24 - Advances in membrane technology for the treatment and reuse of food processing wastewater

Abstract

Publisher Summary The food processing industry generates a large volume of wastewater and a large amount of solid waste that can induce environmental problems; this waste should thus be reduced and treated. The impurities classified by size are solutes (small molecules – acids, bases, salts – and macromolecules – proteins, peptides, etc.); colloidal suspensions (referred to as pseudo-solutions – these are generally two-phase heterogeneous systems, less than 100 µm in size); and particulate (suspended solids visible under microscope, for example, algae, bacteria, etc. and/or larger particles, such as sludge particles). Practically all of the existing membrane processes are in use in the food and beverage industry and/or in its wastewater treatment. The classic applications of membrane technology in the food industry and its wastewater treatment are Microfiltration (MF), Ultrafiltration (UF), Nanofiltration (NF), and Reverse Osmosis (RO). These filtration processes are applied for clarification, sterilization, concentration, decoloration, demineralization, product recovery, etc. The most recently introduced membrane processes for industrial applications are Electrodialysis (ED), Pervaporation (PV), Membrane Contactors (MC), such as membrane strippers/scrubbers, membrane extractors, membrane distillation, membrane osmotic distillation, for demineralization, removal of organic pollutants, etc. Besides these membrane separation processes, the differently configured Membrane Bioreactor (MBR) is the most widely applied process for wastewater cleaning and treatment in the food industry. This chapter briefly describes membrane separation methods and MBRs. It discusses the most important mass transfer rate equations and/or the characteristic equations of membrane fouling and the concentration polarization layer forming on the surface of the filtration membrane. It also presents some applications for wastewater treatment.