This study represents a few basic steps of municipal solid waste management practiced in the six major cities of Bangladesh, namely, Dhaka, Chittagong, Khulna, Rajshahi, Barisal, and Sylhet. A six-month field study was conducted to identify the solid wastes management steps such as storage at source, separation, on-site storage, collection, transportation, treatment, reuse, recycling, and ultimate disposal. This study addresses the role of the city authority to meet the demand of the city dwellers in solving this emerging socioenvironmental issue and the initiatives taken by some nongovernmental organizations and community based organizations. The problems and constraints of the solid wastes management system are also identified to find a sustainable management concept for the urban areas of Bangladesh.
In this study, the performance of a laboratory scale upflow anaerobic sludge blanket (UASB) reactor operating at mesophilic temperature (35 °C) was examined. Cattle slaughterhouse wastewater (CSWW) was used as the main substrate. The total and effective volumes of the reactor were 8 L and 6 L, respectively. Twelve different organic loading rates (OLR) were applied and the performance was evaluated. The chemical oxygen demand (COD) removal efficiency was more than 90% during batch study. In the continuous study, COD removal was also approximately 90% at OLR 0.4 g/L d−1 which subsequently dropped to below 50% when the loading rate increased to 15 g/L d−1. Approximately 5 L/d of biogas was obtained with high methane concentration at stages VI and XI corresponding to OLR of 2 and 10 g/L d−1, respectively. It was observed that the concentration of volatile fatty acids was low and that the alkalinity of the wastewater was sufficient to avoid acidification. Specific methane yields of 0.36 and 0.38 LCH4/g COD added were achieved at OLR 7 and 10 g/L d−1. A hydraulic retention time (HRT) of 1 day was sufficient to remove greater than 70% of COD which correspond to 89% methane concentration. Parameters like soluble COD, NH3-N, pH, alkalinity, total suspended solid (TSS), fats, oil, and grease were also investigated. The results show that the UASB reactor could serve as a good alternative for anaerobic treatment of CSWW and methane production.
Vermicomposting is a process to biotransform organic solid wastes into valuable product, namely vermicompost using epigeic earthworms. Vermicomposting technology may provide a low-input basis for sustainable management of organic solid waste. The present study was to investigate the suitability of oil palm empty fruit bunches to be reused as feedstocks of Eudrilus eugeniae for the duration of 12 weeks. Empty fruit bunches were mixed with cow dung in different ratios to produce five different treatments for laboratory screening of solid waste. The growths of E. eugeniae were monitored weekly. All treatments encouraged the growth of E. eugeniae except the treatment with empty fruit bunches alone. The maturity and quality of vermicompost were assessed through carbon-tonitrogen ratio, calcium, phosphorus, potassium and magnesium. Generally, all treatments showed increases in total contents of calcium (39.38-373.17 %), phosphorus (15.15-390.54 %), potassium (45.55-153.66 %) and magnesium (55.86-370.93 %) but a decrease in carbon-tonitrogen ratio (11.24-76.24 %) after 12 weeks of vermicomposting process. Besides, parameters such as pH and electrical conductivity were also investigated in this paper.Among all the treatments investigated, empty fruit bunches that were mixed with cow dung in the ratio of 2:1 were biotransformed into the most superior quality vermicompost (carbon-to-nitrogen ratio, 18.53; calcium, 7.76 g/kg; phosphorus, 3.63 g/kg; potassium, 12.81 g/kg; and magnesium, 4.05 g/kg). In conclusion, vermicomposting could be used as an efficient technology to convert empty fruit bunches into nutrient-rich organic fertilizers if the wastes were mixed with cow dung in an appropriate ratio.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.