Excessive heavy metal content is one of the main characteristics of waste oil. Heavy metals may become the characteristic chemical components of waste cooking oil due to pollution in the recycling process or the introduction of heavy metals after contact with metal utensils.

Is it watered?

Personally, I think it is rare, because gutter oil is also used for cooking. If there is too much water, the oil will splash after adding it, which will seriously affect cooking and cannot be used. Besides, I have seen reports on TV before. Waste oil must be refined after it is collected. Of course, refining will drain water, right?

I'm not a connected person, and very few connected people come here.

Supplement:

Detection methods, talk about domestic.

Main research progress in China 2. 1 analysis of physical and chemical indexes 2.2 heavy metal detection 2.3 fatty acid composition analysis 2.4 cholesterol content 2.5 conductance method 2.6 thin layer chromatography 2.7 fluorescence method (see the research status of differential detection methods for gutter oil for details).

As mentioned above, other conductive substances, mainly the residue particles in gutter oil, contain a certain amount of salt, and the rancid compounds will also improve the conductivity. See the academic paper above, thank you.