Too many good things
For centuries, farmers have used their manure as fertilizer. This manure is rich in nutrients and water and is simply spread in the fields to help crops grow. However, the large-scale animal husbandry that dominates modern agriculture today produces much more manure than it used to produce on the same amount of land.

“Although manure is a good fertilizer, spreading it can cause runoff and pollute precious water sources,” Thurston said. “LWR’s technology can recover and purify water, and concentrate nutrients from sewage.”

He said that this kind of processing also reduces the total processing volume, “providing a cost-effective and environmentally friendly alternative for livestock operators.”

Thurston explained that the process involves mechanical and chemical water treatment to separate nutrients and pathogens from the feces.

“It focuses on the separation and concentration of solid and valuable nutrients such as phosphorus, potassium, ammonia and nitrogen,” he said.

Each step of the process captures different nutrients, and then, “the last stage of the process uses a membrane filtration system to recover clean water.”

At the same time, “zero emissions, so all parts of the initial water intake are reused and recycled, as a valuable output, reused in the livestock industry,” Thurston said.

The influent material is a mixture of livestock manure and water, which is fed into the LWR system through a screw pump. The separator and screen remove solids from the liquid. After the solids are separated, the liquid is collected in the transfer tank. The pump used to move the liquid to the fine solids removal stage is the same as the inlet pump. The liquid is then pumped into the feed tank of the membrane filtration system.

The centrifugal pump drives the liquid through the membrane and separates the process stream into concentrated nutrients and clean water. The throttle valve at the nutrient discharge end of the membrane filtration system controls the performance of the membrane.

Valves in the system
LWR uses two types of valves in its system-globe valves for throttling membrane filtration systems and ball valves for isolation.

Thurston explained that most ball valves are PVC valves, which isolate system components for maintenance and service. Some smaller valves are also used to collect and analyze samples from the process stream. The shut-off valve adjusts the discharge flow rate of membrane filtration so that nutrients and clean water can be separated by a predetermined percentage.

“The valves in these systems need to be able to withstand the components in the feces,” Thurston said. “This may vary depending on the area and livestock, but all our valves are made of PVC or stainless steel. The valve seats are all EPDM or nitrile rubber,” he added.

Most of the valves in the entire system are manually operated. Although there are some valves that automatically switch the membrane filtration system from normal operation to the in-situ cleaning process, they are electrically operated. After the cleaning process is complete, these valves will be de-energized and the membrane filtration system will be switched back to normal operation.

The entire process is controlled by a programmable logic controller (PLC) and an operator interface. The system can be accessed remotely to view system parameters, make operational changes, and troubleshoot.

“The biggest challenge facing valves and actuators in this process is the corrosive atmosphere,” Thurston said. “The process fluid contains ammonium, and the ammonia and H2S content in the building atmosphere is also very low.”

Although different geographic regions and livestock types face different challenges, the overall basic process is the same for each location. Due to the subtle differences between the systems for processing different types of feces, “Before building the equipment, we will test each customer’s feces in the laboratory to determine the best treatment plan. This is a personalized system,” Seuss He said.

Growing demand
According to the United Nations Water Resources Development Report, agriculture currently accounts for 70% of the world’s freshwater extraction. At the same time, by 2050, world food production will need to increase by 70% to meet the needs of an estimated 9 billion people. If there is no technological advancement, it is impossible

Meet this demand. New materials and engineering breakthroughs such as livestock water recycling and valve innovations developed to ensure the success of these efforts mean that the planet is more likely to have limited and precious water resources, which will help feed the world.

For more information on this process, please visit www.LivestockWaterRecycling.com.