Water is the source of life, is one of the substances necessary for the maintenance of life. The study of epidemiology and bacteriology proved that water is indeed an important medium for the spread of disease, so people began to look for ways to disinfect water, and in about a hundred years ago, the use of chlorination disinfection method. And has been used to this day, become a conventional disinfection method. However, with the development of science and technology, it was found that some regrettable results occurred after chlorination of tap water! What substances are produced by chlorinated water? These substances will affect human health? How can we get both clean and safe drinking water?
Most of the human drinking water is processed through the water plant production. China's tap water plant tap water production disinfection using chlorination, the main role of substances used in the production process is chlorine. Tap water production in the water plant is divided into four stages: water intake, filtration, disinfection, water transmission. Tap water into the water plant, the first process is filtration, our water plant with polyaluminum chloride (plus SO) as a precipitant, the concentration of AICI in the pool 6%, the concentration in the water is 2mg / L. Polyaluminum chloride can be removed in the water of trihalomethanes parent substances, to prevent the production of carcinogenic substances.
The filtered water should be disinfected, disinfectant with chlorine. Chlorine gas is dissolved in water, combined with water to generate hypochlorous acid and hydrochloric acid
CL + HO = HCL = NaCLO
In the entire disinfection process its main role is hypochlorous acid. It can completely chlorinate and disinfect the cell wall of the odor producing inorganic material, chlorinate its enzyme system (enzyme is a biocatalyst) to make it inactive, so that the bacterial life activities are impaired and die. Hypochlorous acid itself is neutral, easy to approach the bacterial body and show good sterilization effect, hypochlorite ion also has a certain disinfection effect, but it is negatively charged and difficult to approach the bacterial body (bacterial body with a negative charge), and thus compared to hypochlorous acid, its sterilization effect is much worse, so chlorine disinfection is better than the use of bleach disinfection. Water plant is from Meizhou, Xiamen and other places to buy liquid chlorine, the use of liquid chlorine through the pressure reducing valve to reduce pressure, and then into the chlorine machine into the water. We made a survey in the city, the tap water often has a strong bleach flavor, the masses are very concerned about this issue, that in the end this will not affect human health? We have studied, to the city's water plant to ask the relevant technical staff, learned that the tap water with bleach flavor does not affect human health, it is the main reason for the formation of the main amount of chlorine cast in the water plant to improve, because long-distance water delivery, the pipeline will produce sulfur and iron bacteria and other harmful substances, the tap water with high chlorine used to sterilize to prevent the tap water to reach the user before being subjected to secondary contamination. Tap water plant chlorine injection to improve, in order to ensure the safety of water quality, residents should be sympathetic to this point, in order to minimize the drinking water with a strong taste of bleach, we recommend that residents of the drinking water habits should be changed, so that it is further scientific. Tap water before drinking should be placed for a period of time, so that the residual chlorine in the water volatilization, which can reduce the water bleach flavor. At present, with the city's economic development, rapid industrial development, water pollution is gradually increasing. Chlorination disinfection and how to ensure the quality of tap water and other issues. We have studied, to the water plant to make the following suggestions:
(1) do a good job before chlorination. Dengxian water plant should cooperate with environmental protection and other departments to carry out comprehensive remediation of water pollution sources to ensure the water quality of the water source.
(2) Reform the chlorine disinfection process, chlorination disinfection process, strong mixing effect is the key to obtain continuous disinfection effect. Qionghai Dengxian water plant now has an advanced chlorine machine, but later also need to pay attention to the chlorine disinfection process to improve.
(3) The use of optimized disinfectants. At this stage, the disinfectant in addition to chlorine, there are chlorine dioxide, ozone, the use of alternative disinfectants can reduce the generation of harmful substances, while improving the processing efficiency.
Investigation and analysis
A questionnaire survey of 20 municipal water plant leaders and workers, the comprehensive analysis is as follows:
(1) the city's water production using chlorination method of disinfection is better.
(2) the city's waterworks cited by the water quality is good, the disinfection process of environmental protection to do more thoroughly, perfect.
(3) The city's tap water plant chlorination disinfection of water almost no harmful substances.
(4) Everyday water sometimes has a bleach flavor, but it is not harmful to human health.
Second, the urban residents of the questionnaire about drinking water problems 50, the actual receipt of 50, 50 valid questionnaires. Organize the questionnaire to get the following table:
Reflected by the above table:
(1) about which disinfection method is better, the chlorination method to support the views of 100% that 50 people, chlorine used for disinfection of tap water is still recognized and supported at this stage.
(2) of the water supply plant water pollution that "no pollution" accounted for 84% of the number of people, that "pollution in general" accounted for 16% of the total. This shows that people are always concerned about the water quality of the water plant water source.
(3) of the disinfectant chosen by the water plant, "agree" accounted for 100% of the number of people, which reflects the "chlorine" trust is still high.
(4) The disinfectant used in the water treatment plant is mainly imported from overseas, and is not produced locally, which is one of the reasons for the high cost of tap water.
(5) For the amount of chlorine used in the disinfection process of tap water, 92% of the total number of people think that it is "appropriate", and 8% of the total number of people think that it is "too high", i.e. 4 people. This shows that people are still satisfied with the effect of tap water disinfection.
