What are the requirements for a vessel to have a sewage holding tank or STP?
Every ship that is 400 GRT and above, which is engaged in international voyages and carrying minimum 15 persons on board.
Explain the process of sewage treatment plan
The biological type of sewage treatment plan comprises of 3 main chambers. Aeration, Separation/Settling, and, Sterilization/Chlorination.
Aeration – The first section where the aerobic bacteria is maintained and breaks down the solid by supplying air using blowers. In this compartment, the aerobic bacteria will decompose the raw sewage into carbon dioxide, water, and inorganic sewage.
Settling – The decomposed sewage from the 1st stage goes to the 2nd chamber which is use for settling purpose. Here, the sludge settles at the bottom and clear liquid float on top. The bottom sludge is sent back again to the 1st chamber for further decomposition.
Chlorination/Sterilization – The clear liquid produced from settling tank is overflown and the liquid is disinfected with the help of chlorinator to treat the final stage water for discharging overboard. The liquid in this chamber is discharge to overboard or to holding tank depending on the geological position of the ship.
What is the importance of air blower or air compressor on STP?
Air blower/Air compressor is use to supply air for decomposing and breaking down of sewage. Additionally, the air coming from the air blower/compressor is important for the lives of aerobic bacteria or good bacteria because they are the one who decompose and eliminate the poisonous gases and foul smell inside the STP.
How do you ensure the proper operation of the sewage treatment plant?
I monitor the biological and chemical processes involved in treating wastewater, perform routine maintenance on pumps and filters, and ensure that the effluent meets discharge standards
What steps would you take if the sewage system becomes clogged?
If the system becomes clogged or malfunctions, I will clean the filters, inspect the pumps, and check for any electrical or mechanical faults that need attention.
