Liquid Egg Processing Planning and Design
Facing an increasing demand for liquid egg products, the company decided the fastest way to bring a new plant online was to convert an older grading facility into one that could produce liquid eggs. An existing egg-grading facility was located and evaluated by our firm for conversion. Although the facility needed major upgrades for conversion, such concerns did not deter Perham Egg from retrofitting the space, partly due to the large on-site storage and access to a shell egg supplier.
The plan was devised to create an efficient layout and design for the manual tasks involved in egg processing. Such tasks included receiving and placing shell eggs into cold storage, moving to warming rooms to heat the eggs prior to breaking, and placing the egg flats for automatic unloading. Machines were selected and placed into the layout for the automated washing, candling, breaking, and separation (yokes from whites). Pumps, heat exchangers, and storage tanks were then integrated into the layout for the pumping, chilling, and storage of the liquid yoke and egg whites.
Food Processing Environment
A hygienic, washable environment was created to accommodate the breaking and storage of liquid eggs. The walls, floors, and ceilings were built using impervious material that can withstand high-pressure wash hoses. In addition, the air handling system was designed for high levels of filtration. The filtration level is MERV 17 (99.97% @ 0.3 microns), and the room temperature is designed at 75°F. One hundred percent of the air in this system is outside air. These areas are maintained under positive air pressure to prevent air infiltration from other spaces.
Waste Handling: Solid and Liquid
The removal and treatment of both solid and liquid waste was a primary concern for the renovation of this facility. The process of breaking eggs to extract the liquid contents creates large amounts of inedible by-products, including shells and waste liquid egg. The plant was designed by FPE to handle this waste in two ways:
- Inedible product captured in the process—by workers or by the automated processing equipment—is moved via a screw conveyor to a shell separator, which separates the shells from the liquid inedible product. Shells are then conveyed to a solids trailer that is removed from the site on a weekly basis. The liquid inedible product is pumped to a by-product holding tank, which is then pumped as needed to an inedible product handling truck for off-site disposal.
- Inedible product captured by the building floor drain system during sanitation is pumped to a rotary drum screen to separate the solid waste. The solid waste is conveyed to a solids trailer that is removed from the site regularly.
A new pre-treatment system was needed to handle the amount of liquid waste generated by the plant. The challenge was to create a system that would work with the existing location of the plant sewer discharge while collecting liquid waste on the opposite side of the plant. The solution was to pump the liquid waste to an equalization tank located closest to most of the generated waste. The equalization tank also serves to control and maintain the pH. Equalized liquid waste is then pumped through flocculent tubes and into a dissolved air filtration (DAF) for treatment located on the other side of the plant. Clean wastewater is tested and balanced for pH and sent to the city sewer system. The remaining by-products from the DAF system are pumped to the by-product holding tank, which is then pumped as needed to an inedible product handling truck for off-site disposal.
