Abstract:

Through continuous monitoring of the parameters, such as DO, pH,ORP and water quality, of every reaction tank at various stages of the first half cycle of the operation of the CMICAO technology (commutative multi-influent cascade A²/O), relationships between the parameters and water quality were explored. It was found that when the CMICAO operation went on under optimal conditions, the concentration of TN, NH₄⁺-N, NO₃^--N and TP in the effluent was measured to be 9.9, 1.3, 6.4 and 0.47 mg·L^-1, respectively. During the operation, when the anoxic tank turned from positive into negative in d pH/d t, the anaerobic tank turned from negative into positive or approached to zero in d ORP/d t, the aerobic tank turned from negative to near zero in d ORP/d t or soared up suddenly in d ρ(DO)/d t, and the convertible reaction tank went on to the next phase of the operation; when the 1st-4th tanks finished their reactions for the first half of the cycle, the fifth would also finish its reaction for the first half of the cycle and enter the second half cycle. All the findings suggest that the state parameters (DO, pH and ORP) can be used as indicators for real-time control of the CMICAO process, thus enhancing its effect of N and P removal.

Key words: CMICAO process, real-time control, nitrogen and phosphorus removal, control parameter