Wastewater treatment plants/sewage tanks can produce a lot of toxic and harmful gases. Although there are various types and complex components of toxic and harmful gases, they can be divided into three categories based on the different modes of harm: toxic gases (suffocating gases), corrosive gases, and flammable and explosive gases.

Toxic and harmful gas detection points generated by sewage plants/sewage tanks：

Sewage tank, concentration tank, underground sewage, sludge gate well, non flowing sewage tank, disinfection facility, grid room (coarse grid, fine grid), lifting pump room, pump station, aeration tank, sludge digestion tank, flow distribution well, cyclone sedimentation tank, secondary sedimentation tank, sand removal room, deodorization workshop, and treatment workshop.

Detection of toxic and harmful gases generated by sewage plants/sewage tanks Gas types:

1. Toxic gas. Usually refers to gases that cause harm to other tissues and organs inside the human body through the respiratory organs, such as hydrogen sulfide H2S, hydrogen cyanide HCN, carbon monoxide CO, carbon dioxide CO2, ammonia NH3, etc. Due to their general function of inhibiting the oxygen exchange capacity of internal tissues or cells in the human body, these gases cause hypoxia in the body tissues and result in asphyxiation poisoning, hence they are also called asphyxiating gases.

2. Corrosive gases. Generally, when disinfectant gases such as chlorine gas CL2, ozone O3, chlorine dioxide CLO2 leak, they corrode the respiratory system of the body and cause toxicity.

3. Flammable and explosive gases. They cause harm by mixing with air to produce a certain proportion, which can ignite or even explode when exposed to open flames, such as methane CH4, hydrogen H2, etc

The detection of toxic and harmful gases generated by sewage plants/sewage tanks:

1. Poisoning caused by irritant and suffocating gases: hydrogen sulfide H2S (irritant and suffocating), methane CH4 and carbon dioxide CO2 (purely suffocating), hydrogen cyanide HCN (suffocating, caused by high concentrations)The main causes of casualties in sewage tank cleaning personnel include acid generation, ammonia gas NH3 (irritating and corrosive), etc.

2. Poisoning caused by highly toxic substances: arsenideWaiting for hydrogen cyanide HCN, such as accidental ingestion, eye damage, and skin damage, is a secondary cause of injury or death to personnel cleaning sewage tanks.

3. Possible hazards caused by processing procedures. Aeration and sludge digestion are usually high-risk areas for biogas production. The biogas produced from sludge contains harmful substances such as methane, hydrogen sulfide, and carbon dioxide. Besides being highly explosive, methane can also cause a decrease in oxygen concentration, thereby increasing the risk of suffocation. On the other hand, hydrogen sulfide has a special odor at low concentrations (0.0047ppm), which is easily distinguishable; But when the concentration exceeds 150ppm, the human olfactory nerve will be damaged and unable to smell its odor, thus masking its true existence. Even if hydrogen sulfide reaches a lethal concentration of 800ppm, workers will not be able to smell its odor, posing a fatal danger. Due to the high flammability of biogas, the biogas produced during sludge digestion can be used for power generation. Therefore, if it leaks out of the digestion tank, it will be very dangerous and may lead to an explosion.

Solution for detecting toxic and harmful gases generated by sewage plants/sewage tanks:

Composition of front-end monitoring equipment:

Portable toxic and harmful gas detector+fixed toxic and harmful gas detector

Data transmission:

1. Wired transmission: The toxic and harmful gas detection instrument transmits a 4-20mA current signal or RS485 bus digital signal to the gas alarm controller, and then converts the signal to transmit to the computer terminal;

2. Wireless transmission: The toxic and harmful gas detection instrument transmits data to the gas alarm controller through 4G wireless module or Lora wireless module, and then wirelessly transmits it to the computer terminal through the Internet network.

Backend monitoring management:

1. Controller: Implement display and alarm functions in the monitoring area, and can activate ventilation function.

2. Platform display: The front-end toxic and harmful gas monitoring data is transmitted to the IoT monitoring software platform through data transmission, achieving functions such as display, analysis, and alarm.

3. Monitoring center or monitoring platform system: Customer's own PLC, DCS and other systems or platforms.