If you have similar queries about any aspect of your Domestic Waste Water Treatment Plant, plant please call one of our dedicated service technicians who will be happy to advise you.
What is a grease trap?
There are two types of grease trap, a passive grease trap or a grease recovery unit (GRU).
Passive Grease Trap
This a large tank that can be mounted above or below ground and can be called a separator or an interceptor. They are constructed with walls, called baffles, within the unit mounted at differing heights that will still allow liquids to pass but perform some important functions.
- They assist to slow the flow of water by acting as a barrier or partial blockage the liquid must flow around
- The lower mounted baffle will generally be connected to the floor of the unit and the top will be submerged below the surface, this allows it to collect any solid debris such as food and prevent it from making its way downstream out of the grease trap
- The upper mounted baffle’s upper edge will sit above the surface level of the tank and the lower edge will only extend a portion of the way below the liquid level. This baffle will catch any FOG’s that have separated and floated to the surface of the liquid.
They should also have a deep seal or drop down section of pipe at the inlet & outlet of the chamber. The deep seal at the outlet will prevent any contaminants based on the surface of the liquid from flowing out of the grease trap. The deep seal at the inlet is another flow restriction method and will reduce turbulent flows entering the grease trap. Both deep seals on the inlet and outlet will increase the efficiency of a passive grease trap. There are many sizes, shapes and different materials available for passive grease trap construction.
Grease Recovery Unit (GRU)
A GRU is a undercounter or kitchen based unit. GRU’s offer a method of FOG’s management in a different manner to the passive grease trap. Whereas the passive trap relies on retaining the FOGs within itself, the GRU will actively attempt to remove the FOGs from the liquid as it passes through it. This is generally performed by mechanical aids such as heating the liquid up via a heating element or skimming the surface of the liquid via rotating drum or disks. As with the Passive grease traps, there are many different manufacturers and sizes of these units.
Why do I need a grease trap?
Any commercial property, from a café to a pharmaceutical plant that has a catering facility is required by law to have a grease trap. It’s size and specification is established at build stage when a Trade Effluent Discharge Licence (TEDL). The primary goal of installing a unit, be it a passive grease trap or a GRU, is to prevent FOG’s from entering the sewer system. FOG’s can cause damage to Pump stations and waste water treatment plants which in turn can cause them to be less efficient. When this happens, it damages our waterways and beaches as the treated water leaving the plant, which should be acceptable for the local environment it is discharged to, exceeds safe levels for local flora & fauna.
Why do I need to maintain a passive grease trap?
A passive grease trap will, due to its design, attempt to retain the majority of the FOG’s content that pass through it. There will generally be three distinct layers of material within the chamber:
- On the base will be debris. This is primarily food debris and other kitchen detritus that makes its way down the drains.
- In the middle will be a liquid layer. This will comprise of mostly of water, some detergents and emulsified FOG’s
- On the surface will be a crust or layer of FOG’s. This segment of the chamber materials is where most of the FOG’s content from the kitchen will separate to.
So, with this in mind, we must look at the lifecycle of the grease trap contents. Following a de-sludge or empty of the unit, the middle layer will take up the most space. The tank will be refilled by the contractor and liquid effluent from the kitchens will re-enter the tank and the separation process will begin again. Over time, the other two layers will build up and begin to take a greater share of the space available. Once the base layer hits 25% of the overall depth of the tank, it is time to get the trap de-sludged.
If this is not performed, then there is a risk that the debris on the floor of the tank will build up to a higher level and reduce the efficiency of the trap to effectively separate FOG’s from effluent leading to excessive FOG’s being discharged from the grease trap. In this event, there may be a blockage caused by the amount of excess FOG’s making their way out of the grease trap or if a sample is taken by Irish water or the EPA, then a breach of compliance may be recorded resulting in various diffident penalties or requirements being met.
Why do I need to maintain my Grease Recovery Unit?
A Grease Recovery Unit is an electro/mechanical unit designed to actively remove FOG’s from liquid effluent. In order to do this, the unit will require maintenance just like a car or any other electro/mechanical piece of equipment. Due to the varying nature of the units available, it is impossible to accurately describe the exact maintenance method of them all here. However, we do advise following all manufactures guidelines in reference to the prescribed maintenance regime they recommend.
If the unit is not maintained, then the results can be the same as with the passive grease trap above, blockages and compliance issues with your governing authority. But with these units, a lack of maintenance can also lead to component failures and costly repair bills.
How big should my grease trap be?
Both Passive Grease traps and GRU’s are sized based on data given based on the kitchen operation, it’s output and equipment. With the GRU’s, a sizing is done on the direct fittings or fixtures they will be connected to under the Plumbing and Drainage Institute Guidelines 101 (PDI-G 101). These units are generally connected to a single sink or a combioven.
With passive grease traps, they are sized based on IS EN 1825: 2002 & 2004 Parts 1 & 2. There are two calculations which can be performed under this standard. A calculation based on the fittings and fixtures that produce the FOG’s, and one based on the hours of operation and the estimated meals per day. These calculations will often produce different sizes and in these circumstances the IS EN 1825 standard recommends that the larger size interceptor/separator be selected for installation.
If you would like to arrange a sizing to be performed on you kitchens, call us today for a free consultation
What happens to grease that is sucked out of traps?
All Effluent that is de-sludged from grease traps is required by law to be taken by a licenced contractor to a suitable waste disposal facility. These facilities can compost the waste or process it through Anaerobic Digestor processes. With the Anaerobic digestion process, it is possible to produce electricity from the gases produced from the process making this a more environmentally friendly option. Both Compost and Anaerobic digestion will also produce compost and fertiliser products for the farming industry meaning that the waste product removed from your grease trap by licensed contractors will be processed correctly for environmental benefit
Why should I use Dyno-Rod to maintain my Grease Trap?
Dyno-Rod has over 20 years’ experience with grease trap maintenance. We provide our customers the highest level of service and this has meant that a number of our clients have been with us since the day we started.
Using our specially formulated BioFlo bacterial Dosing System, regular de-sludging, compliance documentation and years of experience Dyno-Rod can provide you with the best value for money on the market today. Our Grease Trap Maintenance division is managed by a team of Mechanical, Civil and Environmental Engineers and our operators are highly experienced in this field.
Dyno-Rod can manage any grease trap project from start to finish meaning we can Size, Supply, Install and then Maintain your entire FOG’s management system. By ensuring this comprehensive service, Dyno-Rod is at the forefront of the drainage industry and can provide specialist troubleshooting and consultative services when issues occur such as breaches in FOG levels or when repairs to grease traps are required.
Call us today to arrange a meeting to discuss your Grease Trap Maintenance
We operate 24 hours a day, 7 days a week, 365 days a year across Dublin, Cork, Galway, Limerick, Kildare & all of Ireland to ensure that you are always covered when domestic, commercial and industrial drainage problems arise.