De La Rue - Containerised Effluent Treatment

Project Background

The banknotes you find in your wallet are likely to have been printed by De La Rue. Using innovative technologies, the company provides end-to-end currency solutions to over half the central banks and issuing authorities worldwide.

At its printing facility in Nairobi, Kenya, the existing effluent treatment plant for ink removal began showing its age after more than 20 years in operation. This resulted in the following issues arising:

• Corrosion of chemical storage tanks
• Original carbon filtration plant undersized for production output
• Only had a manual print wash solution system
• Lack of auto-dosing and level control
• Much of the plant was beyond economical repair

We were approached by De La Rue to design and prefabricate a fully integrated, containerised effluent treatment. The system needed to be seaworthy, with little work required to transport and recommission it at any plant. 

Our Solution

The final solution consisted of three shipping containers, each housing different elements of the effluent treatment system.

• Container 1 - Main reagent tanks and print wash plant
• Container 2 - Main control panel with HMI and four system treatment tank
• Container 3 - Three sand and carbon filter vessels

Before delivery, we wet-tested the system at our engineering facility in North Shields. This involved working in close collaboration with local De La Rue personnel. The testing process resulted in an on-site commissioning time of just 48 hours in Nairobi.

The treatment process works as follows:

1. Effluent is pumped from the existing sump tank, which was also upgraded with an ultrasonic level controller and a submersible aeration pump to keep the tank agitated
2. The effluent then moves into a four-stage treatment tank, where it is automatically dosed with hydrochloric acid (on pH control), aluminium sulphate, Cleanfloc CS51H, lime (on pH control) and flocculant Cleanfloc CE45TRM
3. A filter press removes the ink solids
4. Filtrate is pumped through a sand filter, and then two carbon filters
5. Effluent is monitored for pH and Chemical Oxygen Demand (COD) prior to discharge

Outcomes

Using our experience in wastewater treatment, we were able to design and deliver an entire containerised system that is easy to operate and maintain. Applying a ‘plug and play’ philosophy means the client can quickly relocate the system to any of its global manufacturing sites, improving operational efficiencies and introducing cost savings. The system also ensures that De La Rue continues to play its part in improving environmental sustainability by effectively treating its wastewater.