At present, physicochemical and biochemical treatment methods are still the main research direction of accelerant wastewater, and are also the main wastewater treatment technology adopted by accelerant enterprises at home and abroad.
1 physicochemical treatment
Physicochemical treatment methods mainly include extraction, distillation and evaporation, coagulation, air floatation, adsorption, etc.These technologies are mainly in the laboratory research stage, and the corresponding research has a good effect on the removal of some pollutants in the waste water, these directional removal function also limited their industrial applications.Du huiling et al. [2] and bayer et al. [2] showed that the extraction method achieved a better removal effect on specific organic compounds in the promoter wastewater, but did not change the salt content of the wastewater, and the amount of extraction agent was large, bringing secondary pollution and so on.Distillation and evaporation can reduce the content of inorganic salts and organic compounds in wastewater [3-4], but this method has high energy consumption and operation cost, and is suitable for treating wastewater with high salinity and small amount of water.Flocculation test [5] shows that conventional flocculants have poor effect in the direct treatment of high concentration accelerator wastewater. Although diatomite compound coagulant [6] significantly improves the effect of coagulation pretreatment accelerator wastewater, it is difficult to prepare such coagulant.Adsorption method has a better effect on the removal of dissolved organic matter that is difficult to be oxidized and degraded by both conventional biological and chemical oxidation.Studies have found that activated carbon, a common adsorbent, has a better adsorption effect on wastewater with low COD concentration [7]. In addition, due to its high price, it is not economical to pretreat wastewater with high concentration, and it is generally used as the effluent control index for subsequent treatment.
2 chemical treatment
Chemical treatment methods mainly include chemical precipitation, chemical oxidation and micro-electrolysis.Chemical oxidation is a method of oxidative degradation and removal of organic pollutants in wastewater.Several commonly used oxidants are Fenton reagents, chlorine oxidants and ozone.Studies [8-11] have found that these oxidants do not have a high ability to remove COD, and the amount of reagents added is large, the operation cost is high, and a large number of by-products will be produced after ozonation [12].Iron carbon micro-electrolysis process is simple, can achieve the purpose of “waste to waste”.However, the disadvantage of this method is that pH needs to be adjusted before and after the reaction, and a large amount of iron sludge needs to be disposed after the reaction, resulting in high treatment cost.Therefore, iron-carbon micro-electrolysis is generally combined with other treatment technologies, such as coagulation and Fenton oxidation, to improve treatment efficiency and reduce treatment cost.
3 biochemical method
Biological treatment is the traditional and economical method of organic wastewater treatment.However, most of the accelerant wastewater is difficult to be directly treated by conventional biochemical methods, especially the wastewater with high salt, high ammonia nitrogen and high toxic organics, which is still the bottleneck of the application of biochemical treatment technology.