Search

This paper characterizes the sugarcane bagasse ash as a pozzolan and investigates its influence on the hardened properties of concrete. In Pakistan, the sugar industry recycles raw bagasse for power generation, and as a result, tonnes of bagasse ash are produced every year. For this study, the bagasse ash sample was obtained from one of the local sugar mills of Pakistan. The physical, chemical and mineralogical of bagasse ash were investigated by employing X-ray diffraction (XRD), X-ray fluorescence and laser particle size techniques, while the microstructure was studied through scanning electron microscope. In addition, the evaluation of hardened properties like compressive strength, tensile strength, flexural strength and thermal conductivity was also carried out. Here, the concrete mixtures were prepared by replacing the cement with bagasse ash in the ratio of 5 to 30% (by weight). The chemical, physical and mineral results reveal that this local bagasse ash has all pozzolanic properties. The evidence of amorphous and crystalline phases was found in the XRD pattern, along with silicon dioxide (SiO2) which was recorded more than 70% in the ash. It was observed that the workability for bagasse ash-blended concrete mixtures increases with ash content. Furthermore, the bagasse ash mixtures with 10% substitution were found optimal for achieving higher compressive, flexural and tensile strength, while the thermal conductivity showed a consistent drop with higher ash content percentage. [ABSTRACT FROM AUTHOR]

The conventional jar test was used to evaluate the % mixed microalgae harvesting efficiency from domestic wastewater by using different natural coagulants such as de-oiled Jatropha curcas cake, Moringa oleifera, Conocarpus erectus and neem (Azadirachta indica) seeds compared to alum as a chemical coagulant. The highest microalgae removal efficiency (97.91%) was achieved with powdered neem (A. indica) seeds at 100 mg/L dosing, mixing speed 100 rpm, with 10 min agitation time and pH 9. Interestingly, it was observed that % removal of microalgae was found above 94% in all cases with neem (A. indica) seeds as compared to other coagulants. Then, the % removal is followed by C. erectus with 93.44 % and alum 91.62%. However, the consumption of alum was very high (200 mg/L) to achieve higher % removal efficiency making it uneconomical. Statistically, it was found that both coagulants neem (A. indica) and de-oiled cake of J. curcas seeds were having a percentage contribution of coagulant dosing on the harvesting results. The techno-economic analysis showed that the powdered neem (A. indica) and M. oleifera seeds were found the most economical in terms of mixed microalgae harvesting cost per litre of wastewater, i.e. (US$ 0.0068/L) and (US$ 0.0052/L), respectively. De-oiled cake of J. curcas seeds can effectively remove microalgae with % removal 84.98 %, but the cost analysis revealed that de-oiled cake of J. curcas seeds has higher harvesting cost per litre (US$ 0.0103/L) compared to neem (A. indica) and M. oleifera seeds. Thus, it is suggested to use the neem (A. indica) as coagulants for mixed microalgae removal from domestic wastewater with effective % microalgae removal in a cost-effective manner for biodiesel production. [ABSTRACT FROM AUTHOR]

Refined Pongamia pinnata L. (pongame) oil obtained from indigenous sources in Pakistan was converted successfully to biodiesel using alkaline transesterification in a batch reactor. The optimum reaction conditions (temperature 60 °C, methanol-to-oil ratio 48 % by volume, HSO-to-oil ratio 0.2 % by volume, KOH-to-oil ratio ≈ 1 % by volume, stirring speed 600 rpm and reaction time 180 min) were determined from several experiments. The pongame oil biodiesel was analysed according to the American (ASTM D 6751) and European (EN 14214) international standards, showing that its properties were better than that of canola oil and jatropha oil biodiesel fuels. Environmental emissions profile of pongame B20 (20 % biodiesel blended with 80 % mineral diesel) from a compression ignition engine was better than those obtained with canola B20 and jatropha B20. Engine performance of pongame B20 was found to be comparable to jatropha B20. From results obtained in this research it appears technically feasible to harness biodiesel from native pongamia pinnata instead of imported jatropha curcas to meet the ever increasing energy demands of Pakistan. [ABSTRACT FROM AUTHOR]