NANOFILTRATION OF PROTEIN RICH WASTEWATER- STUDY FOR CONCENTRATING POTATO FRUIT JUICE

At present, in potato starch industries, not only starch is extracted from the process but even proteins and fibers are recovered as they are economically valuable. Unfortunately, the process used for protein recovery can only partially recover protein from the potato fruit juice (PJ), while the reaming PJ is concentrated using an evaporator and is later on used as fertilizers. Potato starch industry is considered to be one of high energy consuming industry and one of the reasons for this is the usage of an evaporator for the concentration process, which has high energy requirement. For the above mentioned reason, this study was performed to compare and evaluate the impact of a nanofiltration system integrated as pre-treatment to evaporator in terms of energy and cost. To achieve this objective, process parameter study was carried out for the seven nanofiltration membranes which consists of, two ceramic membranes LC1 and LC2 and five polymeric membranes Koch 34, Koch 36, NP 10, NP 30 and Solsep. Process parameter study for ceramic and polymeric membranes were carried out using different model setups. The retention capacity of the membranes was also determined in the process parameter study. Finally, the better performing membrane among seven membranes was selected and used in the concentration studies. Concentration studies was carried out to for 22 hours to determine the volume reduction capacity of the membrane, which was useful during the techno economic analysis. Based on the process parameter study results, Koch 34 proved to be the best performing membrane. Fifty percent of volume reduction was achieved using Koch 34 in the concentration studies. 87% of total solids and proteins were retained and similarly 87% retention in sugars and other soluble solids and 67% retention in conductivity was observed during these studies. Techno economic analysis was carried out to compare between evaporation and membrane filtration integrated with evaporation in terms of cost and energy consumption in a potato starch factory. For conducting techno economic analysis (TEA), the capital investment and the operating cost for the membrane filtration system was calculated using the numerical data from the literature. In case of the evaporator, only operating cost was calculated as the system was already existing in the company. The cost calculation shows that, when evaporator alone was used for the concentration process, it costs 6.8 Euros/m3 of water removal from the PJ. On the other hand, the use of nanofiltration system as pre-treatment for the evaporation process costs 1.2 Euros/m3 of water removal from the PJ. The results show that the, use of nanofiltration as pre-treatment to the evaporation process is economically feasible and reduces the energy consumption. (Less)