Membrane separation processes are successfully applied for the recovery and re-use of acids and bases.
In this field, the almost classic membrane separation processes are applied such as diffusion dialysis, electrodialysis, reverse osmosis and nanofiltration, depending on the concentrations of acids, bases and their impurities. Concentrated solutions are treated by energy-efficient concentration-driven diffusion dialysis while less contaminated solutions are treated by low-investment pressure-driven nanofiltration.
High volume flows of acidic and alkaline process and rinsing water can be concentrated by electrodialysis and, to a limited extent, by reverse osmosis for recycling purposes. A combination of processes often provide particularly attractive solutions, even for problematic cases.
- Recovery of concentrated acids and bases by diffusion analysis
- Recovery of low-contaminated acids and bases by nanofiltration
- Concentration of diluted acids and bases by electrodialysis or reverse osmosis
A very high-quality cleaning agent is needed to keep the plant free of microbiological activity. The most important cleaning agent in the food and beverage industries is a hot alkaline solution. However, cleaning efficiency is reduced as the concentration of impurities in the alkaline solution increases.
The fumatech® nanofiltration process for the treatment of alkaline solutions removes impurities from the solution such as COD, paint and particles and separates any carbonates that are formed. Cleaning efficiency is greatly improved by filtering the alkaline solution. Furthermore, in bottle washing machines, there is a decrease in the transfer of the alkaline solution into the rinsing zones, thus reducing the use of disinfection chemicals in the warm water zones.
For the recovery of alkaline solutions, FuMA-Tech has developed a process based on nanofiltration that treats spent cleaning solutions very efficiently. It can be applied for:
- Alkaline cleaning solutions in bottle washing machines
- CIP alkaline solutions in equipment cleaning as well as PVPP stabilisation
- CIP alkaline solutions from evaporator cleaning in dairies
As far as bottle washing machines in particular are concerned, the huge advantages of alkaline solution recycling by nanofiltration have been confirmed many times in practical applications. It is only by nanofiltration that COD-inducing impurities, as well as hardening agents and carbonates can be removed from the solution. As a result, caustic soda solutions, additives, and anti-foaming agents can be saved and the efficiency of the bottle washing process can be increased by stabilising the solution quality e.g. at a COD level of 2500 mg/l.
The transfer of alkaline solution into the rinsing zone is also lowered, hence reducing the consumption of disinfection chemicals while there are less shut-downs due to petrifaction in the washing machine. On the whole, particulate contamination decreases throughout the zones in the washing machine. The first reference plant was set up im 1996 and is still running successfully.
All the nanofiltration plants for REF-PET bottle washing machines are standardised and can be supplied at minimum delivery times. They have been designed as space-saving add-on units (base area 4000 mm x 1000 mm, height according to size of structure), fitted with an intelligent control system, which obviates the need for signal exchange with the washing machine.