Performance and emission characteristics of a diesel engine fuelled by biodiesel from black soldier fly larvae: Effects of synthesizing catalysts with citric acid.

Biodiesel has several environmental benefits, such as biodegradability, renewability and lower soot emissions. However, biodiesel has undesirable properties such as higher viscosity and density and low calorific value compared to petroleum diesel, resulting in high Brake Specific Fuel Consumption (BSFC), reduced Brake Power (BP) and increased NOX emissions creating an environmental concerns in biodiesel development. This study investigated the effects of synthesizing transesterification catalysts (CaO and NaOH) with Citric Acid (CA) on the quality of biodiesel and biodiesel blends produced from Black Soldier Fly Larvae (BSFL) (Hermetia Illucens). The quality of biodiesel and blends was determined based on fuel properties, engine performance and emission composition characteristics. The tests were performed on a single-cylinder, four-stroke, Compression Ignition (CI) diesel engine at five loads at a constant speed of 1500 rpm. The results showed that synthesizing the catalysts with CA significantly affected the fatty acid profile of the biodiesel compared to physical fuel properties. B100 (pure BSFL biodiesel) exhibited higher BSFC by 10.57-13.97 % and lower BP by 4.21-7.83 % than diesel fuel. However, the Brake Thermal Efficiency (BTE) of biodiesel was higher than that of diesel fuel by 0.82-4.34 % at maximum load. Synthesizing catalysts with CA improved the viscosity of biodiesel by 0.93-2.81 % and effectively reduced NOX, HC and Smoke opacity by 2.23-3.16 %, 4.95-5.83 % and 20.51-41.15 %, respectively.

Heating and emission characteristics from combustion of charcoal and co-combustion of charcoal with faecal char-sawdust char briquettes in a ceramic cook stove.

Over reliance on charcoal has accelerated deforestation in sub-Saharan Africa. Seeking alternative sustainable and environmentally friendly sources of biomass energy to meet the escalating energy demand is therefore vital. However, limited evidence exists on the concentrations of toxic emissions of different biomass fuels. Herein, dried human faeces and sawdust were pyrolyzed at 350 °C to produce biochar and mixed in equal ratio to produce briquettes through densification, with molasses (10 wt.%) used as a binder. A comparative study on the heating properties and emission level of carbon monoxide (CO), nitric oxide (NO), and hydrogen sulphide (H2S) during combustion of charcoal, and co-combustion (50:50 wt. %) of charcoal with briquettes was conducted. The thermal profile of the flue gases indicated rapid combustion of volatile gases followed by slow oxidation of the char. Co-combustion significantly (P < 0.05) enhanced the amount of heat energy released with flue gases temperatures reaching a peak of 475 °C. The briquettes had a gross calorific value of 19.8 MJ/kg which was lower than 25.7 MJ/kg for charcoal. Combustion of charcoal did not emit NO, however the concentration of CO was above the critical short term limits of 35 ppm. The concentration of CO and H2S was above the short term exposure limits of 35 ppm, and 0.005 ppm, respectively, during co-combustion, whereas NO concentration was below dangerous exposure levels of 100 ppm. These results suggest that co-combustion of charcoal with the briquettes is a promising approach to generate safe and sufficient heat energy for cooking and reduce deforestation.

Evaluation of water quality and potential scaling of corrosion in the water supply using water quality and stability indices: A case study of Juja water distribution network, Kenya.

Drinking water quality describes the conditions for water to be accepted as suitable for human consumption. The water quality index is characterized by including, in the assessment process, water quality parameters such as physical, chemical and micro-biological. The availability of adequate management strategies to maintain good quality water has always been a challenge for water utilities. To proffer a solution to ths problem, a simple and effective tool that can be used to easily assess the quality of water is required. Water Quality Index (WQI) and Water Stability Index (WSI) are the most reliable tools for assessing water quality and aggressiveness. This study, therefore assessed the water quality, potential scaling and corrosion of the water supply in the Juja water distribution network by using WQI and WSI based on Langelier Saturation Index (LSI). Five sampling locations including the treatment plant outlet and consumption points were selected for physical, chemical and bacteriological water quality analysis and determination of WQI and WSI. It was found that 100 % of the collected water samples had Calcium concentrations within the World Health Organization (WHO) and Kenya Bureau of Standards (KEBS) acceptable ranges. Additionally, all the collected water samples had TDS concentrations within the WHO and KEBS acceptable ranges. However, water quality parameters such as Residual Chlorine, E. coli, Alkalinity, and Turbidity deviated from the WHO and KEBS standards. The pH values ranged from 6.29 to 8.06 and were generally within acceptable limits. The WSI ranged between - 3.04 to - 0.99, indicating that the water is generally corrosive and may pose a risk to water quality and shorten the lifespan of the network facilities. Generally, the water from the Treatment Plant was of good quality, while at consumption points, JKUAT Main Gate, JKUAT Campus, High Point, and Juja Stage had fair water quality based on the calculated WQI. Also, low concentrations of residual chlorine and E. coli slightly dropped the water quality at all the stations. Overall, the water quality deteriorated in the distribution network and was corrosive throughout the system right from the Treatment Plant based on the WQI and WSI. The water company needs to improve on the water quality chemically by adjusting the Calcium and Alkalinity concentration up to 40 mg/L CaCO3 as recommended for stable water and relook at management strategies of the network to provide better services to consumers.

