Current Situation Analysis and Suggestions for Solid Waste Management Practices among Households in Freetown

Freetown which is the capital city of Sierra Leone is facing challenges with population growth, urbanization, and industrialization, leading to an increase in municipal solid waste (MSW) generation. The study aims to evaluate MSW generation, composition, and disposal methods, as well as the impact of collection fees, policy implementation, and women’s participation in municipal solid waste management (MSWM). The study used both qualitative and quantitative methods for data collection and analysis. The study administered 393 structured questionnaires in three selected sections to collect data on variables such as family size, education, level of knowledge, etc. The study used door-to-door data collection to determine the rate of solid waste generation, composition, and disposal in 66 households from two of the selected sections and 34 households from the other section to evaluate the current situation of MSWM practices among households in Freetown. The study used a descriptive statistic to analyze the data collected using Origin-Pro9 and MS Excel software. The findings showed that with a 4.2% urban growth rate, Freetown had a population of 1,467,543 in 2023, generating 851 tons of MSW per day, with organic waste accounting for 78% of the total MSW generated. Plastic waste generation also increased from 7.6% in 2020 to 13% in 2023. The study emphasizes the need to sustain the MSWM system by prioritizing solid waste collection fees, policy enforcement, and women’s participation in the MSWM sector. It further suggests and provides recommendations for developing an efficient and sustainable MSWM system in Sierra Leone, including knowledge transfer from countries like China and the US.

Recovery of valuable elements from spent YBa_2Cu_3O_(7-x)/Agcomposite superconductor bulks

Silver as a highly conductive metal is usually doped in YBa2Cu3O7-x superconductor bulks to improve critical current density of YBa2Cu3O7-x superconductor.The valuable metal elements silver,yttrium,barium and copper in waste YBa2Cu3O7-x/Ag composite superconductor bulks were recovered,respectively.Silver was recovered with process at first,the waste was dissolved by nitric acid and silver chloride was precipitated by adding chloride acid,then silver pig was obtained by melting silver chloride together with sodium carbonate at 1 000℃.The effective factors on recovery ratio and purity of silver were studied.The chemical analysis proves that the purity of silver ingot is 95.86%.The recovery ratio of silver is calculated to be 92.56%.The loss of silver may be due to the loss of silver chloride during filtering and the volatilization of silver when silver chloride and sodium carbonate are smelted at high temperature.For other three metal elements,Y3 +,Ba 2+and Cu 2+,in the surplus waste liquid after recovering silver, they were separated with the sequence of barium,copper and then yttrium step by step.First,sulfate acid was used to precipitate barium sulfate.Then,sodium sulfide was added to the surplus solution so that copper could be separated as copper sulfide.During this separation procedure,it was important to control the pH value to be 1-2.After that,oxalic acid was added into the surplus solution to obtain yttrium oxalate.Finally,yttrium oxide was formed by burning yttrium oxalate.The XRD results indicate that the final products are all single-phase compounds as BaSO4,CuS and Y2O3,respectively.

Lessons learned from the Ezgeleh-Sarpol Zahab earthquake of November 2017:status of damage and disposal of disaster waste

A massive earthquake of magnitude Mw 7.3 shook Kermanshah Province in Western Iran along the Iraqi border on November 12,2017.The epicenter of the earthquake was approximately 10 km southwest of Ezgeleh Town in Kermanshah Province.Field observations almost 4 months after the disaster indicated that the earthquake had caused tremendous damage to most structures in both urban and rural areas,and left an enormous amount of disaster waste.To investigate the status of the dam-age and disposal of the disaster waste,remote sensing was conducted using an unmanned aerial vehicle(drone).Through the capture of low-altitude images by drone and the generation of 3D models,the quantity of debris accumulated in a waste disposal facility near Sarpol Zahab was estimated at approximately 480,000 m3.A compositional analysis of the disaster waste was performed using an imaging technique.This revealed that the disaster waste was largely composed of concrete(39.6%),hollow brick(35.4%),and gypsum(21.2%)in the urban area,whereas soil was the dominant component(77.4%)in the rural area.The damage caused to most buildings was essentially due to their non-standard construction.The manage-ment of debris from the damaged buildings was a critical issue for the authorities,and the lack of preparedness was a serious drawback that consumed an enormous amount of time,budget,and workforce.A practical post-disaster preparedness plan would help the decision-makers and the public to manage the otherwise overwhelming nature of the post-disaster conditions in a more reasonable manner.