general methods for sewage treatment in domestic catering industry

grease trap is the most commonly used method for sewage treatment in domestic catering industry. The principle of grease trap is to separate grease naturally by using the different densities of grease and water in sewage. Because natural separation takes a certain time, and this time is related to the specific state of the oil in the treated sewage, most of the oil and suspended particles in the restaurant sewage are very small, so it is difficult to separate them by gravity within a limited residence time. For this part of the oil and suspended particles, the oil separation tank can be said to be helpless.

The oil separation tank has its own design specifications. However, in practical engineering application, due to various objective, subjective and economic reasons, the owners often adopt crude design, which leads to low oil separation efficiency. What's more, some small restaurants don't have oil separation equipment installed at all, and the restaurant sewage is basically in a state of direct discharge. Therefore, the biggest disadvantage of the grease trap is that there is no way to effectively remove grease and suspended substances.

There is another way to treat oil and fat, air flotation. The treatment effect of air flotation on restaurant sewage is relatively good in theory, and the removal rate of oil and fat can reach 98% to 99%. However, the biggest disadvantage of air flotation is that the investment and operation costs are too high, which makes it difficult for domestic restaurant operators to actually use it. It is only a theoretical model and cannot become a real commodity.

Coagulation is also a common treatment method. Specifically, by adding coagulant to sewage, oil and suspended particles are converted into sludge for precipitation. The biggest problem of this method is how to adjust the coagulant dosage in time according to the change of sewage, so it is generally difficult to ensure stable oil removal efficiency.

in addition to the above methods, there are some less commonly used methods such as biological treatment and electrolysis. The exact effect of these methods is still not recognized.