The initial response to concerns about pollution in the 1960s was to develop end-of-pipe treatment systems (treating pollutants at the end of the process). End-of-pipe treatment does not solve pollution problems. It only alters the problem, shifting it from one form to another. The form of the waste may be changed, but it does not disappear.
The limitations of such an approach have been recognized since the mid-1970s. Waste minimization has been identified as the only sustainable means of dealing with the waste problem. Waste minimization can be defined as “Prevention and/or reducing the generation of waste, improving the quality of waste generated, including reduction of hazard, and encouraging re-use, recycling and recovery”. Several reasons may be put forward in favour of waste minimization. The main reasons are:
1. The generation of huge volumes of waste causes the depletion of largely nonrenewable resources.
2. Increasing total cost for the collection, transport, treatment and final disposal makes waste minimization attractive.
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3. Increased legislation and public pressure are likely to be mitigated only by waste reduction.
4. Waste equals inefficiency, therefore reducing waste increases efficiency and profitability.
Life Cycle Assessment (LCA)
Before examining waste minimization techniques and strategies it is imperative to examine the life cycle assessment (LCA) of a product. LCA is a developing environmental management technique. LCA can briefly be defined as the systematic compilation and evaluation of the inputs, outputs and the potential impacts of a product system throughout its life cycle, i.e., from raw material acquisition to final disposal of the product.
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It is an attempt to attribute all the environmental impacts in the life cycle of a marketable product. It recognizes that raw materials, production and disposal may be as significant environmentally as the product’s manufacture. The first reported LCA was carried out for Coca Cola containers in 1969. It is an area of on-going research and development which saw a large expansion in the 1990s.
(i) raw material acquisition
(ii) bulk material processing
(iii) engineered and special material production
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(iv) manufacture and assembly
(v) transport and sales
(vi) use and service
(vii) retirement and recycling
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(viii) treatment and disposal.
Every stage has material, labour and energy inputs and may have outputs in terms of waste. Within the cycle, these wastes may be reused or recycled to minimize the net output. However, all of these consume energy and generally suffer some degradation of material.
Waste management hierarchy
Prevention of waste generation is preferable to treating the waste after its production. This makes one to think of waste management hierarchy. The various options given below are in the decreasing order of environmental preference:
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(i) source reduction
(ii) reuse
(iii) recycling
(iv) recovery
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(v) treatment
(vi) disposal