Microporous Aeration Discrete Control System Based On Can Bus

Water is one of the most important natural resources that human relies on. However, with the rapid development of industries, water resource is destroyed immensely and water pollution has become the major factor that restricts the human evolution. So how to prevent water resource by adopting some effective methods to treat sewage has become more and more necessitous.Integrated oxidation ditch, which is also called integral combined oxidation ditch, can integrate functions such as aeration deposition, separating mud and water, and polluted mud circumfluence without a separate second-depositing ditch. It is more advanced and it needs less investment and less area requirement. But the major chemicophysical method, which is used to treat sewage in most of integrated oxidation ditch currently, is turning-rinse aeration. The obvious disadvantage of the method is high-energy requirement. At the same time, since the automatic control of the whole system is not realized, manual work instead, the maintenance for the system is very complicated and inefficient. Moreover, it cannot be avoided that the index of the water quantity is unstable.This thesis has discussed the work flow and design method of biology processing system of integrated oxidation ditch with activated sludge method askernel technology, and proposed a new aeration method------micropore areation, toreconstruct original technique system. Micropore aeration is to make the air flow out from the holes with diameter of mm degree into the water to form minutial bubbles. So the air can touch with the water fully. To deal with polluted water by using the micropore aeration can make the touching area between the air and the water thousands, even ten thousands of times larger, which depends on the diameter of the micropore. By this means, we can greatly improve aeration efficiency and save energy.We construct the whole control system for the integrated oxidation ditch by using the model of sewage treatment DSC, which is based on CAN bus. The system is divided into two-degree bus network model. It is means that Server and Client forminthe multi-function ends bus model and opened filed bus model for field process control. The system mainly includes center control unit, field control machine, field data collection and operating cells. We have made a detailed explanation for the structures and functions of different parts of the system respectively. Introduce of the CAN bus is included too.The thesis also discussed the closed control for Dissolved Oxygen (DO). The dense of DO in the sewage is an important index for sewage treatment when using activated sludge method. We use two-degree-closed-loop control. The feedback of the outside loop is the value of Chemical Oxygen Demand (COD) in the water, which is the index to confirm that the sewage is purified. The computer collects data from COD testing instrument in a fixed time interval, and combines it with the suspension concentration value and temperature at that time, then uses the expert system to abstain the targeted DO value. The feedback of the inside loop is the value of DO in the sewage. The computer compares the targeted DO value with the real one obtained from the oxygen meter and control the air pressure and flow of the air compressor by using fuzzy control. So the DO value in the sewage can be controlled. Sufficient dense of DO can guarantee the result of sewage treatment.