The Research On Real-Time Online Monitoring System Of Zeta Potential And Its Application In Wastewater Treatment

Wastewater has become one of the factors that damage the environment and human health, and the paper mill wastewater is particularly serious. At present, Flocculation process is generally adopted in the middle section of paper making. The flocculant mostly uses PAC and PAM. The addition of PAC and PAM relies on the artificial experience, which is not accurate enough. It is likely to cause the addition insufficient or excessive. When the addition is inadequate, wastewater treatment will be not complete, increasing the burden on the subsequent processing wastewater. When the addition is too much, wastewater will be polluted again by the flocculant, and the cost of processing will be increase.This paper analyzes the mechanism of flocculant, The Zeta potential of the middle section of papermaking wastewater was selected as the basis for guiding the coagulant dosage, In this paper, the on-line determination method and optimal dosing control of flocculant are studied, in order to realize the automatic optimization of flocculant dosing.At present, of all measuring instruments of Zeta potential, SZP04 and Nano-ZS90 type particle size analyzer are most wildly used, but both are off-line measuring instruments, which cannot be used for the automatic on-line coagulant dosing. According to the classical Helmholtz-Smoluchowski formula and the streaming potential method, this paper has developed a set of zeta potential real-time on-line determination device. The device includes viscosity, conductivity meter, differential pressure transmitter, the composite ceramic membrane tube, PLC, etc. In addition, for the accuracy of zeta potential determination, this paper also studies the influence of pressure difference to find out the best operating conditions, which makes the accuracy of Zeta potential determination as high as possible. This paper also made a comparative experiment with Malvin particle size analyzer, basically reflecting the change trend of Zeta potential, which can be used for the automatic dosing of flocculant.Based on the on-line measuring device, Zeta potential values were measured under different doses of flocculant. Least square method is used for curve fitting to obtain the Zeta potential when the flocculation effect was the best, which is the goal of the neural network PID controller. The controller consists of BP network and PID controllers. The three parameters of PID are adjusted by the BP network to control the dosage of flocculant.