The Disgusting Future of Water
We’re back again this week to ruin your appetite with another look into waste water. After our last few articles left lead sales guy Scott unable to eat his breakfast (the pancakes were delicious), we’ve been ordered to write about something clean this week. In that spirit we’re going to look into the future of recycling all sewage into usable water. We advise you finish your breakfast and lunch before reading.
Increasingly we are running into a problem with having enough water to drink. Despite the Earth’s surface being about 70% water, we can only drink about 0.01% or less of it. The issue we run into is that ocean water would kill us. There’s too much salt and bacteria in it. This is why we have fresh water and salt water fish. The environments are so drastically different that few, if any fish can survive in both environments.
We can only drink water which isn’t from the ocean. This is a massive restriction. It means all of society has to survive on water from lakes, rivers, and underground aquifers. The problem is exacerbated when we experience droughts, which leave us drawing on our water reserves. Unfortunately, for the past century or so, that’s what we’ve been doing. We pump water out of wells and end up draining them faster than they can be replenished. Certain large drink companies make the issue worse by buying water at less than pennies per gallon (less than taxpayers pay) and selling it back at multi-thousand-percent mark ups.
Over-using the water like this is going to eventually lead to a lethal situation. We won’t have enough to drink and survive on, let alone water our yards or run any kind of manufacturing. The old adage is to reduce, reuse, and recycle. That begs the question of just how much you can reuse. Once water’s been… tainted, we can’t affordably cleanse it, right?
Water Is Still Water
With enough work, any source of water can be purified. Regardless of what we do to the water, it still contains H20. Beyond that, we’re already doing a lot to clean up fresh water. Our lakes, rivers, and streams are all full of animal waste, dirt, bacteria, rotting flesh, and chemical run off. What’s in our own waste water that’s not already out in the wild?
Well, human waste is a bit harder to clean up. We have drugs and industrial chemicals in our waste water at a far higher concentration than any drinkable reservoirs. The big challenge is finding a way to remove everything but the water. If you made a pot of soup and we asked you to give us just the water out of it, we’d get some funny looks, but that’s the sort of challenge we’re facing.
The immediate, obvious answer is to just boil off the water. When water fully evaporates, pushed into dry-steam, it carries no dissolved material with it. The water itself becomes so hot that it will destroy most contaminants. We use this sort of technology in desalination plants, where there is no choice but to purify ocean water. There are a few differences though. Ocean water doesn’t have as many pharmaceuticals and other waste chemicals in it that might survive the boiling with the water and it’s incredibly expensive to put that much energy into water.
To process this much material efficiently, in our existing systems, and at scale, we need to use near passive processes. We need some really big, fancy filters to get this all started.
3 Steps to Drinkable Sewage
Step one is to remove the solids as much as possible. We’ll pass our water through a series of huge filters that will gradually get smaller and smaller. This will allow us to capture solids such as pills, wipes, and other solid waste. We’ll remove these and process them separately to be sterilized and disposed of. Some systems would cook these waste elements so the dried waste could be incinerated and used for electrical power generation.
Step two is to use a chemical filter that will only allow certain atoms and molecules through. This is a process we call Reverse Osmosis. We’ll use a special plastic membrane which will generally speaking only allow water molecules to flow through it. This is often demonstrated in High School chemistry and biology classes around the world using specific brands of plastic bags. The cells in your body use an osmosis process, it’s part of why having too much salt can kill you: it causes your cells to attempt to match the water levels of their surroundings.
Step three is to ensure nothing harmful has made it through the process. The reverse osmosis filtration should have left us with near pure, elemental water, but there are some things that won’t capture. Luckily, we have a lot of ways to sterilize what is nearly pure water: Ultra Violet Radiation and Chlorination.
UV Radiation is the same radiation that gives you sunburns and causes skin cancer. It destroys cells by breaking down their cell walls and damaging their insides such as the vital DNA (and therefore causing cancer if exactly the right thing goes wrong). The Earth’s Ozone protects us from most of the sun’s UV Radiation, if we lost that, life just wouldn’t exist on Earth. You can imagine what happens to bacteria and viruses when we saturate the water in UV rays with comparable intensity to the sun outside our Ozone.
For good measure, chemicals such as Chlorine may be added to the water. These will further prevent the development of any biological threats, breaking them down, poisoning them, and so on. At this point the water will test cleaner than any drinking standards. Someone could take it straight from the end of the processing center.
And That’s Exactly What We Do
In many areas relying on water services, that’s exactly what happens. People are terrified of the thought of drinking waste, even if its processed, so most waste water sterilized to this point is safely dumped in a lake or river. These happen to be the very same places we pick up fresh water from to process and drink. When you ask where the water comes from, the honest answer is usually “a local, fresh water source,” which is the truth.
As waste water processing improves, we’ll eventually make some bigger changes. Right now, it’s only possible to sterilize a portion of our waste to this degree. Cities like El Paso have started to aggressively re-use waste water to combat droughts, but it’s only a small percentage of their waste water.
In the future, we’ll see two major changes: 100% waste water recycling and we might not even bother to send it to a reservoir first. As a society, we could move to a complete, closed-loop water system. It will ultimately become a necessity as the population grows and our need for drinkable water increases beyond what nature provides through groundwater and rain.
Categories: Sanitation Tech