Agricultural and Environmental Engineering

CALCINATION AND SYNERGISTIC RATIO OPTIMISATION IN THE PRODUCTION OF HYBRID AGRICULTURAL POZZOLANS FROM AGRICULTURAL WASTES FOR THE CONSTRUCTION INDUSTRY

2023-06-01T00:00:00Z

CALCINATION AND SYNERGISTIC RATIO OPTIMISATION IN THE PRODUCTION OF HYBRID AGRICULTURAL POZZOLANS FROM AGRICULTURAL WASTES FOR THE CONSTRUCTION INDUSTRY MAC-ETELI, Happiness Davies Cement is an important material in the construction industry. However, the environmental problems associated with the mining and calcination of limestone for cement production necessitates the search for supplementary cementitious materials with minimal threat to the environment. Periwinkle and clam shells, processed into ash are potential substitutes for cement in concrete. This study was designed to investigate the suitability of Periwinkle Shell Ash (PSA) and Clam Shell Ash (CSA) and a hybrid of both as partial replacements for cement in concrete. Shells were sourced from Amassoma, Bayelsa State, Nigeria, washed, sun dried and calcined at varying temperatures (200, 400, 600 and 800 oC). These were pulverised to pass through 75 µm sieve to produce PSA, CSA, and hybrids of both, mixed at 70:30, 60:40, 50:50, 40:60 and 30:70. Grade M20 concrete specimens were produced at varying Portland limestone cement (PLC) replacement levels (0, 20, 30, 40 and 50%) with 0% as control, and cured for 28 days prior to testing. Specific gravity, flexural strength, compressive strength, Water Absorption Index (WAI), Chloride Induced Strength Loss Index (CISLI), and Sulphate Induced Strength Loss Index (SISLI), were conducted in accordance with British Standards. Combined mixture methodology was used to develop regression models from laboratory data, analysed and optimised at 95% confidence interval to ascertain Optimum Pozzolanic Reactivity (OPR) based on Strength Activity Index (SAI). Emissions of CO2 associated with calcination of samples were analysed and compared to that of PLC using data from energy demand and carbon footprint. Specific gravities were 3.12±0.24, 2.96±0.01, 3.00±0.10, 3.14±0.03, while flexural and compressive strengths were 5.29±0.14, 2.83±0.10, 2.83±0.08, 3.36±0.21 and 27.74±1.41, 18.27±1.10, 19.21±0.25, 21.67±2.29 N/mm2 for PLC, PSA, CSA and 60% PSA:40% CSA, respectively, at 40% cement replacement level, produced at 600 oC. Compressive strengths of 60% PSA:40% CSA, were 78.1% of PLC, 118.6% of PSA and 112.8% of CSA; implying that the hybrid was stronger than PSA or CSA. Also, WAI, CISLI, and SISLI, were 1.98±0.19, 2.84±0.08, 3.25±0.17, 2.75±0.13; 24.56±2.15, 19.34±0.37, 0.44±0.08, 6.10±0.84; and 16.47±1.43, -10.97±1.32, - 16.88±0.68, 4.09±0.62 for PLC, PSA, CSA and 60% PSA:40% CSA. The PLC had the least WAI but diminished more in strength due to chemical attacks and absence of pozzolans compared to PSA and CSA. The OPR based on SAI was 55.5% PSA:44.5% CSA, and cement replacement levels were 19.7, 23.2, and 44.0%, for PSA, CSA and 55.5% PSA:44.5% CSA, respectively, produced at 425, 527, and 607 oC. A uniform compressive strength of 20.8 N/mm2 was obtained for PSA, CSA and 55.5% PSA:44.5% CSA, produced at 425, 527, and 607 oC, respectively, satisfying the SAI criteria. Optimised WAI, CISLI, and SISLI of PSA, CSA and 55.5% PSA:44.5% CSA were 2.46, 2.52, 2.51; 2.10, 3.06, 12.72; and -33.16, -31.48, -0.08%, when produced at 425, 527, and 607 oC. A kilogram of pozzolan emitted 350g of CO2 at calcination, while that of PLC was 490g; providing a 28.60% savings in CO2 emissions. Periwinkle and clam shells enhanced cement replaceability and satisfied the strength activity index pozzolanic criteria, when synergised and ashed optimally. Consequently, environmental pollution associated with excessive limestone harvest and processing was mitigated.

