What is sewage chlorine test in ship?

What is sewage chlorine test in ship?

The sewage chlorine test on a ship is a procedure used to measure the concentration of chlorine in the ship’s sewage system. This test is conducted to ensure compliance with environmental regulations and to assess the effectiveness of the ship’s sewage treatment system. Chlorine is commonly used as a disinfectant in sewage treatment systems to kill bacteria and other harmful organisms present in the wastewater.

However, excessive levels of chlorine can be harmful to marine life when discharged into the sea. Therefore, regulatory bodies often impose limits on the chlorine concentration in sewage discharged from ships.

          A fresh STP sample is collected and a clear sample indicates that STP is working satisfactorily and we compare the fresh sample with last sample that is taken a week before which is before backwashing due to which the old sample is a bit dirtier. The fresh sample doesn’t have any solid particles and smell present in it.

sewage chlorine test

We use a STP comparator test kit to carry out the STP test which has three compartments-

sewage chlorine test
  1. The first compartment is for sewage where we have to put 10ml of sewage which has a range of 0.2-1mg/l or ppm.
  2. The second compartment is filled with fresh water for comparison in the colour coding’s by which we can get the respective values.
  3. The third compartment is also for sewage where we can put 10ml of sewage which has a range of 1.5-8ml/l or ppm. 

Procedure for chlorine test:

  1. Take 10ml of fresh sample and put it in the first compartment.
sewage chlorine test

2. Put one DPT indicator tablet in the first chamber and we will see the change in the colour.

sewage chlorine test

3. Now crush the tablet with the crushing stick because of the tablet reaction takes place with the chlorine content inside the STP sample.

sewage chlorine test

4. After the mixing we compare the colour with the matching end and find out the value.

sewage chlorine test

5. If it is showing less than 0.2ppm then we have to add more chlorine tablet or see what is going wrong in the plant. The safest ppm value given is 0.2-0.5ppm, value of the sample taken is below 0.2 ppm as the colour should be pinker. Then we could have ensured that proper disinfection is taking place.

sewage chlorine test

We didn’t fill sample water in the third compartment because we know that STP onboard ship does not contain very high ppm. 


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