Hotel Service Unit 14 Q3

Superchlorination is a process used to disinfect a freshwater system, typically on board a vessel, by temporarily increasing the chlorine concentration to a much higher level than normal. This is often done to eradicate bacteria, particularly Legionella, or to address persistent contamination issues.  

1. Superchlorination | Queensland Health

Process for Superchlorinating the Freshwater System:

1. Preparation:

• Isolate the Tank: Isolate the freshwater tank to be superchlorinated from the rest of the system. This prevents the highly concentrated chlorine solution from entering other parts of the system or reaching the taps.
• Drain and Clean: Empty the tank and, if possible, open it for inspection and cleaning. Remove any visible debris or sediment.   1. Super-Chlorination Procedure on board? – Shipsan www.shipsan.co.uk

2. Superchlorination:

• Prepare Chlorine Solution: Prepare a concentrated chlorine solution, typically using calcium hypochlorite or sodium hypochlorite, to achieve a target concentration of 50 ppm (parts per million) of free chlorine in the tank.   1. Super-Chlorination Procedure on board? – Shipsan www.shipsan.co.uk
• Fill and Circulate: Fill the tank with the chlorine solution, ensuring it reaches all corners and surfaces. If possible, circulate the solution throughout the tank and associated piping for better distribution.
• Contact Time: Maintain the 50 ppm chlorine concentration for a minimum of 1 hour. Some guidelines may recommend longer contact times, such as 2 hours at 20 ppm, depending on the severity of contamination or the specific target microorganisms.   1. Super-Chlorination Procedure on board? – Shipsan www.shipsan.co.uk
• Monitoring: Test the chlorine level frequently (every 15 minutes) using a suitable test kit (e.g., DPD test kit) to ensure it remains at the desired concentration. Add more chlorine solution as needed to maintain the 50 ppm level.   1. Super-Chlorination Procedure on board? – Shipsan www.shipsan.co.uk

3. Flushing and Rinsing:

• Drain and Flush: Once the contact time is complete, drain the chlorine solution completely from the tank and the entire associated pipework system.
• Refill and Flush: Refill the tank with clean freshwater and flush the entire system until the chlorine residual at the farthest outlets is reduced to a safe level for drinking water, typically 0.2 ppm.   1. Super-Chlorination Procedure on board? – Shipsan www.shipsan.co.uk
• Monitoring: Continue to monitor the chlorine residual at various points in the system until it stabilizes at the desired level.

4. Post-Treatment:

• Water Testing: Collect water samples from various points in the system and send them for laboratory analysis to confirm the absence of harmful bacteria and ensure the water meets drinking water standards.
• Normal Chlorination: Resume normal chlorination practices to maintain a residual chlorine level of 0.2-0.5 ppm in the system for ongoing disinfection.

Important Notes:

• Safety Precautions: Take appropriate safety measures when handling concentrated chlorine solutions, including wearing PPE and ensuring adequate ventilation.   1. Safe Handling of Sodium Hypochlorite: Dos and Don’ts – Tikweld products and Services tikweld.com
• Crew Awareness: Inform all crew members about the superchlorination process and warn them not to drink or use the water until it’s been adequately flushed and tested.   1. Potable Water Super-Chlorination Procedure – Shipsan www.shipsan.co.uk
• Record Keeping: Document the entire superchlorination procedure, including dates, times, chlorine concentrations, and test results, in the ship’s logbook or maintenance records.

By adhering to these guidelines and safety precautions, superchlorination can effectively disinfect the freshwater system, eliminate harmful bacteria, and ensure the provision of safe and potable water onboard the vessel.

Superchlorination is a process used to disinfect freshwater systems on vessels by temporarily increasing the chlorine concentration to a much higher level than normal. This is typically done to address contamination concerns or to eradicate specific bacteria like Legionella.  

1. Superchlorination | Queensland Health

Process for Superchlorinating the Freshwater System:

1. Preparation:
   • Isolate the tank: Shut off the tank to be superchlorinated from the rest of the system, preventing the high chlorine concentration from reaching other areas or taps.
   • Drain and clean: Empty the tank completely and, if accessible, thoroughly clean its interior to remove any debris or biofilm.
2. Superchlorination:
   • Prepare chlorine solution: Using calcium hypochlorite or sodium hypochlorite, prepare a concentrated chlorine solution to achieve a target concentration of 50 ppm (parts per million) free chlorine in the tank.
   • Fill and circulate: Fill the tank with the chlorine solution, ensuring it reaches all corners and surfaces. Circulate the solution for better distribution if possible.
   • Contact time: Maintain the 50 ppm chlorine concentration for a minimum of 1 hour. Alternatively, a concentration of 20 ppm can be maintained for at least 2 hours.
   • Monitoring: Test the chlorine level frequently (every 15 minutes) using a chlorine test kit to ensure it remains at the target concentration. Add more chlorine solution as needed.   1. Super-Chlorination Procedure on board? – Shipsan www.shipsan.co.uk
3. Flushing and Rinsing:
   • Drain and flush: Completely drain the chlorine solution from the tank and the entire associated pipework system.
   • Refill and flush: Refill the tank with clean freshwater and flush the system until the chlorine residual at the farthest outlets is reduced to a safe level for drinking, typically 0.2 ppm.   1. Super-Chlorination Procedure on board? – Shipsan www.shipsan.co.uk
   • Monitoring: Continue monitoring chlorine levels at various points until they stabilize at the desired level.
4. Post-Treatment:
   • Water testing: Collect water samples from various points in the system and have them tested by a lab to confirm the absence of harmful bacteria and ensure compliance with drinking water standards.   1. Mobile Unit Water Testing Requirements dec.alaska.gov
   • Normal chlorination: Resume normal chlorination practices to maintain a residual chlorine level of 0.2-0.5 ppm for ongoing disinfection.

