology, 2015-03) Manyuchi, M.M; Ikhu-Omoregbe, D. I. O; Oyekola, O. O.
The biochemical properties for Acti-zyme, a biocatalyst were characterized for potential use in anaerobic sewage treatment with the aim of producing biogas. Sterile Acti-zyme media containing peptone water was plated on the MacConkey Agar, Starch Agar, Kliger Agar, Urease Agar, Sulphide Indole and Motility Agar at 37.5°C for 24 hours, at a pH of 7±0.2. Acti-zyme was found to be immotile and contained several enzymes that have different applications in sewage treatment. These included catalase which detoxified harmful substances, protease which broke down the proteins as well as amylase which broke down the polysaccharides available in sewage. However, Acti-zyme did not contain urease; an ammonium catalyzing enzyme. Acti-zyme did not to promote H2S production which is a contaminant in biogas production. Acti-zyme also did not contain pathogenic Enterobacteriaceae such as E. Coli and Salmonella. The identified Acti-zyme biochemical properties make it useful in sewage treatment co-producing biogas
Adsorption of Methyl Orange, Pb2þ and Cd2þ from Aqueous Solution by Composites of LignocelluloseMontmorillonite Modified with Methacryloxypropyl Trimethoxysilane
(WILEY-VCH Verlag GmbH & Co. KGaA,, 2012-03-07) Tavengwa, Bunhu; Lilian, Tichagwa
A composite material based on lignocellulose and montmorillonite clay (MPSgLig-NaMMT) was prepared and evaluated as an adsorbent for the removal of pollutants (dyes and heavy metals) from aqueous solution. The lignocellulosemontmorillonite composite was prepared by in situ intercalative polymerisation, using methacryloxypropyl trimethoxysilane (MPS) as a coupling agent. The composite material was characterised by FTIR, TGA and SAXS. The lignocellulose-montmorillonite composite was assessed as an adsorbent for methyl orange dye from aqueous solution. The composite material showed enhanced adsorption of methyl orange (MetO) compared with the NaMMT or lignocellulose separately. Competitive adsorption studies were carried out from binary mixtures of MetO with Cd2þ or Pb2þ in aqueous solution. The adsorption process of MetO onto the composite material was found to follow the Freundlich adsorption model. The adsorption of methyl orange from binary mixtures, were found to follow both the pseudo first-order and pseudo second-order models
Bio-conversion of Food Wastes into Vermicompost and Vermiwash
(International Journal of Science and Modern Engineering (IJISME), 2013-09-10) Manyuchi, Mercy; Phiri, Anthony; Muredzi, Perkins; Chirinda, Ngoni
Vermicomposting technology is the bio-conversion of organic waste into bio-fertilizers using earthworms. Vermicomposting is widely being used for solid waste management. Various food wastes were vermicomposted over 30 days using Eisenia fetida earthworms. Vermicompost and vermiwash were obtained as vermi-products. The vermicompost nitrogen, phosphorous and potassium composition was 2.1%, 0.29% and 0.19% respectively. Whereas, the vermiwash only contained 0.58% nitrogen and 0.47% potassium. Vermicomposting technology is necessary as a food wastes management strategy.
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.
Bioremediation of Transport Industry Contaminants Using Vermicompost
(International Journal of Environmental Engineering Science and Technology Research, 2014-01-01) Manyuchi, M.M; Phiri, A
Transport industries pose environmental challenges due to leaks of engine oils both to soil and water. Engine oil is highly organic therefore there is need to bio-remediate the contaminated soil and wastewater in order to preserve the environment. Soil and wastewater contaminated with diesel engine oil were bio-remediated using vermicompost containing live Eisenia Fetida earthworms and cocoons over a 4 week period. The contaminated soil and water pH and electrical conductivity (EC) were monitored during this period. Furthermore, the wastewater dissolved oxygen (DO) and biological oxygen demand (BOD) were determined. The pH in the contaminated soil decreased from 7.2 to 6.2 whilst that in the contaminated wastewater increased from 5.8 to 7.2. The EC in both the diesel contaminated soil and wastewater showed a decrease of more than 19%. The DO in the wastewater showed a decrease upon addition of vermicompost and then later on increased. Lastly, the BOD in the wastewater, decreased by 16.9% upon addition of the vermicompost. Vermicompost can be used for the vermiremediation of soil and wastewater contaminated with engine oil in the transport industries.
