Removal of excess TDS and excess sulfate + chlorine usually employs traditional water softeners or RO systems. Reverse osmosis systems remove 80-90% of these constituents depending on their design. Conventional water softeners are effective, but are not designed to handle large volumes of water and require an acceptable place to dispose of the brine flush water needed to recharge the system. Depending on the number of animals served, it may be necessary to design a water treatment system in such a way that large volumes of “treated” water can be stored for use at times of peak demand (2).
Oxidation systems are mainly employed to remove excess iron from cattle drinking water. The “iron curtain” system employs aeration to convert the iron to a precipitate (Fe+3) which is then subsequently filtered from the water. The hydrogen peroxide (H2O2) system employs the Fenton Reaction which converts iron from Fe+2 (soluble in water) to Fe+3 (insoluble in water) and then filters out the Fe+3 as a precipitant. This system injects H2O2 into the drinking water (8 oz of 35% H2O2 per 1,000 gallons of water). This system is quite cost effective. A suitable injection pump costs around $500 and the cost of 15 gallons of 35% H2O2 solution is around $100 (enough to treat ~240,000 gallons of water)(2).
When working with water treatment vendors it is absolutely essential they understand the following items about your farm’s situation (2):
1) Do they know how much water your dairy uses? More than likely, your dairy uses much more water per day than the typical water treatment professional is accustomed. I have put together a short paper, Estimating Water Usage on Dairy Farms, that helps producers understand the volumes of water needed on a modern dairy farm. The paper also has an accompanying spreadsheet that producers can use to estimate daily water needs on their operations. To get a copy of the paper and/or the spreadsheet, send me an e-mail request specifying your request.
2) What is the treatment rate (volume/time) of their system? Again, your dairy will most likely consume water, particularly at peak demand periods, with which typical water treatment professionals are unaccustomed. Can their systems keep up and provide enough treated water to meet your peak demand?
3) Does the water treatment provider guarantee their system will meet peak demand and reduce the undesirable constituent to acceptable levels? Will their system meet this requirement throughout the expected useful life of the system? Are they willing to provide such guarantees in writing?