| Today’s more stringent laws and more frequent checks of authorities reflect the environmental concerns currently supported by our society.
Thus, waste water is only allowed to be discharged into a sewage system if its pH does not exceed legal requirements.
Carbon dioxide is being increasingly used to neutralise alkaline waste water. When dissolved in water, carbon dioxide forms carbonic acid. Unlike mineral acids, carbon dioxide has many advantages: it prevents excessive accumulation of salts such as chlorides, sulphates, etc. Plus, excessive acidification of waste water is virtually impossible, owing to carbon dioxide’s flat neutralisation curve.
Carbon dioxide is also much safer to use than highly corrosive acids; it virtually eliminates corrosion problems.
The picture on the right shows a Linde mobile neutralisation system.
Industries generating alkaline waste water are, e.g.
- Beverage industry (cleaning of reusable bottles)
- Dairies, slaughterhouses and meat-processing plants
- Bakeries and confectionery industry
- Electroplating industry (surface treatment of metals)
- Pulp and paper industry
- Leather industry
- Textile industry
- Laundries and dyeing plants
- Cement and concrete industry
- Photochemical industry, etc.
- Construction industry
Below you can see a comparison of the neutralisation curves of a caustic soda solution and carbon dioxide (click to enlarge):
Advantages of neutralising waste water with CO2
- Carbon dioxide is a natural water compound – mineral acids are not
- No fees incurred for excessive salt concentrations
- Extended service life on account of reduced corrosion
- No risk of excessive acidification
- Little space and low staff requirements
- Low maintenance cost
- Low operating cost
The SOLVOCARB® process injects carbon dioxide into water:
- SOLVOCARB® -B
- Carbon dioxide enters via finely perforated aeration hoses
- SOLVOCARB® -D
- Carbon dioxide enters via ball-head nozzles
- SOLVOCARB® -R
- Carbon dioxide enters via special reactors
|