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 Mercy
Contamination 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.
Catalytic Activity of CeO2 -NiO for Low Temperature Soot Combustion
(IJERT, 2014-09-20) Mahofa, Eubert Privilege; Narsaiah, T. Bala; Chakra, Shilpa; Kumar, Pramod; Aftabtalab, Adeleh
CeO2 (Ce) and CeO2-NiO (CeNi) nano- catalysts were synthesized by co-precipitation from nitrate precursors using 25% ammonia solution (NH4OH) as the precipitating agent. The catalysts were calcined in air at 500ÂºC and 800ÂºC for 4h to evaluate the thermal stability. XRD and DLS techniques were used for catalyst characterization. A Thermo gravimetric/Differential Thermal Analyzer (TG/DTA) was used to determine the catalytic activity and soot oxidation reactions. Compared with Ce, Ce-Ni nanocomposite showed lower soot oxidation temperature.
Cleaner Production options in sand casting in foundries.
(International Journal of Sustainable Energy and Environment, 2013-04-06) Masike, Rujeko; Chimbadzwa, M.J
The purpose of this paper was to assist foundries in pollution prevention by devising clean technologies which maintain or improve the quality of the ambient surrounding. The paper used Cleaner Production and its opportunities to minimize material consumption, optimize production yield and to prevent polluting the air, water and land. The reseachers reviewed how sand casting foundries can implement Cleaner Production and benefit from the created conducive environment as well as saved financial capital. The review gave an overview of the environmental aspects and impacts of foundry operations. It also outlined best practices to improve the energy, material, and environmental efficiency, and the product output of the operation. The current environmental status and performance of foundry companies in Zimbabwe was determined from the initial environmental review, energy and environmental audits. Once the environmental status was established, Cleaner Production options were then modelled. The feasibility of the options were also analysed, and life cycle analysis of casted products was carried out. The researchers concluded that raw materials, water, and energy were to be saved if foundry companies implemented Cleaner Production options.
Comparison of Vermicompost and Vermiwash Bio-fertilizers from Vermicomposting Waste Corn Pulp
(World Academy of Science, Engineering and Technology, 2013-07-07) Phiri, A; Muredzi, P; Manyuchi, M.M; Chitambwe, T
—Vermicomposting is the conversion of organic waste into bio-fertilizers through the action of earthworm. This technology is widely used for organic solid waste management. Waste corn pulp blended with cow dung manure was vermicomposted over 30 days using Eisenia fetida earthworms species. pH, temperature, moisture content, and electrical conductivity were daily monitored. The feedstock, vermicompost and vermiwash were analyzed for nutrient composition. The average temperature and moisture content in the vermi-reactor was 22.5◦C and 42.5% respectively. The vermicompost and vermiwash had an almost neutral pH whilst the electrical conductivity was 21% higher in the vermicompost. The nitrogen and potassium content was 57% and 79.6% richer in the vermicompost respectively compared to the vermiwash. However, the vermiwash was 84% richer in phosphorous as compared to vermicompost. Furthermore, the vermiwash was 89.1% and 97.6% richer in Ca and Mg respectively and was 97.8% richer in Na salts compared to the vermicompost. The vermiwash also indicated a significantly higher amount of micronutrients. Both bio-fertilizers were rich in nutrients specification for fertilizers.
