Waste Products: Boon For Nation Development

Anything that has been treated as dream in the past are now been possible with in a fraction of second, its all due to the enhancement in science and technology. Due to the rapid evolution on technology, the daily life of human has achieved the satisfactory level. Wastes and residuals are undeniably part of human society along with its development. The accumulation of these materials and the “throw-away philosophy” result in many environmental and health issues and safety hazard problems, and prevent sustainable development in terms of resource recovery and recycling of waste materials. According to the World Bank, the world currently generates about 4 billion tons of all types of waste per year. The world’s cities alone generate about 1.5 billion tons of solid waste per year. This volume is expected to increase to 2.4 billion tons by 2025. In lower income countries, waste generation will more than double over the next 25 years. Three-fourths of this waste is disposed of in landfills, with only one fourth being recycled. In addition to increasing waste generation, the global demand for energy will increase by 56 percent between 2010 and 2040. There is a lack of awareness and capacity to divert most of the waste for material and energy recovery. This would reduce the costs for waste disposal and would generate the revenue from the sale of the recovered materials and energy.

Energy can be recovered from waste by various technologies. It is important that recyclable material is removed first, and that energy is recovered from what remains, i.e. from the residual waste. Anaerobic digestion (AD), which uses microorganisms to convert organic waste into a methane-rich bio-gas that can be combusted to generate electricity and heat or converted to bio-methane. Bio-gas/AD plants operate at low temperature, allowing microorganisms to work on the feedstock, turning it into bio-gas, which is a mixture of carbon dioxide and methane. They are typically much smaller than the combustion or gasification plants. A bio-gas plant is most appropriate for wet organic wastes, such as food waste, sewage sludge, agricultural residues or energy crops. In many ways, biomass is a new source of power. Biomass energy, for the most part creates no harmful carbon dioxide emissions. Many energy sources used today struggle to control carbon dioxide emissions, as these cause harm to ozone layer and increase the effect of Green house gases, potentially warming the planet. Bio-gas is environment friendly as it is clean energy source. Since they come from living sources, and life is cyclical, these products potentially never run out, so long as there is something living on the earth and there is someone there to turn that living things components and waste products into energy. Thus, produced bio-gas can be used for several purposes including household, industrial, production of electrical energy and so on.

Incineration is another technology that is widely used to produce electricity and heat. An important factor to decide if the waste should be incinerated or digested is the amount of water in the waste that affects its energy content. If the waste is too wet, the energy that should be added for incineration will be more that the energy that is produced by incineration. In this case, the waste has negative energy value. Therefore, the dry wastes are generally passed to incineration, while the wet wastes go to anaerobic digestion. The wastes are incinerated and make a flue gas with more than 800 ºC temperature. The energy is used to produce high pressure steam, which pass through turbines and produces electricity. The rest of the energy (from the low pressure steam) is used to heat up warm water that takes the energy to the city by pipelines for heating the houses and also warm water of the households.

For the developing countries like Nepal, where agriculture is the main occupation of the population and the most focus sector from the government point of view, development of bio-gas power plant plays a crucial role for the rapid increasing energy demand and long term faced loadshedding problem. Emphasis from the government on time is required for the independency of nation for energy sources. As the world’s population increases, so does the demand for energy and products, and so will the amount of waste generated. This waste represents both a threat to the environment and human health, but also a potential source of energy for Nation Development.