Pineapple peel biochar and lateritic soil as adsorbents for recovery of ammonium nitrogen from human urine.

Human urine is a rich source of nitrogen which can be captured to supplement the existing sources of nitrogen fertilizers thus contributing to enhanced crop production. However, urine is the major contributor of macronutrients in municipal wastewater flows resulting into eutrophication of the receiving water bodies. Herein, pineapple peel biochar (PPB), and lateritic soil (LS) adsorbents were prepared for the safe removal of ammonium nitrogen (NH4+-N) from human urine solutions. Physicochemical properties of PPB, and LS were characterized by scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS), X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA) to investigate the relationship of their properties with NH4+-N adsorption. Langmuir, Freundlich, and Dubinin-Radushkevich (D-R) isotherm models were employed to correlate the experimental equilibrium adsorption data. The effect of contact time and initial concentration of NH4+-N adsorption was also evaluated. The D-R isotherm model best described the behaviour of NH4+-N adsorption on both PPB and LS based on the coefficient of correlation values. This model showed that the adsorption of NH4+-N on both samples was a physical process with PPB and LS having mean surface adsorption energies of 1.826 × 10-2, and 1.622 × 10-2 kJ/mol, respectively. The PPB exhibited a slightly higher adsorption capacity for NH4+-N (13.40 mg/g) than LS (10.73 mg/g) with the difference attributed to its higher surface area and porosity. These values are good indicators for assessing the effectiveness of the materials for adsorption of NH4+-N from human urine.

Occurrence, distribution, and risk assessment of pharmerciuticals in wastewater and open surface drains of peri-urban areas: Case study of Juja town, Kenya.

The occurrence of Active Pharmaceutical Ingredients (APIs) in the environment is becoming a major area of concern due to their undesirable effects on non-target organisms. This study investigated the occurrence and risk of contamination by five antibiotics and three antiretrovirals drugs in a fast-growing peri-urban area in Kenya, with inadequate sewer system coverage. Due to poor sewage connectivity and poorly designed decentralized systems, wastewater is directly released in open drains. Water and sediment samples were collected from open surface water drains, while wastewater samples were collected from centralized wastewater treatment plants (WWTP). Solid-phase extraction and ultrasonic-assisted extraction for the aqueous and sediment samples respectively were carried out and extracts analyzed by liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) using isotopically labeled internal standards. APIs were observed with the detection frequency ranging from 36% to 100%. High mean concentrations of 48.7 µg L-1, 108 µg L-1, and 532 µg L-1 were observed in surface drains for Lamivudine (3 TC), Sulfamethoxazole (SMX), Ciprofloxacin (CIP) respectively. Drain sediments also showed high concentrations of APIs ranging from 2.1 to 13,100 µg kg-1. APIs in this study exceeded those observed in existing literature studies. JKUAT WWTP removal efficiencies varied from -90.68% to 72.67%. Total APIs emission load of the study area was 3550 mg d-1 with WWTP effluent contributing higher loads (2620 mg d-1) than surface water drains (640 mg d-1). Zidovudine (ZDV), nevirapine (NVP), and trimethoprim (TMP) loads in drains, however, exceeded WWTP effluent. Low to high ecotoxicity risk of the individual APIs were observed to the aquatic environment, with high risks for the development of antibiotic resistance in microbiome as determined by the risk quotient (RQ) approach. Risk management through efficient wastewater collection, conveyance, and treatment is necessary to suppress the measured concentrations.