Continuous flow-through vermireactor for medium scale vermicomposting
(Asian Journal of Engineering and Technology, 2013-04-01) Manyuchi, Musaida Mercy; Chitambwe, Trymore; Chigumo, Michelle T. C.; Phiri, Anthony; Muredzi, Perkins; Kanhukamwe, Quinton
Vermicomposting is increasingly becoming popular as an organic waste management technology whereby earthworms feed on the organic waste to produce vermicasts and vermiwash. Several vermireactors have been used for this process as batch systems. However, there is need to design a continuous flow-through vermireactor which allows the simultaneous addition of the organic waste at the same time harvesting the vermicasts. A 5m X 2m X 1.5m vermireactor was proposed to process an initial feed of 7 500kg. A 10cm thick bedding comprising of office paper, card board paper and Eisenia fetida earthworms stocked at 1kg/m2 of the vermireactor was used as an initial bedding. The feed bed was 20cm thick and comprised of paper, cow dung, corn pulp and vegetables. The pH, temperature and moisture content in the vermireactor ranged between 5.5-7.5, 19-25°C and 28-52% respectively. 7kg/day of vermicasts were produced given the earthworms produced 75% of their bodyweight as vermicasts per day. The caked vermicasts were expelled by the aid of a breaker bar. The vermireactor was constructed from polyvinyl chloride. Vermicasts containing nitrogen (4.19%), phosphorous(1.15%) and potassium (6.18%) were obtained. The continuous flow-through vermireactor design allowed the production of stable vermicasts and can be used in medium scale vermicomposting.
Design of a material handling system that feeds bagged powder into polyvinyl acetate paint disperser as a Cleaner Production option
(International Journal of Scientific & Engineering Research, 2012-12-05) Winnie, Mutenhabundo,; Ngoni, Chirinda,; Tauyanashe, Chikuku
This project is about designing a material handling system that feeds bagged powder into the disperser as a Cleaner Production, (CP) option. Initially, waste streams were identified; the levels of dust emissions were assessed as well as their impacts to humans and environment. The researchers set their objectives seeking to reduce these negative effects. Attempts were made to recognize potential sources of airborne dust using Cleaner Production Assessment and assess the dust load upon workers in several process stages by comparing observations with standard values assigned by American Conference of Governmental Industrial Hygiene, (ACGIH). Loading pigment material generates dust which can cause serious health problems as reported in Material Safety Data Sheets. The new technology option of CP in form of a design led to a reduction in dust emissions thus reducing potential health hazards and also a reduction in material consumption. The researchers therefore recommend this design to enable Cleaner Production.
Design of a pyrolysis reactor for biochar production for ‘motocharcoal’ briquettes
(5 th Anniversary of ANSOLE (2011-2016): International Conference on Renewable Energy, 2016-02-03) Kanyenga, P.; Manyuchi, M.M
Zimbabwe is an agro-based country and as a result produces a lot of agro-waste ca. 70 000 tons per year. This waste occurs primarily in the form of waste cornstover, bagasse and sawdust which are currently not being utilized. There is potential for conversion of this agriculture waste to charcoal briquettes using the slow pyrolysis technology which increases the waste materials’ heating value. This paper presents a design for a pyrolysis reactor that can be used for conversion of agricultural waste to biochar which can then be used to make, Motocharcoal which is a trade name for the densified charcoal briquettes that are currently being made in Zimbabwe. It is an eco-fuel that can be used for heating and cooking purposes with a heating value of 22.5 MJ/kg. The pyrolysis reactor design was carried out based on an operating capacity of 12 tons/hr for an 8 hour working period based on the availability of the raw material which was mainly cornstover with a density of 200 kg/m3 . Pyrolysis took place under anaerobic conditions to enhance carbonisation. This was done at a temperature of 300 °C and a retention time of 3 hours to increase the calorific value of the biochar before briquetting. A conversion rate of 70% from agro-waste to biochar was achieved. The pyrolysis reactor will be constructed using stainless steel. Temperature and pressure were identified as the critical process parameters that must be controlled as these affect the quality of the biochar which in turn affects the briquettes quality. The pyrolysis reactor volume was 15.3 m3 with atmospheric pressure as the working pressure and a design pressure of 14.9 MPa. Fiberglass will be used as the insulation material to minimise heat losses and water used as the cooling agent. The designed pyrolysis reactor will ensure optimal conversion of the agro-waste to biochar for high quality briquettes
Design of a waste management model using integrated solid waste management: A case of Bulawayo City Council
(International Journal of Water Resources and Environmental Engineering, 2013-01-21) Mwanza, Bupe; Phiri, Anthony
The purpose of this research paper was to design a waste management model for Bulawayo City Council (BCC) based on integrated solid waste management system. The increasing solid waste generation in the city of Bulawayo is evidenced by increased number of illegal dumping of waste in the urban communities. In this paper, a model that identifies cost-effective and efficient combinations of scientific and engineering tools to manage solid waste and also incorporating the key performance indicators (KPIs) or metrics for solid waste management services has been designed. Literature on different types of waste management models, quantitative analysis of waste at Ross camp, direct observations made in the city locations and policy documents of the Zimbabwean Government (EMA acts), founded the development of this model. The design shows a clear depiction of the environmental management acts (EMA) and the municipality by-laws. Performance measurement which is very critical in waste management has been incorporated. Model design focus was on waste type which is a determinant of the waste receptacles, collection, transportation and disposal methods have therefore been depicted in the model. The model provides easy access to data for the formation and implementation of effective solid waste management policies, strategies and programs to achieve sustainable waste management.
