DEVELOPMENT OF THE INTERMITTENT CYCLIC PROCESS FOR SIMULTANEOUS NITROGEN AND PHOSPHORUS REMOVAL

Technology to simultaneously remove nitrogen and phosphorus from waste water by carrying out aerobic and anaerobic operations in a single rea ctor has been developed by the authors. The Intermittent Cyclic-Proces s can be used with two reactors, operating at opposite stages, to rece ive and treat influent on an uninterrupted basis. Research has been ca rried out in the: laboratory; pilot plant; and in a 540 m(3) full scal e wastewater plant. Experiments with aeration time ratios (aeration ti me to total cycle time) from 0.125 to 1 have been made, and 0.125 yiel ded the best nitrogen and phosphorus removal results in the laboratory study. In the pilot plant average nitrogen and phosphorus removal rat es of 86% and 82% were achieved. In over three years of operation, the full-scale plant realized rates of 87% and 74% respectively. Performa nce has further improved with our recently developed controller which uses ''fuzzy logic'' to automatically determine optimal mixing and aer ation periods. Measurements of DO, pH, ORP, and reactor water level ar e constantly relayed to the fuzzy controller. Average nitrogen and pho sphorus removal ratks in the full-scale plant were 96% and 93%. The st udy demonstrates that the fuzzy controller is practical and enhances n itrogen and phosphorus removal. Copyright (C) 1996 IAWQ.