The picture above shows the scene of the explosion that night.
The sewage treatment plant is equivalent to the kidney of the city. Sewage can be divided into domestic sewage and industrial sewage, and the treatment standards and processes are also different. Sewage treatment is mainly to remove suspended solids and improve oxygen consumption, and sometimes other treatments are needed. Because of the serious pollution, the sewage from the factory needs to be treated by heavy metals, oil pollution and other pollutants before it can be discharged to the urban sewage treatment plant.
The picture above shows the sewage treatment tank.
Generally, sewage is discharged into normal water by sedimentation and aeration (aeration is a means to make air contact with water strongly, which is to dissolve oxygen in the air in water or release unnecessary gases and volatile substances in water into the air), and then the pollutants in water are gradually cleaned by activated sludge and microbial treatment, and chlorine gas is added for disinfection and sterilization.
The picture above shows activated sludge from a sewage treatment plant.
To explode, three elements must be met, one is to have flammable substances, the other is to reach the explosion limit and the third is to reach the ignition point. In a closed environment, with the continuous accumulation of combustible gas and even mixing with air, sometimes the sparks generated by metal collision can also cause explosion when reaching the explosion limit. Explosion is actually an extremely violent large-scale combustion phenomenon. Intense combustion will make the air expand rapidly, and eventually produce a strong shock wave, destroying everything around.
Urban sewage generally contains a lot of organic matter, which is easy to produce combustible biogas. When sewage flows in the sewage pipeline, it is always in a closed state, and these biogas will gather in these closed spaces in large quantities, which may explode when it meets an open flame. Previously, there were cases in which children threw firecrackers into sewers and caused explosions, and the manhole cover was lifted several meters high.
In the process of sewage treatment, toxic, corrosive, flammable and explosive gases will be produced, so the sewage treatment plant must also pay attention to ventilation and fire prevention. In addition, those toxic and harmful gases cannot be directly discharged into the atmosphere and must be collected and treated.
The explosion occurred in an industrial wastewater treatment plant located in the chemical industry park, and the explosion source was the hydrolysis and acidification workshop in the plant. Hydrolytic acidification is a process of hydrolyzing insoluble organic matter in water into soluble organic matter and transforming difficult-to-degrade macromolecules into easy-to-degrade micromolecules through the fermentation of microorganisms, thus improving the quality of sewage. In this fermentation process, combustible gas (such as methane) will be produced, which may explode if it is not handled properly.
The picture above shows the hydrolytic acidification tank.
Fortunately, sewage treatment plants are generally far away from residential areas, and even if there is an explosion, it will not cause too many casualties. For this kind of chemical units, we must always supervise, check for leaks and fill gaps, and find out potential safety hazards. For non-compliance, it is necessary to order rectification.
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