Month: March 2023

In early March, we first checked the condition of the tank.

When we opened the big lid, we were surprised to see the blackish shining surface. It was oily and sticky, 3-4 millimeters thick layer.

And two big holes were also found. One hole was just under the pipe inlet, may be the water dropping in made the hole. Through such holes, water may be run quickly without enough filtering. 

We need to resolve two issues, oily layer and holes.

We decided just remove oily materials from the surface and keep it next to the wall not through away out of the tank.

For holes we decided to fill with sand and coconut fiber. Also we planned to set a wooden pallet on the surface where water dropping in.

Let us see how the condition will be the same in coming months.

Is the filtering tank working well to clean the waste water?

Through the laboratory test, it is confirmed the tank is surely reduce the pollution.

At the site, we checked the value of COD, Chemical Oxygen Demand. The values of both, before and after the filtering, were the same around 120 mg per little. A bit strange result.

So Jun brought back the sample water to Japan and asked the laboratory test.

The result was the value of COD reduced from 200 to 130 mg/l. BOD, Biological Oxygen Demand, was also reduced from 370 to 200. (Correction: I am sorry that I was saying the values were reduced more than half. It was wrong.)

Somehow the value of surfactant which is harmful specially within some weeks after discharging into the nature, was increased from 54 to 290 mg/l. It was considered as the result of maintenance work of the tank. Oily layer at the top of sand filter might be catching surfactant and was released after the maintenance work, Prof. Nakano suggested.

In other words, surfactant was well trapped inside of the tank, not released into the ecosystem.

We may keep monitoring the water quality continuously. New test kit for COD was already sent to Yap from Japan. So let us see the result…

How we can purify the bubbled water with a lot of chemical materials?

We asked help to Professor Nakano at Nihon University in Japan.

It is of course important to have clean clothes for comfortable life but just take a look of the backside of the laundromat and follow the situation of waste water.

He is a professional on “artificial wetland” to purify the waste water.

He kindly came to Yap in 2017 and since then, he has been supporting our activities.

With his suggestion, we use a big tank for the filtering. In the 1,500 gallons tank, we set sand and coconut fiber inside for three layers. All the mechanism was set in December 2022.

Now the tank is working to purify the waste water.

Did you see the back side of the laundromat? Let us see the situation together.

In Yap, many laundromats are in active every day and demand for washing is still increasing.

It is of course important to have clean clothes for comfortable life but just take a look of the backside of the laundromat and follow the situation of waste water.

Some chemicals from the detergents are harmful for the environment and human. Careful use of chemical detergent is one of the key to protect environment and your health.