Modeling flume transport of broiler offal to predict the environmental effect on poultry processing wastewater: I. Feathers

Abstract

Two experiments were conducted to model and predict the environmental effect of flume transport of broiler offal feathers on poultry processing wastewater (PPW) under controlled laboratory conditions. In experiment 1 (Exp1; 24 experimental flock broilers) and experiment 2 (Exp2; 120 commercial flock broilers), birds were randomly assigned to 4 treatment groups: short bleed (60 s), soft scald (50°C); short bleed, hard scald (60°C); long bleed (120 s), soft scald; and long bleed, hard scald. Birds were processed individually (Exp1) or in groups of 5 (Exp2). Each broiler was electrically stunned, decapitated, and bled for either 60 or 120 s. Carcasses were then scalded for 2 min individually (Exp1) or as a 5-bird group in succession (Exp2) in a water-filled container at either 50 or 60°C. A representative volume of feathers was removed from each carcass (Exp1) or group of 5 carcasses (Exp2) and agitated for 2 min in either 2 (Exp1) or 4 L (Exp2) of potable water. The resulting feather rinse PPW was sieved (500 µm) to remove feathers and analyzed for concentration (mg/L) of chemical oxygen demand (COD; Exp1 and Exp2), total solids (TS; Exp1 and Exp2), total suspended solids (TSS; Exp1 and Exp2), total volatile solids (TVS; Exp1), and total Kjeldahl nitrogen (TKN; Exp1). A PPW load in grams per kilogram of live weight (g/kglwt) was calculated for each concentration (mg/L) data point. Mean loadings (g/kglwt) for experimental flock broilers (Exp1) were 0.908 for COD, 0.640 for TS, 0.513 for TVS, 0.291 for TSS, and 0.088 for TKN. Mean loadings (g/kglwt) for commercial flock broilers (Exp2) were 2.040 for TS, 1.033 for COD, and 0.344 for TSS.