Has the taste of water changed？ Zhengzhou Water Supply Company： All the tests are up to standard, so we can rest assured to drink.
In the past few days, some citizens in Zhongyuan District of Zhengzhou have reported that water is boiled with tap water at home, and the scale is more than before, and the water is slightly salty. What is going on? Is it related to the switching of the Yellow River water source in Shiyuan Waterworks? Will it have adverse effects on human health? On April 12th, the reporter specially came to Zhengzhou Stone Buddha grit chamber and Shiyuan Water Plant to answer these questions for you.
The Shiyuan Water Plant switched the Yellow River water, and the staff took water from the stone Buddha grit chamber for testing.
On the morning of April 12, the reporter came to Zhengzhou High-tech Zone. After the staff stationed here opened an iron gate, a large area of water came into view. It is the main water source of Zhengzhou Shiyuan Water Plant-the stone Buddha grit chamber.
On the southeast bank of the stone Buddha grit chamber, two workers from Zhengzhou Monitoring Station of the National Urban Water Supply Quality Monitoring Network are taking water, and then they will return to the laboratory to test the water quality of the raw water of the Yellow River.
According to the staff of Zhengzhou Water Supply Company, in 2002, the open channel of Mangshan main water conveyance canal was transformed into a concealed pipe project in Zhengzhou City, and the stone Buddha grit chamber was excavated. The stone Buddha grit chamber covers an area of 420,000 square meters, with a depth of 5 meters, a total storage capacity of 1.5 million cubic meters and an effective storage capacity of 1.25 million cubic meters. It plays a role in pre-settling, water storage and regulation during the whole water supply process. The raw water of the Yellow River is extracted from Mangshan irrigation station, and flows into this area for pre-sedimentation through more than 10 kilometers of underground pipes, then pressurized by Shifo Pumping Station, and directly transported to Shiyuan Waterworks through a 7-kilometer-long water pipeline.
When visiting the Shiyuan Water Plant in Zhengzhou, the reporter saw that the stone Buddha grit chamber was directly transported to the Shiyuan Water Plant through a 7-kilometer-long water pipeline. In Shiyuan Waterworks, the Yellow River water delivered from the grit chamber is introduced into a huge pool by the water intake pump station. After being processed by powdered activated carbon, pre-ozone, coagulant, sodium hypochlorite, coagulant aid, etc., it enters the clean water tank in the mechanical mixed folded plate advection sedimentation tank, and then enters the ozone contact tank, activated carbon filter and sand filter, and finally enters the water distribution network through the water supply pump station and flows into thousands of households.
In the pump room of the water plant, the staff of the resident laboratory of the water quality monitoring center of Zhengzhou Water Supply Company also carried out water intake testing for tap water sent to thousands of households.
After boiling water in some residents’ homes, the scale increases and tastes slightly salty. Why?
Since all the indicators of tap water are normal, why do some citizens report that in the past half month, the scale has increased after boiling water at home, and the water is slightly salty?
Lou Ning, director of Zhengzhou Shiyuan Water Plant, said that at 7: 55 am on March 28, the raw water pipeline of Shiyuan Water Plant, which transported the water source of South-to-North Water Transfer Project, leaked. Shiyuan Water Plant closed the water inlet valve of the water source of South-to-North Water Transfer Project in the factory area and urgently started the Yellow River water source for water supply.
After Shiyuan Waterworks was switched from South-to-North Water Transfer Project to Yellow River Water, the anion content in the water changed due to the difference between the two water bodies. For example, the chloride content of Danjiang water is below 10mg/L, and the chloride content of Yellow River water is 80-90 mg/L. Because of the increase of chloride content, there will be a slightly salty taste in the water. However, this change can only be recognized by people who are relatively sensitive to taste. For daily cooking, making tea and drinking coffee has little effect. "The national" Hygienic Standard for Drinking Water "stipulates that the limit of chloride is not higher than 250mg/L, and the test results of the Yellow River water source fully meet the national standards, so citizens can rest assured to drink it." Lou Ning said.
