Minimising environmental harm

The fundamental concept to controlling environmental pollution is that it is better to prevent environmental damage rather than have to cure the harm after an event has occurred. Apart from the environmental improvement there are other considerations and possible advantages to be considered. These include the legal and regulatory implications and the potential of commercially based incentives. 

This assessment should identify all the waste streams from all stages of the process. Such work should include all minor releases from storage tank vents, effluent pit emissions, etc. For each waste stream consideration should be given to the waste hierarchy of reduction, reuse, recycle as well as end of pipe treatment and disposal. 

The list of possible options for the management of each waste stream should be reviewed using an approach similar to step (b) above. The waste management hierarchy of Avoid - Minimise - Reuse - Recycle -Recover energy - Dispose should be followed. 

This action involves assessing in detail each of the options identified in (f) above where releases to the environment have been identified and quantified. It may be necessary to carry out dispersion calculations for releases to air and water. From this data comparisons are made with local environmental quality limits. The option creating the least overall environmental impact can then be identified. 

Section (g) identifies the BPEO for each waste stream. Other aspects of the waste management options such as energy use, technical feasibility, cost, etc., are likely to influence the final selection of the best practical waste management option for each stream. The review should also include consideration of other waste treatment facilities that are already in existence on the site so that the most cost-effective combination of waste treatment methods can be identified. 

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The most important principle of green chemistry is to prevent or at least minimize the formation of hazardous products, which may be toxic or environmentally harmful. The effect of hazardous substances if formed may be minimised for the workers by the use of protective clothing, engineering... 

Although environmental protection must not compromise safety, there is a duty to minimise harm to the environment from prescribed processes at all times. There is a hierarchy of needs which includes ... 

Prevent and/or minimise the entry of harmful chemicals into the environment and reduce the need for difficult and costly environmental remediation. 

The management of impurities is an important issue both in Process Design and Operation. A key point is the interaction between these two aspects. Strict environmental regulations forbid the dump of harmful materials in the environment. Therefore waste minimisation, aiming to zero effluents, is a fundamental feature of sustainable process design. The increased number of recycles in integrated plants, makes the control and the operation much more difficult. 

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