Key Points:

• Safety First: Handle chlorine solutions with caution, using appropriate PPE and ventilation.   1. Chlorine – CCOHS www.ccohs.ca
• Crew Awareness: Inform the crew about the superchlorination and warn them not to use the water until it’s safe.   1. Potable Water Super-Chlorination Procedure – Shipsan www.shipsan.co.uk
• Record Keeping: Document the entire process, including dates, times, chlorine concentrations, and test results.

Superchlorination is an effective way to disinfect a freshwater system and eliminate harmful bacteria, ensuring the safety and potability of the water onboard.

Copper Staining

Copper staining refers to the bluish-green or sometimes reddish-brown discoloration that can appear on surfaces or fixtures in contact with water containing dissolved copper. It’s a common issue in plumbing systems, particularly those using copper pipes or components.  

1. How to Identify and Remove Copper Stains from Your Water

Causes:

• Corrosion: The primary cause of copper staining is corrosion of copper pipes or fittings. This corrosion can be accelerated by various factors, including:
  • Low pH (Acidic Water): Acidic water can dissolve copper more readily, leading to higher copper levels in the water and increased staining potential.   1. Relationship between pH and copper in water samples tested. – ResearchGate www.researchgate.net
  • High Water Velocity: High water flow rates can erode the protective layer inside copper pipes, exposing the metal to corrosion.   1. Copper Pipe White Paper – WSSC Water www.wsscwater.com
  • Galvanic Corrosion: When dissimilar metals, such as copper and steel, are in contact in the presence of an electrolyte (water), galvanic corrosion can occur, leading to accelerated corrosion of one of the metals (often the copper).   1. Copper Pipe Corrosion & Corrosion Prevention – American Valve americanvalve.com
  • High Water Temperature: Elevated water temperatures can also contribute to increased copper corrosion.   1. Corrosion Behavior of Copper at Elevated Temperature – ResearchGate www.researchgate.net

Treatment to Prevent Copper Staining:

1. Address the Root Cause:

• Water Chemistry Adjustment:
  • If the water is acidic, consider installing a pH neutralization system to raise the pH to a less corrosive level (typically between 7.0 and 8.0).
  • If the water is soft, it may be more aggressive towards copper. A water softener may be helpful in some cases.   1. Are Water Softeners Bad For Copper Pipes? – Aquatell Canada www.aquatell.ca
• Corrosion Control:
  • If corrosion is due to high water velocity, consider reducing flow rates or using larger diameter pipes.   1. Corrosion of copper piping – Aquify Cape Town Borehole drilling and irrigation systemsWater www.aquify.co.za
  • If galvanic corrosion is suspected, investigate the plumbing system and isolate dissimilar metals using dielectric unions or other methods.   1. Will Using Dissimilar Plumbing Pipe Metals Accelerate Pipe Corrosion? – NuFlow Midwest www.nuflowmidwest.com

2. Filtration and Treatment:

• Sediment Filters: Install sediment filters to remove particulate matter that can contribute to corrosion and staining.
• Phosphate Treatment: Phosphate-based inhibitors can be added to the water to form a protective film on copper surfaces, reducing corrosion and staining.
• Ion Exchange Systems: Specific ion exchange systems can be used to remove dissolved copper from the water, preventing staining.   1. Copper Removal from Industrial Wastewater – ElectraMet electramet.com

3. Pipe Replacement:

• Severe Corrosion: If copper pipes are severely corroded or pitted, replacement may be necessary to prevent leaks and ongoing contamination of the water.
• Alternative Materials: Consider using alternative piping materials, such as PEX or CPVC, which are more resistant to corrosion than copper.

Specific Considerations for Marine Applications:

• Seawater Contamination: In marine environments, seawater intrusion into freshwater systems can accelerate copper corrosion due to its high salt content. Ensure proper sealing and separation of freshwater and seawater systems.
• Galvanic Corrosion: The presence of various metals in marine environments increases the risk of galvanic corrosion. Use appropriate anti-corrosion measures, such as sacrificial anodes or impressed current systems.   1. Understanding Galvanic Corrosion: Concepts, Causes, and Prevention armoloy.com
• Water Stagnation: Stagnant water in infrequently used areas can promote corrosion and copper leaching. Implement regular flushing procedures to maintain water flow and prevent stagnation.   1. Understanding Corrosion in Water Systems watertreatmentservices.co.uk

Additional Tips:

• Regular Monitoring: Regularly test the water for copper levels to identify any potential issues early on.
• Cleaning Stained Fixtures: If staining has already occurred, various cleaning methods can be used to remove copper stains from fixtures and surfaces.

By addressing the root cause of copper corrosion and implementing appropriate treatment and preventive measures, it’s possible to minimize copper staining, protect plumbing systems, and ensure the quality and safety of the water onboard a vessel.