ENVIRONMENT AND ENERGY
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heat. Residual sludge might yield biogas or may have no other fate
than disposal.
ADDRESSING THE RESOURCE CHALLENGE
If wastewater is accepted as a positive input, rather than an unwanted
output of industrial activity demanding disposal, there is a logical and
preferred process from its elimination to proactive use and recycling.
• Reducing pollution and pollution prevention
As with many environmental issues, the first step is to prevent or
minimise pollution. The goal is to keep the volumes and toxicity of
pollution to a minimum at the point of origin. This goes to the core of
new green industrial engineering, where the elimination of pollution and
wastewater is part of the equation from concept to design for operations
and maintenance.
However, with established plants, while some re-engineering is possible,
pollution reduction might be the only option. This includes substitution
with more environmentally friendly raw materials and biodegradable
process chemicals, as well as staff education and training to identify
pollution issues and remedy them.
• Removing contaminants
Industries discharging into municipal systems or surface water have
to comply with discharge by-laws or other regulations to avoid fines,
so in many cases end-of-pipe treatment is required at the plant before
release. In some situations, industries find it also more economical to
pay fines than to invest in treatment to meet regulations.
Mixed effluents require complex treatment trains and result in one
quality of wastewater discharge to mee