Evaluation of ultrafiltration membranes for treating poultry processing wastewater

Abstract

The US poultry industry produces over 60 billion gallons of poultry processing wastewater (PPW) per year which requires treatment prior to discharge. In this work, nine different commercially available ultrafiltration membranes, having different nominal molecular weight cut-offs (10–300 kDa) and made of different polymeric materials (polyethersulfone and regenerated cellulose), were screened for treating PPW streams obtained from bird washer and chiller operations. Wastewater samples were treated for recycling and reuse purposes. Bird washer wastewater was found to cause more fouling as it contained higher biochemical oxygen demand (BOD), chemical oxygen demand (COD), fat, oil and grease (FOG) and total suspended solid (TSS) compared to the chiller wastewater.The presence of suspended particles can lead to plugging of the membrane pores. Thus, it is important to select the most appropriate membrane (pore size, polymeric material, flux, etc.) that minimizes fouling and maximizes contaminate rejection. For the feed streams considered here, membranes with 30 kDa nominal molecular weight cut-off provided the most stable performance in laboratory scale tangential flow filtration. Larger pore size membranes displayed rapid flux decline most likely due to entrapment of smaller particulate matter within the membrane structure. These particles were excluded from the smaller pore size membrane by size exclusion. The particle size distribution of the feed stream affected the level of contaminate rejection. Significant removal of BOD (up to 93%), COD (up to 94%), TSS (up to 100%) and FOG (up to 100%) was obtained for both wastewater streams.