What is the purpose of measuring dissolved oxygen in sewage treatment

What is the purpose of measuring dissolved oxygen in sewage treatment? In the process of sewage treatment, too high or too low dissolved oxygen will affect the treatment efficiency. The reasons for the high DO value of the dissolved oxygen content in the aeration tank include sludge poisoning and low sludge load. Sludge poisoning will cause microorganisms to lose their activity and reduce the function of absorbing and utilizing oxygen. If the sludge load is low, the amount of aeration and oxygenation will exceed the absorption and utilization of oxygen by the sludge, resulting in excessive accumulation of oxygen in the mixed solution. The reasons for the low DO value of the dissolved oxygen content in the aeration tank are that the mixed liquor sludge concentration is too high and the sludge load is too high. If the excess sludge is not discharged in time, sludge will accumulate in the mixed liquid of the aeration tank, and the increase in the oxygen consumption of the sludge itself will make the amount of aeration and oxygenation insufficient to supplement the oxygen absorption and utilization of the sludge. Excessive excess sludge discharge makes the sludge concentration of the aeration tank mixture lower than the normal value, the increase of the influent and the increase of the organic content of the influent are all the reasons for the excessive sludge load. Excessive sludge load will cause oxygen consumption to exceed oxygen supply, resulting in a low D0 value in the aeration tank. The solution to the high or low dissolved oxygen in the aeration tank is to adjust the quality and quantity of the influent water, the discharge of excess sludge, the amount of aeration, and the number of operating rooms of the aeration tank according to the specific situation. Therefore, in the operation of the sewage treatment system, it is also very important to control dissolved oxygen, and dissolved oxygen is also an important factor affecting microorganisms. Determination of dissolved oxygen in sewage by electrode method 1. Measurement principle Fluorescence method dissolved oxygen sensor is based on the principle of quenching active fluorescence by specific substances in physics. The blue light from a light-emitting diode (LED) shines on the fluorescent material on the inner surface of the fluorescent cap, and the fluorescent material on the inner surface is excited to emit red light. By detecting the phase difference between the red light and the blue light, and comparing with the internal calibration value Comparison, so as to calculate the concentration of oxygen molecules, and output the final value after automatic compensation of temperature and air pressure. 2. Before using the dissolved oxygen meter, prepare the dissolved oxygen meter to remove the protective cover. Before installation, please take off the front-end protective cover of the dissolved oxygen sensor, keep the protective cover properly, and tighten the protective cover. Fluorescence DO determination of dissolved oxygen in water is simple and quick. The fluorescence method LDO does not need to be calibrated for the determination of dissolved oxygen in water, the response time is fast, the measurement result is stable, there is no requirement for the flow rate, no interference, less cleaning frequency, and low maintenance. Fluorescence dissolved oxygen meter has four advantages over electrochemical dissolved oxygen meter: 1. No preheating, no electrolyte, easier to use; 2. No maintenance and frequent calibration, longer service life; 3. No flow rate limit, response within 10 seconds, higher detection efficiency; 4. High precision, anti-interference, better stability and higher durability.