Abstract
The major mechanisms for wastewater treatment in sub-surface flow constructed wetlands (SSF-CW) are physical, chemical, biological and ecological processes. The paper reviews the latest developments in the design methods of SSF-CW system for organic carbon removal. Conventional plug flow exponential decay model, background concentration model and time dependent rate constant models were applied for a typical situation and the land area required for each case is calculated. The limitations of these design methodologies are discussed.