Attainment by wastewater treatment, water machine wastewater treatment technologies can be divided into primary, secondary and tertiary treatment.
Level processing is mainly through the sieve, precipitation and other physical methods for wastewater pretreatment aims to remove the suspended solids and water floats, to prepare for the secondary treatment. After a treated wastewater, the BOD removal rate is generally only about 30%.
Secondary treatment is mainly used to remove various biological wastewater treatment methods were colloids and dissolved organic contaminants. The two treated wastewater, the BOD removal rate up to 90%, processing water discharge standards.
Tertiary treatment at the primary, secondary processing, based on the refractory organic matter, phosphorus, nitrogen and other nutritive substances for further processing. Tertiary treatment methods are coagulation, filtration, ion exchange, reverse osmosis, ultrafiltration, and disinfection.
For waste water treatment method according to the implementation of the role of pollutants can be divided into two categories: one is through a variety of external forces to hazardous substances is separated from the waste water, known separation method; another by chemical or biological role of the harmful substances into harmless substances or separable (and then be removed after separation), known transformation method.
1.1.1 transformation method
Chemical transformation method can be divided into two types of law and biochemical transformation method. Chemical conversion method including neutralization, oxidation-reduction, chemical precipitation, electrochemical method; biotransformation including activated sludge, biofilm, anaerobic biological treatment, biological pond.
The presence of contaminants in wastewater forms of diversity and physico-chemical properties of the opposite sex separation method determines the diversity. Ionic contaminants optional ion exchange, electrolysis, electrodialysis, ion adsorption, ion flotation method for processing. Molecular contaminants optional extraction, crystallization, distillation, adsorption, floatation, reverse osmosis, evaporation method for processing. Colloidal contaminants choose coagulation, flotation, adsorption, filtration method for processing. Suspended solids contaminants can choose gravity separation, centrifugal separation, magnetic separation, sieving method, flotation processing.