Modeling flume transport of broiler offal to predict environmental impact on poultry processing wastewater: II. Viscera

Abstract

Two experiments were conducted to model and predict the environmental impact of flume transport of broiler offal viscera on poultry processing wastewater (PPW) under controlled laboratory conditions. In experiment 1 (24 experimental flock broilers) and experiment 2 (120 commercial flock broilers) birds were randomly assigned to 4 treatment groups: short-bleed (60 s) and soft-scald (50°C), short-bleed and hard-scald (60°C), long-bleed (120 s) and soft-scald, and long-bleed and hard-scald. Birds were processed individually (experiment 1) or in groups of 5 birds (experiment 2). Each broiler was electrically stunned, decapitated, bled, scalded for 2 min, and defeathered. Each carcass was manually eviscerated and the individual viscera (experiment 1) or group of 5-viscera (experiment 2) were sequentially agitated in potable water for 1 and 3 min. The resulting viscera rinse PPW was sieved (500 µm) and analyzed for concentration (mg/L) of chemical oxygen demand (COD; experiments 1 and 2), total solids (TS; experiments 1 and 2), total suspended solids (TSS; experiments 1 and 2), total volatile solids (experiment 1), and total Kjeldahl nitrogen (experiment 1). A PPW load in grams per kilogram of live weight (g/kglw) was calculated for each concentration (mg/L) data point. Neither bleed time nor scald temperature played a significant role in the effect of viscera on PPW mass loading. However, viscera agitation duration did play a significant role in PPW mass loading. Commercial flock broiler mean PPW mass loadings (g/kglw) generated by 1 min of viscera agitation were 0.674 for COD, 1.160 for TS, and 0.111 for TSS. Mean loadings at 3 min of agitation were 1.007 for COD, 1.399 for TS, and 0.188 g/kglw for TSS.