The main pollutants contained in machining waste liquids are oils (slick oil, emulsified oil, etc.), surfactants, refractory organics and some residual soluble metals or sediments. The main method for processing mechanical wastewater is chemical method. , physical methods, biochemical methods and the combination of various methods, the following describes each treatment method.
1. Pretreatment method for machining cutting fluid
Due to its complex composition and good chemical stability, the cutting waste liquid is difficult to handle directly. Generally, it needs to be pretreated and then processed. The pretreatment is mainly to break the waste liquid to remove the oily substance in the water or the oil in the oil. Depending on the action of the emulsifier, the reasons for the stability of the emulsion include interfacial tension, properties of the interface film, and interfacial charge. Emulsified waste liquid can be destabilized according to these influencing factors during the demulsification treatment and easy to handle.
2. Processing method of mechanical processing wastewater
The usual acid precipitation treatment method refers to a method in which certain substances are separated from a dissolved state or a colloidal state into a suspended state under acidic conditions, thereby separating oily substances and the like from the liquid, and the method is simple in operation, and the agent used is generally used. For concentrated acidic substances such as sulfuric acid and nitric acid, it is also possible to use a waste acid solution instead of a pure acidic reagent. Demulsification treatment of waste emulsion with nitric acid results in a COD removal rate of 97.80%, a small amount of oil, and provides suitable pH conditions for subsequent Fenton treatment. The acid photo-demolition emulsified wastewater was acidified and demulsified by concentrated sulfuric acid. When the pH was adjusted to below 4, the COD removal rate was 75.2%. The waste liquid was clear and transparent, and the precipitate was easy to be separated.
