| After the quality of pharmaceutical wastewater and the problems of its treatment processes used were analyzed completely, two-stage SBR (TSSBR) as a trial reactor was selected. The operating parameters and the automatic control process with DO and pH as on-line feedback variables were studied. To make the effluent meet standard and carry out real-time control, the CASS was transformed.TSSBR was the process that organic material and nitrogen were removed in different reactors—SBR1,SBR2 in turn, which avoided the problem that the proportion of nitrifiers was too few in the activated sludge caused by higher rate of Carbon and Nitrogen. At the same time, the control of the reaction course by online detecting the DO and pH, ensured nitrification-denitrification via nitrite and avoided the problem of deficient nitrification owing to the shorter aeration time. After treatment, the effluent concentrations of CODcr, NH3-N and NOx-N were less than 100mg/L, 1mg/L and 2mg/L respectively, which were below the pharmaceutical chemically wastewater effluent standard that CODcr was less than 100mg/L, NH3-N and NOx-N were not required.Firstly, for the control of TSSBR, the common variation rule of DO and pH were confirmed. In SBR1, DO decreased with a smaller speed after leaping to an equilibrium point while pH increased; when decomposable organic material was used up, DO increased suddenly and pH decreased. In SBR2 during nitrification, the law of DO was the same as that of SBR1, while pH did not decrease but increase suddenly. The laws referred to above had not special case because the quality of pharmaceutical wastewater through adjusting tank and hydrolysis tank was stable, therefore the use of DO and pH as parameters that on-line monitored and controlled the treatment process of pharmaceutical wastewater was reliable.Secondly some conclusions were drawn in the study on the optimizing control:Under the same initial conditions, the balanced DO with pre-aeration was lower than that without pre-aeration, and the small fluctuations of DO in the course of reaction were also seldom. This showed that pre-aeration could strengthen the activity of microorganism and quicken reaction. It was not suitable for constant DO experiments with or without pre-aeration that 2.00mg/L DO was regarded as the restriction factor standard of microorganism reaction. The standard was on the low side for the former and on the high side for the latter.In the operational condition of constant DO, reaction speed could be raised under the precondition of saving energy. According to the rule that balance DO during the pharmaceutical wastewater treatment was a straight line whose numerical value reduced at a fixed speed with time passing, increasing the aeration at a fixed speedcould make DO constant in the stage of balance DO. DO was the feedback parameter of the reaction course and pH was that of the end. There were two kinds of methods to adjust aeration—the continuous and the intermittent. Drug had to drop high performance to the organism and DO can sensitively respond the microorganism activity, both of which formed the theory basis that DO could be used to on-line monitor and judge the toxicity of pharmaceutical wastewater. DO curve of poisonous pharmaceutical wastewater appeared the peculiar periodicity fluctuation, which was the seasonal alternation between detoxification and decomposition of organic matter by activated sludge microorganisms.Extended aeration of SBR1 reduced the average reaction speed of TSSBR and the organic matter of SBR2 which made the low-agglomeration nitrifier lose, because nitrifier could not be kept without the heterotrophic bacteria, and made the bacteria of denitification lose activity.The reasons that formed nitrification via nitrite were that: 25℃ was the critical limit of stabilization, and the nitrification speed could not be raised too much when the temperature is higher than 25℃; Controlling the reaction terminal point by pH and DO in long term made the proport...
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