The drying and air treatment process as far as we have researched, is the first of its kind in the U.S.
We have done this project to help reduce truck traffic eliminating 4000 loads of treated waste being applied to the field as well as reducing odor. This also provides us with recycled bedding, reducing our purchases of kiln dried sawdust by approximately 300 loads a year. Through the entire process we have worked closely with the DNR to ensure the process is done in the most environmentally sound manner possible. Certified emission testing is done to ensure safe emissions from this process.
The manure stream from the barns is directed to a process system where the water is separated from the solids across a large screen. The solids are then squeezed in a rolled press where it is approximately 70% water, 30% solids. The pressed solids are then augured into a 40’ rotating drum.
Inside the drum there is 800-degree air being blown through to dry the treated manure solids. The solids then come out of the drum with only 10% water content. This is the area all the steam is being generated. After leaving the drum, 50% of the dried product is dumped into a truck to be used for animal bedding. The bedding is used in the free stall barn where the cows lay down to relax and rest. This bedding keeps the cows clean, dry and comfortable. The remaining 50% of the dried material is used as the fuel source to create heat from the drum. The system is self-sufficient and needs no additional fossil fuels for the process.
The water that is separated from the solids flows into our “first stage” clay lined lagoon. Once it enters the lagoon 28 aerators constantly stir oxygen into the water. This turns the water waste into an aerobic environment. This allows the remaining small material to become digested by the aerobic bugs. The water then flows into the large lagoon where continual aeration happens. The aeration process also reduces odors omitted from the lagoon. The water is then pumped into the large black tanks.
This water is then flushed down each cow alley, approximately every two hours. This keeps the alleys clean for the cattle at all times. Once the water leaves the alley it then returns to the agitation pit. We recycle approximately 2 million gallons of water a day in this process.
Since this dryer is one of the first in the country we have tried several different control devices to capture this fine dust. We have now found a control device which is called a bag house. With the help of Mid-State Contracting of Wausau and Energy Unlimited, the dryer manufacturer, the bag house, that is now installed, has 375 filter bags where the exhaust gas is blown through to capture the fine dusts. We have spent hundreds of hours and over $60,000 in testing and research to ensure we are operating the dryer in the safest most environmentally friendly manor. As you drive by you will sometimes see steam exhausting from the exhaust stack. The reason you see it sometimes and sometimes not depends on the outside temperature. The warmer it is the less steam will be seen. The exhaust air from the dryer is always sent through the control devices to be sure it is safe to omit into the atmosphere.
The dryer is very important to our business! Saving over 4000 loads of treated waste that would have to be transported on town roads and also saving 14,000 gallons of diesel fuel per year. The dryer saves our operation from purchasing over 300 semi loads of bedding per year which cost approximately $1,800 per load. The bedding product is a sterile dry product which we have found our cattle prefer over any other bedding product supplied.