Why does the scale and floating objects in the water increase? Lou Ning explained that, generally speaking, natural water bodies have hardness, and the Yellow River water has high hardness. Its main components are calcium and magnesium, which exist in the form of calcium bicarbonate and magnesium bicarbonate in water. When heated, it will become magnesium carbonate or calcium carbonate suspension or sediment, which is commonly known as scale.
Among them, the indexes of magnesium carbonate, calcium carbonate and other substances in the South-to-North Water Diversion Project of Shiyuan Waterworks are kept at about 140mg/L, while the indexes of magnesium carbonate, calcium carbonate and other substances are kept between 300 mg/L and 320 mg/L after switching to Yellow River water. However, the detection results of the above indexes are all within the limit of 450mg/L stipulated in the National Hygienic Standard for Drinking Water, so it is harmful to human body.
"In the past, Zhengzhou people always ate Yellow River water, but now they eat Danjiang water from the South-to-North Water Transfer Project and suddenly eat Yellow River water, so this change will happen." Lou Ning said that the water supply area of Shiyuan Waterworks is mainly to the west of Beijing-Guangzhou Railway, to the south of Jinshui Road (west extension line), to the east of West Third Ring Road and to the north of South Third Ring Road. Therefore, only the citizens in this area may be affected.
How to ensure the water quality safety after the Shiyuan Waterworks is switched to the Yellow River water source?
The reporter learned that on March 28, after the raw water pipeline of the South-to-North Water Transfer Project leaked, Zhengzhou Urban Management Bureau organized the first time to carry out excavation inspection on the leaking place, and found that there were bulges and leaks in the pipeline, and other places were suspected of leaking. Zhengzhou Urban Management Bureau coordinated the ownership of the pipeline, and the municipal water conservancy department seized the time to organize emergency repair. At present, the Zhengzhou water conservancy department is still repairing the damaged pipeline, and the specific completion time is temporarily unknown.
How to ensure the water quality safety after the Shiyuan Waterworks is switched to the Yellow River water source? Wu Xinping, director of the Water Quality Monitoring Center of Zhengzhou Water Supply Company, said that according to the requirements, Zhengzhou Monitoring Station conducted weekly tests on 11 indicators such as permanganate index, ammonia nitrogen (in N), chemical oxygen demand and petroleum for the three surface water sources of Taohuayu Yellow River Diversion Gate, Shifo grit chamber and raw water of Shiyuan Water Plant. Twenty-nine water quality tests were conducted on three surface water sources every month, and all water quality indexes met the Class III water standard of the National Environmental Quality Standard for Surface Water (GB3838-2002)Ⅲ).
Zhengzhou monitoring station tested 42 indexes of the factory water and the end water of the pipe network in Shiyuan Waterworks. Carry out seven pipe network monitoring for the pipe network monitoring points in the region; After testing, all the measured indexes meet the limit requirements of the National Hygienic Standard for Drinking Water (GB5749-2006).
During the water source switching, the laboratory of water quality monitoring center of Zhengzhou Water Supply Company in Shiyuan Waterworks carried out process simulation coagulation and stirring experiments and chlorine requirement experiments on raw water entering the factory to find the best dosage of coagulant and guide the production process to add chemicals reasonably. The raw water entering the factory, the outlet of sedimentation tank, the outlet of carbon filter, the outlet of sand filter and the outlet of factory water of Shiyuan Water Plant were tested at least twice a day. The vehicle of water purification agent must be inspected to ensure that the water purification agent is qualified.
"From the current situation of water quality testing in the city, the water quality meets the requirements of the National Hygienic Standard for Drinking Water. Zhengzhou Water Supply Company will optimize the water treatment process, strengthen the testing of public water supply in Zhengzhou City, and ensure that the water quality of urban water supply is safe and qualified. Please feel free to drink. " Wu Xinping said.
