Cheap enzyme dosing grease management, busting the cheap grease trap myth. Dosing vs grease trap

Drain dosing system, Enzyme Dosing System or Biological dosing systems as they are often called are sold to offer an ingenious solution to the Fat, Oil and Grease (FOG) issues such as blockages, compliance, odour and more. The basic claim is that it breaks down / eat up FOG before leaves the building so that it cannot cause damage or problems further down the line. It is stated that an eco-friendly bacteria solution dosed in to the drains effectively metabolise FOG before the water leaves the pipes.

The key questions are is it true or does it work, but more importantly is it a cost effective solution to the problem and does it prevent blockage and damages.

On the first question, does it work?

Legally the answer is NO as per High Wycombe Magistrates’ Court on May 28 - 2021

A pub chain at High Wycombe Magistrates’ Court on May 28 - 2021, pleaded guilty to breaches of the Water Industry Act 1991 and was fined £75,000, the highest amount handed out for this section of the act, along with £3,000 in compensation and costs of £13,000 for solution the sewers.

The court heard pubs was using a type of grease management called enzyme dosing, which doesn't remove fats and oils at source, meaning they can still cause problems in the sewer network. For full details click her

Process wise the answer is very doubtful if not a straight NO

Several studies by universities have not been able to prove a clear result when it comes to using Enzyme dosing as a FOG management system. Anecdotally there are many kitchens that do not see the benefit of dosing system.

Going back to basic biology "metabolise" means breaking down food, using oxygen to release energy to sustain an organism. Looking at this in the context of a drain or drain pipe. Drain pipes are designed to carry everything away and do not allow for a host or organised to establish itself, while P-traps and U-bends prevent the flow of oxygen and air. Therefore a drain pipe is one of the most inhospitable environments to support a metabolising organism even for short periods of time.

Cost effectiveness of enzyme or biological dosing. One of the key benefits highlighted for dosing systems is that no daily interactions are required, therefore we are including a daily maintenance costs of 5 minutes of labour at £12 per hour and running cost of £0.25 per day to make this a fair comparison.

While the first part of the article established that any treatment claims made for dosing systems are dubious at best, it now turns out that even cost effectiveness is questionable and only works if biological dosing systems are operated in a low or standard setting. Increasing the dosing intensity immediately effects the running cost of an enzyme dosing system and very quickly tips the overall cost in favour of an automated grease retention unit.

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