Grease trap
Grease separators separate fats and oils from the wastewater . The greasy and oily dirty and rinsing water from kitchens in the catering, hotel or communal catering sectors must be disposed of using a grease trap. Grease separator systems pre-purify commercial wastewater before the water drains into the sewer system .
Fat floats due to its lower density , collects on the surface and can be removed. The oil- and grease-free wastewater flows into the sewer. Since the flow rate of the wastewater also decreases in the system, heavy solids (leftover food) sink to the bottom and settle in the sludge trap.
function
Most grease traps operate on the principle of gravity; H. the difference in density between fat and water phase separates , while heavier solids sink to the bottom.
Grease separators consist of an inlet with a baffle wall or a similar device to calm the water, an outlet that takes the water from below the fat layer, and the central fat collecting space, on the bottom of which also sediment settles, unless a separate chamber is upstream as a sludge trap. Furthermore, after the grease trap there is a need to take samples, e.g. B. in the form of a shaft.
Fats and oils emulsified in the wastewater ( emulsion ) pass through a grease separator that works exclusively according to the principle of gravity, mostly unhindered. In particular in industrial companies and regions where low waste water limit values are required for oils and fats, more extensive waste water treatment downstream of the grease separator is necessary. Conventional grease separators cannot achieve the limit values required here. By using a splitting or flotation system , the limit values can be permanently and safely undercut.
There are grease separators for installation in the ground and systems that are set up freely.
conditions
Grease separators for underground installation are to be installed outside of buildings near the source of the dirty water, at a point that is easily accessible with the suction hose of the disposal vehicles. Freely installed grease traps must be in frost-free rooms.
The installation of grease separators in rooms in which food is prepared is not permitted for reasons of hygiene.
Mobile installed grease separator systems are only permitted for temporary structures such as mobile sales stands or at parties.
Grease separators that are installed below the backflow level must be connected to the sewage system with a lifting system (with backflow loop).
The installation of grease traps is subject to approval.
The nominal size (NS; formerly: NG) of a grease separator system is based on the amount of waste water that accumulates and is measured in liters per second.
If the inlet line above the separator system does not have a vented connection line over a length of 10 m, then according to DIN EN 1825-2 the inlet line must be provided as close as possible to the grease separator with an additional ventilation line in the cross section of the inlet pipe (DIN EN 1825-1), which extends up to is to lead over the roof. Connection lines longer than 5 m to the vented main supply line must be vented separately.
The ventilation lines of the supply line and, if necessary, the grease trap can be combined to form a collective ventilation system, to which, however, the ventilation line of a lifting system (DIN EN 12056-4) or other ventilation systems (DIN 1986-100) may not be connected.
Complete or partial disposal
Complete disposal : According to DIN EN 1825, classic grease separators should be completely emptied, cleaned and then topped up with fresh water at least every four weeks by a waste disposal company. Modern grease separators have a permanent connection for the disposal line. The line is permanently installed inside the building and ends with a coupling on the outside of the building. The coupling is usually housed together with a remote control in a surface-mounted or flush-mounted box; with fully automatic grease separators, disposal is automated. The contents of the grease trap can thus be discreetly picked up by a tanker.
Partial disposal: There are also grease separators in which grease and sludge are separated in handy plastic drums and then disposed of. The operator can dispose of the collecting drums with the concentrated residues himself if necessary. Due to the needs-based disposal, the operating costs are usually lower than with complete disposal by tanker. In addition, the amount of material to be disposed of is reduced to around ten percent compared to complete disposal. In the case of grease separators with partial disposal, the disposal of grease and solids can also take place directly via a connection to a central wet waste disposal system. The separated materials are sucked into a central collection container together with other food waste and are regularly disposed of from there.
Statutory Regulations
The use of grease separator systems is regulated by the standards DIN EN 1825-1 and DIN EN 1825-2 as well as the national annex DIN 4040-100. It applies to businesses with commercial food distribution such as restaurants , hotels , large kitchens and snack bars that produce fatty wastewater.
In contrast to DIN EN 1825, DIN 4040-100 requires a separate sludge room and sets fixed specifications for the necessary minimum volumes of sludge trap, grease collecting room and grease separator as a whole as well as for the minimum surface area of the grease separator room, while according to DIN EN 1825 with hydraulic verification , these values are also not reached is possible.
Industrial food processors ( dairies , cheese factories , fish processing , dishwashers, kitchen waste treatment plants) produce wastewater with a high proportion of emulsified fats / oils. This wastewater is not always treated effectively in grease separator systems based on the principle of gravity. Further wastewater treatment may be necessary.
Overview of the legal regulations
Technical regulations:
- DIN EN 1825-1, Separator systems for grease - Part 1: Construction, functional and test principles, labeling and quality control; German version EN 1825-1: 2004
- DIN EN 1825-2, Separator systems for grease - Part 2: Choice of nominal size, installation, operation and maintenance; German version EN 1825-2: 2002
- DIN 4040-100, separator systems for fats - Part 100: Requirements for the use of separator systems according to DIN EN 1825-1 and DIN EN 1825-2
- DIN EN 1717, protection of drinking water against contamination in drinking water installations and general requirements for safety devices to prevent drinking water contamination through backflow - technical rule of the DVGW
- DIN 1986-100, drainage systems for buildings and properties - describes the basic application and some boundary conditions
- DWA - DVWK - M 767, wastewater from the meat processing industry
- DWA - DVWK - M 768, wastewater from the fish industry
Legal provisions:
- Section 57 (requirements for the discharge of wastewater) and Section 58 (2) No. 3 of the Water Management Act - WHG (federal government)
- Drainage statutes of the respective municipalities, z. B. § 2 No. 10 and § 5 Wastewater Statute of the City of Düsseldorf
- Food hygiene regulations of the federal states
- Animal By-Product Disposal Act - TierNebV (Federal Government)
- Biowaste Ordinance - BioAbfV (Federal Government)
- Guidelines for the operation and monitoring of grease separator systems
- Building supervision certificate of usability of the specific system
- State building regulations (LBO)
- Municipal drainage statutes name limit values and discharge conditions for public sewage systems ( sewer systems ) and mostly refer to DIN EN 1825
literature
- Jürgen Mühltner: Biological fat separator aftertreatment. In: IHKS-Fachjournal: 2005/06. download
- Marco Eulenstein: Grease separators in practice. In: IHKS-Fachjournal: 2004/05. download
Web links
- w as knowledge information on recycling of (cooking) waste oil and grease trap residues
Individual evidence
- ↑ a b Planning manual for grease separators from Kessel, accessed in March 2017
- ↑ Current regulations for grease traps