Table 1.

Design characteristics and operating parameters of the gravel bed hydroponic treatment units

Design parameters	Values
Number of treatment units	4
Length (L)	2 m
Width (W)	0.75 m
Unit area	1.50 m2
Gravel depth	0.40 m
Gross capacity	0.60 m3
Macrophyte type	Typha latifolia
Operational parameters
Hydraulic loading rate	2.33 cm d− 1
Loading rate
TKN	0.44–1 g m−2d−1
NH4+ − N	0.42–0.72 g m− 2d− 1
NO3− - N	0.2–0.4 g m− 2d− 1
PO43−-P	0.19–0.54 g m−2d− 1
Hydraulic retention time	5 days