I. INTRODUCTION
Sewage treatment is an important measure about ecological and environmental protection. It has a broad and far-reaching significance. With the continuous development, perfectness of automation and computer technology, the automatic control of the modern sewage treatment is entering the computer intelligent control phase. However, the process of sewage treatment is a complex, nonlinear, multi-variable control process. Sewage treatment has considerable difficulty as the turbidity of the raw water, PH value, water flux, water temperature and other factors during the course of treatment. The control of conventional sewage treatment plants adopts routine instrumentation and manual control mostly. It relies on the knowledge and experience of the operator. This sewage treatment mode is instability in water quality and low in labor productivity. In order to improve water treatment quality and reduce the cost of water treatment, advanced automatic control equipment and technology must be used to design the automatic control sewage treatment system. In this paper, according to sewage treatment technology in a certain chemical industry, designs and realizes a sewage treatment control system based on fuzzy PID.