Waste management evolution in the last five decades in developing countries - A review

Reproducible Polybutylene Succinate (PBS)-Degrading Artificial Consortia by Introducing the Least Type of PBS-Degrading Strains

Polybutylene succinate (PBS) stands out as a promising biodegradable polymer, drawing attention for its potential as an eco-friendly alternative to traditional plastics due to its biodegradability and reduced environmental impact. In this study, we aimed to enhance PBS degradation by examining artificial consortia composed of bacterial strains. Specifically, Terribacillus sp. JY49, Bacillus sp. JY35, and Bacillus sp. NR4 were assessed for their capabilities and synergistic effects in PBS degradation. When only two types of strains, Bacillus sp. JY35 and Bacillus sp. NR4, were co-cultured as a consortium, a notable increase in degradation activity toward PBS was observed compared to their activities alone. The consortium of Bacillus sp. JY35 and Bacillus sp. NR4 demonstrated a remarkable degradation yield of 76.5% in PBS after 10 days. The degradation of PBS by the consortium was validated and our findings underscore the potential for enhancing PBS degradation and the possibility of fast degradation by forming artificial consortia, leveraging the synergy between strains with limited PBS degradation activity. Furthermore, this study demonstrated that utilizing only two types of strains in the consortium facilitates easy control and provides reproducible results. This approach mitigates the risk of losing activity and reproducibility issues often associated with natural consortia.

Towards integrated, and sustainable municipal solid waste management system in Shashemane city administration, Ethiopia

Solid waste generation is attested to be unavoidable product of human activities. Sustainable management of such waste is a pressing challenge faced in many developing countries today. The study was motivated by the fast growing population and the inefficient waste management system threatening the public health and the image of Shashemene city in Ethiopia. The objectives of the study were: to explore the existing household solid waste management practices, to examine the current governance system of municipal solid waste management, to investigate the contemporary challenges and opportunities of municipal solid waste management, and forward integrated and sustainable municipal solid waste management system for Shashemene city. Data were collected from sampled households, key informants, focus groups, and the city's environment. Data were analyzed by employing quantitative and qualitative methods. 94.8 % of the respondents opined that the solid waste generated in their city is organic in nature (Ash, and sweeps; leftover food, and vegetable peels; paper, and cardboards; green leaves, and grass; and cattle dung). 96.7 % of respondent households opined that they have temporary waste storage in their yards and trash bags were asserted to be widely used (87.6 %) in handling the trash in the courtyard. The waste sorting and recovering practices among the residents is very low and is certainly the major cause for inefficient and unsustainable management system of municipal solid waste in Shashemene city. Generally, a grand mean of 2.23 confirmed the absence of good governance in municipal solid waste management system in Shashemene city. Moreover, the significant proportion of responses ( ≥ 50 %) for each of the nine principles of good governance as either poor or very poor asserted governance failure of the municipal solid waste management system in Shashemene city. The results of the study confirmed that low public awareness on waste management; inadequate collection capacity; poor integration and coordination of stakeholders; environmentally unsound dump site; and illegal dumping by key stakeholders are the major challenges underpinning the unsustainable municipal solid waste management in the city. It is recommended that Shashemene city must adopt integrated sustainable municipal solid waste management system to substantially enhance the waste management service in the city leading to ultimate advancement of public health and environmental quality.

First principles insights into the interaction mechanism of iron doped thermally activated kaolinite with Cd and Pb pollutants in organic solid waste incineration flue gas

Incineration of organic solid wastes is accompanied by the heavy metal emission through flue gas. As an inexpensive and efficient heavy metal adsorbent, the improvement of kaolinite adsorption performance for heavy metals has drawn widespread interests. In this work, the interaction mechanisms between various kaolinite surfaces and Cd/Pb species are explored through first principles calculations. The results show that the combination of Fe doping and dehydroxylation enhances the activity of kaolinite surfaces, analysis of adsorption configurations reveal that both Cd and Pb species are immobilized through chemisorption on the -H + Fe surface. At the microscopic level, further electronic structure analysis shows that the composite modified kaolinite surface has more electron transfer and more pronounced orbital hybridization and overlap compared to the original kaolinite surface, demonstrating that the modification means of dehydroxylation and Fe doping indeed enhanced the activity of the kaolinite surface, especially the activity of the O atoms in the vicinity of the Fe atom and that the O atoms are more efficiently bonded as ionic connecting Cd/Pb species for the purpose of trapping Cd/Pb species. This study points out the research direction and provides basic theoretical support for the development of new kaolinite adsorbents in the future.