Impact of scalding duration and scalding water temperature on broiler processing wastewater loadings

Authors: Harris, Caitlin; GOTTILLA, KEVIN - University Of Georgia; BOURASSA, DIANNA - Auburn University; Bartenfeld Josselson, Lydia; KIEPPER, BRIAN - University Of Georgia; Buhr, Richard - Jeff

Submitted to: Journal of Applied Poultry Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/27/2018
Publication Date: N/A
Citation: N/A

Interpretive Summary: Three experiments were performed to evaluate scalding tank poultry processing wastewater loading following the slaughter and scalding of commercially raised broilers. The scalding protocols that were evaluated were: hard vs. soft scalding (experiment 1), scalding immersion time and temperature individually (experiment 2), and the presence of residual blood (experiment 3). Similar processing methods were used for each experiment, which was conducted in a pilot plant containing 3 triple-pass scald tanks that were air agitated. One-liter water samples were taken from each scald tank and analyzed for chemical oxygen demand, total solids, and total suspended solid concentrations, which were then used to calculate wastewater loading (g/kg broiler live weight). For experiment 1, there was significantly higher wastewater loading for soft scald/ tank 1 (1.8 g/kg-lwt) than hard scald/ tank 1 (1.5 g/kg-lwt) protocol for chemical oxygen demand. There were no other significant differences between scalding protocols for experiments 1 and 2, but there was a trend that the longer immersion time protocols resulted in wastewater higher loading for all 3 analytics. For all three experiments, the use of sequential scalder tanks significantly reduced wastewater loading for both organic and solid materials (chemical oxygen demand, total solids, and total suspended solids) with tank 1 being significantly higher (50 to 89%) than tanks 2 and 3. Residual blood following a 120 second bleeding time did not impact wastewater loading compared to non-bled carcasses. These results indicate that scalder immersion time appears to be the major indicator for predicting wastewater loading in scalders and shows decreases with each sequential scald tank. These results also verify the importance of multiple-tank systems in order to clean carcasses prior to defeathering.

Technical Abstract: Three experiments were performed to evaluate scalding tank poultry processing wastewater (PPW) loading following the slaughter and scalding of commercially raised broilers: hard vs. soft scalding protocols (experiment 1), scalding immersion time and temperature individually (experiment 2), and the presence of residual blood (experiment 3). Similar processing methods were used for each experiment, which was conducted in a pilot plant containing 3 triple-pass scald tanks (740 L each) that were air agitated. One L water samples were taken from each scald tank and analyzed for chemical oxygen demand (COD), total solids (TS), and total suspended solid (TSS) concentrations, which were then used to calculate PPW loading (g/kg broiler live weight). For experiment 1, there was significantly higher PPW loading for soft scald/ tank 1 (1.834g/kg-lwt) than hard scald/ tank 1 (1.510 g/kg-lwt) protocol for COD. There were no other significant differences between scalding protocols for experiments 1 and 2, but there was a trend that the longer immersion time protocols resulted in PPW higher loading for all 3 analytics. For all three experiments, the use of sequential scalder tanks significantly reduced PPW loading for both organic and solid materials (COD, TS, and TSS) with tank 1 being significantly higher (50 to 89%) than tanks 2 and 3. Residual blood following a 120 s bleed time did not impact PPW loading compared to non-bled carcasses. These results indicate that scalder immersion time appears to be major indicator for predicting PPW loading in scalders and shows decreases with each sequential scald tank.