(6) The answer to the question of whether the water treatment plant in the production process to improve the disinfection method, "yes" accounted for 80%, while "no" accounted for 20%, that is, 10 people. Continuous improvement is not only conducive to improving the credibility of the waterworks, but also to continuously improve the quality of water supply, to ensure the health of residents drinking water.
(7) that chlorination disinfection of water does not produce harmful substances accounted for 94% of the total number of people, 6% of people abstained. It can be seen that the quality of water after chlorination disinfection is better and less harmful to the human body.
(8) In the entire disinfection process, pointed out that manufacturers take into account environmental issues accounted for 54% of the total number of people, 46% of people abstained. Environmental protection is today's social concerns, especially chlorine is a toxic gas, more attention must be paid to avoid polluting the environment, breaking the ecosystem. By the survey, we know that the waterworks are doing better in this regard.
(9) daily drinking water sometimes bleach flavor, the number of people who hold this view accounted for 20%, that there is no 80%. Nowadays, the amount of chlorine input in the disinfection process is more accurate, the amount of chlorine is about 1kg/1000 tons of water. Appearance of bleach flavor because of the high chlorine content in the water, but this is to prevent secondary pollution in the process of tap water input, the harm to the human body is extremely low.
Research analysis
The survey *** issued 50 questionnaires, the actual receipt of 50 questionnaires, 50 valid questionnaires. The following is a comprehensive analysis of the answer sheet:
First, the residents of the degree of understanding of tap water production.
For different areas, the water quality is different, and the disinfection methods and disinfectants used in tap water production are also different. So, do the residents understand some disinfection methods of tap water? Survey data are as follows:
From the above table:
1, residents of the tap water production knowledge is only general, the survey that the waterworks use chlorine as a disinfectant accounted for 84%, 42 people, and the other only accounted for 16%, that is, 8 people.
2, chlorine for tap water disinfection has the advantages of good disinfection, low cost, almost no harmful substances. 30% of the survey that the disinfection effect is good, 30% think that the cost is low, only 4% think that there is no harmful substances, 36% do not know. Overall, it seems that chlorine for tap water disinfection does have its unique advantages.
3, chlorination disinfection of tap water can produce carcinogenic substances, after the survey, 36% of the people on the issue of "do not know", 34% of the people believe that "a indefinite", 20% of the people think "can be ", 20% think "can", 10% think "can not". It can be seen that the people of chlorination disinfection of water has not produced carcinogenic substances after the poor understanding of the process, but does not indicate that the tap water produced by the tap water plant does not exist carcinogenic substances.
4, the pros and cons of chlorine disinfection, 38% of the people think that "the advantages outweigh the disadvantages", that "the disadvantages outweigh the advantages" accounted for 12%, that "the advantages and disadvantages of half" and accounted for 30%, "do not know". 30%, "don't know" accounted for 20%. In short, people believe that chlorine disinfection or more advantages than disadvantages.
Second, the evaluation of the quality of tap water produced by the tap water plant.
No matter how much theoretical information we find, it is not as accurate as the facts, the eyes of the masses are bright. Tap water quality produced by the tap water plant, the masses know best. We designed a few questions for the survey, the results of the survey are as follows:
From the above table can be sent to see, for the taste of tap water slightly odor or no odor of the view that the tap water is sweet only accounted for 22%, that the tap water has a strong odor only accounted for 62%, that there are only 28%. Regarding the evaluation of the overall water quality, 72% thought that the tap water produced by the waterworks was of average quality, 20% thought that the water quality was very good, and only 8% thought that the water quality was very poor. Twenty-six percent were in favor of increasing the chlorine standard for feed water at the tap water plant, while 32 percent were against the practice.
So on the whole, the quality of tap water is relatively good, but sometimes slightly off-flavored.
Third, residents drinking tap water some habits.
Life we use tap water, health, good drinking habits are necessary, is a guarantee of good health. Whether people pay attention to the development of good drinking water habits, we designed 11 to 15 questions four questions, the results of the survey are as follows:
As can be seen from the table above, the tap water placed for a period of time before drinking accounted for 40%, no accounted for 56% of the tap water used for aquaculture organisms have been placed for a period of time after the first or add chlorine removal agent before use only accounted for 32%, there is no accounted for 60% of these Reflect the residents' drinking habits are not so scientific. At present, 36% of households drink pure water or mineral water. 64% drink tap water. Drinking water from the tap is 64%, and some families drink pure water, etc. They think that pure water is better than tap water, cleaner, and contains fewer harmful substances. 44% of the people think that the local tap water quality is good, 22% of the people think that the water quality of the foreign tap water is good.
The above analysis can be summarized in the following conclusions:
(1) residents of the tap water production have a certain understanding, and generally believe that the advantages of chlorine for tap water disinfection outweigh the disadvantages.
(2) The residents of the tap water produced by the waterworks water quality assessment is relatively good.
(3) Residents' drinking habits are poor, and they do not know much about healthy drinking water.
With the continuous development of science and technology, we believe that the tap water production is more and more perfect, in the near future, chlorination disinfection method will bring some problems will be solved, people can feel at ease to drink sweet tap water. In the survey, the residents reflect the city's high water prices, but we know that the water plant equipment investment is huge, but also to pay attention to improve the quality of water, capital costs are also quite high, the residents of this should be sympathetic. In the summer and autumn seasons, the tap water in the high content of harmful substances, we drink tap water, it is best to extend the boiling time, so that the water is difficult to volatilize organic substances to be sterilized to ensure health.