FOULING CHARACTERIZATION OF MEMBRANE CONTACTORS USED FOR THE RECOVERY AND CONCENTRATION OF AMMONIA FROM UNDIGESTED PIG SLURRY

The main obstacle impeding implementation of membrane contactors for the
recovery and concentration of ammonia from swine manure is the phenomena of
membrane fouling. Fouling is defined as the accumulation of suspended or dissolved substances on the membrane surface and/or within its pores. Due to the different types of fouling which can occur in a membrane system, characterization of fouling is a complex problem. Fouling intensity, morphology and composition of fouling layers has been determined using Scanning Electron Microscopy, X-ray Energy Dispersive Spectrometry and Attenuated Total Reflectance Infrared Spectrometry. Based on the analysis of fouled membranes, it is concluded that membrane fouling is dominated by organic fouling in combination with biofouling mainly due to adsorption and deposition of undegraded organic matter. The average fouling layer thickness was estimated to 127.4 μm after a week of running the contactor without cleaning. This
indicates that fouling could be a severe problem. The intensity of fouling can be
reduced by feed pretreatment and by optimizing the operating conditions of the
membrane contactor. This will also facilitate removal of ammonia.