Krystyna Konieczny

Application of coagulation and conventional filtration in raw water pretreatment before microfiltration membranes

Two step coagulation using iron coagulant (FeCl 3 ) with anionic polyelectrolyte in the first step and aluminum coagulant in the second one was made to reduce the negative effect of the fouling phenomenon. The process was operated on the commercial scale. The raw water was the blowdown water from the power plant cooling system. The dead-end microfiltration units provided with 0.2 μm polypropylene membranes produced about 210 m 3 /h of water. The results of statistical tests show a significant difference between the concentrations of turbidity, total hardness, sulfates (VI), total iron, aluminum, silica, nitrate nitrogen, ammonia nitrogen, oxygen consumption and absorbance (254 nm) in the water during the whole process. The results of previous observations showed that the formation of the cake layer had been the main reason for the fouling phenomenon occurring on the investigated membranes. It is significant that 75% of the suspension has been removed during the pretreatment stages. The hydrobiological observations show the presence of Bacillariophyceae and Cyanophyta. It is possible to remove them during the coagulation and prefiltration stages. The investigation results show that it is possible to protect the polypropylene membrane from fouling occurring inside the membrane pores as well as the formation of the cake layer. The use of a hybrid process combining the traditional raw water pretreatment with a membrane process may be well-founded.

Modelling of membrane filtration of natural water for potable purposes

Abstract Three different methods have been proposed for the mathematical description of the microfiltration process of natural waters, that is: the model describing the changes of permeate flux in time — the “relaxation” model, the model of filtration resistance and the Hermia model which allows determination of the mechanism of pore blocking in the membrane. In order to assess the adjustment level of the proposed mathematical models with experimental data, the Fishers statistical test was applied. The optimal time of filtration and membrane washing cycle for which the yield is the highest was also determined.

Fouling phenomena in unit and hybrid processes for potable water treatment

Abstract Studies were carried out on the treatment of water for potable purposes using ceramic and capillary membranes. The studies involved the processes of unit microfiltration and ultrafiltration as well as hybrid processes, In the hybrid processes, adsorption on activated carbon and membrane separation was combined. Two types of activated carbon were applied: pulverized and granular. The activated carbon was from the Hajnowka plant in Poland and the granular one was from the Chemviron Carbon firm in Belgium. The testing medium was natural water taken from the Vistula River. The membrane flux was assessed, and physico-chemical analyses of the selected water pollution indexes were carried out. The emphasis was placed on the fouling of the membranes during the treatment of natural waters. Therefore, the filtration of deionized water was carried out before and after each test on natural waters. In this way it was possible to determine the fouling of the membranes, its character and whether the fouling was reversible or irreversible. The studies also covered an evaluation of the influence of activated carbon on the yields and stabilization of permeate flux.

Pervaporative desulfurization of gasoline—separation of hydrocarbon/thiophene mixtures using polydimethylsiloxane (PDMS)-based membranes

AbstractA series of vacuum pervaporation tests were carried out to investigate the performance of the commercial composite membrane with an active layer made of polydimethylsiloxane (PDMS). The effects of feed temperature, the sulfur content in the mixture, and feed composition on membrane performance were investigated. Toluene/thiophene and n-heptane/thiophene binary organic mixtures (thiophene concentration 0.8–1.6% by mass) simulating gasoline were separated at 30–50°C, at laboratory scale. Studies have shown that the concentration of thiophene in the mixture and the temperature of the feed have a significant impact on the yield and selectivity of the desulfurization process. Experimental results indicated that higher feed temperature yielded higher total and partial fluxes and a lower sulfur enrichment factor. The total and partial fluxes increased as the sulfur content in the feed increased. The sulfur enrichment factor decreased with the amount of thiophene added in the gasoline. The experiments als...

Pressure driven membrane techniques in the treatment of water containing THMs

The paper presents the investigations concerning membrane treatment of water containing chloroform. Reverse osmosis (RO), nanofiltration (NF) and ultrafiltration (UF) techniques were applied. Removal degrees of chloroform and flux drop during membrane filtration were determined. Basing on the results of flux-time relationship, two models for flux drop have been adapted: resistance model and Hermii model. It was stated that RO, NF and UF could be used for THMs removal from water and the proposed models are suitable to describe the change of permeate flux during membrane filtration.

Biomembrane wastewater treatment by activated sludge method

The paper compares the biomembrane and classical activated sludge methods of wastewater treatment and presents the influence of ultrafiltration on the activated sludge condition. It specifies the difference of enzymatic activity of activated sludge in both systems. In effect of both activated sludge performance and separation properties of the ultrafiltration membrane, the effluent from the biomembrane system is less loaded.

Pervaporative desulfurization of gasoline – separation of thiophene/n-heptane mixture / Perwaporacyjne odsiarczanie benzyny – separacja mieszanin tiofen/n-heptan

Abstract This paper presents the recent advances in pervaporative reduction of sulfur content in gasoline. Methods of preliminary selection of membrane active layer material are presented. Interactions between gasoline components (typical hydrocarbon and sulfur species) and membranes are showed. Influence of pervaporation process parameters i.e. feed temperature, downstream pressure and feed flow rate on the separation efficiency is discussed. Investigations of the influence of sulfur concentration in fluid catalytic cracking (FCC) gasoline on membrane performance have been conducted. A series of PV tests was carried out to investigate the separation properties of the commercial composite membrane with an active layer made of poly(dimethylsiloxane) and to determine the efficiency of organic sulphur compound (thiophene) removal from model thiophene/n-heptane mixture depending on its concentration. W pracy zaprezentowano dotychczasowe osiągnięcia w perwaporacyjnym odsiarczaniu benzyny krakingowej. Przedstawiono kryteria wstępnego doboru materiału warstwy aktywnej membran. Omówiono ponadto wpływ typowych węglowodorów oraz związków siarkoorganicznych obecnych w benzynie krakingowej na selektywność i właściwości transportowe membran jak również wpływ parametrów procesowych (temperatury nadawy, ciśnienia po stronie permeatu oraz szybkości przepływu nadawy) na efektywność procesu perwaporacyjnego odsiarczania. W pracy przedstawiono możliwość zastosowania komercyjnych membran kompozytowych z warstwą aktywną wykonaną z poli(dimetylosiloksanu) (PDMS) w procesie perwaporacyjnego odsiarczania benzyny pochodzącej z fluidalnego krakingu katalitycznego (FCC). Określono wpływ stężenia organicznych związków siarki na efektywność ich usuwania z organicznych mieszanin tiofen/n-heptan metodą perwaporacji próżniowej.

Modelling of the ultrafiltration of electrophoretic emulsion paint

Abstract Attempts of modelling mathematically the ultrafiltration process of soluble emulsion paints have been presented. Analyses were carried out based on data of ultrafiltration experiments performed with tubular polyacry-lonitrile and poly(vinyl chloride) membranes at a paint concentration of 10%. The constants of the general dimensional mass transfer correlation, as well as the general dependence of the volume permeate flux on ultrafiltration process parameters (i.e., transmembrane pressure and cross-flow velocity), have been determined.