Evaluation of Innovative Filter Materials and Operating Conditions in Vertical Flow Wetlands for Greywater Treatment

Abstract

The reuse of greywater has benefits such as both the protection of water resources and the reduction of the economic burden of water supply and wastewater treatment. Greywater must be treated in accordance with legislative requirements for reuse. Natural treatment systems such as constructed wetlands are increasingly being used for this purpose. This study investigated greywater treatment performances of vertical flow (VF) constructed wetland systems with different filter materials under different operating conditions. Perlite and gravel reactors exhibited similar performance in COD removal when the reactors were operated without a rest phase, while perlite reactor performed slightly better when there was a distinctive flood and rest phase. Reactor operating conditions significantly impacted TKN removal efficiencies. It was hypothesized that operating the VF wetland system with a fully saturated flood phase followed by a rest phase created a hybrid system effect where anoxic and aerobic zones develop in turn conducive to nitrification and subsequent denitrification reactions. The higher removal efficiency observed in the perlite reactor was attributed to the better oxygen transfer capacity of perlite due to its porous structure. The innovative filter material perlite exhibited superior performance compared to gravel and proved to be effective as a promising alternative material in VF wetland reactors.