Green cleaning in place, or Green CIP for short, is a technology enabling the re-use of caustic soda during parts cleaning in food and drink production.

The principle is that pipes and tanks are flushed through with hot alkali (instead of cold water) as a first step, resulting in a liquid which is very high in organic matter. The used caustic soda is then passed into the Green CIP process in which a clay-based reagent is used to separate alkali from solids, resulting in a sludge.

Green CIP is not a mechanical process (using membranes or centrifugation), but a ‘soft process’ of coagulation and flocculation paralleling that in a standard wastewater treatment plant. The sludge from the Green CIP is sufficiently clean to be spread on farmland as a fertiliser or even fed to animals. Crucially, the effluent from the caustic soda flush does not need to be ‘cleaned up’ in an expensive wastewater treatment plant before being discharged to the municipal drains.

Green CIP can function at any pH, enabling the cleaning up and regeneration of both alkali and acid effluent. The caustic soda regenerated in the process can be re-used multiple times, and tests indicate that the regenerated caustic soda is more effective than virgin alkali in its task of removing solids. Installation costs for Green CIP equipment are broadly equivalent to building an on-site wastewater treatment plant. However, the regeneration of caustic soda offers substantial additional financial benefits.

These include:

• Shortening the downtime by between 5 % and 20 % due to faster cleaning, so increasing productivity and revenue while reducing caustic soda use
• Cutting energy and water consumption
• Lower waste charges; avoiding discharge of effluent to sewage plants