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Example Neutralisation Plants

Construction measures very often affect aquifer layers. As soon as the water gets into contact with concrete (e.g. pouring of underwater concrete), the chemical properties of water are modified. A strong increase of the pH value has to be expected.

Either mineral acids (such as sulphuric acid or hydrogen chloride) or carbon dioxide (CO2) are the most appropriate agents for the neutralisation of alkaline waters. However, neutralisation by means of mineral acids leads to an increase in the salinity of the water and is therefore harmful to the environment. In addition, specific requirements as to the storage of the material, and strict safety regulations have to be observed.

Carbonic acid, in contrast, is a natural water component, whose different dissociation states basically form the water’s buffer system. Contrary to the use of mineral acids, the use of carbonic acid does not cause the increase of water salinity.

Compared to mineral acids, it has to be stated that the use of carbonic acid allows for a much better, i.e. more exact adjustment of the pH-value in the relevant range between approximately 6.5 and 9.0. The use of mineral acids can easily lead to an overdosing thus causing the pH-value to fall below the admissible value.

Scope of application:

  • Alkaline water, e.g. trench drainage for the pouring of underwater concrete
  • pH-value regulation in the water in case of remediation measures

Technical details:

  • Simple systems in open tanks for short interventions
  • Preliminary neutralisation systems for the use in construction pits
  • Neutralisation tank including CO2-injection system
  • Compact CO2-container plant
  • pH-control systems for intake and discharge
  • Safety equipment
  • Dosing equipment, dosing tables

Advantages:

  • Environmentally compatible procedure by preventing the increase in salinity
  • Rapid availability
  • The possibility of acidification can be basically ruled out
  • No handling with dangerous and aggressive substances required
  • No additional charges for increased salt content in the wastewater
  • Reduced space and staff requirements
  • Reduced maintenance and operational costs
  • Economic efficiency
  • Safety
  • Flexibility