found that water is toxic
. For a long time, many people have envied the American people to drink cold water, and drink it when the tap is turned on, without boiling water, which proves that the water is good.
Almost ten years ago, people in California, USA, felt something was wrong with their tap water. What's wrong? Because this water was found to be poisonous!
California is a special place with a developed economy, but there are many areas with drought and water shortage, and its water needs to be transferred from far away delta areas after treatment. There is one thing in the treated water that cannot be removed, that is bromide.
Americans are used to drinking cold tap water. There is nothing wrong with
bromide itself. It is a completely safe mineral and is very common in salt water. Because of its small molecules, it is difficult to remove from water. However, water plants need to add chlorine when disinfecting water. This chlorine is added to the water to act as a catalyst. After exposure to the sun, bromate, a carcinogenic substance, is formed. When I heard that they had been drinking toxic water for many years, Californians were displeased. The council came up with a law after deliberating and asking water plants to remove the carcinogenic bromate. If it doesn’t work, add it to all reservoirs. Cover, do not allow sun exposure.
Add a lid to Silver Lake in California? As
said earlier, the bromide in the reservoir water is difficult to get rid of. In order to sterilize the chlorine, the only way is to cover all the reservoirs.
California's countermeasures
The water plant has a large reservoir area. It is actually a lake with an area of 1.85 million square meters. It is not a small challenge from the perspective of money or technology to completely cover it. A biologist, Brian White, thought of "bird balls". The bird ball is not a ball for birds but a bird-proof ball. It was originally used in the pool near the airport to cover the water.
bird ball
We know that the airport needs some water for fire fighting. These levels are stored in a huge open-air pond, and many birds will fly over to drink water and make their homes nearby. But the airport does not welcome birds. They fly around the airport and easily hit the plane and cause an air disaster. Therefore, the airport will throw some hollow plastic balls into the pond. The plastic balls densely cover the water surface, and the birds cannot drink. When it comes to water, it won't come again. This plastic ball is called a bird ball.
bird is a risk factor at the airport.
Los Angeles Water and Electricity Bureau asked a company to customize this kind of plastic ball. It is obviously inappropriate to call it bird ball, so a new name is called "Shade balls", which is also called shadow ball. The
shadow ball is about 10 cm in diameter and is made of polyethylene plastic. Due to the addition of a large amount of carbon black, the whole body is black. The ball is hollow and filled with some drinking water, so that it can float on the water without being blown away by the wind. As long as the lake is densely covered with shadow balls, it is equivalent to adding a cover to the reservoir, which seems to be a perfect plan.
The mayor of Los Angeles and the ball
The usefulness of the shadow ball
You may wonder why the shadow ball should be made black. The reflectiveness of white is better than black! This is a good question.
We know that the reason why Californians pour the ball into the reservoir is to block the sun from reaching the lake, and among all the colors, only black is invisible to most light. If you take a white plastic ball to the sun, you can see that it is illuminated, indicating that the white ball is leaking light, but the black ball will not. Another is that although the black ball will absorb heat in the sun, the water under it will not sink after being heated, and the black ball will dissipate heat faster at night.
Nearly 100 million black plastic balls fell into the reservoir.
Because the shadow balls block the sun, it also reduces the evaporation of lake water by 80 to 90%, which can save a lot of water a year. This is very important for California, which is drought and water shortage. Most of the water is drawn from far away. Previously, the annual evaporation of the reservoir reached more than 2 meters, which is not a small expense. Another side effect of
is that the growth of algae in the reservoir is inhibited due to lack of sunlight. This is mainly for domestic water. Americans do not raise fish and do not need aquatic plants, so they have no ecological problems.
plastic balls can be reducedThe evaporation of water
The voice of opposition
is like the two sides of a coin. Everything has two sides. Since the day when the California water plant started to throw plastic balls into the reservoir, the voice of opposition has never stopped. Some people at
calculated that the investment in these balls could not save much money due to water saving, because the authorities said that the shadow balls could save 1.1 million tons of water each year, which seems to be a lot. But 1.1 million tons of water is only worth US$2 million, and the cost of 96 million balls is US$34.5 million. Even if maintenance costs are not included, it will take 17 years to pay back. Moreover, the actual life of these balls is only 10 years. Increased security risks.
Reservoir staff
Some people think that these plastic balls seem to save water, but in fact a lot of water has been consumed in the process of producing these balls. Take the 96 million plastic balls in the Ivanhoe Reservoir. These polyethylene plastics are produced from petroleum. The process of manufacturing these balls requires at least 2.9 million tons of water, which means that money costs are not counted. From the perspective of water consumption alone, it will take two and a half years to "pay back". No wonder Los Angeles Weekly bluntly called it "a very stupid way to save water." At the same time, some people pointed out that polyethylene plastics are not always safe, because the total amount is huge and the balls need to be soaked in water for ten years. Such a long time of sunlight, soaking and collision and friction will accelerate the aging of plastics, and it will add to the water. Release of plastic particles, and in more serious cases, it will also release endocrine disrupting chemicals (Yang 2011) and endocrine disruptors such as bisphenol A (BPA) that interfere with the hormone system of animals and humans.
plastic balls are risky
Los Angeles is constantly scooping balls
In the past few years, the Los Angeles Water Department has first thrown balls into the reservoir with great fanfare, and then 9.4 million sunshade balls are picked up from the reservoir every year. The media says that the four large reservoirs have so far Three have been emptied, and now there is only one ball in the reservoir. In order to comply with the regulations that the lake cannot be exposed to the sun, on the one hand, they planned to build underground water storage facilities, and at the same time they figured out a way to replace the shadow ball with an awning. This meant that the previous attempt failed and more investment was needed.
The water is drained
Should we study Los Angeles?
First of all, we need to see the particularity of California's water resources. It is because the water contains excessive bromate and cannot be removed, so we have to "cover" the reservoirs in accordance with laws and regulations. We have not heard that many other places in the United States also Plastic balls are thrown into the reservoir to save water.
Pouring tens of millions of plastic balls into the reservoir is not a cost-effective investment, no matter from the perspective of saving water or money. In fact, in many of our places, there are examples of using open water to build solar power stations. This aspect can greatly reduce water evaporation, generate electricity, and allow birds to have a place to inhabit and drink water. Although building a water power station is not perfect, it is at least much better than throwing tens of millions of black plastic balls into the lake.
What do you think?
Water surface photovoltaic power station can do more than one thing
