14A-14

Protein from carcass debris and blood is one of the major pollutants in the poultry processing wastewater (PPW) and requires intensive treatment before being discharged.  Attempts to utilize the protein as fertilizer or animal feed were unsuccessful due to their low profitability.  However, the value of protein could be leveraged if it could be used as fermentation nitrogen source.  Ultrafiltration (UF), a membrane-based process, has been successfully employed for protein purification in dairy industry.  We hypothesize that UF may be an effective means to recover protein from PPW.

Our objectives were: (1) to recover the protein from PPW using UF; and (2) to evaluate its compositions as compared to commercial nitrogen sources.

PPW collected from local plants after primary treatment was kept refrigerated before UF.  Polysulfone membrane with 30,000 MWCO was used.  The crude protein (CP), total solids (TS), and chemical oxygen demand (COD) before and after UF were evaluated, whereas the molecular weight (MW) and its amino acid (AA) were determined respectively by SDS-PAGE and AA analyzer.

The average flux was ~100 L/(m²×hr) throughout operation regardless pH fluctuations.  With flux profiles similar to that of bovine serum albumin, however, the membrane performance could be restored by flushing with detergent containing sodium hypochlorite.  The CP, TS, and COD in PPW were reduced from 110, 1173, and 858 ppm to ~0, 753, and 355 ppm, respectively.  Almost all crude protein was retained in the retentate with a concentration of 390 ppm.  The MW of the recovered protein was found to range from 50 to 75 kDa, with an AA composition comparable to commercial nitrogen sources.

The results suggest that UF could be used to effectively recover protein from PPW.  The composition of recovered protein indicates a value-added potential for the protein to be used in industrial fermentation.