A large percentage of fruit mass is left as waste after the consumption or processing of citrus fruits. The inappropriate disposal of these wastes directly leads to environmental and economic concerns. However, scientific investigations have demonstrated that citrus wastes, due to their high concentration in soluble sugars, can be a source of cellulosic biomass for biogas recovery. d-Limonene, the major constituent of essential oils present in citrus wastes, is however, known to hamper the conversion process of citrus wastes to biogas. With the aim of improving biogas production, a study on the pre-treatment of lime fruit waste to reduce the effect of d-limonene was carried out. The pre-treatment process was done using hexane as the solvent in a solid–liquid extraction process to leach out essential oils from lime wastes. Solid–liquid extraction was carried out in a Soxhlet apparatus with pulverized lime waste at 68 °C for 180 min; then the residue was washed and aerated. From the pre-treatment procedure, 21.3 mL of essential oil was recovered, indicating an oil yield of 3.8%. Substrates of untreated and pre-treated lime waste were digested in batches under mesophilic conditions for a period of 28 days. The biogas yield of each substrate was evaluated and the results compared. Substrate of untreated lime waste yielded 66.9 mL/g VS. biogas after the digestion period. In comparison, pre-treated lime waste gave a better biogas yield of 93.2 mL/g VS. after 28 days, indicating an improvement in biogas yield by about 40%. The findings of this research show that there is a viable recovery option of biogas from lime waste, and recommendations of this research can be further explored to develop an economically viable biogas plant process that efficiently utilizes citrus wastes. This would boost the drive of government towards alternative sources of energy and also fulfil two of the sustainable development goals presented by the United Nations.

The coronavirus disease, popularly known as COVID-19, is a new infectious disease and Nigeria is one of the 213 countries and territories affected by its pandemic. The pandemic has practically affected every sector of the economy with substantial impacts and implications. The current waste management practice at all health care and isolation centres during this period also calls for concern. This paper focuses on the effects of COVID-19 on Waste Management Practices, the Nigeria Economy, and the Way Forward. Responses at the three tiers of government are identified; the involvement of private and public sectors with the role of international organizations, donors, public participation, and the impact of religion on COVID-19 response in Nigeria are also considered. The implications on Sustainable Development Goals, Agriculture, Manufacturing, Trade, Mining and Quarrying, and Education Sectors are discussed. SWOT analysis of waste management processes in Nigeria during the pandemic is presented. Based on the study, it is recommended that concerted effort on the part of the government be focused on maximizing welfare policy programs that would erase the sufferings of the people as regards access to primary health care and other social infrastructure that could enhance peoples' living standard. Effective responses and recovery plans in the short-, medium and long-term should also be prioritized and consider the pandemic's different dimensions, as a measure to grow truly necessary extraordinary change toward a sustainable society.

The burning and open dumping of wastes is a common practice in developing countries such as Nigeria. These practices are causes of environmental concern as they generate air pollutants, contaminate surface and underground water resources, and breed disease vectors, consequently affecting public health. Nevertheless, composting has been identified as a sustainable technique to efficiently manage and dispose these wastes while also recovering a marketable resource. This study was aimed at assessing the potential recovery of compost from mixed fruit wastes as a method of proper disposal. Fruit wastes generated within a university campus were mixed with dry leaves and manure and decomposed in a composting process for 6 weeks. The physico-chemical properties such as temperature, pH level, moisture content, and NPK value of the resulting compost were determined during and after the process. The experimental results indicated a temperature range of 25°C to 56°C and pH level ranging from 6.6 to 8.1 during the composting process. The moisture content of the compost pile was detected to gradually reduce from 56% to 40% during the experiment. The NPK ratio of the final compost product was evaluated to be 0.61:0.40:0.73. The compost produced in this study could be used for agricultural purposes to supply nutrients to growing plants and the soil.

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