Constructed wetlands: Prediction of performance with case-based reasoning (part B)

Abstract

The aim of this research was to assess the treatment efficiencies for gully pot liquor of experimental vertical-flow constructed wetland filters containing Phragmites australis (Cav.) Trin. ex Steud. (common reed)and filter media of different adsorption capacities. Six out of 12 filters received inflow water spiked withmetals. For 2 years, hydrated nickel and copper nitrate were added to sieved gully pot liquor to simulatecontaminated primary treated storm runoff. The findings were analyzed and discussed in a previous paper(Part A). Case-based reasoning (CBR) methods were applied to predict 5 days at 20°C N-Allylthiourea biochemicaloxygen demand (BOD) and suspended solids (SS), and to demonstrate an alternative method ofanalyzing water quality performance indicators. The CBR method was successful in predicting if outflowconcentrations were either above or below the thresholds set for water-quality variables. Relatively smallcase bases of approximately 60 entries are sufficient to yield relatively high predictions of compliance ofat least 90% for BOD. Biochemical oxygen demand and SS are expensive to estimate, and can be cost-effectivelycontrolled by applying CBR with the input variables turbidity and conductivity