Nanofiltration increases water production capacity at beverage plant

A six-month project, completed by Ovivo Australia in just 12 weeks, has enabled two large beverage companies to increase their production capacity by 420%.

The joint venture between Frucor NZ and Slade’s Beverages in Thomastown, Victoria, was to increase the production of water supply by installing a nanofiltration system. This has allowed for the production of a new range of V Energy drinks and other products using water directly from the potable supply.

The client required a 30 m³/h supply of consistent quality demineralised water to ensure that flavours were not affected. The nanofiltration system was recommended by Ovivo Australia due to its small filter pore size which is fine enough to remove contaminating flocculants and divalent metal ions.

The process, designed to take feed water from Melbourne’s potable water system and treat it to remove fine flocculent particles and dissolved metal impurities, was completed by Ovivo Australia with the support of Van-Der-Molen GmbH, a member of the Ovivo water group.

The integrated nanofiltration plant and permeate transfer system was delivered at the end of May 2011. As well as removing the impurities, the system also allows for a consistent quality of product water in terms of hardness, TDS and pH. This enables the client to accurately control the flavour as well as the carbonation process in soft drink making.

Analysis of local potable water samples showed TDS levels of 100 mg/L. The system was designed to reduce these to less than 55 mg/L and maintain a consistent pH of 6.2 to 6.5. The system was also designed for an 82-85% recovery of the potable water feed utilising a 3-stage, single-pass treatment process.

The nanofiltration plant utilises mains water pressure to feed through a pretreatment process which involves PID controlled dosing of antiscalant and SMBS for membrane protection. Additional cartridge filtration prior to the NF plant is in place to protect against particulates from depositing on the membrane. A 15 kW vertical multistage pump drives the 36 m³/h feed to the required pressure to push the water through the membranes.

The generated permeate is maintained below an 80 µS/cm conductivity setpoint by a discharge conductivity meter. Permeate which is above this limit is discharged to sewer via an off-spec valve to maintain a consistent quality product in the permeate tank. The permeate is stored in a product tank being delivered to the client’s processes via two VSD controlled centrifugal pumps. An integrated recycle system is implemented to allow delivery of permeate from the product tank back to the nanofiltration plant for use in the CIP process.

As the feed water is potable water, the discharge TDS on the brine side is extremely low. TDS levels in the discharge are only 370 mg/L with a pH of 7.8, which has meant the water can be recycled.

Ovivo provided an online quality control system to ensure all water delivered was within the 85 µS/cm quality specification. The integrated control system means the plant operates as a self-contained turnkey plant and HMI software includes a CIP procedure walkthrough feature to remove the risk of operator error during membrane cleaning.

As well as the challenge of meeting a 12-week delivery schedule, Ovivo Australia faced a second test of having to increase the package size when product storage was added to the project scope and delivered with just four weeks remaining. An integrated automatic product transfer pumping solution, including three pumps and a secondary VSD control panel and upgrades to the existing NF control panel, were also added to the scope and delivered within 10 days.

There are a number of benefits of nanofiltration over a reverse osmosis system. Nanofiltration uses a small enough filter pore size to remove contaminating flocculants and divalent metal ions, and the water quality still contains vital dissolved salts so that it does not require significant remineralisation for human consumption. The energy required per unit of product is lower and there is lower capital expense in implementation. Also, the product water, due to its high quality, can be used for both the manufacture of the beverage flavouring as well as the carbonated make-up water.