Chlorine is a disinfectant commonly used by water companies because of its low price, low dosage, reliable disinfection and mature technology. Therefore, chlorine is suitable for sewage treatment and can ensure the stability of recycled water quality. However, because chlorine (Cl2) is a toxic and harmful gas, to prevent chlorine concentration leakage or excessive concentration lead to poisoning, sewage treatment pool and other places need to install chlorine concentration detection alarm, detect whether the chlorine concentration exceeds the standard.

Sewage treatment is the process of making sewage reach the water quality requirements for drainage or reuse, and purifying it. Sewage treatment is widely used in construction, agriculture, transportation, energy, petrochemical, environmental protection, urban landscape, medical, catering and other fields, and more and more into the daily life of ordinary people. There are many ways to treat sewage, which can be generally summarized as physical, chemical and biological methods. In 2013, urban domestic sewage discharge has become the main source of urban water in China. Urban domestic sewage treatment is the top priority of urban water saving and urban water environment protection at present and in the future. This requires us to take the construction of domestic sewage treatment facilities as an important part of urban infrastructure, and it is an urgent matter.

With the development of science and technology, the direct use of sewage has become possible, the use of sewage source heat pump system for the use of urban raw sewage. The so-called raw sewage directly discharges untreated domestic or industrial wastewater from the city. At this stage, the utilization method is that the raw sewage directly enters the sewage source heat pump system for heat exchange, which consumes a small amount of electricity for indoor cooling and heating of urban buildings.

Wastewater reuse has several technical difficulties to overcome: blockage, corrosion, heat transfer efficiency. Sewage source heat pump system is composed of two parts: sewage heat exchanger and sewage source heat pump. After the urban primary sewage directly enters the sewage heat exchanger for heat exchange, the heat exchanged is transferred to the indoor by the heat pump work inside the sewage source heat pump. The advantages of reuse of urban primary sewage are: energy saving and environmental protection, no pollution.

Sewage treatment can be divided into physical, biological and chemical methods according to its role. Physical method: the main use of physical separation of non soluble substances in sewage, in the process of treatment does not change the chemical properties. Commonly used gravity separation, centrifugal separation, reverse osmosis, air flotation and so on.

physical method：The treatment structure is relatively simple and economical, and is used in villages and towns with large water capacity, strong self-purification capacity and low requirements for sewage treatment.

Biological law:Using the metabolic function of microorganisms, the organic matter in the dissolved or colloidal state in the sewage is decomposed and oxidized into stable inorganic substances, so that the sewage is purified. Activated sludge method and biofilm method are commonly used. The degree of biological treatment is higher than that of physical method.

Chemical method:It is a method that uses chemical reactions to treat or recover dissolved substances or colloidal substances in sewage, and is mostly used in industrial wastewater. Commonly used are coagulation method, neutralization method, oxidation reduction method, ion exchange method, etc. The chemical treatment method has good treatment effect and high cost, and is mostly used as the effluent after biochemical treatment for further treatment to improve the quality of the effluent.

In small sewage treatment plants, the current sewage treatment in the control of chlorine concentration is basically the use of empirical control method, according to the experience of operators to control the air volume of chlorine fan, generally to increase or decrease the number of chlorine fan to achieve the purpose of controlling chlorine concentration. The above-mentioned control method is too extensive. At present, the current situation of this method is that most factories have too high chlorine concentration, which not only wastes electric energy but also is not conducive to the subsequent improvement of water quality.

The chlorine concentration regulating device for sewage treatment includes: chlorine fan, air guide pipe, chlorine concentration sensor, computer, control board, instrument panel and cable. The chlorine fans are evenly distributed in six groups with the center of the sewage treatment tank as the central axis. The chlorine fans are fixed at the edge of the sewage treatment tank through anchor bolts. The other end of the air guide pipe extends to the inside of the sewage treatment tank. The chlorine concentration sensor is connected with the computer through cables, the control board and the instrument panel are fixed on the edge of the sewage treatment tank by screws. The control board and the instrument panel are connected to the computer through cables. The motor part of the chlorine fan is a servo motor, and the servo motor in the chlorine fan is connected to the computer through cables. The computer contains a chlorine concentration sensor signal analysis module.Chlorine concentration regulating device for sewage treatmentMediumSensors for detecting chlorine concentrations, recommend useChlorine gas sensorCL2-B1 for chlorine monitoring.

CL2-B1 main characteristics of electrochemical chlorine gas sensor
Sensitivity:-600 ~-950nA/ppm
Response time: Linear range: 20ppm
Overload: 60ppm
Resolution: 0.02ppm
Size: Φ32.3*16.5
Service life: 2 years
Storage period: 6 months
Working temperature:-20~50 ℃
Working humidity: 15 ~ 90% RH
Load resistance: 33Ω

Electrochemical Chlorine Gas Sensor CL2-B1 Typical Applications
Waste water treatment, industrial environment toxic gas measurement