96 million black balls in the Los Angeles Reservoir: why are they there?
Some time ago, 96 million black balls were poured into one of the reservoirs in Los Angeles, which were immediately dubbed shadow, protecting the water from evaporation. Looking at them, many questions arise: why are they black, is it safe to drink the water in which they were, do they really reduce evaporation? Why are these balls really needed, let's understand.
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Why in the reservoir of Los Angeles, black balls fell asleep
The story begins with the fact that a local beverage manufacturer found bromates (carcinogens) in drinking water, the concentration of which was 3 times higher than the permissible values. But how could they appear in drinking water? After all, at the filter station, from where water flows to consumers, all indicators were normal.
A concentration of 3 mg bromates per liter is acceptable, and 30 is too much
In the early 2000s, new bromate rules came into force in the United States. In fact, they said that at all wastewater treatment plants it is necessary to monitor the concentration of these substances, which should not exceed 10 mg per liter of water. Therefore, measurements at the filtration stage were carried out regularly.
How bromates ended up in drinking water
The reservoir, in which black balls were subsequently filled, is located between the filtration station and consumers. That is, after purification, water gets into it, and only then to the residents of Los Angeles.
From the filter station, water was supplied to the consumer through the storage
Therefore, the decision to take measurements in it was quite logical. But the result was unexpected: the level of bromates in the samples of water from the storehouse jumped sharply, many times exceeding the permissible standard. The causes of the appearance of carcinogens in drinking water turned out to be a combination of events that they did not know anything about before:
- Water in Los Angeles flows through the aqueduct for many miles. It contains impurities of salts and, in particular, bromide, the presence of which is quite natural and harmless.
- For disinfection, chlorine is added to the water.
- The third factor is the scorching sun of Los Angeles, under whose rays there is an open reservoir with water.
Bromides, from which no one expected a dirty trick, in combination with chlorine and under the influence of sunlight, turn into bromates - the strongest carcinogen.
Search for a solution
It turns out that the presence of a carcinogen in water is due to three factors, and it was not possible to refuse two of them:
- bromides are almost impossible to remove for technical reasons;
- and chlorine simply cannot be removed, because the water needs to be sanitized somehow.
There were cases in Los Angeles when there were so many algae in the reservoir that water with a greenish tint came from the taps in the houses. It was potable, but the color of many was alarming. And this is one of the reasons for the use of chlorine.
Therefore, the only thing that could be corrected was to remove the solar effect on water. Various options were considered:
- Covering the surface of the reservoir with tarpaulin is a standard solution, but the work would have taken several years.
The idea of “covering the tarp with water” seemed too complicated
- Make something like a trampoline, stretch it above the water between the PVC pipes. But then the birds will take a fancy to him and dirtied the whole tank.
The idea of "trampoline" also did not like
- They remembered about pipes made of high density polyethylene. They are often used, and they are great afloat. But to cover them with the entire tank was difficult and expensive.
The pipe idea is too expensive
- There was even an idea to grind the pipes and fill them with the entire surface of the water. But they decided that from a pile of plastic on the surface of warm water under the rays of the sun we get a Petri dish - a laboratory vessel for the cultivation of bacteria.
Plastic chips are trash on the surface of the water.
- Dr. Brian White suggested using shadow balls. Only at that time no one called them that way.
Plastic ball surface is the best idea
Why exactly shadow balls
The use of balls was not know-how, before they were already used to protect waterfowl in reservoirs near airports, so that birds did not settle in dangerous places, did not drink dirty water, and then did not get into the engines of aircraft. That is, the original goal was to drive birds and other animals away from the water. It worked - with the advent of the balls, the birds disappeared. This time the goal was different. Of course, no one knew in advance how effectively the balls could protect water from the formation of carcinogens in it. Therefore, an experiment was conducted:
- Three small inflatable pools were filled with water from the storage.
- One of them was left open under the sun, the other was covered with tarpaulin, the third was with balls.
The experiment was conducted in three pools
- More precisely, the balls solved the problem, so this option became a working one.
Today, shadow balls are used in other places where there is a problem of a hot climate. And sometimes they come up with something of their own. For example, there are hexagons that fasten together in water and perform the same functions.
Sometimes plastic hexagons are used to protect water
In addition to protecting water from carcinogens, shadow balls also have other advantages:
- Plastic balls significantly reduce water evaporation (by 80–90%), which is very important for arid places like Los Angeles.
- Without the sun, algae does not grow in water. This can significantly reduce the amount of chlorine used.
Looking at the black balls, it’s hard to guess that there is generally water under them
Why are the balls black
The color of the balls is not random. Black is better than others to block sunlight and prevent the formation of bromates. The balls are made of high density polyethylene, essentially food-grade plastic, which is widely used in the household but is transparent. Being colorless, the balls under the action of sunlight would not last long. Therefore, they added carbon black, which is safe for drinking water and can be outdoors for years under the sun. Due to this, the service life of the balls will be at least 10 years.
The possibility of using other colors was also tested. So, 3 different shades of blue were ordered from the supplier company. But the pigment in them was unstable, and the warranty period was reduced to 1 year. Their use was economically disadvantageous.
The blue color of the balls did not match the quality characteristics
Are they definitely safe?
The security issue is so important that it’s better to ask again and check everything. For example, what will happen to the balls when heated under the sun, will they become toxic? Marty Adams, head of the Los Angeles Department of Water and Energy, says the balls are completely inert and there’s nothing to worry about. In an interview with Derek Muller, an Australian video blogger, journalist and TV presenter, he said that theoretically you can bite a piece of the ball and chew, there will be nothing, this is food grade plastic, and it is completely safe.
Marty Adams showed that shadow balls can even be chewed
Video: Derek Muller understands on the spot why there are 96 million balls in the Los Angeles reservoir
The hidden danger of shadow balls
With their unusual appearance and the functions performed, the balls aroused lively interest. Those who wish to purchase them for a private reservoir or pool were found. However, balls are good for drinking water tanks. For other objects, they, in the best case, will cause harm, and in the worst - they can lead to tragedy:
- In a pond covered with balls, algae will stop growing. So, the fish will disappear.
- Riding a boat, making its way through the crystal lattice of balls, is quite problematic. Engine life will be significantly reduced.
Balls block the boat
- Swimming in a pool with balls is extremely uncomfortable and life-threatening. Balls located in one layer reduce the swim speed and hit the head painfully. A multi-layer coating of balls acts like quicksand, dragging its victims to the bottom.
Balls pull a person to the bottom
Video: why you can’t swim in the "shadow balls"
Thus, black shadow balls really protect water from structural changes under the influence of sunlight. However, it is not recommended to use them in private reservoirs and pools. They are good only for reservoirs with drinking water.
