Would you drink beer brewed with toilet flushing water?

Recently, Singapore, which has always paid attention to environmental protection, launched a "special" beer, which is widely welcomed by consumers. Why is this beer "special"? Because the beer is brewed with recycled toilet flushing water. It's okay if you don't know it, but knowing it will have some impact, right? It's actually popular, isn't it a bit unbelievable? Today, let's talk to you about this incredible beer!

01. About this news

This news contains both gimmicks and technology.

Let's talk about the gimmick first. Everyone knows this. Beer is brewed with recycled toilet water, and it is also limited in quantity, so it is not special that it is sold out. After all, whether it is the first batch or limited in quantity, it is a good practice to increase the value, so it is normal for those who want to try it out or collect it to buy it out.

Among them, what deserves more attention is: technology. Many people may think that turning recycled water into drinking water is a very mature technology.

For example, this is what the Shenzhou mission does in space, treating sewage and turning it into drinking water. Even the astronauts' urine will be treated and turned back into drinking water.

However, there is an important issue here: cost. The cost of treating wastewater to a level that is drinkable is extremely high, which is why large-scale scientific research activities such as aerospace, which basically do not consider costs, are willing to use various high-tech technologies regardless of cost.

But in reality, it is basically impossible to do so because the cost is too high.

02. How to treat domestic sewage?

The sewage in our lives will of course be sent to the sewage treatment plant for treatment. The main sewage treatment process adopted is a combination of primary treatment and secondary treatment. The primary treatment uses physical methods to remove large-volume impurities in the sewage; the secondary treatment uses biological methods to purify the sewage and reduce the nitrogen and phosphorus concentrations in the sewage. However, the result of this treatment meets the national emission standards, not the drinking water standards.

Therefore, these treated wastewater cannot be drunk directly and are often used for urban greening irrigation, road washing, vehicle washing, construction, fire fighting, etc.

Of course, some are discharged into natural rivers after treatment. Some people may think that this is equivalent to the utilization of sewage. In fact, it is different. You cannot underestimate the dilution of sewage by natural water bodies and the objective self-purification ability of nature. Therefore, "water mixed with sewage is different from 100% sewage."

The process by which polluted water gradually recovers its original properties through a series of physical, chemical and biological processes is called self-purification of water body.

Of course, there is an upper limit to the self-purification capacity of water bodies.

But it cannot be used directly for drinking. The drinking water we use often comes directly from rivers and lakes and then enters the water plant for treatment before it can be drunk.

03. Why can’t urban wastewater be turned into drinking water?

Then you will certainly ask, in this case, can we make urban wastewater cleaner? Of course, we can use various osmosis and reverse osmosis membranes to make urban wastewater into clean water, but the cost will increase dramatically.

You might as well think about it, even if we use a water purifier to treat the water, the cost is very high, not to mention meeting the needs of the entire city.

Therefore, urban wastewater will basically not become drinking water, and cost is the key.

Singapore has actually been working on this for decades. As early as the last century, the Singapore Public Utilities Authority began to explore how to convert urban sewage into drinking water. It took decades to solve this problem, and cost control was the key.

Only low cost can make wastewater utilization normal, otherwise it will be unsustainable.

Therefore, in this regard, we do not need to laugh at each other. We should develop corresponding technologies to see if we can find cheaper technologies to achieve this process. If this is achieved, it will be a huge improvement in the country's water use.