DEVELOPMENT AND OPTIMISATION OF AN INTEGRATED SEMI-AUTOMATED GRADING MACHINE FOR COWPEA (Vigna unguiculata (L.) WALP) SEEDS

2023-01-01T00:00:00Z

DEVELOPMENT AND OPTIMISATION OF AN INTEGRATED SEMI-AUTOMATED GRADING MACHINE FOR COWPEA (Vigna unguiculata (L.) WALP) SEEDS AUDU, John Nigeria is the largest producer of cowpea. Despite this relatively large production, its export has been hindered by poor seed grading and inefficient processing. Existing cowpea grading machines are mostly for unit operations. Integrated grading machine are needed for improved seed grading and efficient processing. Therefore, this study was designed to develop an integrated semi-automated cowpea grading machine. Standard methods were used to determine the optical and electrical parameters of three indigenous cowpea seed varieties (NG/AD/11/08/0033, NG/OA/11/08/063 and NGB/OG/0055) for the automation unit design considerations. This was carried out at seed moisture levels (8.0, 10.0, 12.0, 14.0 and 16.0%), light wavelength (320, 420, 520, 620 and 720 nm) and current frequency (1, 500, 1000, 1500, 2000 kHz). Thereafter, an integrated semi-automated machine with three separating units was developed and automated using machine vision technology. Operational parameters used for evaluation were speed of drum (40, 60 and 80) rpm, bucket conveyor speed (250, 300 and 350) rpm and metering disc (12, 16 and 20) rpm; seed variety and grade (9.8%, 16.0% and 21.0%) of impurity. The total machine system output was evaluated and optimised in terms of efficiency, throughput, maximum capacity, actual utilisation and backlog, using response surface methodology. Prediction interval and multiple regression analysis were used for validation at α 0.05. The optical properties ranged from: 0-1.8%, 0-1.0%, 0-12.0%, ([38-92.2%] [0.7-9.0%] [13.6-27.3%]) for absorbance, reflectance, transmittance and colour (L* a* b*), respectively; while electrical properties ranged from 1.926-15.625 Ω, 0.272-2.209 Ωm, 0.064–0.519 S, 0.453–3.671 S/m, 1.800x10-11–1.380x10-7 F, 0.500-4928.570, 6.020 x107- 9.040x1021 H) and 1.150x106–1.450x107 Ω, for resistance, resistivity, conductance, conductivity, inductance and impedance, respectively. The two separating units (sieve drums) removed impurities > 12 mm and < 2 mm with efficiency of 76.6±9.343% and 85.3±11.1%; throughput of 0.220±0.139kg/hr and 0.144±0.111kg/hr, respectively. The third digital automated sorting unit separated diseased and insect damaged seeds by colour with efficiency of 82.1±7.2% and throughput of 1.386± 0.758kg/hr. Operational parameters were found to have significant effect on all evaluation terms. The efficiency, throughput,vi maximum capacity, actual utilisation and backlog of the total system output ranged from 63.5-80.4%, 0.574–3.732 kg/hr, 6.882-44.778 kg/12hr, 0.083-0.083 (8.3%) and 0.03–0.182 kg, respectively. At 80.4% efficiency, the impurity of grade 3 was reduced to grade 2, and 2 to 1 based on the standard export grade range. The integrated machine system optimisation achieved two best solutions. The first and second having maximum total system impurity separating efficiency of 81.3 and 79.9%, maximum total system throughput of 3.470 and 5.077 kg/hr and minimal total system backlog of 0.064 and 0.07 kg, respectively. The validation data were within 95% low and high prediction intervals. The evaluation terms had coefficient of determinations (R2) values > 0.9 showing no significance between predicted and validation data. The developed integrated semi-automated grading machine for cowpea reduced the impurity in indigenous cowpea varieties to exportable grade.

MACHINE PARAMETERS FOR KENAF PELLET PRODUCTION FOR REMEDIATION OF CRUDE OIL POLLUTED WATER BODIES

2023-08-01T00:00:00Z

MACHINE PARAMETERS FOR KENAF PELLET PRODUCTION FOR REMEDIATION OF CRUDE OIL POLLUTED WATER BODIES KADIRI, Azeez Oluwaseun Remediation of crude petroleum polluted water for agricultural activities is a challenge. Kenaf has been found to have potentials for remediation and pelletising it will improve handling and recovery. Literature is sparse on the appropriate operating parameters for kenaf pelleting machine. This study was designed to investigate the effects of Screw Pitch (SP), Speed of Rotation (SR), and Die Diameter (DD), on kenaf pellets properties suitable for crude oil spill remediation. A pelleting machine was designed for kenaf using standard procedures. The machine was evaluated using response surface methodology. The variables were SP (40, 50, 60, 70 and 80 mm), SR (40, 50, 60, 70 and 80 rpm) and DD (27.5, 30.0, 32.5, 35.0 and 37.5 mm). Thirty experimental combinations were generated from the variables to get responses on machine efficiency (Pelleting Efficiency (PE) and Percentage Recovery (PR)), pellets’ mechanical properties (Force, Deflection, Energy, Young modulus and Durability Index, (DI)) and remediation potentials (oil recovered and changes in pH). At different combinations, the machine was used to pelletise samples of kenaf, starch and water (1:1- 2:3) mixture. Machine efficiency and mechanical properties were determined using ASABE and Universal Testing Machine. The oil recovered was determined by comparing oil contents before and after remediation using a spectrophotometer according to AOAC standards, while changes in pH were determined by comparing pH values before and after remediation. The process was simulated and optimised using artificial neural network and its accuracy determined using mean square error (MSE) and coefficient of determination (R2). Data were analysed using ANOVA at α0.05. The PE and PR ranged 82.3-95.8% and 68.4-88.3%, respectively. The PE and PR increased with increase in DD and SR. Forces at peak, yield and break ranged 84-280, 108-342 and 142-504 N, respectively. Deflection at peak and break were 2.01-5.48 and 3.89-10.24 mm, respectively. Minimal Energy to peak, yield and break were 4.93, 6.75 and 9.42 Nmm/s, respectively. The Young’s modulus and DI were 0.03 N/mm2 and 98.9 %, respectively. The SP, DD and SR significantly affected the mechanical properties. Oil recovery ranged between 97.6 % and 99.8 %, while changes in pH ranged 0.01-0.22, signifying the occurrence of remediation. Increase in SP and DD yielded an increment in oil removal and increased changes in pH, while a rise in SR led to a reduction in quantity of oil removed and an increase in the changes in pH. The MSE and R2 of the models varied between 0.0003 and 125545469.3; 0.2589 and 0.9978, respectively. The optimal operating conditions for the production of kenaf pellets for remediation were 54 mm SP, 68 rpm SR and 34 mm DD. Kenaf pellets were good absorbents for remediation of crude oil polluted water bodies. Optimal conditions for the production of durable kenaf pellets for the effective remediation of crude petroleum polluted water bodies were established. An efficient pelleting machine for the production of kenaf pellets was developed.

