© stock.adobe.com/au/Nik
DAIRY
How to droughtproof infant formula plants
The infant formula industry offers Australian manufacturers significant opportunities for water re-use.
R
aw milk contains roughly 85–87% water, most of which is removed in the production of whole milk powders and high-value infant formula blends. Water is removed either by drying the milk using milk evaporators or by using membrane processes such as nanofiltration (NF) and reverse osmosis (RO). An infant formula processing facility which takes in 1 million litres of milk per day can be left with 850,000L of wastewater commonly known as ‘cow water’. The quality of this water is extremely good, as it contains very little dissolved salts and very low levels of organic matter due to the distillation/membrane filtration processes used in production of milk powders or infant formula. This much water represents a significant opportunity for Australian manufacturers to improve their sustainability and ‘droughtproof’ their operations. There are other separate wastewater streams generated by cleaning and general processes within the factory which are a far higher strength, and would require robust treatment before re-use; however, the opportunity to recycle this cow water presents the possibility for dairy plants to be either net neutral water consumers or even water producers. This offers considerable savings in the upfront investment and operation of wastewater treatment plants. Even if the wastewater is clean enough to discharge to sewer without treatment, the fee for the volume that is discharged can be avoided by recycling. This offers savings of typically $1–$3 per kL of water that is recovered, with an additional offset to the purchase price of water. There is a misconception that since the treated water is still regarded as recycled that it must have limited re-use possibilities 32
January/February 2018
within the dairy — this could not be further from the truth! The water can be used in any part of the process apart from make-up water in the final product (such as liquid infant formula blends). The key is to ensure it is appropriately treated before use. It is important to note that the cow water should not be sent directly to the infant formula wet mix processing plant. This is due to the protein (carbon) content being too high in the cow water and leading to the growth of microorganisms within the pipe network. Although high doses of chlorine can be used to counter this, this leads to the production of carcinogenic trihalomethanes as well as an impact on final product quality and taste. Hydroflux has previously written about the importance of treating this process water to ensure the quality of this ‘white gold’ that is infant formula here. Easy re-use options for cow water that can use basic chlorination for treatment include using the chlorinated cow water for washdown and first flush CIP. Better treatment of the cow water increases its potential uses, which typically involves polishing with NF or RO. A common misunderstanding regarding the design of the treatment system is that a typical ‘dairy milk RO’ plant is all that is required. Dairy milk RO plants and water treatment RO plants are very different. Dairy RO plants are designed for treating liquid with very high solids content, and require a higher cleaning frequency as a result — usually once to twice per day. Dairy ROs also operate an overall lower design recovery rate. Due to the high value of the milk-based products that these systems produce, the internal rate of return on the investment in the equipment is less impacted by the costs and downtime associated with higher
www.foodprocessing.com.au