Study On The Instrumentation And Application Of Online Respirometry In Wastewater Treatment Plants

The water environmental issues in China is becoming more and more prominent, and the emission standards are becoming stricter and stricter. This brings forward higher requirements for the operation and management of Wastewater Treatment Plant?WWTP?. In this reasearch, an online respirometry is developed, which can support the operation and management of WWTP. This instrument is based on open reactor measurement method for aerobic respiration rate, measure continuously respiration rate of microoganism after exposure to influent of WWTP. And this measurement can be used for evaluation on influent inhibition of activated sludge, the characteristics of influent loading fluctuation.Firstly, this study discusses continuous measuring method for respiration rate based on open reactor, and establishes mathematical model for the continuous measurement of respiration rate, and gives out estimation method for key parameters, such as saturated dissolved oxygen concentration in waste water?DOs?, oxygen transfer coefficient(K_La), dissolved oxygen at balance state(DO_bl), and so on.Then, design and develop online respirometry using carrier biofilm instead of the common activated sludge, and the automatic measurement of respiration rate and parameters estimation are realized. The algorithm of data preprocessing is improved and the exponential filtering method?coefficient? =0.7? is adopted. The influence factor for parameters of model is studied, and the temperature expression for DObl is determined.Thirdly, the online respirometry is debugged and optimized on-site. On a field of WWTP in Beijing, study the effect on respiration rate from parameters such as carrier quantity, sample rate, and aeration flow, and so on. And determine a better operation condition is: the number of carrier in reactor is 15, the sample rate is 380 m L/min, and the aeration flow is 5L/min.Finnally, the engineering performance of online respirometry is applied and verified. By comparing with the influent water quality data of WWTP, confirms that the online respirometry can repose to the flutuation of COD concentration quickly, and indicate influent inhibition effect on microoganism. Based on this, the process optimized control strategy based on online respirometry is proposed.