Processing Magazine

How to turn eggshell waste into income

Drying system reduces pathogen risk; residue used as fertilizer or animal-feed mineral additive

April 4, 2013

By Karin Galloway

eggshell waste, Kemutec_Egg-Shell-Dryer
°Celsius Eggshell Dryer with capacity of 2200 lb. per hour

Each year, an estimated 76 billion eggs are consumed in the United States. Prior to final consumption, about 25 billion of those eggs are first processed into egg products. The egg-processing plants must break those eggs before further processing occurs. In doing so, these plants generate an estimated 600,000 tons of eggshell waste per year.

It’s likely that processed egg consumption — currently 30% of all eggs produced — will grow due to increased demand for ready-prepared meals, cake mixes, fast-food and other food-preparation formats. While this is good for the egg-product processing plants, the disposal of eggshell waste is an ever-increasing problem.

Eggshell waste disposal can be costly. Medium-sized egg-product processing plants can generate as much as 7 tons of wet eggshell waste daily. These eggshells typically are centrifuged, but still contain moisture in the 14-18% range. Many egg-processing plants must rely on the costly hauling of this waste to landfills.

Moreover, while waiting for disposal, the messy holding containers exude an unpleasant odor affecting the work environment and neighboring community. It is also not at all unusual that as local landfill sites close, egg processors end up hauling the eggshell waste to ever-more-distant landfills.

Smaller companies often compost their eggshell waste and spread it onto their crop growing acres. This method of recycling works until, as might be expected with a growing business, the volume of shell waste exceeds field capacity. The processor may then find itself facing the same costly hauling to landfill sites.

A viable alternative

To offset the disposal cost, an alternative is to heat-treat the eggshells for recycling. The heat treatment not only dries the excessive and smelly moisture, but also sterilizes the waste. The now valuable, natural product can be sold to fertilizer manufacturers or as a mineral additive in animal feed. 

A few egg-product processing plants already have integrated eggshell dryers, most of them being tumble or rotary dryers. Drawbacks to these arrangements can include high dryer energy consumption, air pollution and limited batch-processing capacity. Processors can also never be sure if all eggshells are treated at the right temperature and duration to be absolutely free of possible contaminants, including salmonella. 

Understandably, U.S. egg-product processing plants see return on investment as the determining force behind decisions to upgrade or add capital equipment. Adding production process steps unrelated to revenue generation can be difficult to justify. However, it’s estimated that reducing or eliminating the high costs of current eggshell disposal methods, such as landfill disposal, can save a staggering $100,000 annually for a mid-sized breaker plant.

In addition, the environmental and potential health risks of messy eggshell waste are greatly reduced. These risks are taken seriously in the European Union, which already bans “landifying” or composting eggshell waste with a moisture content of over 4%. Similar regulations are being considered in the United States.

A solution worth considering

The °Celsius Eggshell Drying systems, presented by Kemutec, make eggshell waste disposal safer and less costly. The processed eggshells can also become an income source.

Shells are dried at a temperature of 270 F, resulting in sterile, fine-grained, high-quality lime with a maximum moisture content of 1%. Drying the eggshell waste at these fairly high temperatures is critical for decreasing the potential of contamination by pathogens such as salmonella.

The eggshell dryer’s operating principle relies on a screw heat exchanger that is heated by thermal oil. Drying occurs in an enclosed atmosphere, resulting in a dust-free environment, a significant concern for any food-processing plant.

The eggshell dryer’s low energy consumption reduces operating costs compared to traditional dryers. For example, 150kWh are required per ton of dried eggshell waste and with a typical average price of around 8 cents per industrial kWh, the costs would be about $12 per hour to dry one ton of centrifuged eggshells.

The dried and sterilized product can be used as soil conditioner or as lime additive in the cement or animal feed industries. In essence, the eggshell dryer converts eggshell waste into a reusable and saleable commodity.

Finally, egg-product processors in The Netherlands — the top egg-product producing country in Europe — confirm that the energy-efficient, compact °Celsius Eggshell Dryer addresses “pesky” eggshell waste issues, as well as associated high-disposal costs. Many egg-processing plants in Europe are part of co-operative groups that incorporate safe eggshells into animal feed mills, making recycling of sanitized and sterilized eggshell waste a very efficient option.

°Celsius Screw Heat Exchangers are installed for many applications in the food, environmental and chemical industries. Application examples include cooling frozen fruit at an exact temperature and retention time to guarantee the fruit retains its color and taste; flash cooling of dairy powder to avoid chemical reactions; drying of sludge and manure to reduce hauling costs or produce bioenergy; and high-temperature cooling of activated carbon, manganese and other materials.

Karin Galloway is a sales engineer at Kemutec Group Inc. focusing primarily on thermal treatment solutions in the food, chemical, pharmaceutical and environmental industries. Galloway earned her degree in ceramic engineering in Germany, and her background includes work devoted to market research, business development and investment banking.

Kemutec is the sole distributor in the United States, Canada and South America of °Celsius Eggshell Dryers, as well as the complete assortment of °Celsius Screw Heat Exchangers. The inclusion of this equipment into Kemutec’s product line is complementary to its powder-processing equipment that includes sifters, screeners, mills, grinders and valves. Please contact 215-788-8013 for further information.