Effect of Photooxidation on Nanofiltration Membrane Fouling During Wastewater Treatment from the Confectionery Industry

Abstract

The research in this article aimed to present the possibilities of wastewater treatment coming from the confectionery plant in the nanofiltration (NF) process and the use of photooxidation to mitigate membrane fouling. The process was carried out initially in a dead-end flow system, where the most favorable membrane was selected. Next, the purification efficiency and blocking intensity of this membrane in the system were compared with cross flow. The next research involved the use of a photolytic oxidation process to pretreat sugar wastewater. UV radiation was emitted by a medium pressure mercury UV lamp model TQ 150 V. The effectiveness of the process was also evaluated based on the degree of pollutant load removal. The evaluation of the efficiency of a treatment process was based on the change of wastewater quality indicators before and after the membrane process. The following parameters were controlled: color, COD (chemical oxygen demand), TOC (total organic carbon), absorbance of UV254, nitrate, phosphate, ammonium, conductivity, and pH. During the course of pressure filtration, the following properties of the membrane were determined: the dependence of the volumetric flux of the permeate on the process duration, the permeability of the membrane, as well as the contact angle of the membranes. It was found that the use of UV reduced the phenomenon of fouling of nanofiltration membranes. The value of the permeate volumetric flow after the hour of running the process increased by 17%. However, no impact of UV on the efficiency of wastewater treatment was found. However, the NF process provided the required quality of treated wastewater that can be reused in industrial applications. The NF process resulted in a total decrease in absorbance, 99% TOC removal, and 98% color removal.For the wastewater treatment in a closed cycle, mainly physicochemical methods are used, such as chemical precipitation, sorption, and membrane filtration. More expensive, more modern technology of wastewater treatment, such as nanofiltration or reverse osmosis, allows more effective purification. The advantage of these methods is that, after the treatment process in the wastewater, there are no semi-finished products of pollutants decomposition and additional chemicals [4,5].The main advantages of membrane processes are low power demand, small device constructions, high flexibility in terms of installation efficiency and effectiveness, the ability to incorporate membrane modules into existing systems of wastewater treatment equipment, removing a whole pollutants range, and not only changing them into forms of occurrence, effective removal of pathogenic microorganisms, effective removal of organic fouling, and obtaining water of better quality than specified in the requirements [5]. However, as is well known, these processes are accompanied by the inherent phenomena contributing to the reduction of the membrane performance owing to the increase of filtration system resistance. They include the fouling phenomenon. There are many studies r...

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