Solid waste management practices and challenges in Besisahar municipality, Nepal.

This study is a comprehensive assessment of the waste management system in Besisahar municipality. Information and some data have been collected from the municipality of Besisahar, followed by interviews with municipal officials responsible for waste management, stakeholders, waste workers, and residents. A total of 230 households, 20 schools, 10 government and private offices, 10 financial institutions, 60 commercial hotels, restaurants, and shops, and 20 medical shops and healthcare institutions, were selected in this study by random sampling. An extensive field study was conducted within all municipal wards and at dump sites. The results indicated that 42.14% of solid waste was collected through door-to-door collection services, 5.87% was mismanaged in open public places, 11.21% was used as compost manure, and the rest was discarded on riverbanks, dug up, and burned. A large component of the characterization of household waste consisted of organic waste (68.03%), followed by paper/paper products (8.13%), agricultural waste (5.5%), plastic (5.21%), construction (3.81%), textile (2.72%), metals (0.54%), glass (1.01%), rubber (0.10%), electronic (0.05%), pharmaceutical (0.1%) and others (4.78%) in the Besishahar municipality. Solid waste generation was found to be at 197.604 g/capita/day, as revealed by cluster sampling in 230 households. Around 4.285 tons-solid waste/day were generated in urban areas, while 16.13 tons-solid waste/day was estimated for the whole municipality. An important correlation between the parameters of solid waste was found by statistical analysis. Currently, solid waste is dumped on riverbanks, open fields, and springs, creating environmental and health hazards. The findings of this study will be useful to Besisahar municipality and its stakeholders in forming policies that facilitate waste management practices in this region and promote sustainable waste management systems.

Calcium alginate entrapped Eupatorium adenophorum Sprengel stems powder for chromium(VI) biosorption in aqueous mediums.

A novel biosorbent, Eupatorium adenophorum Sprengel-alginate beads was used for chromium(VI) biosorption from aqueous solutions. Biosorption process was optimized at pH 2.0, biomass concentration 1.0 g/L, contact time 60 min, and temperature 30 oC respectively. Maximum uptake capacity of Cr(VI) was calculated at 28.011 mg/g. It was found that the overall biosorption process was best described by pseudo second-order kinetics with high correlation coefficient values. Intraparticle diffusion model suggested that Cr(VI) biosorption may proceed within multiple steps. Data obtained from the batch studies confirmed well to the Langmuir, Temkin, and Hill-der Boer isotherm models. Scatchard plot analysis further supported the mono-layer biosorption of Cr(VI) ions on Eupatorium adenophorum Sprengel-alginate beads as described by Langmuir isotherm model. Numerical values of E obtained from Dubinin-Radushkevich isotherm model identified the physisorption as predominant mechanism for Cr(VI) biosorption. The negative values of ΔGo confirmed the spontaneous and feasibility nature, whereas positive value of ΔHo showed the endothermic nature of biosorption process. Positive value of ΔSo indicated an increase in the randomness at the solid/solution interface during the biosorption process. The endothermic nature of Cr(VI) biosorption was also described by Temkin isotherm model. The results indicated that Cr(VI) biosorption was not significantly affected by the presence of co-ions at lower concentrations. Desorption of Cr(VI) ions from metal-loaded Eupatorium adenophorum-alginate beads was observed at 92.091% with 0.5 M HNO3 solution in solid to liquid ratio of 1.0 g/L.

Bioremoval of heavy metals by bacterial biomass.

Heavy metals are among the most common pollutants found in the environment. Health problems due to the heavy metal pollution become a major concern throughout the world, and therefore, various treatment technologies such as reverse osmosis, ion exchange, solvent extraction, chemical precipitation, and adsorption are adopted to reduce or eliminate their concentration in the environment. Biosorption is a cost-effective and environmental friendly technique, and it can be used for detoxification of heavy metals in industrial effluents as an alternative treatment technology. Biosorption characteristics of various bacterial species are reviewed here with respect to the results reported so far. The role of physical, chemical, and biological modification of bacterial cells for heavy metal removal is presented. The paper evaluates the different kinetic, equilibrium, and thermodynamic models used in bacterial sorption of heavy metals. Biomass characterization and sorption mechanisms as well as elution of metal ions and regeneration of biomass are also discussed.