Distillery Effluent Treatment Using Membrane Bioreactor Technology Utilising Pseudomonas Fluorescens
(International Journal of Scientific Engineering and Technology, 2013-12-01) Manyuchi, M.M; Ketiwa, E
Distilleries produce vast amounts of contaminated effluents which if disposed to the water bodies will pose environmental problems hence need to treat this effluent. A membrane bioreactor with Pseudomonas fluorescens as a decolorizing micro-organism was employed for treatment of distillery effluent over 10 days. The effluent pH changed from being acidic (4.2-5.0) to neutral (7.3-8.0). The effluent BOD, COD, TDS and TSS was significantly reduced by more than 90%. The membrane bioreactor sufficiently improved the effluent water quality parameters due to the degradation of the organics and removal of the suspended matter through microfiltration. Membrane bioreactor technology can be used for treatment of distillery effluents.
Effect of Drying on Vermicompost Macronutrient Composition
(International Journal of Inventive Engineering and Sciences (IJIES), 2013-09-05) Manyuchi, M.M; Phiri, A; Muredzi, Perkins; Chirinda, N
Vermicomposting is widely being used for bio-conversion of organic wastes into bio-fertilizers. Vermicompost which was obtained from various food wastes was dried at 105◦C for 5 minutes in a moisture analyzer. The dried vermicompost macronutrient composition was analyzed and quantified over the raw vermicompost. The dried vermicompost total nitrogen content was 31.25% lower as compared to the raw vermicompost whereas , the phosphorous and potassium content were 63.75% and 72.86% higher in the dried vermicompost compared to the raw vermicompost respectively. Vermicompost can be dried for easier packaging, storage and transportation as the drying process in overall enhances nutritional value to the vermicompost
Effect of Vermicompost, Vermiwash and Application Time on Soil Micronutrients Composition
(International Journal of Engineering and Advanced Technology (IJEAT), 2013-06-03) Manyuchi, Musaida Mercy; Phiri, Anthony; Muredzi, Perkins
Vermicomposting is increasingly becoming popular as an organic solid waste management strategy. The technology results in two bio-fertilizers, vermicompost and vermiwash. The bio-fertilizers were applied to the soil and their impact on the soil micronutrients time was quantified. A maximum of 1000g of vermicompost and vermiwash was applied over 40 days. 23 factorial designs were used to determine the effects of the bio-fertilizers and application time on the soil micronutrients. Increasing the vermicompost quantity resulted in increased soil zinc, manganese and iron content. Increased vermiwash quantities resulted in increased soil iron content but resulted in decreased copper content. Furthermore, increased application time of the two bio-fertilizers resulted in enhanced soil copper and iron content but decreased the zinc and manganese content. The loam-clay soil, organic material from the bio-fertilizers and microbial activity played a significant role in altering the soil micronutrients.
