Gábor Keszthelyi-Szabó

Treatment of oily wastewater by combining ozonation and microfiltration

AbstractIn process industries, a large amount of wastewater is generated in the form of oil-in-water emulsions, which cannot be treated effectively using traditional physical methods. The aim of our investigation was to examine the applicability of the membrane technique and the effect of pre-ozonation in oily wastewater treatment. Pre-ozonation followed by microfiltration (MF) was investigated to determine the main effects of ozonation on the oily water and the filtration parameters such as permeate flux, organic content retention and membrane fouling. Experiments were carried out with a laboratory-scale batch-stirred filtration device, using polyethersulphone MF membranes with a pore size 0.2 μm. The model oily wastewater that was used in these experiments contained petroleum. The results demonstrated that the chemical oxygen demand could be eliminated more effectively through the combination of ozone pre-treatment and membrane filtration, compared to membrane filtration alone.

Investigation of module vibration in ultrafiltration

AbstractMembrane fouling is still a critical issue which limits the application of industrial membrane utilizations. Membrane processes operating at a high shear rate are frequently used to control flux decline by reducing the deposition of particles on the membrane surface. In this work, ultrafiltration (UF) of a dairy model and industrial wastewaters was investigated. Membrane module vibration and no-vibration mode were compared by a laboratory mode vibratory shear enhanced processing device during membrane filtration with the same operational parameters. Membrane fluxes, rejections, and energy consumption were measured and calculated for comparison of the vibration effectiveness. Turbidity, chemical oxygen demand, and total organic carbon were measured. The UF experiments were carried out with constant parameters at a temperature of 50°C and recirculation flow rate of 910 L h−1 at 0.8 MPa. Furthermore, to understand the fouling mechanisms in depth, contact angles of the clean, prewetted, and fouled mem...

Application of dielectric constant measurement in microwave sludge disintegration and wastewater purification processes

It has been numerously verified that microwave radiation could be advantageous as a pre-treatment for enhanced disintegration of sludge. Very few data related to the dielectric parameters of wastewater of different origins are available; therefore, the objective of our work was to measure the dielectric constant of municipal and meat industrial wastewater during a continuous flow operating microwave process. Determination of the dielectric constant and its change during wastewater and sludge processing make it possible to decide on the applicability of dielectric measurements for detecting the organic matter removal efficiency of wastewater purification process or disintegration degree of sludge. With the measurement of dielectric constant as a function of temperature, total solids (TS) content and microwave specific process parameters regression models were developed. Our results verified that in the case of municipal wastewater sludge, the TS content has a significant effect on the dielectric constant and disintegration degree (DD), as does the temperature. The dielectric constant has a decreasing tendency with increasing temperature for wastewater sludge of low TS content, but an adverse effect was found for samples with high TS and organic matter contents. DD of meat processing wastewater sludge was influenced significantly by the volumetric flow rate and power level, as process parameters of continuously flow microwave pre-treatments. It can be concluded that the disintegration process of food industry sludge can be detected by dielectric constant measurements. From technical purposes the applicability of dielectric measurements was tested in the purification process of municipal wastewater, as well. Determination of dielectric behaviour was a sensitive method to detect the purification degree of municipal wastewater.

Enhancing biogas production of meat industrial wastewater by microwave pretreatment

The effects of microwave pre-treatment of meat industrial wastewater were investigated in this study. The focus of this investigation was to determine the optimum conditions in a continuous flow microwave treating system under which the microwave pre-treatment of meat industrial wastewater would facilitate the maximum biogas yield. Response surface analysis was applied to screen the effects of volumetric flow rate (FR), number of treating (NT) and power of the magnetron (PM).

The Effect of Advanced Oxidation Pre-Treatment on the Membrane Filtration Parameters of Dairy Wastewater

Abstract The dairy industry generates wastewater characterised by high levels of biological and chemical oxygen demands representative of their high degree of organic content; mainly carbohydrates, proteins and fats that originate from milk. Several investigations have been conducted into the reuse of dairy wastewater, e.g. membrane processes are a promising method to treat such wastewater. Earlier works have proven that with membrane filtration an appropriate degree of retention can be achieved and the permeate can be reused. However, membrane fouling is a limiting factor in these processes. Advanced oxidation processes (AOPs) are widely used in the fields of water and wastewater treatments and are known for their capability to mineralise a wide range of organic compounds. AOPs also exhibit some other effects on the filtration process, e.g. the microflocculation effect of ozone may play a significant role in increasing the elimination efficiency and causing a decreased level of irreversible fouling. By comparing ozone and Fenton pre-treatment (FPT) processes it can be shown that the fouling propensity of pre-treated pollutants does not depend on the pre-treatment method, while FPT was proven to be more efficient in improving the level of flux.

