Wastewater treatment methods for separating and recovering insoluble pollutants (including oil film and oil beads) in wastewater by physical action can be divided into gravity separation method, centrifugal separation method and screen filtration interception method according to different physical actions.
Compared with other methods, physical method has the advantages of simple equipment, low cost, convenient management and stable effect, and is mainly used to remove floating objects, suspended solids, sand and oil in wastewater.
Physical methods include filtration, gravity separation and centrifugal separation.
Chemical treatment method
A wastewater treatment method is characterized in that dissolved and colloidal pollutants in wastewater are separated and removed or converted into harmless substances through chemical reaction and mass transfer. Can be used to remove metal ions, fine colloidal organic matter, inorganic matter, plant nutrients (nitrogen, phosphorus), emulsified oil, color, odor, acid, alkali and so on.
Chemical methods include neutralization, coagulation, redox and electrochemistry. [ 1]
(1) neutralization method
In chemical and oil refining enterprises, when the low-concentration wastewater containing acid and alkali has no value of recovery and comprehensive utilization, neutralization method is often used for treatment. Neutralization is also commonly used in wastewater pretreatment to adjust the pH value of wastewater.
(2) Coagulation precipitation method
Coagulation method is to add coagulant into wastewater. Because coagulant is electrolyte, it forms micelles in wastewater and neutralizes with colloidal substances in wastewater to form floc precipitation. Flocculation and sedimentation can not only remove fine suspended particles with the particle size of 10-3~ 10-6 from wastewater, but also remove rich nutrients such as chromaticity, oil, microorganisms, nitrogen and phosphorus, heavy metals and organic matter.
(3) redox method
After redox treatment, the organic and inorganic substances contained in wastewater can be transformed into non-toxic or less toxic substances, thus achieving the purpose of wastewater treatment. Commonly used oxidation methods are: air oxidation, chlorine oxidation, ozone oxidation, wet oxidation and so on.
(4) electrolytic method
Electrolysis is the process of dissolving redox reaction by direct current. Generally, according to the purification mechanism of pollutants, it can be divided into electrolytic oxidation, electrolytic reduction, electrolytic coagulation and electrolytic flotation.
Physical and chemical methods
Physical therapy method
Wastewater treatment methods for separating and recovering insoluble pollutants (including oil film and oil beads) in wastewater by physical action can be divided into gravity separation method, centrifugal separation method and screen filtration interception method according to different physical actions.
Compared with other methods, physical method has the advantages of simple equipment, low cost, convenient management and stable effect, and is mainly used to remove floating objects, suspended solids, sand and oil in wastewater.
Physical methods include filtration, gravity separation and centrifugal separation.
Chemical treatment method
A wastewater treatment method is characterized in that dissolved and colloidal pollutants in wastewater are separated and removed or converted into harmless substances through chemical reaction and mass transfer. Can be used to remove metal ions, fine colloidal organic matter, inorganic matter, plant nutrients (nitrogen, phosphorus), emulsified oil, color, odor, acid, alkali and so on.
Chemical methods include neutralization, coagulation, redox and electrochemistry. [ 1]
(1) neutralization method
In chemical and oil refining enterprises, when the low-concentration wastewater containing acid and alkali has no value of recovery and comprehensive utilization, neutralization method is often used for treatment. Neutralization is also commonly used in wastewater pretreatment to adjust the pH value of wastewater.
(2) Coagulation precipitation method
Coagulation method is to add coagulant into wastewater. Because coagulant is electrolyte, it forms micelles in wastewater and neutralizes with colloidal substances in wastewater to form floc precipitation. Flocculation and sedimentation can not only remove fine suspended particles with the particle size of 10-3~ 10-6 from wastewater, but also remove rich nutrients such as chromaticity, oil, microorganisms, nitrogen and phosphorus, heavy metals and organic matter.
(3) redox method
After redox treatment, the organic and inorganic substances contained in wastewater can be transformed into non-toxic or less toxic substances, thus achieving the purpose of wastewater treatment. Commonly used oxidation methods are: air oxidation, chlorine oxidation, ozone oxidation, wet oxidation and so on.
(4) electrolytic method
Electrolysis is the process of dissolving redox reaction by direct current. Generally, according to the purification mechanism of pollutants, it can be divided into electrolytic oxidation, electrolytic reduction, electrolytic coagulation and electrolytic flotation.