MOISTURE SORPTION AND SELECTED THERMODYNAMIC CHARACTERISTICS OF MORINGA (Moringa oleifera Lam.) SEED AND GRITS

2023-07-01T00:00:00Z

MOISTURE SORPTION AND SELECTED THERMODYNAMIC CHARACTERISTICS OF MORINGA (Moringa oleifera Lam.) SEED AND GRITS AKINTOLA, Akintunde Moringa seed is a raw material that needs long period of storage. This necessitates drying the seed so as to extend its shelf life. An important factor in ensuring stability of moringa seed and grits in storage is its water activity (aw). However, there is dearth of information on the sorption characteristics of moringa seed and grits. This study was therefore, designed to investigate the sorption and some thermodynamic characteristics of moringa seed and grits during storage. Moringa seeds and grits (particle size 106-212 μm) were kept in two packaging materials (Polypropylene [Pp] and Low-Density Poly-Ethylene [LDPE]) and stored at ambient condition for 12 days, and shelf life was predicted using Heiss-Eichner model. Sorption Isotherms (SI) of moringa seed and grits were obtained by determining the Equilibrium Moisture Content (EMC) at a temperature range of 20-40℃ and nine aw (0.09-0.92) levels using thermostatic water bath and concentrated H2SO4. The sorption data were fitted into six selected models namely: Brunauer-Emmett-Teller (BET), Guggenheim-Anderson-De Boer (GAB), Hailwood-Horrobin (HH), Modified Hasley (MH), Modified Henderson (MHM) and Modified Hailwood-Horrobin (MHH) models. The performance of the models was tested using Root Mean Square Error (RMSE), co-efficient of determination (R2) and Residual Sum of Squares (RSS). The effect of temperature on the monolayer moisture content (Mo) of the seed and grits was determined using BET, GAB and Caurie models. Clausius-Clapeyron equation was used to determine the isosteric heat (ΔH) and entropy of sorption (ΔS) of the seed and grits. Data were analysed using ANOVA at α0.05. The predicted shelf life in Pp and LDPE were 1,852 and 1,446 days; 994 and 748 days for seed and grits, respectively. The SI curves generated were sigmoidal in shape indicating Type-II isotherm. The GAB and MHM were the best-fitted models and predicted the EMC at all temperatures with highest R2 (0.9994, 0.9999) in adsorption and (0.9994, 0.9999) in desorption processes for seed and grits, respectively. The BET and HH models did not fit well at all temperatures with R2 (0.6957, 0.6869); (0.8439, 0.8149) for seed and grits, respectively, while MHH fitted well with R2 (0.9111) for grits at a temperature of 20℃ only. The GAB gave the least RMSE and RSS and it ranged 0.0775-0.2124 and 0.0060-0.0431, respectively. The Mo for the seed and grits ranged 2.9–5.9% db and 2.1–4.4% db, respectively. Hysteresis did not have significant effect on Mo for both seed and grits. The ΔH decreased as the EMC increased and it ranged 9.90-40.86 kJmol-1 for seed and 4.75-38.71 kJmol-1 for grits in adsorption; 10.85-45.09 kJmol-1 for seed and 4.82-41.66 kJmol-1 for grits in desorption. The ΔS ranged 0.03-0.124 kJmol-1K-1 for seed and 0.014-0.113 kJmol-1K-1 for grits in adsorption; 0.033-0.137 kJmol-1K-1 for seed and 0.015-0.124 kJmol-1K-1 for grits in desorption. The ΔH and ΔS increased exponentially as the EMC decreased. Sorption isotherm of moringa seed and grits demonstrated Type-II behaviour. Moringa seed and grits stored in polypropylene had longer shelf life and less interaction with the micro-environment during storage than Low Density Polyethylene.