Due to the wide range of sources of oily wastewater, the properties and differences of oily wastewater are also great. Generally speaking, the oil content of oily wastewater is tens of thousands to thousands of mg/L, or even tens of thousands of mg/L. So what harm will oily wastewater detection pollution bring? China is the most populous country in the world. Demand for water will also be higher than in other countries. With the high demand for water, sewage discharge will also increase. There are many types of sewage, such as domestic sewage and industrial wastewater. What harm can oily wastewater pose? Let's find out. 1. If untreated oily sewage is discharged at will, it will pollute our daily drinking water sources. Once the drinking water source is polluted, it will not only spread diseases, but even cause food poisoning. In addition, there will be a certain amount of carcinogens in oily water. Therefore, oily sewage may increase the incidence of cancer in polluted areas. 2. The concentration of oily sewage is lower than normal water quality. If these untreated oily sewage is discharged into rivers and lakes, the pollutants in the sewage will adhere to the water surface, making the atmosphere and water bodies unable to exchange normally, the oxygen in the water will become less and less, and the organisms in the water will not be able to grow normally. In addition, the water quality is polluted, which also greatly reduces the utilization rate of water resources. 3. If oily sewage is used for land irrigation, the oil in the sewage will be deposited on the surface of the crops, preventing the soil from exchanging air with the outside world, slowing down soil metabolism, affecting crop growth, and even causing crop death. These oily crops can also be harmful to our health if we consume them. Next, let's look at the causes of groundwater pollution and the methods of sewage treatment. Mercury-containing wastewater mainly comes from non-ferrous metal smelters, chemical plants, pesticide plants, paper mills, dye plants, and thermal instrument plants. The methods for removing inorganic mercury in wastewater include sulfide precipitation method, chemical coagulation method, activated carbon adsorption method, metal reduction method, ion exchange method and microbial method. Alkaline mercury-containing wastewater is usually treated by chemical coagulation or sulfide precipitation. Acidic mercury-containing wastewater can be treated by metal reduction. Low-concentration mercury-containing wastewater can be treated by activated carbon adsorption, chemical coagulation or activated sludge. Organic mercury wastewater is difficult to treat. Organic mercury is often oxidized to inorganic mercury prior to disposal. The toxicity of various mercury compounds varies widely. Elemental mercury is basically non-toxic; methylmercury in inorganic mercury is highly toxic, while phenylmercury in organic mercury decomposes quickly and has low toxicity; methylmercury is easily absorbed by the human body, not easy to degrade, and excreted slowly, especially in the brain accumulate. The most toxic diseases, such as Minamata disease, are caused by methylmercury poisoning.