Sewage treatment plant checklist

Certification

1. Vessel International Sewage Pollution Prevention Certificate valid and STP details and holding tank details are appropriate.
2. Sewage plant has nameplate fixed to it.
3. USCG approval certificate posted near the STP.

Operation Instruction and MSDS

1. Operational instructions posted near the plant.
2. MSDS of chlorine tablets kept near the plant.
3. Placards with disposal requirements posted near the STP.

Sewage Plant

1. The STP always in use or does the vessel bypass the STP once they are in open seas.
2. The aeration blower should be run continuously. The interruption of its continuous running will kill the microorganisms within the sewage treatment tank. This will cause loss of the purification ability, resulting in the production of a poisonous gas or a bad smell. Also, there is a possibility that the air discharge nozzle clogs.)
3. The air blowers working properly. The normal working range is 0.2- 0.4 bar.
4. Aeration nozzles in good order. The inspection cover of the sewage plant is to be opened to see the bubbling inside. In some STP there is a flexible tube indication the carryover of effluent from one chamber to another indicating proper functioning of aeration blowers and nozzles.
5. Air vent pipe: Checks vents are clear.
6. Bio Coarse filter (packing media) inside the sewage plant – check visually through the Inspection door, if is in good condition or any fouling observed. Backflush to be done if any fouling noted.
7. Check supply of Disinfectant (chlorine tabs) by removing the cap of the sterilizer. There should be regular consumption of the disinfectant.
8. Piping – No soft patches and in good order. All valves in the line are free to operate and holding.
9. STP 3-way or isolation valves: In good order; free and easy to operate. Proper identification marks for easy understanding of the position as well as for the valve movement when testing. Valve sealing arrangement in place.
10. Over-board valves sealing arrangement: STP overboard valves have valve sealing arrangement and are kept in sealed position in restricted waters.
11. Discharge pumps: No leaks from glands / seal, gauges in good order.
12. Casing – No soft patches;
13. Checks in the PMS in accordance with manufacturers manual?
14. Entries in the ER log book when untreated sewage was discharged overboard (when not in restricted waters)
15. The Sewage plant effluent being discharged first to a holding tank when in port and then discharged overboard when a vessel is en-route (if applied)
16. Vessel has enough stock of chlorine tabs for three months use.
17. Critical and Recommended spares: Vessel is stocked with necessary critical spares for the STP. Complete assembly of air blower and discharge pump and one set of V belts for the air blower.

Sewage plant checks

1. Sewage effluent test: The effluent tests must meet the standards.
2. Plant back flushing operation: Being done once in a month. Back-flushing procedure and valve line up procedure available. Each chamber valve marked with identification numbers which correlate with the back-flushing procedure.
3. Bio Filter tank screen: Check if it’s Clear once in a month.
4. Sewage tank High Level alarm: Tried out once in a month to confirm its operation.
5. Dosage of chlorine tablets: Quantity checked and topped up every week.
6. Air blower – Oil level (Regular), belt tension and alignment check (6 monthly), Oil change (6 monthly) and Overhaul (5 Yearly).
7. 3 Way or Isolation valve: Check its operation.
8. STP line valve internal inspection – Dismantle and overhaul - Once in a year
9. Internal inspection of STP – 2.5-year interval.
10. Transfer pump – Overhaul (5 yearly)