Effect of Vermicompost, Vermiwash and Application Time on Soil Physicochemical Properties
(International Journal of Chemical and Environmental Engineering, 2013-08-01) Manyuchi, Musaida Mercy; Chitambwe, Trymore; Phiri, Anthony; Muredzi, Perkins; Kanhukamwe, Quinton
Vermicomposting results in the production of two bio-fertilizers, vermicompost and vermiwash. The bio-fertilizers were applied to 4kg of loam-clay soil over a period of 40 days. The effect of the vermicompost, vermiwash, application time and their combined effect on soil pH, electrical conductivity and nitrogen, phosphorous and potassium content were analyzed. Increasing the vermicompost quantity decreased the soil pH, electrical conductivity and nitrogen content, however, this resulted in a slight increase in the phosphorous content but the potassium content remained unaltered. Increasing the vermiwash quantity increased the soil pH, electrical conductivity and potassium content but resulted in reduced nitrogen and phosphorous content. In addition, increasing the application period of either the vermicompost or the vermiwash resulted in increased soil pH, electrical conductivity, phosphorous and potassium content but resulted in reduced phosphorous content. The reduction of the soil nitrogen content is attributed to de-nitrification, whilst the increase in phosphorous content is attributed to increase in soluble phosphates and release of nutrients into the soil due to microbial activity in the bio-fertilizers. Furthermore, loam-clay soils have good absorbing properties for potassium. The soil properties and micro-organisms present in the bio-fertilizers play a critical role on the modification of the soil physicochemical properties
Effect of vermicomposting period, substrate quantity, cow dung composition and their interactions on Eisenia Fetidaduring vermicomposting
(International Journal of Current Microbiology and Applied Sciences, 2014-08-01) Manyuchi, m; Whingiri, E
Vermi-technologyisincreasinglybecomingpopularinvariousapplications.Theworkfocusedonthefactorsthataffecttheearthwormgrowthrateintermsofchangesinlengthandmassduringvermicomposting.Thestudylookedat3parameterswhichincludedvermicompostingperiod(days),cowdungcomposition(%(v/v))andsubstratequantity(kg).ThestudywascarriedoutatHarareInstituteofTechnologyforaperiodof50daysbetweenAprilandMay2014.Eiseniafetidawereusedasearthwormsandthesubstratecomprisedoffoodwasteandcowdungofvaryingcompositions.Vermicompostingperiodsof30-50days,substratequantitiesof2.5-5kgandcowdungcompositionof20-40%(v/v)wereemployed80.59mX031mwormbins.Aloadingrateof150worms/m2wasusedforearthwormswithanaveragelengthof50mmandmassof1g.23factorialdesignswereusedtodeterminetheoptimumconditionsrequiredforincreaseinearthworm lengthandmass.STATISTICA,astatisticalsoftwarewasusedtodeterminethesignificanteffectsat75%confidenceinterval.Paretochartsandcontourplotswereusedtoquantifytheresultsatap-valueof0.25.Increasingthevermicompostingperiod,thesubstratequantityandthecowdungcompositionincreasedtheearthwormslengthandmassbyafactorofmorethan3.Atthesametime,increasingthecowdungcompositionandtheinteractionbetweenincreaseinvermicompostingperiodandincreaseinsubstratequantityalsoresultedinincreasedearthwormmassbyafactorof2.8.Earthwormsgrowthinvermicompostingispromotedbyincreaseinvermicompostingperiod,substratequantity and substrate composition
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, Anthony
Vermicomposting 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.
Effects of Calcination Temperature on properties of Mg-Al mixed oxide nanoparticle.
(Materials Today: Proceedings 2, 2015-01-01) Govhaa, Joseph; Narasaiaha, T. Bala; Chakrab, Ch.Shilpa; Kumar, Pramod
The limited size and high density of surface sites that characterize nanoparticles result in unique chemical and physical properties. Magnesium aluminum mixed oxide was synthesized by co-precipitation method using Al2 (SO4)3.16H2O and MgSO4.7H2O precursors in 1:1 molar ratio. The calcination temperature was varied from 250, 300 and 700o C. Nanoparticles synthesized were characterized using X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and TGA-DTA. At low temperature synthesized spherical particles are amorphous and they start to transform into spinel crystalline structure around 650o C. Generally particle size increased with increase in temperature.