CORRELATION BETWEEN DIELECTRIC PROPERTIES AND AEROBIC BIODEGRADABILITY OF MEAT PROCESSING SLUDGE

The dielectric properties, namely the dielectric constant and the dielectric loss factor are important for predicting the behavior of materials during microwave processing, because both of them determine the interaction between the molecules with the oscillating electromagnetic field. Because the dielectric properties are not known for food industry sludge, our main aim was to measure the dielectric constant and dielectric loss factor for meat industry sludge, and to investigate the correlation between the dielectric parameters and the biodegradability indicators. Our experimental results show, that despite of the high moisture content of sludge, temperature depending behavior of ’ was different that of can be known for water. Sludge had a decreasing tendency in the temperature range of 20-60 ̊C, but over a critical value of the temperature increasing induced an increment in the value of ’. Our experimental results verified that the change of sCOD/tCOD has a good linear correlation with the dielectric loss factor. Similar to the trends determined for the solubility change, a good correlation was found between the dielectric loss factor and the change of biodegradability measured by the BOD/tCOD parameter. Our experimental results verified that the change in the value of dielectric loss factor correlate with the disintegration degree and the biodegradability of sludge, as well Correlation between the electrical parameters and biodegradability indicators enable to develop a real-time and inline measuring and control system for batch and continuous flow microwave sludge conditioning technology.

DEVELOPMENT OF BIODEGRADABILITY INDICATORS FOR MICROWAVE SLUDGE CONDITIONING

Microwave irradiation has a good potential to increase the ability of organic matter for biological degradation. Because of the strong disintegration effect of microwave irradiation on extracellular polymeric substances (EPS), which form complex sludge structure, and also on microbial cell walls has led to enhanced solubility of organic matters, given by the ratio of soluble to total chemical oxygen demand (SCOD/TCOD). From the aspect of the further utilization of sludge, the change of biochemical oxygen demand (BOD), which correlates the degradable organic matters of sludge under aerobic condition, can be considered advantageous. For comparison purpose, and for modeling and optimization of process, it is needed to create novel control parameters, by which can be measured the changes in organic matter fraction of sludge independently from the varying characteristic or different origin of raw sludge. Based on our results, it has established that in the range of 90-1050 kJkg-1, and 0.5-5 Wg-1 for IMWE and MWPL, the surface fitted by constructed model can be characterized by a maximum value for BDI. Microwave treatment carried out over a certain value of MWPL and IMWE has resulted in lower biodegradability. Optimum range of IMWE and MWPL was concluded as 600-650 kJ and 2.5-3.0 Wg-1, respectively, and both process parameters have significant effect on the change of BDI and SLI, as well.

Membrane separation and sonication in bio-ethanol production

AbstractThe importance of biofuels is growing for both environmental and economic point of view. The usage of wastes in bio-ethanol production is investigated in our paper. Cellulose contained wastes i.e. byproduct of tobacco is used for experiments. The paper is focused mainly on the investigation of the enzyme recovery that followed the saccharification process. The membrane filtration combined with sonication was used for enzyme recovery. Our results show that recovered enzyme did not lose its activity. The patterns were originated from fermented solutions made from tobacco byproducts. Based on our results, the ultrasound accompanied by a membrane separation would be a possible and effective operation of bio-ethanol production technology.

The effect of the implementation of ultrasound in enzyme separation

Enzymes are biological catalysts that generally are designed to do one job well, but to do one job only. Therefore, the enzymes that catalyze the hydrolysis of cellulose to sugar do not break down the sugars. Enzymatic hydrolysis processes have been under development for only 10 years. The important research issues include understanding the processes necessary to render the crystalline cellulose easily digestible, understanding and improving the basic mechanisms in the hydrolysis step, and developing better and less expensive enzymes. The other way to make a process less expensive may be the recycling of enzymes. The essential unit operation in the bioethanol production is the cellulose enzymatic degradation, so the question of recycling is very important. In our work the sonication assisted ultrafiltration was investigated as a potential method for enzyme recycling. The results showed the ultrasound effects the permeate flux since the resistance is reduced by the sonication. The sonicated enzyme keeps its activity so the recycling mechanism might be used for bioethanol production.