Disposing of solid waste with prudence
Generation of solid waste in voluminous amount in modern cities has multifarious environmental implications. So its management is one of major environmental concerns. Municipal solid waste not only contains solid phase waste but also many semisolid or liquid, at times volatile substances. Over time it degrades with action of microbes and creates nuisance to the citizens if not properly handled and disposed of. Solid waste containing organic substances may pollute surface and ground water, air and soil, but can be very useful resource if properly managed. Two principles
* Virgin materials vs recycled materials: Virgin materials used in production must be very minor in comparison with recycled materials. * Action for economic prosperity and environmental protection should be balanced. Open dumping is risky: Open dumping of solid waste which is practiced in Bangladesh has serious environmental consequences. Dumpsite becomes a pollution site as well with time. Run off of rain water contaminates the surface water system with the decaying organic matters that harbour various types of pathogenic microorganisms and vectors of infectious diseases. Gas coming out of the rotting garbage is also of great environmental concern. Incineration is not a welcome solution: Incineration of solid waste much of which could be used as raw materials for composting in fact generates loss. Incineration destroys the organic matters along with beneficial microorganisms. The smoke produced by burning waste is particularly potential source of air pollution .Incineration may give rise to chemical process of generating Dioxin and Furan. Incineration of waste also produces particulate matters in the exhaust gas. Waste that have very low water and high cellulose content are suitable for incineration. Unless well equipped air emission control technologies are employed incineration is harmful for the environment. Sending to the origin: After using/consuming things biodegradable remnants should be discarded to the agricultural fields, remnants of the factory products to the factories and useless earth and construction materials should be utilised for land filling. If the three processes i.e. recycling, composting and landfilling are used simultaneously, virtually there shall be no waste. But there may be some materials that are not suitable for the target process then we may apply burning and burying method. Resource recovery: Recycle glass, paper and metal. Produce biofertilizer through biotransformation by composting. Production of various organic compounds based on municipal waste, and energy from dry organic waste materials by burning are far more environment friendly than rendering them to biodegrade in toxic condition. Biogas plant can produce energy and fertilizer at the same time. Energy recovery: The energy content of waste products can be harnessed directly by using them as a direct combustion fuel, or indirectly by processing them into another type of fuel. Pyrolysis and gasification are two related forms of thermal treatment where waste materials are heated to high temperatures with limited oxygen availability. Pyrolysis of solid waste converts the material into solid, liquid and gas products. The liquid and gas can be burnt to produce energy or refined into other products. The solid residue (char) can be further refined into products such as activated carbon. Avoidance and reduction: Another important method of waste management is the prevention of waste material being created. Methods of avoidance include reuse of second-hand products, repairing broken items instead of buying new, designing products to be reusable (such as cotton instead of plastic shopping bags), encouraging consumers to avoid using disposable products (such as disposable cutlery), and designing products that use less material to achieve the same purpose (for example, light weight of beverage cans). Hierarchy of treatment effectiveness: The waste hierarchy refers to "reduce, reuse and recycle," which classify waste management strategies according to desirability in terms of waste minimization. This waste hierarchy remains the cornerstone of most waste minimization strategies. The aim of the waste hierarchy is to extract the maximum practical benefits from products and to generate the minimum amount of waste. Extended producer responsibility: Extended Producer Responsibility is a strategy designed to promote integration of all costs associated with products throughout their life cycle (including end-of-life disposal costs) into the market price of the product. Extended producer responsibility is meant to impose accountability for the entire lifecycle of products and packaging introduced to the market. Polluter pays principle: The Polluter Pays Principle is a principle where the polluting party pays for the impact caused to the natural environment. With respect to waste management, this generally refers to the requirement for a waste generator to pay for its appropriate disposal. New arena of reuse industries: Many reuse industries are booming in the developed countries. They range from ethanol to materials used in various commercial goods. Waste from one industry is utilized as raw material for another industry. Traditional view vs modern view: In the traditional view waste generated from various sectors are dumped in separate sites away from the locality. In the industrial ecosystem the raw materials are depleted and pile of industrial waste is just heightened. So, the traditional view and associated waste management system is quite unsustainable. In modern view of waste management cycling of material occurs in the industrial ecosystem. Materials travel from one to another via the customer. A product after utilization when becomes waste will be used as raw material for another industry. The basic philosophy is- do not let the material go to the environmental compartment. Conclusion
Waste management system includes waste collection, processing and disposal mechanism. Various mechanisms are applied for collection, segregation, processing and disposal of solid waste. For environment friendly disposal various components of waste should be carefully segregated. Different parts of solid waste have their own physical, chemical and biological properties. They separately demand distinctive disposal. It will not be wise to burn the waste that can be composted to produce environment friendly biofertilizer and biogas through anaerobic decomposition in a digester. Again, you should not bury the substance you can burn to extract energy and utilize the ash as raw material for certain industry.
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