Root Zone Treatment System

Root Zone Treatment Systems (RZTS) are artificially prepared wetlands comprising of clay or plastic lined excavation and emergent vegetation growing on gravel/sand mixtures and is also known as constructed wetland. This method combines mechanical filtration, chemical precipitation and biological degradation in one step for the treatment of wastewater. Seemingly, low operating cost, less energy requirement and ease of maintenance are some of the attributes that makes RZT system an attractive alternative for wastewater management.

CPCB in collaboration with GTZ, Germany, has taken up a pilot plant study on RZTS of dairy effluents at Mother Dairy, Delhi. At Mother Dairy, two RZTs pilot plants have been constructed - horizontal flow and vertical flow. The load will be increased gradually to find out the performance of this plant in terms of area requirement and desired effluent quality. The size of the horizontal filter bed is 6 m x 4 m x 0.6 m and bottom is lined by plastic liner. The concrete bottom vertical filter bed is 2 m x 2 m x 2 m. The design criteria of the filter beds are as follows:

Characteristics	Horizontal RZTS	Vertical RZTS
Area	4 m2/PE	2 m2/PE
BOD Load	10 g/m2/day	20 g/m2/day
Hydraulic Load	12.5 l/m2/day	25 l/m2/day

PE is Population Equivalent