Organic Fouling Impact in a Direct Contact Membrane Distillation System Treating Wastewater: Experimental Observations and Modeling Approach

Abstract

This study aims to investigate the effect of operational conditions on organic fouling occurring in a direct contact membrane distillation (DCMD) system used to treat wastewater. A mixed solution of sodium alginate (SA) and bovine serum albumin (BSA) was used as a feed solution to simulate polysaccharides and proteins, respectively, assumed as the main organic foulants. The permeate flux was observed at two feed temperatures 35 and 50 °C, as well as three feed solution pH 4, 6, and 8. Higher permeate flux was observed for higher feed temperature, which allows higher vapor pressure. At higher pH, a smaller particle size was detected with lower permeate flux. A mathematical model based on mass balance was developed to simulate permeate flux with time by assuming (i) the cake formation controlled by attachment and detachment of foulant materials and (ii) the increase in specific cake resistance, the function of the cake porosity, as the main mechanisms controlling membrane fouling to investigate the fouling mechanism responsible of permeate flux decline. The model fitted well with the experimental data with R2 superior to 0.9. High specific cake resistance fostered by small particle size would be responsible for the low permeate flux observed at pH 8.

Fouling and Performance Investigation of Membrane Distillation at Elevated Recoveries for Seawater Desalination and Wastewater Reclamation

“…Hot DI water has been proven effective for removing large amounts of foulants; however, it may lead to irreversible fouling [ 34 ]. The fouling factor ( Figure 4 ) shows that the fouling percentage on the membrane surface at 55 °C and 65 °C and for all recoveries was 4% to 9%, respectively, which agrees with previous experimental work findings [ 35 ]. As reported in previous studies [ 2 ], the difference in membrane fouling between 55 °C and 65 °C decreased as the experimental time decreased.…”

Treatment of Aniline Wastewater by Membrane Distillation and Crystallization

“…This is because when the temperature is low, the diffusion coefficient of the organic matter in the wastewater is low, and the membrane surface pollution deposition is fast, so the average surface roughness is low. When the temperature was too high, the aniline wastewater was concentrated quickly, the pollutant concentration in the wastewater increased, and a large number of pollutants were deposited on the membrane surface, which made the membrane surface smooth, decreased the hydrophobicity, and finally, wetted the membrane [ 58 , 59 ]. Therefore, using an appropriate temperature was very important for the MD process.…”

Softening with Ceramic Micro-Filtration for Application on Water Reclamation for Industrial Recirculating Cooling Systems

“…The concentrations of Ca 2+ (1.5–3 mmol L −1 ) and PO 4 3− (0.1 mmol L −1 ) used during the experiments represent the values found in WWTP effluent [ 26 , 27 , 28 ]. The concentration of SA that was previously used to simulate the concentration of organic substances in non-treated domestic wastewater is approximately 0.8 g L −1 [ 27 , 29 , 30 ]. However, to avoid too rapid clogging, only half of the concentration (0.4 g L −1 ) was used during the experiments.…”