What could be more basic than water? It’s a fundamental component of all life. Ubiquitous, ordinary and extraordinary, it’s the universal solvent. Yet it’s immiscible with lipids. Its boiling and freezing points are the references by which we measure temperature. Water is a simple molecule; a single oxygen atom covalently bonded to two hydrogen atoms.
As noted in the famous line by Coleridge, water may be everywhere around us, but it is seldom truly pure. In the case of the “ancient mariner,” seawater is tantalizingly present but far too salty to drink. Among its many remarkable qualities, water is capable of dissolving — and holding in solution — any number of solutes. As the ill-fated sailor discovered, saltwater is unsuitable for human consumption.
A similar problem may afflict process engineers attempting to design suitable mixing strategies. In short, mixer water quality can have an impact on your final outcome. The quality — or more precisely, the purity — of your process water matters. In some instances, purity can greatly affect outcomes.
Soft, Hard and In Between
Terms such as soft and hard are used to describe water with varying concentrations of dissolved solutes. Truly pure water is relatively rare. Drinking water, for instance, often contains at least trace amounts of dissolved minerals and salts. These “extras” may even contribute to its aesthetic appeal.
But attention to the relative softness or hardness of the water used in mixing — for a variety of processes, across a range of industries — is crucial to success. In the food industry, for example, hard water can impede the ability of brine solutions to dissolve and hydrate properly.
Hard water contains dissolved magnesium and/or calcium ions, among other metallic ions. These typically come from carbonates of these elements present in the soil through which the source water has naturally percolated. Some regions of the country feature notoriously “hard” water. The Midwest, for example, was once covered by an inland sea in a distant epoch. As such, areas with significant limestone and chalk deposits tend to have especially hard water.
Sales of water softeners, and the supplies to keep them operating efficiently, tend to be high in these areas — and for good reason. Hard water reduces the effectiveness of surfactants (e.g., soaps and detergents) and leads to problems such as scale buildup on faucets, shower heads and in boilers. It also affects mixer water quality.
The United States Geological Survey (USGS) designates water hardness according to the concentration of dissolved solutes in a given amount of water at a particular pH. Specifically, hardness refers to the concentration of multivalent cations in a given unit of water. Units of measurement are reported as mg/L calcium carbonate equivalent, or alternatively, as parts per million (ppm).
Some scales may list grains per gallon (gpg). For simplicity’s sake, we use here the scale cited by USGS. To be clear, total water hardness is defined by the sum of molar concentrations of magnesium and calcium cations in solution. Other dissolved metallic ions (e.g., aluminum, iron, etc.) can also contribute somewhat to your homogenizer water quality.
USGS Water Hardness
- Soft: <60 mg/L (ppm)
- Moderately Hard: 61-120 mg/L (ppm)
- Hard: 121-180 mg/L (ppm)
- Very Hard: >180 mg/L (ppm)
Per this system, soft water is deemed excellent for all uses. Moderately hard water (especially if it’s high in phosphates) may be more problematic and warrants special attention to ensure compatibility with your process. Hard water can be expected to affect yields adversely; often reducing yields by at least one-third. Very hard water can be expected to cause “severe yield impacts.”
For more information about how to improve your homogenizer water quality, improve yields or streamline your process overall, contact us here, or fill out our handy form to request a quote. Our knowledgeable sales personnel are standing by to assist you.