Waste generation has been on there rise over the past few years, hence their management has proved to be a rather challenging issue recently. First of all, it is important to define waste in order to be able to manage it successfully. Waste can be defined as any substance or object which the holder discards or intends or is required to discard. They can be classified as liquid (such as sewerage) or solid (such as waste plastic bags). Every country produces different amounts of waste and with different composition. This is because waste generated is influenced by the degree of urbanization, patterns of consumption, household revenue and lifestyles in each country (Eurostat, 2014).
Whichever forms they come, waste generation poses personal and environmental dangers. They can be deterrent to a person's health by causing varied kinds of diseases and injuries. Their accumulation in the environment also leads to the pollution which makes the environment unpleasant to live in. Research conducted in this area has shown that wastes, when properly managed, does not only prevent these harmful effects and unpleasantness but is also economically helpful. Thus sustainable waste management practices should be of utmost importance to us the waste generators, the various institutions and the nation as a whole.
The treatment options of waste can be classified in broad terms as: landfill, incineration, recycling and composting. Sustainable waste management is one of the most challenging issues faced by both developed and developing countries. Developed countries are examining how to avoid waste going to landfill, and increase the recycling and recovery of materials. This gives top priority in preventing waste in the first place. Even when waste is finally created, priority is given in preparing it for re-use, then recycling, then recovery and as last resort disposal (i.e. landfill) (Defra, 2011).
Landfilling is being considered in the past years as inappropriate because it poses great risks to human and environmental health. Still there are uncertainties as to how landfills affect human health. Moreover, a common technique to pre-treat waste before it can be disposed in landfill is mechanical biological treatment as this option can lead to the material to be landfilled being relatively harmless. One of the main outputs of landfill is methane, which is produced through the decomposition of organic wastes under anaerobic conditions. This gas can be used either in a gas engine to generate electricity and/or heat, or it may be used into a natural gas grid or for direct utilization as a transport fuel. .
The combustion of waste for recovering energy is called incineration, where under conditions of high temperature these waste treatments are recognized as thermal treatments (WMR, 2009). Incineration reduces the form of the waste from 95 to 96% and this reduction depends on the recovery degree and composition of materials; this means that incineration does not replace the need for landfilling but reduces the amount to be disposed that way (WMR, 2009).
Composting is a term used to describe the biodegradation of organic matter through an aerobic process which converts organic matter into a stable humic substance. In most developing countries an astonishing 50 to 70% of the waste is organic materials which are therefore suitable for composting, so the process can usually be furthered through separation at source (UNEP, 2015). More specifically for this process, the microorganisms employed are part of three main categories; bacteria, fungi, and actinomycetes. The key factors that need to be accounted for to achieve effective composting rates include temperature, air supply, moisture content, the porosity of the material and its carbon to nitrogen ratio. There are many different technologies available for composting which include simple open-air systems (windrow composting and aerated static pile composting) to more sophisticated contained systems. Composting facilities can only operate economically if they function at or near maximum design capacity. Therefore this implies that for every composting facility one needs to secure sufficient waste. Based on their quality, wastederived composts can be used for land reclamation and as a soil improver in landscaping, agriculture and horticulture due to its ability to improve the biological and physical properties of soil in particular of use in arid regions (Environment Agency, 2002; UNEP, 2015)
Anaerobic Digestion is the bacterial decomposition of organic material in almost anaerobic conditions whose by-products include biogas, and digestate. There are two main types of anaerobic digestion called thermophilic and mesophilic – the primary difference between them is the temperatures used in the process; thermophilic processes reach temperatures of up to 60 degrees centigrade and mesophilic normally run at about 35-40 degrees centigrade. The high degree of flexibility associated with this method of composting is considered one of the most important advantages of the method, since it can treat several types of waste, ranging from wet to dry and from clean organics to grey waste.
The process of anaerobic digestion provides a source of renewable energy, since the food waste is broken down to produce biogas (a mixture of methane and carbon dioxide), which can be used to produce energy. The biogas can be used threefold: to generate electricity, to power on-site equipment and any excess electricity can be exported to ECG. Another by-product of the process is the biofertilizer, which is rich in nutrients such as nitrogen, phosphorus and other elements essential for healthy plant growth and fertile soil (WRAP, 2016).
Recycling refers to the systematic collection, processing and reuse of materials, which include the following categories: paper, glass, plastic, wood, aluminum products, and iron. Recycling entails many benefits which include amongst others the following: Reduces the amount of waste sent to landfills and incinerators Conserves natural resources such as timber, water, and minerals Prevents pollution by reducing the need to collect new raw materials Saves energy Reduces greenhouse gas emissions that contribute to global climate change Helps sustain the environment for future generations Helps create new well-paying jobs in the recycling and manufacturing industries.
Conclusion: As it has been presented in this article, waste management is an issue that needs to be addressed with the utmost importance. Regulations and directives around it are trying to find new and effective ways to manage it appropriately and efficiently. Implementation of these rules in our country is carried by several agencies and government institutions, predominantly, the Zoomlion Waste Management Ltd. But it is important as waste generators to play our part by supporting these institutions and also minimizing the amount of waste we produce, that their work can be easy. One key way waste can be made harmless at the generator end is to segregate them into the appropriate bins provided.
Article by: Andrew E. Agyapong
A Physician Assistant Student (BSc), University of Cape Coast.
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