Streamlining Wastewater Treatment in Poultry Processing

This water is laden with proteins, fats and carbohydrates from meat, fat, blood, skin and feathers. The water is also polluted with a fair amount of grit and other inorganic matter. Waste load can be determined by a number of different measurements, including BOD, TSS, the chemical oxygen demand (COD), and fats, oil and grease (FOG), but poultry plant wastewater is most often tested for BOD, a measure of the amount of oxygen needed to degrade the organic matter (feathers, fat and blood) in the wastewater.

Poultry processors are required to remove the majority of the soluble and particulate organic material in their wastewater prior to discharge from the plant in order to achieve compliance with local, state and federal environmental regulations. The problem is that few screening systems are really capable of continuously cleaning out all of this material to a level within the standards of municipalities, and municipalities use BOD loads to determine charges and surcharges for wastewater dischargers.

“We discharge ultimately to a city municipal system and they charge us for anything that we put into the water,” says DeVries. “We have to control our loading costs to avoid additional surcharges. With the Lyco double drum screens, we are able to load up as we process, and then pull everything out of the wastewater before we discharge. It is a very efficient system.”

Lyco’s Double Drum screen uses rotary action to separate waste solids from liquids in one step, eliminating the need for two sequential, single-stage screens. Primary screening takes place when the wastewater enters the inner drum from the inside and screens out solids within the range of 0.062 to 0.022. Secondary screening follows as the wastewater passes through the outer drum, screening particles as small as 0.022. The net result is that more solids are screened out of the wastewater.

“The Double Drum screen, which can handle up to 3,000 gallons per minute, was designed to eliminate the need for primary and secondary screening,” says Terry Brady with Lyco. “Our research shows that in the majority of screening applications processors used a perforated primary screen then pumped the water to a secondary screen. Lyco designed a way to do the primary screening with the inner drum screen first, and then the secondary screening done with the outer screen, which is the finer screen.”

There is also the issue of blinding – poultry is laden with fats and other slimy-type particulates that clog the screen openings. This is a common problem with traditional screening equipment – limiting the volume of wastewater and load that can be moved through a screen, which causes water and particulate to “spill” over the end of it. The Lyco double-drum uses a self-cleaning wedge-wire screen material, and a patented traveling spray system – which can use as little as 10 GPM of fresh water to keep the screen open, compared to typical rotary screens that consume 36 GPM. These features drastically minimize, if not entirely eliminate, screen blinding.

“A lot of other screen designs let material go through because they don’t have the ability to manage it,” says De Vries. “Particularly when it gets into high volume quantities of material going through. This is not the case with the Lyco double drum. It can handle anything we put through it, regardless of the gallons per minute or particulate load.”

“I have been around a lot of screens used in the poultry industry, and have experienced their external and internal problems firsthand,” he continues. “I look for screening equipment that is heavy duty, durable, engineered to be user friendly, tool friendly and mechanic friendly. I want to be able to set it up and have it run with minimal maintenance. We have literally loaded the Lyco double drum with thousands of pounds of product at different times and it has performed without any problems. Our need has been to get our heavily laden particulate out of the wastewater before we discharge it to the municipal system. The Lyco screen manages that for us, particularly with TSS, which ultimately returns thousands of dollars back to us each month.”