Protein Processing Facilities: Sustainable Design in Practice

Poultry are key in sustainable food and agriculture acting as efficient convertors of feed to eggs or meat products. When compared to grazing animals such as cattle or hogs, poultry do not produce substantial amounts of methane during digestion. Carbon emissions can remain in the soil when no-till, crop rotation or over cropping methods are used. Manure, the by-product of these methods, can also fertilize crops.

So while there are certainly sustainable farming factors, what about the facilities that process the animal?

The building process affects the environment in more ways than just the relationship of the building to the site. The selection of building materials can also be respectful of the natural environment. Choosing local raw materials extracted in an environmentally friendly way and transported short distances to the site, or using materials with recycled content are just two simple examples of sustainable material selection.

Design of the building’s shell can use climate to its advantage rather than fight against it. Insulation with both sustainable criteria and energy performance criteria provide an added sustainable function, while exterior glazing can allow sunlight in to reduce energy use for artificial lighting or be absorbed to influence HVAC loads. Epstein's experienced architectural, mechanical, electrical, and plumbing staff uses the integrated design and engineering process to maximize the benefits of building shell and building systems interactions.

Epstein’s engineers designed numerous features for the Prestage Foods facility that benefit the environment including the on-site rendering facility that will process inedible portions into value added non-edible products. Another benefit of onsite rendering is it reduces the number of over the road trucks coming in and out of the Prestage facility. Scrubbers for all exhaust vents in the rendering facility also help eliminate odors. Another odor fighting design element includes completely covering waste water lagoons to eliminate fumes and also to allow for the capture of methane generated during the treatment process. The methane is then used in the Prestage facility boilers to lessen the natural gas requirements.

The Prestage facility also features temperature control throughout the process areas to heighten food safety and quality as well as the potential use of advanced water treatment to allow the recycling of water to wash livestock pens and livestock trailers reducing the water requirements of the plant.

Stormwater runoff collected into a dry detention basin in the southwestern area of the site is released so as not to exceed the pre-developed rate of runoff.

Odor Mitigation

Prestage Food’s leadership recognized that noxious odors from the plant could have a negative impact on the local community. Epstein’s engineers made every effort to understand and mitigate objectionable odors leaving the plant. To achieve this goal, we evaluated the plant design and identified locations of potential odor production, and incorporated odor control initiatives into the design of the livestock barns, rendering and waste water treatment.

Bio Filtration

The Prestage Farms project includes a 6,000 head livestock holding barn. To control odors from the barns, Epstein researched existing and emerging technology for the control of barn odors. Based on this research Epstein recommended using bio filter technology to reduce odors from the barn exhaust. Based upon published research of small and medium sized bio filter projects, Epstein was able to scale up and design an industrial sized bio filtration system that receives 100% of the exhaust from the barn. As the exhaust passes through the filter media, bacteria living in the media will biologically reduce the odor causing elements. The goal of the bio filter is to economically eliminate the odor from the barn exhaust.

Regenerative Thermal Oxidation & Wet Scrubbing

The rendering process generates hydrogen sulfide at a number of points in the process. Hydrogen sulfide is toxic, as well as produces an objectionable odor at low concentrations. At the specific process points where hydrogen sulfide is generated, the system was designed to contain the emissions at these points and exhaust the gases through a regenerative thermal oxidizer. The odorous hydrogen sulfide molecules are thermally reduced to non-odorous sulfur oxides.

In addition to point source control of hydrogen sulfide, and thermal reduction to control odor, a second odor control strategy was employed to control the odors generated and emitted from the rendering building. The building ventilation system has been designed to supply outside air to the building and then control and duct 100% of the building exhaust through a wet scrubber. Chemical addition to the scrubber feed water allows the scrubber to efficiently remove particulates, water soluble gases and hydrogen sulfide.

Wastewater Odor Control Strategies

The wastewater treatment operation treats the incoming wastewater, and then discharges the treated water to a large lagoon system. There are two major odor-emitting points: the equalization tank and the lagoons. To control odors the equalization tank, which is traditionally an open top tank, was designed as a fully enclosed tank and each lagoon will have an integral cover. This simple approach will greatly reduce the odor leaving these operations.

Automation/Robotics

Epstein consulted with Dr. Temple Grandin to develop a harvesting process that is humane and efficient that featured animals moving from a lairage and then lowered via elevators into a pit used for CO2 stunning. To save on water and put less heat/stress on the animals’ skin, the Prestage facility uses filtered water for vertical scalding which also keeps the animal cleaner as it does not use a common bath. CO2 Stunning

Kill Floor

The Prestage plant’s kill floor uses large Marel-designed robots that open the carcasses with an efficiency and consistency impossible for humans to duplicate. Each time the arm opens an animal, the blade needs to be sanitized. Each robotic arm carries two sets of blades and breakers. The arm spins the just-used blade back into a housing for automated clean-in-place sanitation, while another blade comes out of the housing sanitized and ready to open the next carcass in line.

The animal moves to the next station where robotic arms automatically drop the head. Newer to the industry are robotic split saws. This process is one of the harder and more dangerous jobs on the floor, and the automatic split saw removes the need for a person to perform this demanding task.

At the end of the kill and split, automatic touch-free controls load carcasses onto the cooler rails. No handprints on pigs and no bacteria spreading from pig to pig by human hands creates a consistently cleaner and higher quality meat.

Also on the cut floor, vision assist technology ensures accuracy on ham and shoulder cut off. High-speed imagery of the carcass informs the saw and instructs it to move back and forth accordingly. The saw then cuts the meat consistently and perfectly every time, something a human and a laser light is unable to do.

For Prestage Foods’ customers, the automation and technology provide a consistency and uniformity of finished product. This consistency helps the plant’s customers create higher yields from a more dependable and uniform product.