By Jim McMahon
By Jim McMahon
With the steady increase in poultry processing rates, there has been a
corresponding increase in wastewater pollutant concentrations.
With the steady increase in poultry processing rates, there has been a corresponding increase in wastewater pollutant concentrations.
Despite mechanical improvements in wastewater treatment, many poultry processors continue to pay unnecessarily high fees for municipal water discharges.
$100-million-annual processor, Michigan Turkey Producers, in conjunction with Lyco Manufacturing, has set up a patented, state-of-the-art screening system that is an industry showpiece for poultry wastewater treatment.
Like many poultry processors, Michigan Turkey Producers, a medium-sized poultry processor of live tom turkeys handling 4.5 million birds annually, keeps a tight rein on its BOD (biochemical oxygen demand) and TSS (total suspended solids) levels in its discharged wastewater. But, where most processors are careful to prevent poultry processing byproducts from entering and contaminating their wastewater stream (because of the difficulty in removing them prior to discharge) Michigan Turkey operates quite differently.
The company places little limits on the volume of particulate organic matter allowed to be put through their wastewater, because of a unique double screening system they employ, built by Lyco manufacturing, that effectively removes sufficient load before discharge to leave levels of BOD and TSS well within municipal standards.
Michigan Turkey is a live turkey processor, and a boned meat company, located in Wyoming, Michigan. The company processes roughly 20,000 toms per day. Average bird weight is 40 pounds live, and 34 pounds dressed, and 90 per cent of processing is boneless.
Mike DeVries, Plant Engineer for Michigan Turkey, says “we purposely set up our wastewater system to handle anything that comes down it, any volume and concentration of particulate matter. Consequently, we have a lot more load coming down our drains that we have to get out than other processors. This is different from how most poultry operations function, where usually they are trying to keep the load in their wastewater at a continually lower concentration throughout processing, but this is because their screening system can’t handle it. We are moving 700,000 to 800,000 gallons of wastewater a day through our system without any jam ups at the screening, and we are ending up with BOD and TSS ratings well within municipal standards.”
For processing large birds, such as the toms done by Michigan Turkey, water consumption can range from 35 to 40 gallons per bird, up to seven times that required for a broiler chicken. It is not unusual for a poultry processor to generate 750,000 to 1,500,000 gallons of wastewater daily.
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 (biochemical oxygen demand), TSS (total suspended solids) concentration, COD (the chemical oxygen demand), and FOG (fats, oil and grease), 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.
Approximately 84 per cent of poultry processors in the U.S. are using some form of screening application to reduce wastewater particulates – including internally fed rotary screens, externally fed rotary screens, and shaker-and-bar type screens. The vast majority of these are single-screen applications.
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. But with the advent of double-screen technology, processors can now capitalize on a much more efficient and cost-effective system for their wastewater treatment.
“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 0.06" to 0.02". Secondary screening follows as the wastewater passes through the outer drum, screening particles as small as 0.02". 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. 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 with the outer screen, which is the finer screen, he says.
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 travelling 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.”
“In our picking operation we drop right to water with our feathers, and we actually move our feathers via water,” continues De Vries. So we had to have a Lyco screen for that as well. The cost for us on the rendering side, or downstream side of processing, was the moisture content, so with the Lyco double drum screen we found that we generated an extremely dry feather and consequently avoided any surcharging for moisture. That has been an enormous benefit all the way to the point that our rendering actually had to add moisture to process our feathers. The advantages are avoiding a surcharge, and also the advantage of being able to haul more volume with less weight.”
For more information on Lyco Manufacturing, Inc., and their double drum screening solutions, please contact Jon Butt, Division Manager, Liquid & Solid Separation; 115 Commercial Drive, P.O. Box 31, Columbus, Wisconsin 53925; phone 920-623-4152; fax 920-623-3780; e-mail firstname.lastname@example.org; or visit www.lycomfg.com.
To reach Michigan Turkey Producers, please contact Mike DeVries, Plant Engineer, at 2140 Chicago Drive SW; Wyoming, Michigan 49519; phone 616-245-2221; fax 616-247-1545; e-mail email@example.com; or visit www.miturkey.com.