Overview of Basic Wastewater Treatment Methods

 

The commonly used methods for wastewater treatment can be broadly categorized into physical, chemical, and biological methods.

 

 

▲ Physical and chemical methods are commonly used as the initial treatment in general wastewater treatment processes

 

Physical Methods

 

These methods involve separation and recovery of insoluble suspended solids from wastewater through physical processes without altering their chemical properties. They are simple to operate and include gravity separation, centrifugation, filtration, evaporation, and crystallization.

 

Chemical Methods

 

Chemical methods involve adding chemical agents to wastewater to induce processes such as coagulation, neutralization, ion exchange, adsorption, or oxidation-reduction. These processes facilitate the separation, transformation, precipitation, or destruction of pollutants' chemical structures.

 

Biological Methods

 

Biological methods utilize microorganisms to treat organic matter in wastewater. Microorganisms degrade organic pollutants and convert them into harmless substances. Depending on the types of microorganisms and the target organic pollutants, biological treatment can be aerobic or anaerobic. Common biological methods include activated sludge, biofilm, and anaerobic digestion.

 

Summary of Basic Wastewater Treatment Methods

 

Classification	Role	Methods	Treatment Approach
Physical Methods	Adjustment		Adjustment
		Gravity Separation	Precipitation/removal/degassing
	Separation	Centrifugation	Centrifuge
		Magnetic Separation	Magnetic Separator
	Filtration		Fine Screening/Grating/Sand Filtration
	Thermal Treatment		Crystallization/Evaporation
Chemical Methods	Chemical Addition		Coagulation/Neutralization/Oxidation-Reduction/Chemical Precipitation
	Electrolysis		Electrolysis
Biological Methods	Biological Treatment	Natural Biological Treatment	Oxidation Ponds/Wastewater Irrigation
		Artificial Biological Treatment	Activated Sludge/Biofilm/Anaerobic Digestion

 

The design of wastewater treatment units should follow the principle of starting with the simplest methods and progressing to more complex ones. Initially, physical methods such as mechanical means (e.g., screens) are used to remove large pollutants, followed by chemical methods to remove suspended solids, and finally biological methods to address dissolved pollutants that cannot be removed by chemical means.