(374e) Integrated Electrocoagulation-Ultrafiltration System for Treating Poultry Processing Wastewater

Industrial water reuse is considered as necessary for substantial reduction in water supply needs and savings in related costs. In 2016, the poultry industry within the United States processed approximately 8.9 billion broilers, using an average of 26.5 L of water per bird and produced over 60 billion gallons of poultry processing wastewater (PPW) requiring treatment. PPW contains proteins, fats, carbohydrates, feather, blood and skin, resulting in much higher biochemical oxygen demand (BOD) and chemical oxygen demand (COD) compared to municipal wastewater. Dissolved air floatation (DAF) is the most popular treatment method currently utilized in US poultry processors with approximately 80% of slaughter plants employing the technology. While in most cases, the DAF-treated PPW is sent to a biological wastewater treatment plant for further removal of contaminants and discharge into environment, at least a portion of PPW could be recycled and reused.

Ultrafiltration (UF) has been widely used in the food processing industry for the past 20 years. UF is a low-pressure and cost-effective option in terms of higher permeate flux compared to competing technologies (e.g. NF and RO) for treating highly impaired wastewaters. Similar to all membrane separation processes, UF suffers from membrane fouling, which causes a dramatic drop in the efficiency of the water recovery, due to accumulation of separated particles both on the membrane surface and inside the membrane pores. Here, we focus on electrocoagulation (EC) as a pretreatment step prior to UF regarding fouling mitigation. In EC, sacrificial electrodes are utilized to release coagulant counter ions into solution using electricity and aid in physical separation of suspended solids and organic macromolecules from the feed solution.

We report significant membrane fouling of the UF membrane due to high levels of oil and grease (O&G), proteins and suspended solids in the feed water that result in rapid flux decline. However, we show that the membrane fouling can be greatly mitigated using EC. We show that for an EC reaction time of 5 min, equivalent to 0.15 kWh m^-3 energy consumption for EC, followed by 6 h sedimentation, over 85% reduction of O&G, BOD and suspended solids results. This reduction leads to higher initial permeate flux as well as lower flux decline during UF. In addition, higher contaminate rejection is obtained in EC-UF process compared to individual UF. Finally, we show that intermittent cleaning can increase the water recovery to a great extent. Here, the recovered water volume was increased by over 30% in a week of experimental time when employing membrane cleaning after each 24 h.