Breaking news! 5 deaths and injuries caused by the cleaning of a sewage sedimentation tank

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At around 16:30 on July 22, 2019, Great Wall Biochemical Engineering Co., Ltd. in Huailai County, Hebei Province (which is not a chemical manufacturing company), suffered an accident involving exposure to harmful gases while carrying out operations to clean the sewage sedimentation tanks on its premises. Beware! The next two months represent a peak period for sewage treatment plant accidents. Analysis and statistics of such incidents show that the highest number of accidents occur between May and September; during these five months, a total of 27 accidents took place, accounting for 67.5% of all accidents ； The number of deaths was 91, accounting for 69.4% of the total deaths ； The number of injured people is 61, which accounts for 87% of the total number of injuries! Seasonality is a major factor contributing to accidents at wastewater treatment plants. In China, from May to September, when temperatures are relatively high in most regions, the incidence of such accidents is relatively high. In contrast, from October to April of the following year, as temperatures drop nationwide, the occurrence rate of accidents at wastewater treatment plants decreases. In terms of the severity levels of accidents at wastewater treatment plants in our country, the occurrence rates of minor and relatively serious accidents are high, while major accidents are relatively rare. Moreover, compared to minor accidents, the incidence rate of relatively serious accidents is higher. Behind every death incident involving a worker, there is the shadow of your violation of safety rules! Behind every accident, you can find your own reflection; if an accident doesn’t happen to you, it’s merely luck. I hope that all professionals in this field will save this video – watch it before going into confined spaces such as pools or wells, as it could surely save your life! How to clean a sewage tank properly? 1. Steps and precautions for cleaning sewage tanks: Before cleaning a sewage tank, the inlet valve for sewage should be closed, and the water inside the tank should be drained as much as possible, allowing natural ventilation to occur for over 24 hours. Manual cleaning should be avoided as much as possible in favor of mechanical cleaning. 2. Workers entering the pool must be in good health and fully conscious. Persons under the age of eighteen, those with respiratory, cardiovascular, allergic, or skin allergy conditions, as well as women, are not allowed to perform this type of work. 3. A \"Sewage Tank Cleaning Work Order\" must be filled out for sewage tank cleaning operations. On-site safety personnel are designated by the safety responsible person. The site safety officer must provide technical and safety instructions to the personnel carrying out the cleaning work, and both parties involved in these instructions should sign the \"Sewage Tank Cleaning Work Order\". 4. When working in the pool, a site safety officer must be present to oversee the implementation of safety measures throughout the process, and at least two supervisors should be assigned. 5. Personnel entering the pool must wear appropriate protective equipment (gloves, safety helmets, safety belts, safety ropes), as well as carry oxygen tanks and toxic gas detectors; a site safety officer will conduct a check of the safety measures before work begins. 6. Before entering the pool, a multi-functional gas detector must be used to detect harmful gases. The oxygen content in the air of the work area should be between 19.5% and 23%; if the oxygen level is below 19.5%, an alarm signal should be generated. The concentration of toxic substances shall comply with the provisions of GBZ 2.1 and GBZ 2.2. If it is confirmed that there is no alarm due to excessive levels of hazardous gases, the safety officer shall be responsible for supervising the operation on site; meanwhile, approval from the primary safety officer must be obtained before work can proceed in the pool. 7. When gas detection using a multi-function gas detector indicates that the concentration of hazardous gases exceeds the limit, use a blower to force ventilation for 15 minutes before conducting another test with the multi-function gas detector. If the test shows that the concentration of hazardous gases does not exceed the limit, then proceed according to Item 6. 8. After mechanical ventilation is implemented using a blower, if the readings still exceed the allowable limits as detected by the multi-functional tester, the safety management department should be notified immediately so that personnel can be sent to the site to check the safety measures. Only after approval is given in writing by the plant manager responsible for production, and after wearing gloves, safety helmets, safety belts, safety ropes, and isolation respirators, can work be carried out in the pool. Records of such work must be kept, and the duration of work in the pool shall not exceed 30 minutes. 9. After entering the pool, tools and accessories must be lifted using tool bags; throwing them is strictly prohibited. There must be no stones, bricks, or other objects that could cause injury by impact within one meter around the work well. The personnel on the pool surface ensure all safety measures for those entering the pool. 10. A no-entry zone should be marked on the ground in the construction area, and construction signs should be installed to prevent unauthorized persons from entering; a safety ladder should be provided beside the pool. 11. The use of fire is strictly prohibited when working in the pool; flammable and explosive items are not allowed to be taken into the pool. If welding work is necessary and the conditions for such work are met, ventilation equipment must be used, fire-fighting equipment must be available, and a welding permit issued by the relevant safety authorities must be obtained before working in the pool. 12. Open flames and non-explosion-proof equipment are not allowed in areas where flammable gases are present. 13. If a production and operation unit does not have the necessary conditions for carrying out cleaning operations, it shall assign such tasks to a construction unit with the appropriate qualifications, and enter into a contract for assignment as well as a safety production agreement. 14. If the cleaning operation is expected to take a long time, workers should take turns entering the tank. Should any worker experience discomfort such as dizziness, weak legs, shortness of breath, or nausea while working inside the tank, they must immediately leave the tank and rest. 15. During cleaning operations, the on-site safety officers and supervisors must remain at their posts, stay focused, and refrain from engaging in any other tasks. They must maintain contact with the workers underground, pay close attention to their condition, identify any issues promptly, and prevent safety accidents from occurring. 16. In the event of an operational hazard, workers should be immediately rescued and taken away from the site for treatment, while the safety management department and relevant supervisors should be notified. 2. Accident rescue measures: The personnel responsible for rescuing in case of an accident should put on personal protective equipment and take necessary preventive measures before rushing to carry out risk mitigation work. Unrelated persons within the danger zone should be quickly evacuated from the site. Emergency responders must follow instructions, be aware of the toxic substance and the situation at the scene, and wear complete protective equipment. Emergency responders must provide assistance while ensuring their own safety. Emergency responders entering areas with toxic gases must do so in groups of at least two. Transport the injured to a safe area promptly. 3. First aid measures in case of accidents: 1. First aid for hydrogen sulfide poisoning: Quickly move the victim away from the area where exposure occurred to a place with fresh air; remove any objects in the mouth and contaminated clothing. Administer oxygen immediately, loosen the tie and belt to keep the airways unobstructed, and at the same time call emergency services at 120 for help. For those with stopped heartbeat and breathing, artificial respiration should be administered immediately (chest compressions are preferred over mouth-to-mouth respiration; if that is the only option, use several layers of wet gauze between the rescuer and the patient) as well as external chest compressions to improve breathing, until the patient reaches the hospital. 2. First aid for ammonia poisoning: Quickly move the patient away from the site of exposure to an area with fresh air, remove any objects in the mouth and contaminated clothing, thoroughly wash the affected eyes and skin, and at the same time call emergency services at 120 for help. Also, loosen the tie and belt to keep the airways unobstructed.