Getting a Sense of Sulfates
By Jake Anderson |
Water quality has become a primary focus in the animal production model. This focus has led to a pursuit of understanding the composition of animal drinking water and how the concentration of each constituent can impact the animal production model.
In previous articles, we’ve discussed the impacts and solutions for iron and “salty water.” This article, the third in this installment, covers sulfate, its potential impacts, and how to deal with source water high in sulfate.
Sulfate is present in nearly all ground and surface water sources due to naturally occurring sulfur in soils, minerals, and rock. Other sources of sulfate can be attributed to the burning of fossil fuels, mining, and agricultural inputs (MPCA, 1999). Sulfate is highly soluble in water and odorless. It’s not to be confused with hydrogen sulfide, which has a distinct “rotten egg” odor at low concentrations. The amount of sulfate present in a water source is impacted by factors such as geographical location and well depth (Veenhuizen, 1993).
Animals drinking from a water source high in sulfate will often exhibit higher rates of water consumption, diarrhea, as well as a decrease in the amount of fecal dry matter (Anderson et al., 1978). The symptoms described are usually the most evident in young animals and usually subside within 7 days after they are acclimated to the water source (Veenhuizen, 1993).
Three common sulfate salts present in water are sodium sulfate, magnesium sulfate and calcium sulfate (Patterson et al, 1979). Knowing which sulfate salt is predominant in the source water is crucial, as the extent of the animal’s response is not solely dependent on the sulfate concentration but on both the concentration of the sulfate as well as the associated cation (Grout et al., 2006). Magnesium sulfate can exhibit negative impacts on animals at much lower concentrations than sodium sulfate (Adams et al., 1975).
In order to know how much sulfate is present in the water, laboratory analysis of the water needs to be conducted. If the testing shows there are elevated levels of sulfates present, there are two methods to remove the sulfate from the water: anion exchange and reverse osmosis. Anion exchange works by exchanging the sulfate ions for another ion which is generally chloride. The resulting increase in chloride ions will lead to excess intake of chloride by the animals and result in trading one set of problems for another.
Reverse osmosis and sulfate removal
When it comes to animal health applications, reverse osmosis is the only viable application for removing the sulfate from the water. Reverse osmosis systems use semi-permeable membranes and pressure to remove solids from the water. Reverse osmosis works in the process its name describes—it is the reverse process of osmosis. Osmosis is the process of the solvent, or water in this case, moving from an area of low solute (dissolved solids) concentration through a membrane to an area of high solute concentration. Reverse osmosis systems cause the opposite of osmosis to occur by applying pressure to the high solute concentration side of the membrane, forcing water to pass through the membrane but not allowing the solids in the water to do so.
The result is two streams of water: (1) the permeate, or the water that has passed though the membranes, which has the majority of the solids removed from it, and (2) the retentate, which includes the solids and other material that were not able to pass through the membranes. The permeate is the portion that will ultimately end up as the drinking water for the animals and the retentate is a waste stream of water that will need to be discarded. The ratio of permeate to retentate will depend on the composition of the water source.
Reverse osmosis system considerations
There are a few things that need to be taken into account with reverse osmosis systems. First is the size of the system. Each system will need to be sized to fit the individual location to ensure the system can produce enough water to satisfy the water demand on the farm.
The second piece is the incoming water source. There are certain parameters that need to be met by the incoming water source for the reverse osmosis unit to prevent plugging, scaling, or damage to the membranes. Analysis for these problematic constituents, such as calcium, iron, and other particulate matter (sand, dirt, and other solids) should be conducted prior to the installation of a reverse osmosis system. If any of the parameters are above the maximum threshold for the reverse osmosis unit, pre-treatment will need to be put into place in order to remove or mitigate these contaminates before entering the reverse osmosis unit to prevent damage and reduced performance of the membranes.
If you have questions related to sulfates in drinking water and need options for addressing them, please reach out to your MWI Animal Health Territory Manager. We are here to help!
Adams A.W., Cunningham F.E., Munyer L.L.: Some effects on layers of sodium sulfate and magnesium sulfate in their drinking water. Poult Sci 54:707–712, 1975
D.M. Anderson, S. Stothers, Effects of Saline Water High in Sulfates, Chlorides and Nitrates on the Performance of Young Weanling Pigs, J Anim Sci, Volume 47, Issue 4, October 1978, Pages 900–907
Grout, A.S., Veira, D.M., Weary, D M., von Keyserlingk, M.A.G., & Fraser, D. (2006). Differential effects of sodium and magnesium sulfate on water consumption by beef cattle. J Anim Sci, 84(5), 1252–1258.
Paterson D.W., Wahlstrom R.C., Libal G.W., Olson O.E.: Effects of sulfate in water on swine reproduction and young pig performance. J Anim Sci 49:664–667, 1979
Veenhuizen, M.F. Association between water sulfate and diarrhea in swine on Ohio farms. J Am Vet Med Assoc. 1993;202(8):1255–1260.
“What Is Reverse Osmosis?” Puretec Industrial Water | What Is Reverse Osmosis? puretecwater.com/reverse-osmosis/what-is-reverse-osmosis
Minnesota Pollution Control Agency. “Sulfate in Minnesota's Ground Water.”