Challenge

Poultry processing today requires sophisticated, strategic planning in order to be competitive in the marketplace and profitable on the books.  It’s a high volume industry where any one operator processes tens, even hundreds of thousands of birds on a daily basis.  This is especially true for a complete, vertically integrated food industry such as Rocco, Inc. of Harrisonburg, Virginia, which processes approximately 55,000 (fresh) turkeys daily.

Their operation includes feed mills; turkey breeding, hatching and growing operation; processing and further processing plants; even proprietary and private label packaging and distribution.  The turkeys processed on any given day were in the planning schedule as long as two years prior to processing. 

Food industry operations such as Rocco have extensive waste and wastewater treatment requirements; especially at the processing plant level.  The meeting of waste treatment requirements is becoming more and more difficult due to stricter Federal and State regulations.  In addition, many local municipalities have reached their capacity to process wastewater effluent from an expanding industry base.  This requires industry to reduce contaminants in their wastewater prior to discharging their effluent to the sewer system.  Regulations have increased the rates for the wastewater discharged and imposed surcharges for exceeding lowered limits for BOD (Biochemical Oxygen Demand) and TSS (Total Suspended Solids).

Solution

Rocco explored the possibility of using a biological treatment system, but found that the projected costs were too high.  They brought in Clean Water Engineering, Inc. to design a wastewater treatment system.  Their advice was to install a chemical pre-treatment plant as the most cost effective wastewater handling system.  Different chemicals were tried in varying combinations to remove the blood, oil and grease contaminants from the wastewater.  They found a mixture of ferric chloride, lime and polymer reduced BOD and TSS in the wastewater to the desired levels.

The problem they then faced was how to dewater the sludge that was created.  Various alternatives, such as sludge drying beds, belt filter presses and recessed chamber presses were considered.  Representative samples of the sludge were created by simulating the chemical treatment of several hundred gallons of typical wastewater.  These samples were sent to the Siemens Water Technologies laboratory in Holland, Michigan.  The oil and grease content in the sludge inhibited effective dewatering, but the combination of pH control and a high molecular weight polymer created good flocculation of solids and effective dewatering was possible.

Based on these results, Rocco’s management elected to purchase a 1200mm recessed chamber filter press to dewater the sludge generated by the chemical treatment of their average wastewater flow of 750,000 gpd.  The technicians at Siemens Water Technologies worked closely with Rocco’s operating personnel doing on-site test work with a 250mm pilot press to confirm proper dosage prior to operating the full scale press.

Results

The dewatering press performance has been excellent.  Cake solids average 35%, and a very clear filtrate is produced.

The process starts when the water used in the processing plant is flushed into a building containing rotary screens in order to screen out all the heavy matter such as feathers, entrails, etc.  From there, the water is pumped at a steady rate into a series of treatment tanks where ferric chloride is added in the first step of the treatment.  The water is now transferred to a flash mix tank where lime and polymer are added to increase the pH factor and obtain a sludge floc.  The wastewater then flows to a mix tank to allow completion of the chemical reactions.  The treated wastewater is transferred to a clarifying tank and then to a sludge thickening tank where additional polymer is added.  The thickened sludge is then pumped to the Siemens filter press, also known as a J-Press®.

The Rocco wastewater pre-treatment plant at its Turkey Processing Division requires only one operator per shift for the three daily shifts they operate.  The three shifts consist of two slaughters and one sanitation.  They run their filter press for four cycles a day during the two slaughter shifts.  Three hundred cubic feet of sludge are generated on a daily basis for landfill disposal.  Through this system, they have been able to reduce their BOD from 1400 to 300 ppm and their TSS from 550 to 200 ppm. This has resulted in the elimination of the municipal surcharges.  The non-hazardous filter cake discharged from the filter press is hauled to a landfill, and the clarified water is discharged to the municipal system at the standard rate charge. 

With proper engineering, design, chemical pre-treatment, and sludge dewatering, the J-Press filter press has proven to be a cost effective solution to waste management at this major turkey processing operation.