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Feeder Solves Copper Sulfate Dosing Problems

December 2, 2015
Vibra Screw’s AccuFeed volumetric screw feeder treating canal.
Vibra Screw’s AccuFeed volumetric screw feeder treating canal.
Canal with algae before treatment
Canal with algae before treatment
Canal after treatment
Canal after treatment

The State of Washington has led the U.S. in the production of apples since 1920 and currently accounts for 70 percent of our nation’s output. In addition, the state is No. 1 in the production of cherries, grapes, and pears, with these four fruits representing a total production value of over $3 billion. Washington owes its agricultural success to a combination of a diverse climate, rich soils, and large-scale irrigation that enables farmers to produce more than 300 crops each year.
Located about 120 miles east of Seattle, nestled alongside the Wenatchee River, is the town of Cashmere. Nearby lie the Icicle River and Peshastin Creek, two bodies of water that supply the Icicle and Peshastin irrigation districts that operate 40 miles of irrigation canals supplying water to local apple, cherry and pear growers.

The Challenge
In this farming area of Washington, water is money. Farmers must have clean water when they need it because it affects everything – crop quality, production income, property values, and more. A common problem with the water in irrigation canals is the presence of aquatic weeds and algae, the green, slimy material familiar to swimming pools owners. These naturally occurring organic materials can wreak havoc by clogging water filtration and micro drip irrigation equipment resulting in costly man hours to clean and repair these systems. It is essential that irrigation water is treated to kill and control algae and aquatic vegetation and typically copper sulfate (CuSO4), the same product used in some swimming pool algaecides, is the agent of choice.
Copper sulfate is an inorganic compound that combines sulfur with copper. It can kill bacteria, algae, roots, plants, snails, and fungi, and the toxicity of copper sulfate depends on the level of copper content. Copper is an essential mineral found in the environment, foods, and water, and copper sulfate has been registered for use in pesticide products in the U.S. since 1956.
The use of copper sulfate in agriculture is widespread, but it requires meticulous attention. This substance can be toxic if it accumulates in bodies of water, requiring farmers to be careful about how they apply it. When used in water treatment to remove unwanted algae and other organisms, copper sulfate is typically used in trace amounts.
In the past a “slug” method was used to dose the irrigation water with copper sulfate. In this method burlap bags were filled with large copper sulfate crystals and introduced into the feed water serving the canals. Considerable quantities of the copper sulfate were required at high cost and controlling the concentration introduced into the water was very difficult due to variables like flow rate, duration of immersion, and water temperature. If too much copper entered the water it would impart a rusty appearance to pears and reduce the value farmers would receive for their crops.

The Solution
Tony Jantzer is the manager of the Icicle and Peshastin irrigation districts, and responsible for the irrigation water quality for the 40-mile network of canals. Familiar with the limitations of the “slug” method for controlling algae, Jantzer set out to find a more precise way of introducing copper sulfate into the system. After researching a variety of metering devices and approaches on the Internet, Jantzer found the Vibra Screw Co.’s website and the company’s extensive range of dry solids processing equipment.
Jantzer learned that Vibra Screw is a 60-year-old family business and the original inventor and patentor of the controlled vibration screw feeder. The company manufactures a wide range of precision feeders, activators, vibrating bins, conveyors, and related equipment. Jantzer was especially impressed by the Vibra Screw “no conditions guarantee”: if it doesn’t work as promised, Vibra Screw will take it back and refund the cost.
According to Jantzer, “As soon as I read about Vibra Screw’s AccuFeed volumetric screw feeder I knew I found what I was looking for. I wasn’t sure about the best size and configuration so I contacted Doug Holzherr, their regional sales manager, who also connected me with Howard Frischman, director of engineering. He asked me questions about how the unit would be used and worked out the size requirements for the hopper and other specifications.”
The AccuFeed is constructed from molded composite materials for maximum strength and durability with polyethylene and stainless steel contact parts for excellent chemical resistance. Most importantly, the AccuFeed provided the +/-1 to 2 percent feed accuracies for the low feed rates needed in order to treat the irrigation water at consistent dosing rates for longer periods of time.
“Both Doug Holzherr and Howard Frischman were great to work with,” said Jantzer. “They know their products and their focus was on helping me solve my challenge in accurately controlling the copper sulfate dosing. Exact dosing is important because our irrigation district has to meet the permitting requirements of the NPDES (National Pollutant Discharge Elimination System) mandated by the Environmental Protection Agency.”

The Results
In June of 2011, Jantzer purchased a Vibra Screw AccuFeed. The unit was portable so he mounted it in a pickup truck and was able to drive it to the separate canals that he needed to treat. After calculating the amount of copper sulfate that needed to be dosed, Jantzer was able to consistently feed this amount over an extended period of time and the AccuFeed was also able to stop or start when needed. The initial AccuFeed worked so successfully that two more have been purchased with three now set up at separate locations.
Jantzer has been delighted with the outcome. “We’ve reduced the cost of our copper sulfate usage by 50 percent and we’ve also reduced the man hours required in operating our irrigation system,” he said. “This is particularly significant because we are dosing twice per month instead of once per month when we used the slug method. The accuracy is outstanding. We’re able to dose to environmentally friendly levels as low as 5-15 parts per billion. The problem of rusty-appearance pears is a thing of the past and the growers are receiving sparkling clear irrigation water.”

The Impact
Jantzer’s success with the Vibra Screw AccuFeed system at the Icicle and Peshastin irrigation districts is believed to be the first installation of its type in the state of Washington. It has captured the interest of the Washington State Department of Ecology, and Jantzer has made presentations to other districts highlighting the results achieved from this precision approach to copper sulfate dosing. This method of treating their canals has reduced the amount of copper sulfate used by half saving money and environmental impacts.

    Vibra Screw Inc. (Totowa, NJ) offers a variety of solutions for the processing of dry solids in many industries, including agriculture, mining, and pharmaceuticals. For more information, call 973-256-7410 or visit www.vibrascrew.com.

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