13 december 2016
Robert Wiseman Dairies
Reducing water consumption for a higher economic value and a lower carbon footprint
One of the major costs in milk processing is water: 1.3 liters of water is needed for every one liter of milk processed. On top of this, 4.2g of chemical oxygen demand (COD) is produced from every liter of milk processed, which is then discharged into wastewater.
Robert Wiseman decided to optimize its water and wastewater use by aiming to reduce water consumption across its dairy network by 25% over a five year period.
The project was started in their main dairy plant located in Bridgwater, which processes 125 million liters of milk per day.
Veolia Water Technologies (VWT) is supporting Robert Wiseman’s project by providing a Dissolved Air Flotation (DAF) system and a membrane bioreactor (MBR) to reduce COD. The quality of the discharged effluent more than meets the environmental requirements. In fact, the quality of the treated effluent was so good that Robert Wiseman wanted to reuse it.
VWT therefore proposed its reverse osmosis (RO) system: MegaROTM
to recycle the effluent in order to use it for the CIP (Cleaning in Place) system. The MegaRO technology uses a membrane to remove 99% of residual COD, dissolved salts and bacteria from the treated process wastewater, producing water of equal or better quality than the mains supply. VWT was one of the early pioneers of MBRs, thanks to its Biosep process
, and using this expertise VWT were able to feed the MBR effluent directly to the MegaRO system with no set-backs. Robert Wiseman became the first dairy industry business in the UK to install a RO recycle system, enabling them to recover 200m3
/day of process wastewater.
The reverse osmosis process is driven by pressure, but the MegaRO’s low-pressure membranes and high-efficiency pumps make it one of the most energy efficient systems on the market. Low energy use means not only reduced carbon emissions but also low operating costs. Moreover, the quality of the waste concentrate stream from the MegaRO is still good enough for the effluent to be discharged directly into the drainage ditch.
"Because the operating cost of the MegaRO is low, the recovered water actually costs less than mains water even after including capital amortization. We expect to get a payback on the £130,000 (approx. €153,000) investment in about two and half years." said Eleanor Walton, Robert Wiseman Dairies' project manager.
Although the plant has only been in operation for six months, Walton had enough confidence to be talking to Veolia Water Technologies about a second plant to recycle another 80m3
/day of wastewater. “We also want to roll out this kind of technology to some of our other sites where they have an expensive sewer discharge
” she says.
Robert Wiseman Dairies operates six dairies, 14 distribution depots and employs more than 4,700 employees.
Robert Wiseman Dairies supplies a third of the UK’s milk.