Where does the wastewater go?

NOTE: I wrote this post yesterday but believe it or not, I did not have the time to finish it and have it published. Yes I know I am not working right now but the limited internet is not helping me either. And in case you are wondering, Tallinn was awesome today!!!

Good morning from the Baltic Sea. Today we are cruising towards Tallinn, Estonia, home of the most beautiful women in the world, or so my male colleagues say. In my opinion that should be Romania but who am I to judge.

This morning I got to attend the first Ocean’s Ahead presentation. You might say “hey but you already did and attended so many of them in the past.” True, but considering I am on a different class ship, this presentation was very interesting especially because it was the Engineering one. I got to learn how a ship that has 4 diesel engines and no gas turbines (as I got used to in the last years) gets to operate and how it compares in other technical areas with the last ships I worked on.

The last part of the presentation, after the fresh water production was explained, was about waste water. It makes sense to wonder where does all the water we use onboard go, right?

When I do my training with the new crew members I always ask them and let them wonder: what do they think it happens with the water when they take a shower or use the toilet? Where do they think it goes?. They say we adults learn by solving problems meanwhile kids learn by repetition. I have always tried to let the crew figure out by themselves the answers before I go ahead and explain it to them.

So, what do you think it happens with the wastewater onboard the ships?

If you have been on a ship by now you must have heard the terms gray and black water. Onboard we consider gray water, the waste water coming from showers, sinks, galley etc. Black water is what we call on land, the sewage and it contains human related waste. Both gray and black water after being sent to designated tanks, get treated using an advanced (and expensive) waste water purification treatment plant. The core of this plant and the most sensitive part is a bioreactor filled with living bacteria who will break down the solids. Like some Engineers like to describe it sometimes: “is like having millions of babies in the Engine Room! They need proper quantities of oxygen, food, chemical etc in order to live happy and do their job in the water treatment. The Engineer in charge has to make sure they have all the conditions so that the system runs smoothly.”

CleanSea ActiveCell media that support biofilm growth (headworksinternational.com)


After the last stage of the treatment which is the UV disinfection, the clean effluent produced can go overboard only after following the regulations in place for that specific area. The effluent is so clean that it is considered also drinkable and I have seen it in the past from the manufacturers of these specific treatment plants. Even so, I personally am not planning to try it out. Not sure if any ship is using this clean effluent anywhere, (perhaps for their technical areas?), but so far, I have not seen it being reused anywhere.

The Engineer from the presentation did a wonderful job describing the whole process. Here are some pics for you to enjoy.


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