How to solve the secondary pollution of drinking water?

According to relevant data, the average value of the various water quality indicators of the factory water from the respective water plants is in line with the current drinking water sanitation indicators, and the average total pass rate is 99.39%, including turbidity, total number of bacteria, total coliforms and free residual chlorine. The average annual comprehensive pass rate of the four indicators is 98.73%, while the average annual pass rate of the four indicators of turbidity, total number of bacteria, total coliforms and free residual chlorine in the pipeline network is only 95.68%, which is higher than that of the factory water. reduce. The average annual comprehensive pass rate of the four indicators of the secondary water supply is 83.81%, which is significantly lower than the water quality of the factory water. The average value of the total coliform and free residual chlorine does not meet the standard requirements. It can be seen that the adjustment of the secondary pressurized water supply Pollution in storage tanks, water towers and water tanks is even more serious.

With the development of economy and the increase of urban population, more and more people will live in high-rise buildings, and the quality of the secondary water supply will affect the health of more and more residents. Therefore, eliminating the “secondary water pollution” in high-rise buildings is a major event that cannot be ignored! It is also the duty of our water quality workers.

The water supply facilities of high-rise buildings are different from low-rise buildings. The water supply facilities of low-rise buildings are directly supplied by water plants through pipelines, while the water supply facilities of high-rise buildings can only be obtained through secondary water supply facilities. Generally, secondary water supply facilities include high and low water tanks, water pumps, water pipelines and purification and disinfection facilities. The tap water first enters the low-level water tank, and then is delivered to the high-level water tank by a water pump, and then is supplied to the residents in the upper floors by gravity. Before it is supplied to households, the water must be disinfected twice through the secondary disinfection facility to ensure the safety and sanitation of drinking water. Investigation and comprehensive evaluation of the sanitation and management level of secondary water supply facilities in high-rise buildings found that high-rise buildings not only have problems in the design and construction of water supply facilities, but more importantly, there are serious problems in drinking water sanitation management.

There are many reasons for the secondary pollution of drinking water in the secondary water supply system, which are not only related to the nature of the water quality itself, but also related to the nature of the cross-section in contact with the water, and also related to many external conditions. The essence of secondary water pollution is the migration and transformation of pollutants in the water, which is a comprehensive process of physics, chemistry and biology. Physical changes mainly include: dissolution and crystallization, precipitation and suspension, adsorption and desorption, etc.; chemical changes mainly include: oxidation and reduction, electrochemistry, ion exchange, hydrolysis and ionization, etc.; biochemical changes mainly include: degradation, alienation, assimilation, etc. . Under the combined effect of the above-mentioned various factors, the amount of a certain substance (pollutant) in the water either increases or decreases, resulting in a change in water quality. In addition, the influence of various factors outside the system, especially the direct penetration of pollutants, directly changes the water quality in the system and causes the deterioration of water quality. Judging from the current investigation, there are six main causes of secondary water supply pollution:

  1. The internal surface coating of water equipment, such as the peeling off of the anti-corrosive paint of metal water storage equipment, the harmful exudate in the cement mortar surface of concrete and reinforced concrete water storage equipment, affect the water quality of the water storage equipment.
  2. The size of the water storage equipment is unreasonable. The sink is usually combined with domestic water and fire-fighting water. The only requirement is for safety and reliability. This causes the volume of the water storage equipment to be too large and the water stays in the equipment for too long, which affects the quality of drinking water.
  3. The structure of the water storage equipment is unreasonable, and the location of the inlet and outlet pipes is inappropriate, resulting in dead water areas in the pool. The connection between the drain pipe and the sewer pipe is unreasonable. Once the power or water is cut off, negative pressure will be formed in the water pipe and the sewer will be sucked into the tap water pipe and enter the water supply system.
  4. The location of the water equipment is inappropriate, and the surrounding environment is poor. For example, there is a sewage pipe close to the pool.
  5. The supporting facilities of water storage equipment are imperfect, such as no pollution prevention measures for the vents, imperfect sealing of the inlet cover, no leakage prevention measures for the buried parts, no mesh cover at the outlet of the overflow and drain pipes, no secondary disinfection equipment, etc.
  6. Poor management of the secondary water supply system, failure to conduct regular water quality inspections, and conduct cleaning and disinfection in accordance with specifications, resulting in the gradual deterioration of water quality.

The direct result of the pollution of the secondary water supply is that it affects the senses of the user, makes the drinker feel nausea, vomiting, abdominal distension, diarrhea, and even gets sick and endangers human health. In addition, if the quality of the water flowing out of the secondary water supply facilities is severely reduced, it will inevitably lead to accelerated corrosion of indoor pipes, which in turn will pollute the water quality again. Therefore, in view of the main cause of secondary water supply pollution, we suggest:

  1. Strengthen preventive sanitation supervision in the design, construction, and completion acceptance of the secondary water supply system to reduce the existence of hidden dangers.
  2. The selection of materials for water supply tanks in high-rise buildings shall meet the requirements of sanitary standards for drinking water; effective protection and disinfection measures shall be adopted to reduce secondary pollution.
  3. The management unit of the secondary water supply facility should establish a corresponding management system, assign special personnel to manage it, conduct regular water quality inspections, and regularly clean and disinfect. Managers and cleaning and disinfection personnel must hold health certificates.
  4. The health supervision department should strengthen the supervision and inspection of the secondary water supply unit, and frequently conduct inspection and evaluation of water quality, find problems, make timely suggestions, and take measures to prevent problems before they happen.
  5. Do a good job in the publicity of popular drinking water hygiene knowledge, enhance residents’ awareness of personal hygiene protection, and prevent the spread of diseases through water.
  6. Establish and improve sanitation management methods for secondary water supply facilities, formulate corresponding laws and regulations, and bring secondary water supply work into the track of legal management.
World-Environment-Day

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