Resource Centre | Grease Trap Resources

Chemical & Biological Additives

There are many products on the market that claim to reduce, or eliminate, the need for regular interceptor cleaning by reducing or even eliminating the accumulation of grease in the interceptor. New products come and go every week. Harsh chemicals can seriously damage pipes and/or the couplings that connect them. Some products simply "liquefy" the grease, which allows it to be flushed out of the interceptor only to re-congeal down-stream eventually causing even greater problems. Some "bacteria" based products claim to "digest" waste "naturally". However, to our knowledge, no scientific proof exists that this actually occurs - and science suggests that it cannot.

Many of these products have serious health and safety risk associated with their handling and use. Almost all of the products we have reviewed, if used as directed, cost quite a bit more than a proper preventative maintenance pump-out program. As a property owner, you are responsible for what you discharge into the sewer system. As an employer, you are accountable for the health and safety of your staff. Drainage and sewer systems are extremely expensive to replace or repair, and you can be held financially responsible for blockages or damages down-stream.

There are two forms of these products on the market; biological or biochemical products and chemical and/or solvent based products.



Chemical / Solvents

Chemical solvents are intended to dissolve or emulsify grease and promote its discharge through the interceptor into drains and sewers. Dissolved or emulsified grease can accumulate downstream in drains and sewers, leading to blockages. Chemical solvents are often toxic and/or combustible, and require special storage and handling precautions to protect workers health and safety. Most municipalities prohibit the use of chemical solvents.



Bio-augmentation Products

Bio-augmentation products are intended to reduce grease accumulation by biologically degrading the grease in the interceptor. These products typically contain a combination of emulsifiers ("wetting agents"), enzymes, bacteria and other compounds intended to support microbial growth. Bio-augmentation products are commonly promoted as being a "biodegradable" or "environmentally friendly" alternative to chemical solvents. Some even claim to "digest" waste in the interceptor.

Independent study of the performance of bio-augmentation products in grease interceptors supports the experience of many food service establishments; that these products are not effective replacements for regular clean outs.

A study commissioned by the Greater Vancouver Regional District in 19961 found that the literature provided by the manufacturers of bio-augmentation products did not provide reasonable evidence for efficacy in cleaning grease interceptors. It was also noted that there is no independently published scientific or technical information on the biodegradation of oil and grease in grease interceptors using biological additives.

The report describes microbial processes for oil and grease degradation and states that grease interceptors are not a good environment for oil and grease degradation. Most grease interceptors are subject to conditions that can prevent or hinder biodegradation. These conditions include short retention time, presence of compounds toxic to microorganisms and extreme physiochemical conditions (i.e. temperature, pH, oxygen concentration, and the lack of nutrients required for microbial growth). The report suggests that it is reasonable to be skeptical about the efficacy of bio-augmentation products for grease interceptors until evidence in support of efficacy is found.

A separate study2 involving ten restaurants in the City of Toronto was conducted in 1995 by the Ontario Ministry of Environment and Energy. The purpose of the study was to evaluate bio-augmentation products against the claims made by their manufacturers. Claims include reductions in maintenance requirements (i.e. clean outs), odour and grease accumulations in drains and sewers. It was also claimed that, through the use of microbial products, it may be possible to achieve compliance with sewer discharge limits.

Before and after comparisons were used to evaluate the efficacy of biological products against the claims made. Observations and measurements taken demonstrate that, with the exception of a reduction in odours from the grease interceptor in some instances, the products did not perform as claimed. The products did not achieve consistent, significant reductions in maintenance requirements, grease accumulations in drains and sewers, or the strength of the discharged wastewaters.

Finally, grease interceptors also accumulate settled solids that cannot be removed by additives. Neither chemical solvents nor bio-augmentation products can effectively reduce the accumulation of solids in the interceptor. Often these solids contain mop strings, toothpicks, paper towels, creamers, bottle caps and other trash that can cause drain blockages. Settled solids can neither be dissolved nor emulsified nor degraded in the interceptor and must be removed by regular physical cleanouts.

We do not recommend the use of any biological or chemical drain cleaning, or grease interceptor cleaning products.


1 Mohn, W.W., "Report on Microbial Products for Grease Traps", April 1996 (commissioned by the Sewage and Drainage Department of the Greater Vancouver Regional District). Author is with the University of British Columbia, Department of Microbiology.
2 Bio-augmentation in the Restaurant Sector by: H. Kronis, Program Development Branch, Ontario Ministry of Environment & Energy, July 1996



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