With the continuous development of social economy, people pay more and more attention to the quality of the surrounding environment, especially those environmental pollution problems that can damage people’s health. In the field of machining, emulsion wastewater mainly comes from industries such as mechanical cutting, mine machining and cold rolling plant. In the process of metal material cutting and rolling, emulsion plays the role of condensation, lubrication It is mainly composed of surfactant, stabilizer, antirust agent, defoamer, lubricant and other process additives, and the concentration is generally between 2 ~ 10%.
Generally, the emulsion will be treated in a preliminary and timely manner, but with the growth of mechanical processing, a large amount of emulsion, or pretreatment wastewater after oil / water, hydrocarbon / water mixture and other wastewater treatment, as well as waste oil treatment workshop wastewater, site flushing wastewater, laboratory wastewater, initial rainwater, incineration system washing saline wastewater, domestic wastewater and mixed wastewater will be produced, All kinds of chemical additives contained have adverse effects on the growth and development of aquatic animals and plants.
Moreover, the emulsion can also promote many toxic substances that were originally insoluble in water to be dissolved and dispersed in the water, aggravating the harm of water pollution. At present, the treatment systems of emulsion wastewater include ultrafiltration membrane treatment system and electric flotation system. The ultrafiltration membrane treatment technology is suitable for the treatment of wastewater with oil content of thousands of mg / L. however, when the oil content reaches tens of thousands of mg / L, there are some defects, such as easy blockage of membrane pores, frequent replacement of membrane, reduction of COD removal rate and so on; The treatment process of electric floating technology is complex, has high requirements for the quality of electrode plate, and the equipment cost is usually expensive.
The amount of slag in the treatment process is large, and the treatment cost of sludge is high, which is not suitable for promotion in small and medium-sized mechanical processing enterprises. Using traditional treatment system, a single treatment technology is difficult to treat the comprehensive wastewater with increasing total discharge and more complex components in actual production.
After the emulsion wastewater is pretreated, if the main water quality indexes (oil, salt, COD, etc.) meet the requirements for entering the biochemical treatment system, it will be directly lifted into the comprehensive regulating tank and mixed with domestic wastewater before entering the subsequent treatment process. If the main water quality indexes cannot meet the requirements for entering the biochemical treatment system, determine the maximum amount of wastewater that can enter the comprehensive regulating tank according to its water quality and combined with the water quality and quantity of domestic sewage, and dilute it in batches. Production and domestic wastewater and initial rainwater are separately set up in the regulating tank and pumped into the comprehensive regulating tank to control the mixed water quality of the comprehensive regulating tank.
The incineration salty wastewater shall be collected by the owner and transported to the comprehensive regulating tank. The treatment of salty wastewater is not quantitative. The maximum limit of salty wastewater that can be treated shall be determined according to the salt content of the comprehensive wastewater. The water quality and quantity of various wastewater are allocated in the comprehensive regulating tank to make the content of pollutants in the comprehensive wastewater meet the inlet requirements of the biochemical system. The mixed comprehensive wastewater is pumped into the hydrolysis acidification tank to improve the biodegradability of the wastewater through anaerobic hydrolysis of microorganisms. The effluent from the hydrolysis acidification tank is lifted into the UASB anaerobic reactor to remove most of the organic matter in the wastewater through the anaerobic action of microorganisms.