Small standard deviations in removal efficiencies of 3%, 4.6%, 3.4% and 3.1% and effluent concentration standard deviations
of 20, 22, 19 and 13 mg/L for systems 1–4, respectively, holds great promise when considering the influent COD varied from a maximum of 854 mg/L to a minimum of 411 mg/L with average concentrations of 583 ± 92 mg/L.