The attention that high solids anaerobic digestion process (HS-AD) has received over the years, as a waste management and energy recovery process when compared to low solids anaerobic digestion process, can be attributed to its associated benefits including water conservation and smaller digester foot print. However, high solid content of the feedstock involved in the digestion process poses a barrier to the process stability and performance if it is not well managed. In this review, various limitations to effective performance of the HS-AD process, as well as, the possible measures highlighted in various research studies were garnered to serve as a guide for effective industrial application of this technology. A proposed design concept for overcoming substrate and product inhibition thereby improving methane yield and process stability was recommended for optimum performance of the HS-AD process.

The potential presence of toxic compounds in the digestate obtained from the anaerobic digestion of biodegradable waste restricts its application as a biofertilizer for soil conditioning and plant growth enhancement. The aim of this study was to assess digestate quality in terms of plant nutrient composition by evaluating the effects of activated carbon supplementation, inoculum source, and total solids content in the anaerobic digestion medium. The anaerobic digestion of food waste was conducted over a 60-day period at 25 °C in a 2.5 L bioreactor. The results demonstrated that inoculum diversity significantly impacted the digestate composition, particularly the zinc nutrient, with a p-value of 0.0054. This suggests that microbial diversity influences the valorization of organic waste into biofertilizer. However, the effects of inoculum diversity on other nutrients, aside from zinc, were not significant due to substantial interaction effects. Furthermore, assessing the impact of activated carbon supplementation proved challenging, as it was analyzed as part of a subset of the other two factors. The results of the digestate composition analysis indicated that activated carbon supplementation exhibited some influence on nutrient composition, necessitating further research to elucidate its significance. The findings of this study may contribute to enhancing the quality of digestate as a biofertilizer.

The aftermath of man’s continuous depletion of the planet’s natural resource, as well as his inappropriate waste disposal, has manifested over time into severe weather and environmental conditions, which could snowball into an epic catastrophe, if not checked. Therefore, the aim of this study is to develop a viable gas-fired pyrolysis process for extracting bitumen from waste rubber tyres. The pyrolysis system was composed of gas-fired furnace, heavy oil condenser, two cyclones for light oil condensation, scrubber for gas cleaning, and gas storage bag. The extracted bitumen was obtained from the pyrolysis of 9 kg of shredded waste rubber tyres. The bitumen was tested for its asphalt-making potential to verify its suitability as a replacement for the petroleum bitumen commonly used in making asphalt. The performance tests on the asphalt concrete indicated values of 3150 N, 2.6 mm, 3.1%, and 77.4% for Marshall stability, flow value, percent air void in the mixture, and voids filled with bitumen, respectively. When compared with the standard specification of the Nigerian asphalt concrete, all the three properties, except Marshall stability, passed the requirement. In general, results from the study indicated that on further quality improvement, waste tyre bitumen could be used as a substitute to petroleum bitumen.

Tomatoes are preserved to extend their shelf life and prevent wastage due to their high-water content and perishable nature. Using plant extracts as preservatives offers several benefits, such as keeping tomatoes free from chemicals and their associated long-term health risks, while enhancing tomato antioxidant and antimicrobial properties, but maintaining tomatoes nutrients, and having minimal effects on tomatoes overall quality. This study examined the potential of ginger and bitter kola extracts as natural preservatives for tomatoes. Ripe tomatoes were soaked in hot water extracts of ginger, bitter kola, and a combination of both, referred to as GE, BKE, and GBE, respectively. The tomatoes were monitored daily for signs of decay and weight loss while glucose, fructose, potassium, total solids, citric acid, and ascorbic acid levels were measured on days 6, 18, and 29 for the 30-day period of the experiment. Between days 0 and 6, all samples showed weight loss, colour changes, and loss of firmness. From days 6 to 29, glucose remained relatively stable in GE (7.5–7.57 mg/100g) and BKE (7.5–8.21 mg/100g), but it decreased in GBE (9.4–6.54 mg/100g). Ascorbic acid levels remained fairly stable in BKE (28.52–27.04 mg/100g), but decreased significantly in GE (32.45–15.24 mg/100g) and GBE (43.76–17.05 mg/100g). Fructose loss was most pronounced in GE (3.4–2.43 mg/100g), followed by GBE (3.95–3.63 mg/100g) and BKE (3.35–2.9 mg/100g). The results indicated that bitter kola showed potential for preserving tomato quality though there were challenges related to nutrient loss and microbial resistance.

The need to find alternative water disinfectants without negative consequential health effects is imperative in view of the link that had been established between human consumption of chlorinated water and diseases such as cancer. Therefore, this study was set out to evaluate and compare the water disinfection potential of aloe vera and sodium hypochlorite (NaOCl) in order to determine the suitability of using aloe vera as sodium hypochlorite substitute. The coliform count of the faecal thermo-tolerant coliform (non-Ecoli) isolated from well water sample was 49 cfu/100ml. Disinfectant efficacies of the NaOCl and Aloe Vera, stored under various conditions, were evaluated and compared using disc diffusion method to determine disinfection susceptibility of the isolated coliform. The two disinfectants showed increase in level of zone of inhibition of the isolated coliforms with increase in disinfectants storage concentration and sun exposure period. As a disinfectant, aloe vera seemed to be more stable when compared with NaOCl at the storage temperatures of 0, 25 and 35oC. The p-values for using aloe vera and NaOCl as disinfectants under various conditions of concentration, temperature and sun exposure period ranged between 0.247 and 1.000 indicating non-significant difference when aloe vera was used as sodium hypochlorite substitute.

Design defects in a reactor often results in poor reactor performance. This study examined the effects of variations in burner holes and air to fuel ratio on thermal efficiency and emission characteristics of three locally fabricated gas cooking stoves with 48, 96 and 144 burner holes. The purpose of the study was to use the stove design with optimal efficiency and lowest emissions, as a model for improving the design of a gas-fired pyrolysis reactor that had air-fuel intake port defect with consequent incomplete combustion. The results of the study showed that stove with 96 burner holes produced the lowest emissions of 89.672 mg/m3 while stove with 144 burner holes was found to be the most fuel efficient with efficiency of 69.0. The results imply that a trade-off exists in the design of the burners to achieve either the most environmentally-friendly or most fuel-efficient burner. However, a compromise of the two objectives of maximizing fuel efficiency and minimizing emissions was reached by choosing as a model, the burner having 96 holes with thermal efficiency of 64.3% and emissions of 89.672 mg/m3 over burner having 144 holes with thermal efficiency of 69.0% and emissions of 258.974 mg/m3 . Keywords: Air flow, , Burner Holes, Combustion, Emissions, Improved design, Thermal ef