Effects of broiler carcass bleed time and scald temperature on poultry processing wastewater

Abstract

SUMMARY Two experiments were conducted to measure the effects of bleed time and scald temperature on the impact of individual carcasses or groups of carcasses on scalder poultry processing wastewater (PPW). In experiment 1 (24 male broilers) and experiment 2 (120 commercial broilers), birds were randomly assigned to 4 treatment groups: 1) short bleed time/soft scald, 2) short bleed time/hard scald, 3) long bleed time/soft scald, and 4) long bleed time/hard scald (short bleed time = 60 s; long bleed time = 120 s; soft-scald = 50°C; hard-scald = 60°C). Birds were electrically stunned, decapitated, and bled for either 60 or 120 s, with the draining blood captured. Carcasses were scalded for 2 min individually (experiment 1) or in groups of 5 carcasses (experiment 2) in scald tanks heated to either 50 or 60°C. Experiment 1 scalder PPW samples were analyzed (mg/L) for chemical oxygen demand (COD), total solids (TS), total suspended solids (TSS), total volatile solids, total Kjeldahl N, and 18 chemical elements. Experiment 2 scalder PPW samples were analyzed for COD, TS, and TSS. A PPW load in grams per kilogram of live weight (g/kglwt) was calculated for each concentration (mg/L) data point. The highest mean loading (g/kglwt) in the scalder PPW samples from experiment 1 was for COD (2.00), followed by TS (1.66), total volatile solids (1.36), TSS (0.42), and total Kjeldahl N (0.24). The highest mean loading (g/kglwt) in the scalder PPW samples from experiment 2 was for TS (3.02), followed by COD (1.62) and TSS (0.61). There was an 82% increase in TS mean loading (g/kglwt) from experiment 1 (i.e., experimental broilers) vs. experiment 2 (i.e., commercial broilers); hence, broiler external cleanliness significantly affected solids loading in scalder PPW.