Journal of Energy Bioscience 2024, Vol.15, No.3, 147-159 http://bioscipublisher.com/index.php/jeb 149 change (Bhatt et al., 2018). Landfilling, another prevalent method, involves the disposal of waste in designated landfill sites. While it is a straightforward approach, it poses environmental risks such as soil and groundwater contamination due to leachate formation and methane emissions, a potent greenhouse gas (Kaur et al., 2021). 3.2 Environmental and economic impacts of conventional practices The environmental impacts of traditional waste disposal methods are profound. Burning agricultural waste releases large amounts of carbon dioxide, methane, and other pollutants into the atmosphere, exacerbating global warming and air quality issues. Landfilling, on the other hand, contributes to soil and water pollution through the leachate produced as waste decomposes. This leachate can carry harmful chemicals and pathogens into the surrounding environment, posing risks to human health and ecosystems (Kaur et al., 2021). Economically, these conventional practices are not sustainable. The costs associated with managing the environmental damage caused by burning and landfilling can be substantial. Additionally, these methods do not capitalize on the potential economic benefits of converting agricultural waste into valuable products such as biofuels, fertilizers, and other bioproducts (Kirilenko and Tokarchuk, 2020). The inefficiency of these traditional methods highlights the need for more sustainable and economically viable waste management practices. 3.3 Regulatory framework and policies governing agricultural waste management The regulatory framework and policies governing agricultural waste management vary significantly across different regions. In many countries, there are stringent regulations aimed at reducing the environmental impact of waste disposal. For instance, policies may mandate the reduction of open burning of agricultural residues and promote the adoption of alternative waste management practices such as composting, anaerobic digestion, and bioenergy production (Wei et al., 2020). In China, for example, the government has implemented policies to encourage the recycling and utilization of agricultural waste, aiming to reduce pollution and promote sustainable agricultural practices. Similarly, in the European Union, regulations such as the Waste Framework Directive and the Renewable Energy Directive set targets for waste reduction and the use of renewable energy sources, including bioenergy from agricultural waste (Kirilenko and Tokarchuk, 2020).These regulatory frameworks are essential for driving the transition from traditional waste disposal methods to more sustainable practices. They provide the necessary guidelines and incentives for farmers and waste management companies to adopt environmentally friendly and economically beneficial waste management strategies. 4 Technologies for Energy Production from Agricultural Waste 4.1 Anaerobic digestion 4.1.1 Process description Anaerobic digestion (AD) is a biological process that converts organic waste into biogas through the action of microorganisms in the absence of oxygen. This process involves several stages, including hydrolysis, acidogenesis, acetogenesis, and methanogenesis, which collectively break down complex organic materials into simpler compounds, ultimately producing methane (CH4) and carbon dioxide (CO2) as primary biogas components (Chew et al., 2021). 4.1.2 Types of digesters and biogas production There are various types of anaerobic digesters, including batch, continuous, and semi-continuous systems. Portable biogas digesters, which are small-scale units designed for domestic use, have gained popularity for their ability to convert kitchen waste into biogas efficiently (Ajay et al., 2021). Co-digestion, which involves the simultaneous digestion of multiple types of organic waste, has been shown to enhance biogas production and process stability. 4.1.3 Factors affecting efficiency and yield Several factors influence the efficiency and yield of anaerobic digestion, including temperature, pH, retention time, carbon-to-nitrogen ratio, and the presence of inhibitors. Pre-treatment methods such as thermal, chemical, and mechanical treatments can enhance the biodegradability of feedstock, thereby improving biogas yield (Bong et al., 2018). Additionally, the optimization of operational parameters and the use of additives can further enhance the performance of AD systems.
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