Application of membrane technology for food industry wastewater treatment and resource recovery

The food sector plays an important role in ensuring the general people's good health and nutritional needs by maintaining food security and food safety. This industry's scope of activities is covered by food production, postharvest management, processing, manufacturing, packing, transportation, and consumption. However, the growing worldwide population has increased the need for food, but at the ;samo time,thene has been a significant increase in the output of waste generation of the food industry which represented as an ultimate challenge. Mainly, two types of wastes liquid waste (wastewater) and solid waste (food waste), are observed on a large scale, but by treating these wastes, various potential benefits could be obtained in terms of clean water production and resource recovery, respectively. with the emergence of wastewater treatment and resource recovery technologies, membrane process has been identified as a mainstream tool in the last few years due to its unique advantages, including high efficiency, portable facilities, economically feasible, etc. Therefore, in the current thesis, novel electrospun nanofibers membranes have been applied in treating wastewater and pressure-driven membrane filtration used for resource recovery by modulating their proocess intensifaction. As of today, electrospun-based nanofibers membrane materials, usually with smaller diameters (less than 100 nm) and higher surface area, have been used widely to replace traditional adsorbents. Thus, the authors, using an environmentally friendly approach for eliminating methylene blue from an aqueous solution, have developed a unique electrospun nanofiber membrane made of a combination of polyethersulfone and hydroxypropyl cellulose (PEs/HPc). Structures of the newly manufactured membrane were studied using SEM, FTIR, TGA, and XRD. The results show that a uniformly-sized nanofiber with an ultrathin diameter of 168.5 nm and high mechanical stability has been observed in the membrane' Contact angle measurements ,have shown that the'blended membrane exhibits good hydrophilicity, and excellent adsorption capacity. The highest adsorption capacity was found to be 259.74 mg/g at neutral pH under room temperature, and the pseudo-second-order model was found to be accurate. In addition, a novel polyethersulfone/polyacrylonitrile (pES/pAN) blended electrospun nanofiber-based membrane was developed and applied for removing methylene blue from aqueous solutions. SEM results exhibited a smooth surface of the blended PES/PAN nanofiber membrane with an ultrathin diameter of 151-5 nm, much better than the pristine PES nanofiber membrane (261.5 nm). Besides, the blended PES/PAN nanofiber membrane showed a good mechanical stability and hydrophilicity nature, which are vital for adsorption study. Experimental adsorption kinetic data obeyed by the pseudo-second-order (R'z:0.9970) and consistent with the Langmuir isoiherm model (R3:0.99g3) by showing the maximum adsorption capacity of 1010 mgMB/g at neutral pH and room temperature, indicating that that the adsorption process occurred in a monolayer form of the membrane surface. Additionally, the potential of organic waste streams (i.e., food waste) for the sustainable production of precursor chemicals such as volatile fatty acids (VFAs) using anaerobic digestion (AD) has received 'significant attention in the present days within aconsortium of resourcerecovery. AD-derived VfAs have great market appeal if the challenges with their recovery and purification from the complex AD effluent is overcome. In this study, a novel microfiltration immersed membrane bioreactor (MBR) was used for the production of VFAs from food waste and simultaneously in-situ recovery of VFAs. The recovered permeate was then subjected to further purification using a side stream ultrafiltration unit. It was found that VFAs concentration (above 6 glL) was higher for l0 kDa at pH 5.4 in ultrafiltered solution. After that, nanofiltration was carried out using two commercial nanofiltration membranes of 200-300 Da and 300-500 Da under various pH, apptying constant pressure and temperature of 15 bar and 20-2I'C, respectively. As noticed, the membrane with the molecular weight cut-off (MWCO) of 200-100 Da appeared to be more effective with an increased concentration of total VFAs (16.94 g/L) and recovery percentage above 90Yo atpH 9. Moreover, the concentration and recovery percentages of individual VFAs were further enhanced by conducting a sequential permeate recycling process, where, interestingly, recovery percentages of 100% was reached for specific acids. Overall, the novel electrospun nanofibers membrane are promising for future food industry wastewater treatment applications with increased efficiency, while the use of pressure-driven membrane filtration as a post-treatrnent of anaerobically digested food waste-derived effluent could be a potential recovery pathway of VFAs-based chemicals. [edited by Author]