Oil separator is a kind of wastewater pretreatment structure that uses the density difference between oil droplets and water to float up as a way to remove the floating oil substances in oily wastewater. The structure of the oil separation tank is mostly of the horizontal flow type. The oily wastewater enters the rectangular oil separation tank through the distribution tank and flows slowly along the horizontal direction. During the flow, the oil product floats on the water surface and is pushed to the oil collection pipe by the oil collection pipe or the oil scraper set on the tank surface and flows into the dehydration tank. The heavy oil and other impurities settled in the oil separation tank accumulate in the sludge hopper at the bottom of the tank and enter the sludge pipe through the sludge discharge pipe. After oil separation treatment, the wastewater overflows into the drainage basin of the drainage channel for subsequent treatment to remove emulsified oil and other pollutants.
The basic principle of using oil separator and sedimentation tank to treat wastewater is the same, and the purpose of separation is achieved by using the different specific gravity of suspended solids and water in wastewater. The structure of the oil separation tank is mostly of the horizontal flow type. Oily wastewater enters the rectangular oil separation tank through the distribution tank and flows slowly along the horizontal direction. In the flow, the oil product floats on the water surface and is pushed to the oil collection pipe by the oil collection pipe or the oil scraper set on the tank surface and flows into the dehydration tank. The heavy oil and other impurities settled in the oil separation tank accumulate in the sludge hopper at the bottom of the tank and enter the sludge pipe through the sludge discharge pipe.
Oil separators are usually constructed of reinforced concrete or masonry. On a rectangular plane, they are divided into 2-4 grids along the direction of water flow, and each grid is generally not more than 6 meters wide, so as to distribute water evenly. The effective water depth is no more than 2 meters, and the length of the oil separation tank is generally more than 4 times larger than the width of each grid. Chain belt oil scraper and sludge scraper are used to scrape the floating oil and sludge at the bottom of the oil separation tank. Generally, each grid is equipped with a set of oil scraper and sludge scraper, and a sludge hopper. If a baffle is added in the middle of each grid, an oil scraper and a sludge scraper are installed on both sides of the baffle, and a sludge hopper is set, it is called a two-stage oil separator, which can improve the oil removal efficiency, but the increase in equipment and energy consumption increase. If a number of inclined plates are added in the oil separation tank, the oil removal efficiency can also be improved, but the construction investment is relatively high. In cold regions, steam pipes can be set at the bottom of the oil collecting pipes to prevent oil solidification in winter. Generally, the oil separation tank shall be covered, and a steam pipe shall be set under the cover plate for thermal insulation, to prevent fire and oil volatilization in the oil separation tank, and to prevent ash and sand from entering.