Be vigilant! Enterprises that enter the Cesspit for maintenance without permission are ordered to stop production for rectification!

At 6:00 p.m. on June 15, 2023, the six leaders of the special team of the leading group of the special rectification work for the safety development of printing and dyeing enterprises in Keqiao District of Shaoxing led the team to carry out night inspection, and made on-site unannounced visits to supervise the safety development of printing and dyeing enterprises.

Illegal operation of Cesspit is ordered to stop production for rectification

During the inspection, it was found that a printing and dyeing enterprise still had a weak foundation for accident prevention and control in confined space, operated the Cesspit in violation of regulations, and had major potential accidents, so it was ordered to stop production for rectification.

At about 8:00 pm that day, the inspectors came to Zhejiang East China Textile Printing and Dyeing Co., Ltd. and found that the cover of the Cesspit was not locked when they inspected the underground sewage collection tank in Workshop II. After inquiry, the workshop director admitted that at about 5:30 in the evening, he opened the cover for maintenance without permission because he found that the Submersible pump in the Cesspit had failed, and because he did not need to go down to the pool for operation, he neglected the approval and monitoring process.

"The risk of toxic gas accumulation in the underground sewage collection pool is relatively high. You opened it without approval and without any protective measures, which is a major accident hazard." The inspectors then took the monitoring at that time, and the monitoring showed that at 17:52, a staff member opened the Cesspit illegally without taking any protective measures, After that, the four staff members carried out the maintenance and commissioning of Submersible pump at the side of the sewage collection pool, and did not complete the operation until 18:25. After covering the Cesspit, they forgot to lock it.

"Zhejiang Huadong Textile Printing and Dyeing Co., Ltd. was closed down for rectification, and a warning education meeting was held to thoroughly rectify the existing problems and prevent the recurrence of illegal acts." Sheng Guoyang, deputy director of the Keqiao District Emergency Management Bureau, interviewed the safety officer of the enterprise and asked the enterprise to immediately close down for rectification.

During the night inspection on the same day, the inspection team also found that some printing and dyeing enterprises had issues with the storage of hazardous chemicals not strictly following the requirements, the stacking of fabrics in the fire exits of the factory area, the failure to light up the emergency exit lights in the corridors, and incomplete information on the risk notification cards. All of these issues were rectified on the spot. It is understood that since Keqiao District launched the centralized action of starting, renovating and reshaping the safety development, the special team for the safety development and renovation of printing and dyeing enterprises in Keqiao District has responded positively and continued to carry out the major inspection and renovation for the safety development of printing and dyeing enterprises. That evening, a total of 81 various risk hazards were discovered.

"In the rectification work, we found that there is also a phenomenon of" hot up and cold down "in the enterprise, and the actual controller of the enterprise often paid attention to it, but the actual operators would still be lucky. Next, we will work with functional departments and territories to further optimize measures, and pay close attention to the responsibilities of operators such as Cesspit and Hot work." The relevant person in charge of the special work shift said. (Shaoxing Express)

Poisoning and suffocation are the first killers in sewage treatment

According to the literature "Statistical Analysis and Countermeasure Research on Accidents in Sewage Treatment Plants in China", 47 sewage treatment accidents over the past 10 years were analyzed:

Through the classification and summary of 47 collected sewage plant accident cases, the first cause of the accident was poisoning and suffocation, with a total of 29 cases accounting for 75% of the total accident. The second place was due to the collapse of structures, with 6 cases occurring, accounting for 17% of the total accident; The third place is drowning accidents, with 2 occurrences, accounting for 7.5% of the total accidents; In addition, there were also 1 incident of water seepage, electric shock, explosion, etc., which accounted for 3% of the total accidents. From this analysis conclusion, it can be seen that the main type of accidents in sewage treatment plants is poisoning and suffocation accidents.

In the analysis and research, statistics and classification were conducted on substances that cause poisoning and suffocation. The results showed that 57% of the total accidents were caused by hydrogen sulfide poisoning. 31% of the total accidents were caused by poisoning incidents caused by biogas. Accidents caused by other reasons account for 12%. After analysis, it can be found that hydrogen sulfide is the main cause of poisoning accidents, while biogas is the main cause of suffocation accidents.

