Discharging trade effluent

Reducing and treating your liquid waste can lower your trade effluent bills. You can cut costs by:

• reducing the amount of wastewater you generate overall
• reducing the strength of your trade effluent
• reusing wastewater wherever possible

You can use the Mogden Formula to calculate the cost of discharging trade effluent to sewer.

To reduce costs you could consider:

• checking your meters and meter readings are accurate, especially at sites with more than one trade effluent discharge consent - if the total effluent discharge volume of your site is estimated across a number of discharges, a higher volume may be applied to a higher strength discharge resulting in disproportionate charging
• mixing a higher strength discharge with a lower strength discharge
• evaluating whether an effluent stream from one process can be reused as an input to another process
• treating effluents prior to discharge - eg simple physical or chemical treatment of an effluent stream before discharge to sewer will lower the cost of further treatment by Northern Ireland Water (NIW)
• treating a higher strength effluent to recover for reuse a raw material that would otherwise have been disposed of
• ensuring that the composition or volume of effluents does not breach your consent, as you could be prosecuted and fined
• reducing water use to cut your meter charges and your wastewater bill

Install effluent treatment systems

The cost of discharging trade effluent to a sewer is based on the volume discharged and the concentration of contaminants, so it could be worth installing some form of preliminary treatment system. For example, a simple sedimentation tank could remove a large percentage of the suspended solids in the effluent.

You must comply with your duty of care responsibilities when you dispose of waste from an effluent treatment system. This means you must ensure your waste is handled, recovered and disposed of correctly.

You need to manage and regularly maintain treatment systems to ensure that they are working correctly. Consider whether the benefits of reducing the contaminant load and the cost to discharge outweigh the extra maintenance and operational requirements, as well as the initial capital costs.

Some systems are so effective that you might be able to recover and reuse the effluent on site, saving more water and discharge costs. You may also be able to recover raw materials that could be reused.

Establish effluent discharge procedures

Make sure that your staff record the effluents being discharged accurately, particularly if they are responsible for emptying and discharging effluents from specific processes.

If any new processes are added, this will add to the volume and contaminants being discharged. Check the effluent produced to ensure that your consent is still valid.

Have a site plan that identifies all access and entry points to the sewerage system. Workers responsible for discharging effluents should be made aware that the access and entry points are specifically for trade effluents only. Make sure that any surface water drains can't be mistaken for foul sewer drains.