An investigation was carried out to eliminate the decrease of effluent pH value in carbon filter in O3-biological activated carbon process. The influence factors were examined in a pilot test, and pH was adjusted in t...An investigation was carried out to eliminate the decrease of effluent pH value in carbon filter in O3-biological activated carbon process. The influence factors were examined in a pilot test, and pH was adjusted in the pilot and waterworks. Results show that the carbon filter is an acid-base buffer system and the activated carbon is the key factor. Chemical functional groups on activated carbon surface present acid-base properties to buffer the water but decrease with time, so that effluent pH value decreases. The effects of ozone dosage, CO2 in the carbon filter, and the filter influent quality are negligible. A new method to adjust pH is developed: the activated carbon is first modified by soaking in sodium hydroxide solution to make its pH reach the desired value, and then the pH value of inflow is controlled to certain value by dosing lime in sand filter influent. The method is economical and effective.展开更多
Tubular flow reactors are mainly used in chemical industry and waste water discharged units. Control of output variables is very difficult because of the existence of high dead-time in these types of reactors. In the ...Tubular flow reactors are mainly used in chemical industry and waste water discharged units. Control of output variables is very difficult because of the existence of high dead-time in these types of reactors. In the present work, sodium hydroxide and acetic acid solutions were sent to the tubular flow reactor. The aim was to control p H at 7 in the nonlinear region. The p H control of a tubular flow reactor with high time delay and a highly nonlinear behavior in p H neutralization reaction was investigated experimentally in the face of the various load and set point changes. Firstly, efficiency of conventional Proportional-Integral-Derivative(PID) algorithm in the experiments was tested. Then self-tuning PID(STPID) control system was applied by using the ARMAX model. The model parameters were calculated from input–output data by using PRBS signal as disturbance and Bierman algorithm. Lastly, the experimental fuzzy control of p H based on fuzzy model was achieved to compare the success of fuzzy approach with the performance of other control cases studied.展开更多
基金Supported by the National Water Pollution Control and Harnessing Projects (2009ZX07423-003)
文摘An investigation was carried out to eliminate the decrease of effluent pH value in carbon filter in O3-biological activated carbon process. The influence factors were examined in a pilot test, and pH was adjusted in the pilot and waterworks. Results show that the carbon filter is an acid-base buffer system and the activated carbon is the key factor. Chemical functional groups on activated carbon surface present acid-base properties to buffer the water but decrease with time, so that effluent pH value decreases. The effects of ozone dosage, CO2 in the carbon filter, and the filter influent quality are negligible. A new method to adjust pH is developed: the activated carbon is first modified by soaking in sodium hydroxide solution to make its pH reach the desired value, and then the pH value of inflow is controlled to certain value by dosing lime in sand filter influent. The method is economical and effective.
文摘Tubular flow reactors are mainly used in chemical industry and waste water discharged units. Control of output variables is very difficult because of the existence of high dead-time in these types of reactors. In the present work, sodium hydroxide and acetic acid solutions were sent to the tubular flow reactor. The aim was to control p H at 7 in the nonlinear region. The p H control of a tubular flow reactor with high time delay and a highly nonlinear behavior in p H neutralization reaction was investigated experimentally in the face of the various load and set point changes. Firstly, efficiency of conventional Proportional-Integral-Derivative(PID) algorithm in the experiments was tested. Then self-tuning PID(STPID) control system was applied by using the ARMAX model. The model parameters were calculated from input–output data by using PRBS signal as disturbance and Bierman algorithm. Lastly, the experimental fuzzy control of p H based on fuzzy model was achieved to compare the success of fuzzy approach with the performance of other control cases studied.
