The grease trap, also known as the grease trap, is mainly used as a device to separate grease and sundries from water in the wastewater discharged from the catering industry.

I. Classification of oil separators

Oil separators can be divided into stainless steel oil separators, carbon steel anti-corrosion oil separators, carbon steel plastic spraying oil separators, glass fiber reinforced plastic oil separators, etc.

according to the installation method, it can be divided into: above-ground oil separator, buried oil separator and hoisting oil separator.

according to the water inlet mode, it can be divided into: open trench oil separator, pipeline oil separator and so on.

according to whether there is power or not, it can be divided into: ordinary oil separator, automatic oil separator and automatic scraping oil separator.

According to the grille, it can be divided into mechanical grille oil separator, ordinary grille oil separator and

II. Main principles

Generally, the density of oil substances is smaller than that of water, and they can be divided into floatable oil, dispersed oil, emulsified oil and dissolved oil according to their existing state in water, among which floatable oil and dispersed oil have large particle sizes and can be separated from water by the difference in specific gravity between oil and water. The wastewater flows in from one end of the tank and flows through the tank at a relatively low flow rate. During the flow, the oil particles with a density lower than that of water rise to the water surface, and the water flows out from the other end of the tank. An oil collecting pipe is arranged at the upper part of the tank body to collect the floating oil and guide it out of the tank. Emulsified oil cannot be directly removed by static sedimentation, and it needs to be demulsified first and converted into floatable oil before it can be removed. Dissolved oil is dissolved in water and cannot be removed by grease trap

III. Construction standard of grease trap

According to national environmental protection standards and technical specifications of oily sewage treatment engineering, domestic sewage in collective canteens must meet the corresponding sewage discharge standards, so the treatment of catering sewage is very important. According to policy requirements, the determination of treatment method is related to the geographical location of the construction project, the amount and concentration of wastewater discharged. The greater the discharge and concentration of wastewater, the higher the treatment level is required.

(1) residence time t, generally 1.5-2h；;

(2) the horizontal velocity v is generally 2-5 mm/s;

(3) The width b of each compartment of the grease trap is 2m, 2.5m, 3m, 4.5m and 6m. When the oil slick is removed manually, the width of each cell shall be ≤3m. The major refineries in China generally use 4.5m, and the design has been finalized.