Waste Management

A series of incidents in the late 70s highlighted waste as a potential major source of environmental pollution. A series of toxic chemical waste dumping incidents led to increasing awareness of the importance of waste management and the need for a more stringent legislative control of waste. Amongst the most notorious incidents were the discoveries, in 1972, of drums of toxic cyanide waste dumped indiscriminately on a site used as a children’s playground near Nuneeton. The leading of leachate and toxic vapours intra housing development at the Love Canal site, New York state, in 1977, the dumping of 3000 tonnes of arsenic and cyanide waste into a lake in Germany in 1971, and the leak of polychlorinated biphenyls (PCBs) into rice oil in Japan in 1968, the Yusho incident (British Medical Association 1991) (Box 1.1).

The massive adverse publicity and public outcry led to pressure for the problem of waste disposal to be more strictly controlled by the legislature. In the UK, as a direct result o9f the Nuneeton Cyanide duping incident, emergency legislation was introduced inn the form of the d4eposit of poisonous Waste Act, 1972. Further legislation on waste treatment and disposal followed in 1974 with the Control of Pollution Act, which controlled waste disposal on land through a new licensing and monitoring system for waste disposal facilities.
The recognition of the need for environmentally acceptable means of waste disposal following the illegal waste dumping incidents led to a revival of some interest in incineration. However 90% of the municipal waste still being land filled and the majority of the plants had no form of energy recovery to offset disposal costs.

Whilst landfill remains the major option for waste disposal in the UK, increasing regulation has placed tighter controls on leachate and landfill gas treatment monitoring, and site after care, with a consequent increase in disposal costs. New developments in landfill design and operation have resulted in the concept of the flushing bioreactor landfill, which re-circulates the leachate to increase the rate of waste degradation. The combustion of landfill gas to produce energy in the form of electricity of power generation or district heating has now become the norm for modern landfills.

The incineration of waste with energy recovery via either electricity generation of district heating has been developed in the 90s to become an economic viability comparable to landfill. Many of the new wave of incinerators involve the private sector. In addition, several industrial waste, sewage sludge and clinical waste incinerator projects have been initiated during the 80s and 90s involving the private sector in many cases. These incinerators tend to have smaller through puts of waste, and because of the higher costs of disposal of these types of waste are cost effective compared with other forms of disposal. In many cases, the type of waste dictates that incineration is not only the most economic option, but also the best practicable environmental option. The UK’s document ‘Making Waste Work’ takes the concept of sustainable development as a strategy for waste management. The strategy is developed into the concept of a hierarchy of waste management (sustainable Development 1994).
1) Reduction: uppermost in the hierarchy is the strategy that waste production from industrial manufacturing processes should be reduced. Reduction of waste at source should be achieved by developing clean technologies and processes that require less material in the end products and produce less waste during manufacture.
2) Reuse: the collection and reuse of materials for example doorstep mild delivery in the UK involves collection, cleaning and reuse of glass bottles. Tyre rethreading would also come into this category, where many truck tyres are rethreaded many times through out their lifetime. Reuse can be commercially attractive in some circumstances. However, reuse must be made more desirable and the environmental and economic cost of reuse must be subsidised by the state to cover for energy use, clearing, recovery transportation etc. in order to encourage the business.
3) Recovery: there are number of different types of waste recoveries such as material recycling composting, energy recovery. The ways to recover the waste and processing them to produce a marketable product e.g. the recycling of glass and aluminium cans is well established, with a net saving in energy costs of the recycled material compared with virgin production.


- decomposition of the organic fraction of waste to produces a stable product such as soil conditioner and growing material for plants.
- Producing energy by incinerating waste or combustion of landfill gas. Many wastes including municipal solid waste sewage sludge and scrap tyres, contain an organic fraction which can be burnt in an incinerator

4) Disposal: the disposal of waste using processes or methods that do not endanger human health and which cannot harm the environment, such as by incineration or controlled landfill without energy recovery. Landfill is predominant route for waste disposal in the UK.

The UK strategy of targets for waste minimisation, reuse and recycling also require accurate data to determine if and when targets are met. A key element of the UK National Waste Strategy is the gathering of waste arising statistics by the Environmental Agency on a regional basis, which will be used at local and regional level for planning future waste management facilities and at national level to implement the Waste Strategy.


References:
Williams, Paul, T., Waste Treatment and Disposal, Dept of fuel and energy, the University of Leeds, 2002
Dept of Environment, Digest of Environment protection and water statistics, HMSO, London, 1994
British Medical Association, 1991, Hazardous Waste and Human Health, Oxford University Press, Oxford