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Calix's PROTECTA-Mag Product | Sewer Protection


Australia’s $40 billion of concrete sewage infrastructure, if left untreated, could corrode away in 8 years from sulphide attack. 


Concrete sewer manholes are highly prone to corrosion due to acid attack. The corrosion mechanism is fairly simple:

  1. Generation of H2S in sewer lines fills up the Manhole;
  2. Oxidisation of H2to H2SO4 by auto oxidation reduces pH;
  3. Sulphide Oxidising Bacteria (SOB) form colonies as pH drops;
  4. Convert H2to H2SO4 (sulphuric acid) = corrosion of manhole.

One of the solutions to stop corrosion is by spraying PROTECTA-Mag™ (Magnesium Hydroxide coating) on the surface of concrete sewers.


Treat the cause, not just the symptom


PROTECTA-Mag™ prevents corrosion by raising surface pH, thus neutralising acids and inhibiting the formation of acid-producing bacteria. Monitoring results indicate that PROTECTA-Mag™ coating continues to protect the integrity of the concrete walls of the manhole, in spite of continuous sewer flow, for up to 7 years*.


 Compared to existing corrosion protection technologies like plastic lining,

PROTECTA-Mag™ spray coating is 7 times cheaper

over the life cycle of the asset and does not require flow diversion or man entry for application.


A very simple process


Calix's trailer-mounted, purpose-built PROTECTA-Mag™ rig is used to carry out Vertical Spray Operations. A crew of two, trained for the spray application, traffic control and confined space entry (if required) carry out the application.


PROTECTA-Mag™ is sprayed on the concrete surfaces of the man hole using a high pressure air less applicator. For manholes up to 3 metres in depth, spray is carried out using a lance.


For deeper manholes a spray nozzle on a special winch is lowered into the manhole to carry out the cleaning and spraying operation. 

  1. Spraying is carried out without stopping the flow of the sewer or man entry;
  2. An extensive risk assessment is carried out at the site prior to starting work;
  3. The overspray of PROTECTA-Mag™ entering the sewer flows is complementary and beneficial for any downstream Sewage Treatment Plant (STP) and odour control;
  4. The high wall pH and high activity MHL inhibits the re-growth of specific acid forming bacteria (e.g. thiobacillus concretus.

Hassle free delivery, local service and support you can count on   Hassle free delivery, local service and support you can count on


Our AS/NZS ISO 9001 certified quality system and safety, health and environmental management system are vital elements of our engineering and quality services.


Calix has established a network of local distributors and partners who can deliver PROTECTA-MagTM across Australasia, to ensure you receive excellent customer service and support, wherever you are located. 


Would you like a quote or more information about any of our products, solutions or services?

If you'd like to locate a Calix partner near you, contact us now.

Customer stories & relevant articles  Customer stories & relevant articles