The suitability of polysulfone ultrafiltration membranes (UFM) designed for commercial water treatment has been investigated for separation of protein (PR) from sweet whey. Ultrafiltration (UF) of whey originated from dairy has been realized by a self-made pilot plant, which has been in service for about one year. The influence of two whey temperatures (9 and 30 °C) on the efficiency of protein concentration has been examined. Application of investigated UF elements gave whey protein concentrate (WPC) with 5 to 6 times excess amount of protein content compared to the initial. At the same time, the prevalent content of lactose was removed to permeate. Better results were obtained with cold whey filtration. Besides the fact that the molecular weight cutoff (MWCO) of the investigated membranes was 50-100 kDa, the results showed very successful concentrating of whey proteins of dominantly lower molar weights than 50-100 kDa. Investigated membranes are beneficial for design and construction of UF plants for exploitation in small dairies.

The aim of this study was to investigate the performances of polyamide nanofiltration membranes during water reclamation. The study was conducted using nanofiltration concentrates obtained from two different nanofiltration drinking water treatment plants placed in the northern part of Serbia (Kikinda and Zrenjanin). Used nanofiltration concentrates contained high concentrations of arsenic (45 and 451 μg/L) and natural organic matter (43.1 and 224.40 mgKMnO4/L). Performances of polyamide nanofiltration membranes during water reclamation were investigated under various fluxes and transmembrane pressures in order to obtain drinking water from nanofiltration concentrates and, therefore, reduce the amount of produced concentrates and minimize the waste that has to be discharged in the environment. Applied polyamide nanofiltration membranes showed better removal efficiency during water reclamation when the concentrate with higher content of arsenic and natural organic matter was used while the obtained permeates were in accordance with European regulations. This study showed that total concentrate yield can be reduced to ~5 % of the optimum flux value, in both experiments. The obtained result for concentrate yield under the optimum flux presents considerable amount of reclaimed drinking water and valuable reduced quantity of produced wastewater.

A pilot-scale study was performed to explore the possibility of the removal of natural organic matter (NOM) and arsenic from groundwater in the village of Melenci (Northern Serbia) using strongly basic, macroporous ion-exchange resin, commercially available as Amberlite IRA 958-Cl. The influences of the specific flow rate (SFR) and a broad range of contact times were studied using native groundwater and the same water pretreated with sodium hypochlorite (NaClO) for the oxidation of As(III) to As(V) and the degradation of NOM. The investigated SFR exceeded the manufacturer's recommended maximum value by up to ten times. In the range of SFR from 50 to 300 bed volumes per hour (BV/h), a higher efficiency of NOM removal was achieved in the absence of the oxidant, whereas at lower SFR and shorter contact times, the efficiency was higher when the water was pretreated. The arsenic removal from the oxidant-pretreated water was equally efficient at all SFR, whereas in the absence of the oxidant the efficiency was significantly lower and did not depend on SFR. The effectiveness of the resin illustrates the fact that the experimentally determined optimum SFR value of 30 BV/h is stated as the maximum in the manufacturer's specifications.

No abstract

The objective of this work was to study the sorption behavior of the strongly basic and macroporous commercial resin IRA 958-Cl for the removal of natural organic matter (NOM) from groundwater in the Melenci settlement located near Zrenjanin (Northern Serbia). The investigation was performed in a pilot plant using native groundwater and the same water after chlorination with sodium hypochlorite. More efficient removal of NOM and arsenic was achieved without the addition of an oxidant under a wide range of working conditions. NOM removal was more efficient with the addition of the oxidizing agent compared with the overall efficiency for 2,900 bed volumes (BV) of treated water only during the initial phase of operation. Arsenic removal from chlorinated water was more efficient up to approximately 700 BV. At higher BV values, arsenic removal was up to two times more efficient with non-chlorinated water. The results obtained for the NOM sorption affinity to the resin indicated that it is possible to achieve a sorption capacity that exceeds the performance quoted by the resin manufacturer on several occasions.