EFFECT OF FUNCTIONAL FILTRATION MEDIA ON SEWAGE TREATMENT PERFORMANCE IN A MULTISTAGE CONSTRUCTED WETLAND

Abstract

 In this research, the sewage treatment performance of a pilot-scale multistage constructed wetland with functional filtration media (FFM) bed using zeolite, calcium silicate or activated charcoal with sand and non-functional filtration media (n-FFM) bed using just sand were compared, and the effect of FFM on the water purification performance was elucidated. Under the vertical flow condition suitable for aerated treatment, the BOD removal efficiency of 90.2% was obtained even with n-FFM bed and 99.9% NH⁴⁺_-N removal was attained with FFM bed using zeolite. The effect of FFM was, however, negligible on total nitrogen removal under the hybrid condition comprising both the vertical and horizontal flows. Despite of the filtration media, the total nitrogen removal efficiency under the hybrid condition was around 45%. Although the removal efficiency of phosphorus under the vertical flow condition was 21.6% with n-FFM bed, that under the hybrid condition became below zero. The removal efficiency of phosphorus in FFM bed using calcium silicate was, however, maintained at 18.2% even under the hybrid condition, revealing the effect of calcium silicate to sustain phosphorus removal performance in the constructed wetland.