Through the analysis and statistics of poisoning and suffocation accidents in the total accident, it was found that the failure to inspect and use personal protective equipment according to regulations was the main cause of casualties in the accident, accounting for 78% of the total. Defects in the equipment operated by sewage treatment plants were also one of the reasons for casualties in the accident, accounting for 7% of the total. Due to poor ventilation, incorrect operation, risky entry into hazardous areas in dangerous situations, improper storage of items, and other reasons, poisoning and suffocation accidents can also occur. From the above situation, in order to reduce the occurrence of poisoning and suffocation accidents, ensuring the effective and correct use of protective equipment by workers is a key means.

Through the analysis and study of 47 WWTP accidents, it can be seen that the main locations of accidents are inspection wells, Cesspit, pipe networks, trenches and other locations. Among the 10 accidents that occurred in the inspection well, there were 9 poisoning and suffocation accidents, and 1 explosion accident. Among the 9 construction accidents in the Cesspit, there were 7 poisoning and suffocation accidents and 2 drowning accidents. Among the 8 accidents that occurred in the pipeline network, there were 5 poisoning accidents, 1 collapse accident, and 2 water leakage accidents.

Through statistics and analysis of the types of accidents in sewage treatment plants in China, it can be seen that the main types of accidents in sewage treatment plants are: poisoning suffocation, collapse, drowning, explosion, electric shock, water permeability, etc. Among them, the most common type of accident is poisoning suffocation accident, with a probability of occurrence of 70%. From the perspective of the causes of poisoning accidents, hydrogen sulfide is the main cause of poisoning accidents, and biogas is the main cause of suffocation accidents. Moreover, the main reason for personnel injury in poisoning accidents is that personal protective equipment has lost its effectiveness or has not been used in accordance with regulations during the operation period. Moreover, defects in sewage treatment plant equipment, incorrect operation, facilities not meeting prescribed standards, and poor ventilation are all causes of casualties. However, the use of personal protective equipment is the main cause of casualties in poisoning and suffocation accidents, with an incidence rate of up to 78%.

Guidelines for Confined space operation of sewage treatment

Poisoning and suffocation accidents occur frequently in limited spaces for sewage treatment. The main problem is weak safety awareness and inadequate safety measures, which lead to accidents. How to avoid such accidents still needs to be solved through internal and external safety education and strengthened safety measures!

1. Ten Prohibitions for Sewage Treatment Operations

1、 Employees who have not received training and are not familiar with sewage treatment processes and safety risks are not allowed to participate in sewage treatment work.

2、 Do not work in the sewage treatment area after drinking or at night.

3、 It is not allowed to open the locked cover of the Cesspit without approval.

4、 Without implementation of work approval, qualified ventilation and testing, wearing a gas mask (anti sulfide oxygen) or air respirator, and personnel supervision, it is not allowed to work in the pool.

5、 Emergency rescue equipment and equipment such as positive pressure air respirators, gas masks, safety ropes, and gas detectors have not been placed on site, and it is not allowed to work in the pool.

6、 It is not allowed to wash the Cesspit, patrol the Cesspit and salvage the sundries on the surface of the Cesspit without wearing a portable toxic gas alarm and gas mask (anti hydrogen sulfide).

7、 It is not allowed to add acid wastewater, chemicals or materials into the Cesspit without authorization in violation of the sewage treatment process flow.

8、 It is not allowed to use the sewage treatment agent after hazardous waste treatment, to use sewage to flush the agent pool, and to add Sodium sulfide to acidic wastewater.

9、 After the hydrogen sulfide and other gas monitoring and alarm facilities alarm, they should be evacuated in a timely manner. It is not allowed to check without wearing an isolated gas mask (anti hydrogen sulfide) or a positive pressure air respirator, or without doing personal protective work.

10、 Rescue workers are not allowed to rescue people without wearing isolation type gas masks or positive pressure air respirators.

