Multidimensional Assessment of Subsurface Flow Wetland Performance for Treating Primary Wastewater

Monitoring data collected from the subsurface flow wetland system in Minoa, NY (3 units, approx. 60 x 30 x 0.75 m, HRT = 1.3 to 11.4 days), which began treating primary municipal wastewater during January 1996, was evaluated using multivariate statistical techniques. Nine factors accounted for 88.99 % of the variance among 27 monitoring variables. Overall, the most significant factor was "organic biotransformation". The significance of the factor to performance was demonstrated by a multiple regression model to predict COD removal as a function of HRT, temperature, and influent concentrations of COD and TKN; the model accounted for nearly 93% of the variability in COD removal by the system (multiple R²=0.9292, N=164) during the 17 month monitoring period. Work is ongoing to improve empirical and fundamental mathematical models of wetland performance to provide better tools for future systems design.