RAINFALL EFFECTS TO THE PERFORMANCE OF SUBSURFACE FLOW CONSTRUCTED WETLANDS IN LEACHATE TREATMENT

          Constructed wetlands have gained wide acceptance as a wastewater treatment
practice. Rainfall effect needs to be taken into account in designing local constructed
wetlands particularly in tropical countries. This study was carried out to evaluate the
effects of tropical climate (rainfall) towards the performance of horizontal subsurface
flow constructed wetlands (HSFCW) planted with local plant, Typha angustifolia for
landfill leachate treatment. The performance of the constructed wetlands was
evaluated using seven parameters i.e nitrate, phosphorus, ammonical nitrogen,
chromium, cadmium, biochemical oxygen demand (BOD5) and chemical oxygen
demand (COD). Two pilot scale constructed wetlands reactors were used in the
experiments. Performance of HSFCW in leachate treatment was evaluated with
comparison to a blank reactor (without plants) serving as control. Experiments were
run under artificial “monsoon rainfall intensity” in Malaysia. Results show that
rainfall effects towards the performance of wetlands in leachate treatment vary from
parameter to another (-1% to 41% enhancement) depending on the characteristic of
each parameter. All parameters except chromium have better performance in
leachate treatment after rainfall. Rainfall effects (increasing of removal efficiency)
are more critical in control reactor as compared to the vegetated reactors.