2. Code of Practice for Sewage Treatment

1. For personnel engaged in toxic or suffocating operations, it is necessary to provide safety education on drug prevention and first aid, which should include safety knowledge of the work, the hazards of toxic and harmful gases, emergency handling and rescue methods, etc.

2. When entering a confined space for work, it is necessary to analyze the oxygen content, combustible gas content, and toxic gas content of the working environment.

3. When working in toxic areas, protective equipment must be worn and someone must supervise. When entering high-risk areas for inspection, condensate discharge, instrument calibration, sampling, tank cleaning, and other operations, operators should wear protective equipment that meets the requirements, carry portable alarm devices, and two people should walk together, with one person working and one person monitoring.

4. When entering hypoxic or toxic gas equipment for operation, the process treatment work should be effectively carried out, and the confined space should be purged, steamed, and replaced to meet the standards; All pipelines and valves connected to them that may contain flammable, explosive, toxic, and harmful materials shall be isolated with blind plates, and closing valves shall not be used as a substitute for installing blind plates. A signboard should be hung at the blind plate. 

5. Fully recognize the hazards of simple asphyxiating gases such as nitrogen.

6. In toxic or suffocating positions, emergency rescue plans should be developed and corresponding protective equipment should be equipped. The content of the emergency plan should include the escape routes and rescue methods for operators in emergency situations, and life-saving facilities should be equipped on site. Operators should be familiar with the content of the emergency plan. The site of confined space operations must be equipped with a certain number of emergency rescue equipment that comply with regulations (including air respirators, air supply protective masks, lifelines, etc.), and there must be no obstacles inside or outside the entrance and exit to ensure smooth access and facilitate personnel entry and exit, rescue and evacuation.

7. The concentration of toxic media in toxic and harmful places should be regularly tested to ensure compliance with national standards.

When entering a confined space for work, to ensure air circulation and personnel breathing needs, natural ventilation can be used, and if necessary, forced ventilation can be adopted. It is strictly prohibited to inflate oxygen inside. Operators entering confined spaces should not work for too long each time and should rotate or rest.

8. Special personnel must be assigned to manage and regularly inspect all types of toxic substances and anti virus equipment; Equipment and instruments involved in the detection of toxic substances should be regularly inspected and kept in good condition.

9. Establish a sound management system for toxic and harmful substances and strictly implement it. Workplace that fails to meet the prescribed hygiene standards for a long time should stop working. Workplace areas with concentrations exceeding national occupational exposure limits or where poisoning has occurred should be identified as key hidden danger points for rectification or monitoring.

3. Escape and first aid in case of poisoning and suffocation!

1. Self rescue

When symptoms such as dizziness, headache, nausea, and weakness suddenly appear in workplaces where toxic gas leaks may or have already occurred, it is necessary to consider the possibility of poisoning. At this moment, one should hold their breath and quickly run out of the danger zone against the wind. If the wind direction is the same as the direction of the fire or poison source, run sideways; If you are at a height without a fence, grab something at the fastest speed or lie on the windward side to avoid falling as much as possible; If possible, activate the alarm facility as soon as possible. At the same time, quickly soak the clothes, towels, masks, etc. that can be used around you with water, cover your mouth and nose, and leave the scene to avoid inhaling toxic gases.

2. Mutual rescue

The rescuers should first find out the environment of the rescued person, select a suitable Gas mask, and rescue the poisoned person to a fresh air place under the premise of good protection. Rescue personnel should approach the scene from upwind and uphill positions, and blind entry is strictly prohibited.

3. First Aid

In the event of poisoning or suffocation, the leaders present should take the initiative to command. Rescue personnel must wear isolation type protective masks to enter the equipment, and at least one person should be in contact externally. This is very important. After an accident, rescue work should be done every second, but it must be calm and handled correctly, and blind rescue cannot be done. There have been many accidents in various industries that have caused casualties to expand due to improper rescue efforts. After the victim is evacuated from the scene, some simple methods such as artificial respiration can be used for rescue.