I have worked at two separate liquid egg processing plants in my life and the system was the exact same and it was very shocking.
To begin, the eggs are brought to the processing plants from one of three locations.
1: the farm. Eggs are shipped to the plant often covered in fecal matter and dirt. The eggs are not washed before they are stored in giant refrigerated rooms in what are stacks of plastic or cardboard egg crates.
2: supermarket rejected eggs. These eggs are clean but were refused because they were too cracked or too close to their expiration date.
3: farm reject eggs. These eggs are very low quality, usually produced during the final egg laying cycles for older chickens. These eggs are profoundly low quality and often have a sour smell.
Now securely stored in large refrigerated rooms the eggs will sit for days while the plant processes eggs that have been on site the longest. The system is actually reasonably well designed to deal with the quantity of eggs needed to be processed. The eggs will be stored for between 8 to 20 days depending on orders. Over half of these eggs were considered "old" prior to storage.
Once an batch of eggs is up to be processed they are moved onto the processing floor, which is another slightly less refrigerated room and loaded onto machines. Pallets of egg crates are put into a machine by hand where they move via a conveyor belt into a warm water bath with soap where they get a light brush from automated brushes.
This cleaning system isn't very effective for very dirty eggs and rejects are removed by hand. Workers (two per line) watch the eggs move over bright lights where they attempt to remove eggs still covered in fecal matter, those with blood, or those dark over the light (rotten) eggs. Most bad eggs are removed at this point, however enough make it through for the next human workers on the chain to have a job.
The USDA imposed a figure for how much fecal matter can make its way into the breaker machine, and far too often that figure is exceeded and workers aren't payed nearly enough to care.
These workers have to stand on a platform barely larger than themselves for 4-5 hours with no break, followed by a hasty 20 minute lunch break before it's back for another 4-5 hours. Most of these workers are older women, 60+ years old.
The eggs move up the conveyor into a cracking machine which cracks the eggs into white cups which pass under a camera and the eyes of two workers. It is the job of these workers to remove bloody eggs, eggs with green albumin, rotten eggs missed in the previous step, and any other rejects.
The problem. These eggs move in rows of 12 at a rate of about 48 eggs a second. Reject eggs have to be identified, have a small lever on their cup pushed down, in under 2 seconds. This is possible and my reaction time has never been better. However more than a few bad eggs move into the next part of the system.
The eggs are piped into large silos for storage and eventual pasteurization. The eggs are stored for between 8-24 hours, depending on the quantity of orders the plant gets. It is also not uncommon for the eggs to be pumped into freezing tanks so they can be stored for longer periods of time. The last plant I worked at kept one batch of eggs on ice for 4 days waiting on an order from a client that would accept old eggs (usually a factory making packaged cakes).
Samples from each batch are tested in house. Small 4 ounce samples out of a batch of 16,000 gallons of liquid egg.
Once a batch has been cleared they are loaded onto tanker trucks that have been cleaned with soap and water, it takes about 4 hours to pipe the eggs into the tankers, and the temperature is not very strictly controlled. I have observed a tanker sit over night more than once in "cool" temperatures.
These tankers are then shipped along the eastern US to factories making cakes and other confections or to packaging plants where they end up in cartons in the egg section of your local supermarket.
I can promise you that the 18 people responsible for processing these eggs are over-worked and under paid. Many of them are seniors, many don't have legal status (this means they aren't as likely to call out negative and disgusting practices for fear of retribution). I can promise you lots of blood, green eggs, and expired eggs end up where they shouldn't.