pH Correction Additives

pH plays a very significant role in everyday life from affecting blood composition in the human body, to regulating plant growth, and governing the application of paint. Many water treatment processes are pH dependent: effectiveness of chlorination, formation of chloramines, floc formation in coagulation processes, and corrosion of metal equipment and piping.

pH correction must be the first step in a treatment sequence. For most applications, Osorno recommends keeping the pH of  water in the narrow range of 7.7 – 7.8. Our water quality assessment services can determine the type and quantity of pH correction additives required.

As with all Osorno water additives, these products are available in 20 litre delcans or 208 litre drums. Osorno charges a deposit for these containers, which is credited when the containers are returned undamaged.

Sodium HydroxidepH_corrector_sm

Sodium hydroxide is the most valuable  correction additive for raising pH. pH increasing agents are mainly used in water treatment plants. Some examples where sodium hydroxide is required include:

  1. Manganese can be removed only after addition of an oxidant and at a pH of 7.8 – 7.9.
  2. Iron removal requires addition of an oxidant and a pH of 7.4 – 7.9.
  3. After coagulation-flocculation process, the pH of water has to be raised.
  4. Corrosion processes speed up if the pH in water reservoirs and distribution lines is lower than 7.8.

Osorno suggests the use of sodium hydroxide over using sodium carbonate (“soda ash”) because it has twice the capacity to increase pH. This means that for a given pH correction, the sodium content will increase by half – a very important consideration for populations concerned with high sodium content in food and water. There are only a few applications where sodium carbonate is required.

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Hydrochloric Acidph_correct_hcl_sm

Hydrochloric acid is used to decrease pH in swimming pools and water treatment plants.

Swimming pools:

  • The pH level in swimming pools has to be consistently within a  range of 7.4 – 7.6 to avoid eye irritation and itchy, sticky skin.
  • High pH can cause a hazy, murky, or cloudy pool.
  • Chlorination is more effective when pH is below 7.4.
  • Over time, high pH can cause water to scale, resulting in clogged filters and fittings.

Water treatment plants:

  • Manganese removal requires addition of an oxidant, and a pH of 7.8 – 7.9.
  • Iron removal occurs at pH of 7.4 – 7.9.
  • Coagulation processes depend on use of a coagulation agent, and a pH usually below 6.

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