Table 1 Filler selection for the removal of different contaminants.

From: Study on physical clogging process and practical application of horizontal subsurface flow constructed wetland

Pollutant type

Mechanism of action

Type of pollutant

N

Filler adsorption, nitrification and denitrification of microorganisms attached to the surface of the filler

Zeolite, vermiculite, ceramsite, fly ash

P

Physical process (adsorption of phosphorus by filler, interception of precipitation process); chemical reaction (calcium, iron, aluminum ions and phosphorus reaction precipitation) filler surface microbial metabolism

Shale, ceramsite, waste bricks, blast furnace slag

Heavy metals

Filler adsorption, reaction precipitation, filler surface microbial metabolism, plant absorption

Zeolite, expansive soil, fly ash, ceramsite

TSS, organic matter

Filler interception, sedimentation, biofilm adsorption and degradation on filler surface

Peat, gravel, soil, ash, ceramsite

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