Table 2. Related Parameters of Constructed Wetland Fillings.

handle name	filling and its thickness	filler particle size
coal slag	0.8 m cinder	10–30 mm coal slag
ceramsite	0.8 m ceramsite	10–30 mm ceramsite
gravel	0.8 m gravel	10–30 mm gravel
coal slag + gravel	0.2 m coal slag (upper layer) + 0.6 m gravel (lower layer)	10–30 mm coal slag and gravel
ceramsite + gravel	0.2 m ceramsite (upper layer) + 0.6 m gravel (lower layer)	10–30 mm ceramsite and gravel
zeolite + gravel	0.2 m zeolite (upper layer) + 0.6 m gravel (lower layer)	10–30 mm zeolite and gravel