Grease & Fat Traps
A grease trap, or Fat, Oil and Grease (FOG) interceptor, is a plumbing feature designed to capture mostly everything that goes through the drain carried by the water, grease, and other solid and liquid matter from entering a septic system. If grease enters the sewers, it will congeal, forming a solid mass. These solid masses cause backups, clogs and burst pipes. Grease traps are used by businesses, schools, hotels, hospitals and other large institutions that use commercial sized kitchens where a lot of FOG’s are generated. To prevent the FOG’s from going down the drain in these facilities, a grease trap is installed. If these contaminants are not kept in check, they can cause severe problems to your plumbing and sanitation system. All commercial kitchens are, by law, expected to have grease traps installed to collect the FOG’s before they enter the sanitary system.
There are two principles at work; the first is that food debris sink, and the second is that the FOG’s float.
A grease trap generally has two separation basins, separated by baffles which control the water flow thus inhibiting it from washing the debris from the trap during times of fast flow. The first basin fills with all the matter that is drained from the sink. There the matter is cooled. When grease is cooled, it congeals, becoming a solid. Both the solid matter and the congealed grease float to the top while the heavier particles sink and settle in a removable basket, leaving the liquid at the bottom of the first basin. At the bottom of the first basin is an opening that allows all liquid matter to flow into the second basin. The second basin is used to trap any additional grease that may have gotten through the first basin, so the same process is repeated.
As per the National building regulations, Municipal by-laws, (SABS 0400-1990-pp23.3) “A suitable grease trap shall be provided to take the discharge of waste water from any sink or other fixture” The approved standard being Drawing No. S4/729
CleaningThe grease trap needs to be cleaned in order to work properly, and it is possible for the grease trap to become too full to function.
Besides the daily emptying of baskets and other cleaning up it may require there are bacteria that should be introduced to your grease trap. These facilitate the breaking down of the FOG in your grease trap. You should never add any other cleaners, such as bleach, ammonia, or enzymes, as they will interfere with the bacteria. These bacteria will help keep the odors to a minimum and allow the FOG’s to be digested.
Fats, Oils and Grease cause untold troubles at any Waste Water Treatment Works (WWTW) as they are so much more difficult to degrade/breakdown.
Municipalities are applying increased pressure on business to ensure the effluent it releases into the main line system complies with the standards laid down by legislation. Failure to comply is being met with extremely heavy penalties being charged.
The potential loss of revenue, inconvenience, expense and accompanying health risk due to drains blocking, overflowing and stinking are problems we can all do without. We have all at some point experienced it.
One must ensure:
- An effective cleaning program must is in place for the daily removal of the solids from fat trap baskets, drains and spent oil.
- Marked bins should be made available for the disposal of fat trap/wet-waste contents and used oil.
- The current fat trap must comply with the standard laid down by Cape Town City Council. As per the National building regulations, Municipal by-laws, (SABS 0400-1990-pp23.3) “A suitable grease trap shall be provided to take the discharge of waste water from any sink or other fixture” The approved standard being Drawing No. S4/ 729.
- Fat traps have been installed correctly and that it is complete.
- Restaurants, using the services of a Spec/Dip tank, must ensure that the company which services these tanks is utilising organic, environmentally friendly cleaning solvents, if not the contents must not be disposed of down the drains. This practice is unlawful and will kill off any bacteria present in the fat traps. These contents must be taken off the premises and disposed of responsibly/legally.
- An on-going biological (bio-augmentation) maintenance program should be implemented through the kitchen sinks, drains and fat traps.
- Staff is trained regarding the function of a fat trap and the general do’s & don’ts.
- Cleaning chemicals, which ultimately reach the fat trap chambers, should be reviewed. Harsh chemicals will kill off any naturally occurring biological activity. There are a number of reputable suppliers of Bio-friendly chemicals.
- Safety data sheets pertaining to all chemicals used should be available and kept on site. These sheets will provide useful information informing the user what to do in the event of an unwanted spillage, contact with the eyes, accidental swallowing of product etc. It must also indicate if it is environmentally friendly and indicate its composition.
- Floor drain baskets must be in place at all times.
- In shopping centres Centre Management should be informed when a deep-clean is going to be conducted as this requires powerful chemicals. With this being flushed down the drains it will kill off any bacteria present and the consequence to this is bad smells, congestion and potential system back up’s.
The benefits of an effective bio-augmentation program are:
- Vastly reduces and in most cases eliminates the necessity to use vacuum pumping.
- Removes foul odours.
- Prevents and overcomes the problematic build-up of fats, greases and sludge in pumping sumps, drains and pipes and further keeps the effluent free flowing.
- Rapidly breaks down any organic solids build up and suspended solids build up to a liquid form by increasing the natural biodegradation process.
- Prevents the build-up of surface crust and anaerobic sludge which in turn will extend the life of pumps and ensure capacity of the Catchment area is not diminished.
- Improves the biodegradation efficiency per unit volume, hence reducing the BOD (biological oxygen demand)/COD (chemical oxygen demand) and penalties being paid, if not eliminating them completely.
- In the event of harsh chemicals killing off the natural biomass, you are able to regenerate the biomass.
- Will contribute to the reduction of operational expenses.