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Sewer Infrastructure Protection


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


One of the solutions to stop corrosion is by spraying of Magnesium Hydroxide Liquid (MHL) on the surface of concrete sewers. Compared to existing corrosion protection technologies like plastic lining, MHL spray coating is 7 times cheaper over the life cycle of the asset and does not require flow diversion or man entry for application.


Concrete sewer assets and asbestos lined assets are highly prone to corrosion due to acid attack.


Key steps in the corrosion mechanism…

  1. Reduction of sulphates to sulphides (H2S) in anaerobic sewage.
  2. Oxidisation of H2S to H2SO4 by Sulphide Oxidising Bacteria.
  3. H2SO4 (sulphuric acid) corrosion of concrete in sewer crown.

The corrosion in concrete Manholes is a similar process…


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 form colonies as pH drops.

4.Convert H2to H2SO4 (sulphuric acid) = corrosion of Manhole.

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