Background:

Malodorous is to point to the gas material that all stimulates olfactory organ to cause people unpleasant and damage living environment. Odor concentration is a comprehensive factor of air quality, and its value is a comprehensive reflection of mixed air quality. The sources of stench are various and the composition of stench is complex. Therefore, it is necessary to use a comprehensive index to limit it. The method of limiting stench in China is based on the national Emission Standard for Stench Pollutants (GB 14554-93), in which the concentration of environmental stench at the factory boundary is limited to 20OU. We can use gas sensors to monitor odorous gases online.

Necessity of establishing on-line monitoring system for odor：

The development of the city and the requirements of energy conservation and emission reduction, local speed up the construction of sewage treatment plants and related facilities. However, in the process of sewage treatment, odor will be generated in the aeration tank, sedimentation tank, anaerobic tank and sludge treatment area. Affecting the quality of life and health of citizens. In order to prevent sewage treatment each link odor gas pollution and disturbing the environment. It is necessary to realize daily environmental monitoring and take effective and reasonable measures to control the influence of malodorous gas on the surrounding environment.

Sewage treatment plant itself is a benign environmental protection project, the completion of the improvement of regional environment and water quality will have a great effect. However, the operation of sewage treatment facilities will also have a certain impact on the surrounding environment. In order to prevent sewage treatment each link odor gas pollution and disturbing the environment. In order to implement the daily environmental monitoring plan, effective and reasonable measures should be taken to control the impact of malodorous gases on the surrounding environment. Of course, prior to taking measures, it is necessary to conduct in-depth monitoring and analysis of odorous gases in sewage treatment plants.

In China, gb14554-93 Comprehensive Emission standard for malodorous Pollutants lists the following eight gases with low olfactory threshold: ammonia, trimethylamine, hydrogen sulfide, methanethiol, methyl sulfide, dimethyl disulfide, carbon disulfide, styrene. The eight gases are organic and inorganic, and five of them are sulphides. Life often smell odor, peculiar smell is also from this.

A major source of malodorous gases：

1) The emission of malodorous substances carried by water. Both industrial waste water and domestic waste water contain a lot of organic matter. In the process of being sent to the sewage field, complex biochemical reaction will occur, which will make the incoming water with foul smell. And organic volatile gases are inherently offensive. The concentration of these malodorous gases varies with temperature. The higher the temperature, the faster water and harmful gases evaporate, and the higher the concentration of malodorous gases. This is why odorous gas concentrations are lower in winter and higher in summer.

(2) Odor gas is produced in the biochemical stage of sewage treatment. During the operation of sewage treatment plant, biochemical treatment will be taken to remove organic matter, and the incomplete biochemical reaction will produce a lot of odor gas. NH3 mainly comes from the degradation of organic matter, while H2S is mainly produced by incomplete biochemical anaerobic reaction.

(3) Generation and emission of odor in sewage sludge treatment process. Sludge is easy to produce local anaerobic substances, which will produce a large number of hydrogen sulfide, hydrogen sulfide volatilized and air contact diffusion, odor gas generation.

(4) the improper disposal of grille slag and sand sink slag caused by odor emission.

(5) Aeration of wastewater treatment process containing more volatile organic compounds. Inadequate aeration, uneven distribution of burst head and other biochemical oxygen demand supply, local anaerobic, resulting in odor gas.

Stench of urban sewage：

Sulfur-containing odorous gas produced in urban sewage treatment plants are scattered in many locations. But mainly concentrated in the sewage treatment plant water pump, aerated sedimentation tank, as well as the grille and other inlet areas. In addition, there are sludge dewatering room, sludge thickening pool and other sludge treatment area. In addition, the contents of hydrogen sulfide, methanethiol, ethanethiol, sulfur dioxide, carbon dioxide, dimethyl thiamidine, diethyl thiether and ethyl butyl sulfate gradually decreased with the distance from the pollution source. Among them, the concentration of carbon disulfide in sulfur-containing waste gas source of sewage treatment plant is the highest, which is 11.16 mg/m3. Followed by diethyl sulfide, sulfur dioxide and dimethyl sulfide. The highest concentration of carbon disulfide at 50m is 12.05 mg/m3, which is higher than that at the source.

Improper treatment of odor pollution will not only pollute the atmospheric environment. It will also have a serious impact on the lives of people living near the industrial park. The rate of resident complaints due to foul smells is increasing year by year. A series of problems caused by odor pollution have also attracted the attention of relevant departments. Local environmental protection departments for the generation of odor pollution sources, there are clear provisions. Traceability monitoring of odor pollution should be done first, and then targeted deodorization treatment should be carried out according to different properties.

Monitoring and gas sensors for malodorous gases in treatment plants：

The monitoring of malodorous gases can no longer rely on traditional artificial olfactory detection. What we are doing now is we need to quantify the odor detection. To turn sensory things into numbers that can be judged. For odor generation way and source are different. Online odor monitoring system (also known as odor electronic nose) can be used for chemical plant monitoring, sewage treatment, landfill, oil refining, cement fertilizer and other enterprises or departments of internal control. To other emergencies caused by malodorous gas leakage rapid and effective monitoring and information early warning. Provide data support for various environmental odor pollution law enforcement. Monitor routine business operations and emissions, and record sudden odor sources.

Through the deployment of high-precision odor gas acquisition sensors in the factory, it can realize the 24-hour online monitoring of many odor indicators in the air environment, such as ammonia, trimethylamine, hydrogen sulfide, methanethiol, methyl sulfide, dimethyl disulfide, carbon disulfide, styrene, OU value of odor and so on. With fast response speed, high measurement accuracy. Features of good stability. There are now widespread and mature applications.

Introduction of hydrogen sulfide gas sensor：

Portable H2S detector, Hydrogen Sulfide detector, are used in gas storage leakage monitoring, drug factory, food factory, hospital gas disinfection residue detection, electrostatic precipitator, gas generator, air purifier, gas leakage, indoor air gas detection scene.Fixed hydrogen sulfide gas detector with smooth precision, stable performance, sensitive and reliable. Adopt high precision LIQUID crystal display, explosion-proof enclosure, diffused or pumped. H2S gas detector has the characteristics of flexible use and simple operation. H2S gas detector is suitable for all kinds of gas leakage places, such as: city gas, petroleum, chemical, pharmaceutical, steel, special industrial plants and other fields. H2S gas detector explosion-proof grade is CT6. It can be used for on-line monitoring of hydrogen sulfide.

Ammonia sensor monitoring equipment：

Ammonia gas monitoring can use jingxun unblocked independent research and development of ammonia gas detector.The NH3 gas alarm controller is mainly used for 485 series sensors, including two specifications of digital tube display and color screen display. The data readings detected by the sensor are summarized and displayed on the display screen. At the same time, according to the setting, when the current data is greater than the alarm concentration, the NH3 gas alarm controller will carry out a series of alarm actions, such as sound and light alarm, exhaust power failure, etc. (according to customer settings), The NH3 gas alarm controller can support the control system with up to 16 sensor inputs, support two-way relay control, and can linkage exhaust, power failure and other behaviors.More gas monitoring equipment, welcome to jingxun unblocked (JXCT) consultation, we are manufacturers direct sales, reliable quality assurance.