The working principle of wastewater treatment

The working principle of wastewater treatment mainly includes physical treatment, biological treatment and chemical treatment methods, aiming to remove or reduce pollutants in the wastewater to meet the water quality standards for discharge into natural water bodies or reuse. 

Physical treatment

Settling method

: Utilizing the force of gravity to cause suspended solid particles in the wastewater to settle down, such as grates intercepting large debris and sedimentation tanks removing inorganic particles with higher density.

Screening method

: Using filters or grates to separate larger particles in the wastewater. Floatation method / Air flotation method

: By introducing air into the wastewater to form tiny bubbles, the suspended solids are carried up to the surface to form a floating sludge and are removed. Centrifugal separation

: Utilizing the centrifugal force generated by high-speed rotation to separate the suspended solids from the water.

Biological treatment

Activated sludge method

It relies on the microbial community to consume and decompose the organic matter in the wastewater, while removing some nutrients such as nitrogen and phosphorus.

Biofilm method

: Through the formation of a biofilm on the surface of the filler, the organic matter in the wastewater is adsorbed and metabolized. Typical techniques include contact oxidation method and fluidized bed biofilm reactor, etc.

AO biological treatment process

: In the A-stage tank, the microorganisms are in an anoxic state, where organic matter decomposition and nitrification occur; in the O-stage tank, aerobic microorganisms break down the organic matter into CO2 and H2O, and autotrophic bacteria convert NH3-N into NO2-N and NO3-N, ultimately eliminating nitrogen pollution.

Chemical treatment

Coagulation sedimentation

: By adding a coagulant, dissolved and colloidal pollutants coagulate into larger particles and precipitate. Chemical oxidation

: Utilize strong oxidants to destroy refractory organic compounds or heavy metal ions.

Activated carbon adsorption

: Utilize the adsorption property of activated carbon to remove residual trace organic substances and color.

Deep treatment

Reverse osmosis, ultrafiltration, electrodialysis

: Through semi-permeable membranes, selectively remove water molecules and certain ions to achieve deep purification of water quality.

Ozone oxidation

: Utilize the strong oxidizing property of ozone to remove refractory organic substances.

Disinfection treatment

Use chlorine, ozone, ultraviolet light, etc. to kill pathogenic microorganisms in wastewater to ensure the safety of the effluent. Through a series of combined treatment processes, various pollutants in the wastewater are reduced to varying degrees, ultimately meeting environmental protection regulations and achieving the purpose of effective water resource recovery and environmental protection.