ABSTRACT
The role of biomass accretion and decomposition in water quality improvement in constructed municipal wastewater wetlands is very important but has largely been ignored in performance discussions. Two stages in the development of a constructed wetland may be identified: the startup phase, in which the vegetation and litter increase with each passing year; and a stationary phase, in which vegetation and litter vary seasonally but not annually. In both stages biomass has significant effects on water quality. This chapter aims to quantify the rates of key biomass processes and the amounts of nutrients and biomass involved. Concentrations resulting from biomass loss reflect the relative proportions of the nutrients in mineral and degradable fractions of litter. Competition for nutrients will prolong the startup phase and cause longitudinal stratification of biomass and litter. Such phenomena have been documented and modeled for natural wetland systems.
