Drying characteristics of cassava slices was investigated in a mixed mode natural convection solar dryer to obtain a suitable mathematical model describing the drying. The average drying chamber temperature was between 34 ±2 °C and 50 ±1.8 °C, while 10 commonly used thin layer drying models were used for drying curve modelling. Coefficient of determination (R2) and root mean square error (RMSE) were used to determine the models performances. The drying curve of cassava slices showed a reduction of moisture content with increased drying time in the solar dryer, and the variation of moisture ratio exponentially decreased with increased drying time. The Midilli and Logarithmic models showed better fit to the experimental drying data of cassava slices. As compared with other models tested, there were no significant differences (p >0.05) in the R2 values obtained for the Midilli and Logarithmic models; hence, the Logarithmic model was preferable because of the lower RMSE. The diffusion mechanism could be used to describe the drying of cassava slices that was found to be in the falling rate period. A diffusion coefficient (Deff) of 1.22 × 10-8 m2 s-1 was obtained, which was within the established standard for food products.

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Large quantities of agricultural residues produced in Nigeria can provide an alternative way in meeting her energy demand through briquetting. Biomass briquetting is the process of compacting raw biomass materials (wood, charcoal, crop residues, and animal waste) into standard mini-brick units as solid fuel for improved handling and efficiency. A small scale, 40 bar hydraulic operated piston briquetting machine with a capacity of 120 briquettes per hour was developed. The machine comprised of hydraulic, control, press, power, ejection and frame sections, and adopted the binder-less technology. Sawdust and rice husk were used as sample biomass materials. The compressed biomass obtained from the developed machine in form of briquettes had mean diameter and height of 30 mm ±0.02 and 16 mm ±0.01 respectively. The force, deflection, and Young Modulus at peak were 16.30 N, 3.29 mm and 548.11 N/mm2 for Sawdust Briquettes (SB) respectively, while 12.50 N, 1.49 mm; and 481 N/mm2 were obtained for Rice Husk Briquettes (RHB).  The yield stress for SB and RHB were 12 and 9 N/mm2. The heating values obtained for SB and RHB were 51.0 Kcal/g and 39.4 Kcal/g respectively. The output efficiency of the machine was 88% indicating a satisfactory performance of the machine.

The sole purpose of a compacted landfill liner is to contain and mitigate the impact of leachate on the environment. This research assessed the engineering properties of bentonite enhanced termite mound mixture to ascertain their suitability as an alternate landfill liner. The mixture of mound soil and bentonite was proportioned by percentage weight as (100:0), (95:5), (90:10) and (85:15) respectively. The compaction analysis reveals an optimum moisture content ranging from 13.80% to 18.52% and a maximum dry density that varied from 1.72 g/cm 3 to 1.88 g/cm 3. The hydraulic conductivity result of 15% bentonitemound soil mixture (0.23 x 10-9 m/s) established hydraulic conductivity less than 1 x 10-9 m/s, which satisfied the criteria for landfill liner. Hence, a mixture of 15% bentonite enhanced mound soil is found suitable as an alternate bottom liner.

This study is an investigation into the characterization of commercial activated charcoal, sawdust charcoal and rice husk charcoal as adsorbents for water treatment. The ground rice husk and waste sawdust collected, were sieved to obtain a nominal size of 1mm, washed and oven-dried for 12hours. The two materials were pyrolysized in a furnace for 30minutes, and the chars produced were later air-dried. The three charcoals (sawdust charcoal, rice husk charcoal, and the activated charcoal purchased from the market) were all subjected to X-ray Fluorescence (XRF) analysis, Scanning Electron Microscope (SEM) analysis and Energy Dispersive X-ray (EDX) analysis in order to characterize the filter materials. The SEM analysis showed that the three materials developed more pores, which is a property of an adsorbent. Likewise, the XRF and EDX analyses confirm that all the three adsorbents possess larger proportion of Silica, Carbon and Oxygen.