When an egg is processed or a chick hatches, the once vital shell becomes waste.

The nation's egg processing and hatchery industries generate nearly 190,000 tons of shells annually. In Nebraska, which is among the nation's leading egg processing states, shells from plants at Bloomfield, David City and Wakefield are spread on land as calcium fertilizer or reprocessed as a calcium source for poultry diets. In areas with less ag land, shell disposal in landfills runs $20 to $40 per ton.

Where others see waste, Sheila Scheideler, University of Nebraska poultry scientist, and graduate student Jodi Ash of Lincoln see raw material for a dietary phosphorus supplement for poultry, pigs and pets. Eggshell-derived phosphorus supplements could be worth $250 or more per ton compared with $40 per ton as a calcium source in chicken feed.

They've developed a process that turns eggshells into a supplement equivalent to monocalcium or dicalcium phosphate, the most common phosphorus supplements for livestock. The university has filed a patent on this process.

Mixing limestone and phosphoric acid produces monocalcium and dicalcium phosphate. The Institute of Agriculture and Natural Resources researchers use eggshells instead of limestone as a calcium carbonate source. They combine it with phosphoric acid to create a product that contains 18 percent to 21 percent phosphorous, the same as conventional supplements.

"We talked to some chemists and started mixing the products together," Scheideler said. Their process for combining eggshells and phosphoric acid optimizes the chemical reaction and produces monocalcium or dicalcium, depending on the proportions.

Shell-based supplements perform as well or better than dicalcium in both chicks and laying hens, Scheideler said. They also could be used in feed for pets and swine.

The researchers initially worked with the type of waste produced by Nebraska's egg breaking plants. Now they're testing formulas for creating the supplement from hatchery waste.

The idea isn't entirely new, Scheideler pointed out. Tom Sullivan, now retired IANR poultry scientist, experimented with an eggshell-based supplement in the 1970s as a sideline to his phosphorus research. He didn't seek a patent or develop processing information.

The egg and feed industries would benefit if the IANR process is commercialized, she said. So would the environment.

Nebraska is fortunate to have abundant agricultural land for spreading shells, she said, but the state's soil needs little extra calcium. That means egg processors must truck shells farther to spread it.

"In the long run, using eggshells as a phosphorus source should be an environmentally friendly option," she said.

Scheideler has visited with private companies about the process but said commercialization takes time. She wants to study the feasibility and costs of building a plant to process eggshells into phosphorus supplements.

"It will be the waste issue that drives this," she said. "As the cost of waste disposal increases, industry will have more incentive to turn this into a value-added product."

– Vicki Miller

From waste to useful product, the IANR-developed process creates a dry, powdery phosphorus supplement.

Poultry Scientist Sheila Scheideler (right) watches graduate student Jodi Ash stir a mixture of diluted phosphoric acid and eggshells in the lab. They've developed a process that turns eggshell waste into a phosphorus supplement for poultry, pigs and pets.