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Table 1 Key techniques for surface water remediation

From: Key technologies and equipment for contaminated surface/groundwater environment in the rural river network area of China: integrated remediation

Remediation technique

Technique principle

Characteristics

Physic method

 Artificial aeration

Increase the dissolved oxygen of the water body, reduce the concentration of dissolved pollutants in water, improve the living environment for aquatic organisms

High cost, need to be combined with other methods

 Sediment dredging

Dredging the whole or part of the river with serious deposition to restore the normal function of the river

A large amount of engineering, disrupt existing bio-systems

 Mechanical algal removal

Using ultrasonic wave to make algal cell burst, break algal cell inside the airbag, make it lose float ability and precipitate

Unsustainable method

Chemical method

 Chemical precipitation

Adding iron salt or aluminum salt to produces chemical precipitation with inorganic phosphate through adsorption or flocculation, controlling the eutrophication

 

 Enhanced coagulation

Add the appropriate coagulant and the decontamination is carried out by adsorption, chemical precipitation, destabilization flocculation, and adsorption bridging

The addition of chemicals agents raises the cost and introduce secondary pollution

 Acid–alkali neutralization

Acidic or alkaline substances are added to the water body to adjust the pH, meet the growing need and species reproduction in the aquatic ecosystem

 

 Chemical algal removal

Add chemical algal removal agent, the effect is remarkable

Water table damage, high risk

Ecological method

 Constructed wetlands

Simulates natural wetlands by extracting elements from them for artificial enhancement

Large floor space

 Ecological floating bed

Using the principle of soilless cultivation, plants are planted in water and absorb nutrients directly from the water

Generally used to repair small rivers, lakes

 Ecological revetment

Artificially reformed the river revetment to restore or strengthen the ecological capacity of water, which can protect the river bank and purify the water

Suitable for the long-term ecological remediation process