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Safe & Award-winning Solution for Odour Management in Wastewater


Related resources:

Hydrogen sulphide (H2S) - the cause of the rotten egg smell in sewageWhat is that rotten egg smell?

Hydrogen sulphide (H2S) is a poisonous gas produced in sewage that has a distinctive and unpleasant rotten egg smell and is a frequent cause of odour complaints.


Its build-up is a problem endemic to all water utilities resulting in expensive infrastructure damage, problematic odour issues and potential health hazards.



How does H2S form?

Wastewater Layers ChartSewer pH ChartHydrogen sulphide (H2S) is produced largely due to the action of sulphate-reducing bacteria (SRB) in anaerobic (or oxygen-depleted) conditions.

  1. In the “slime layer”… SRB’s convert of sulphates (SO4) to dissolved sulphides (H2S + HS-);

  2. As the pH of the sewer drops below about 8, these dissolved sulphides increasingly combine to form H2S in the liquid or “aqueous phase” (H2S(aq));

  3. Some of this H2S(aq) is released as a gas H2S(g)


H2S Toxicity / Exposure ChartH2S is highly toxic…

At just 0.0047 ppm, your customers will start detecting the characteristic ‘rotten egg’ smell of H2S.






How can you control H2S?

  1. Covering and Scrubbing – this approach is rarely fully effective unless the entire inlet structure & pre-treatment stages are covered and off-gases scrubbed.
  2. Oxidation – various methodologies
    • Direct oxygen addition – application limited by low solubility, need for dissolution technology & safety issues;
    • Chlorine/ Bleach – hazardous and high operating expense;
    • Hydrogen Peroxide/ Ozone - hazardous and very high operating expense;
    • Potassium Permanganate - very high operating expense;
    • Nitrates – potential treatment plant issues with rising sludge in primaries.
  3. Precipitation - Iron salts – corrosive & dangerous, removes alkalinity/reduces pH AND reduced effectiveness at low pH (“chasing your tail”), increased sludges / blockages.
  4. Alkalinity / pH Adjustment – Keeping pH high stops the formation of H2S from dissolved sulphides.

Alkalinity / pH adjustment is becoming the preferred methodology for controlling H2S formation in sewers…



A smart solution for councils & water authorities

Mitigate H2S generation
and increase asset life
Buffer pH / prevent high or low pHnonoyesnonono
Provide alkalinity to sewagenonoyesnonono
Effective life in sewerlongshortvery longvery shortshortna
Suitability for long retention timesnonoyesnonona
Safe, not detrimental to
mechanical equipment in sewers
Minimises sludge formationnonoyesnonono
Safety in handlingnoyesyesnonona
Overall operating costsmediummediummediumhighhighmedium
Reduction of fats, oils and greasesnonoyesnoyesno



ACTI-MAG™ Magnesium Hydroxide Consumption Chart

Not all magnesium hydroxide are made equal



Unlike many other Magnesium Hydroxide slurries, Calix’s ACTI-Mag™ is a concentrated (60%) stabilised suspension of magnesium hydroxide.

more solids = Lower required dose

At a 30% solids concentration, MHL can take more than twice the dose to achieve the same neutralisation capacity as same the amount of ACTI-Mag™:




ACTI-Mag™ is the best magnesium hydroxide available…



Calix is the ONLY company that controls the production process from mining of raw materials, to processing, to locally produced, end-product. We have “perfected” magnesium hydroxide…


This explains why:

  • ACTI-Mag™ is highly reactive
  • ACTI-Mag™ neutralises faster
  • ACTI-Mag™ is more stable
  • ACTI-Mag™ flows better than all other magnesium hydroxides


So…why should you choose ACTI-Mag™?


ACTI-Mag DosingApart from…

ACTI-Mag™ supplies more alkalinity

per dry kilo than caustic soda or lime


AND the fact that…

ACTI-Mag™ buffers to a pH of 9.0 close to

the ideal pH 8.5 – 8.6



ACTI-Mag™ is safe to handle.


CALIX has built its business

on hassle-free delivery,

service & support!

Our customers say it best

Goulburn Valley Water



High H2S level Odour complaints Asset corrosion Scum build up


  • Reduction in H2S levels
  • Reduction in scumming
  • Reduced corrosion
  • Stopping of odour complaints



Queensland Urban Utilties



  • Rural residential catchment with long retention time.
  • Serial pumping with discharge in a residential precinct.
  • Frequent odour complaints at discharge.
  • Fat build-up observed within pump station wet wells.
  • Problem with vehicle access to desired dose point.


  • Trial location at Pump station upstream was effective.
  • Permanent facility installed at the trial location.
  • Cost of access upgrade to original site eliminated.
  • Effective H2S and odour control achieved at both sites.
  • Fat build-up eliminated & water sprays shut-off – reduced water usage & pumping cost.



Whitsundy Regional Council



  • Popular tourist destination with sensitivity to odour.
  • Frequent odours at the Pump station in market precinct.
  • Long retention (>20 km)
  • Minimal success with other chemicals
  • Corrosion at downstream manholes & re-pump stations.


  • Consistent odour control achieved at all critical points.
  • Required only one major and two minor dosing stations.
  • Reduced round the day average & peak H2S levels.
  • Usage optimised to ~100 mg/L (kg/ML) dose.
  • No dangerous chemicals stored or dosed within public parklands.



AJ Bush and Sons



  • Poor anaerobic pond process stability due to low pH.
  • Restricted plant loading <70% of design COD capacity.
  • Restricted gas production .
  • Limited use of power generation & gas fired boiler.
  • High phosphorous levels in effluent.


  • Process stability maintained at near neutral pH.
  • Full design loading achieved with >90% COD removal.
  • Increased gas production.
  • Reduced power imports from grid & coal requirements.
  • Reduced carbon footprint.
  • Generator augmentation opportunities
  • Significantly improved phosphate removal.



Don’t compromise the safety of your people, Protect the environment you live in.


Protect the environment you live in

  • ACTI-Mag™ is safe to handle
  • Non corrosive
  • Safe for the environment
  • Does not add to salinity
  • Improves SAR value in soils









We pride ourselves in the excellence of our engineering and technical support.

Calix delivers tailor made solutions for your council's needs

Calix has setup dosing stations for councils of all sizes


We take a hands-on consultative approach towards your council’s needs to deliver smart dosing solutions and equipment that are tailored to your specific requirements.


We have designed many dosing stations for councils of all sizes.



Anywhere, anytime.


Calix has a reliable network of local partners

 Our network of local partners can deliver our solutions across Australia & New Zealand, to ensure you receive the same high quality of support, product and customer service, no matter where you are.










  • Faster neutralisation with less chemical consumption
  • Reduce dosing system blockages
  • Safe to handle / Non hazardous
  • Buffers at pH 9 if overdosed
  • Better stability in the system
  • Reduced H2S and odours
  • Attractive costs savings
  • Local presence and support


Any questions ?




(02) 8199 7400


9 Bridge St, Pymble NSW 2073 71


Rowsley Station Road, Maddingley VIC 3340 23


Stevens Street, Nerang QLD 4211