Sharif Digital Repository

Critical flux is an important parameter in membrane bioreactors, which studying it can give a better understanding of treatment by these bioreactors and make utilizing them easier. In this study, the effect of some sludge properties like it’s concentration, sludge volum index, concentration of protein and carbohydrate in EPS and SMP and the effect of some operating conditions like aeration flow rate and rest mode on critical flux in a submerged membrane bioreactor are investigated. In addition to comparison of TMP-t figures drived from flux step experiment, the hystersis figures are also compared. Finally, two long term experiments at two sub critical fluxes are done in order to study the... 

Reusing valuable materials such as water is one of the ways to achieve sustainable development. Membrane bioreactor technology (MBR) is one of the ways to reuse water and this is an alternative to another way to upgrade existing refinery.Structure and porosity of the membranes used in MBR Systems, porosity distribution, Hydrophilic or hydrophobicity of the membrane and surface roughness are very important Parameters that impact the ultimate performance of membrane bioreactor. Hence, this project focuses on optimization membrane structure to purification a specific type of wastewater. So amount of polymer and nanoparticle membrane for MBR systems should determined by experiment design.In this... 

This thesis presents the results of the performance of a novel technology called submerged membrane electro-bioreactor (SMEBR). The SMEBR treats wastewater by combining membrane filtration, electrokinetic phenomena, and biological processes in one reactor, and improves treatment performance while helping to control membrane fouling. The newly designed SMEBR system was based on applying an intermittent direct current (DC) field between immersed perforated electrodes around a membrane filtration module. The SMEBR system significantly reduced the fouling rate when iron worked as electrodes and an intermittent DC with an operational different mode was applied.
In Phase 1 of this project,... 

Today, membrane bioreactors (MBRs) process is one of the most important options in industrial and municipal wastewater treatment. In MBRs, membrane has an essential influence on their performance. In this study, polycarbonate was exploited as membrane to evaluate its performance in MBR since it has excellent mechanical properties. However, polycarbonate is brittle and breaks at low elongation at room temperature. Solution blending was utilized to improve polycarbonate’s properties. Blending membrane was characterized and assessed by scanning electron microscopy (SEM) and tensile strength. Polycarbonate solution blending with polyurehatne which has excellent toughness and flexibility enhance... 

The effect of the combination of MBR and MBBR systems to enhance the efficiency of water treatment plants has been studied. In this study, by embedding a UASB reactor in the presence of packing, as anoxic, two MBBR reactors as a single aerobic treatment and a MBR reactor once with and once without packing as the final purification tried to remove pollutants from artificial drainage and extend the life of the membrane system is designed to convey the wastewater treatment and irrigation is its quality standards functionality and the quality of its wastewater treatment standards for agricultural irrigation. Studied pollutants include COD, ammonia, nitrate, nitrite and phosphate. membrane... 

Membrane bioreactors (MBRs) are a combination of activated sludg and mebrane technology. MBRs have been widely used as an advanced process for urban and industrial wastewater-treatment in recent years. Membrane fouling is the main issue that limits their performance and therefor, many studies have concentrated on testing different ways to mitigate the fouling. Ozonation process, that has been proved to reduce the MBR fouling, is studied in this project. Ozonation can provide the conditions for flocculation and therefor improves mixed-liqure properties. Ozon at two concentrations, 0.2 and 0.9 mg/lit was tested. Although results show little change in COD (chemical oxygen demand), but membrane... 

In this thesis was investigated the effect of solid retention time (SRT), Hydraulic retention time (HRT), activated carbon and suspended carrier on styrene and ethylbenzene biological removal and also on membrane fouling. In addition to the typical analysis (COD, MLSS, MLVSS, and SVI), the flocculation ability, sludge particle size distribution (PSD), FTIR analysis, excitation-emission matrix (EEM) fluorescence spectroscopy, soluble microbial product (SMP), extracellular polymeric substance (EPS), microscopic observations, microbial activities, microorganism population, and filamentous bacteria are considered to determine sludge characteristics. This study was done in five sections: in the... 

Submerged Membrane Electro-Bioreactor (SMEBR) was invented to increase the efficiency of Membrane Bioreactor (MBR) systems by reducing the fouling amount. The objective of this study was to understand the physical effects of Electrocoagulation (EC) method on membrane fouling and compares the critical flux number by applying electricity under different conditions and without any electrifying. This paper measured the critical flux, that obtained under different process condition including different MLSS concentrations (8000 ppm, 5000 ppm, 2000 ppm), different current densities and electrodes distance. The best result was obtained during highest CD (30 mA/cm2) and lowest distance of electrodes... 

Clean water is a growing need for humanity all around the Earth. Due to the shortage of clean water resources in most parts of our planet, wastewater treatment and reuse has been of great value in past decades. Much research has been conducted to improve treatment systems. One of the most recent advancements in water and wastewater treatment field is application of membrane bioreactor systems. Despite many advantages of these systems, membrane fouling has been the main drawback since the creation and application of them. The main objective of this research is to investigate the probable fouling reduction and head loss in flat sheet UF membranes due to the application of an anaerobic... 

In this study as representatives of alkenylbenzenes and mono-alkylbenzenes respectively were considered individually and as binary mixtures. It was observed that styrene, and ethyl benzene were inhibitory types of substrates across the tested concentration ranges. Thus, biodegradation kinetic is well described by the Haldane model. Kinetic parameter's assessments from single substrate degradation tests and these parameters were used to predict possibly interaction factors achieved from dual substrate experiments. The achieved outcomes from mixture of experiments revealed that the ratio of depletion for each substrate is affected by the presence of the other. It was also inferred that ethyl... 

Biodegradation is an effective method for removal of hazardous organic compounds such as styrene and ethylbenzene from petrochemical wastewaters. Although using this method for wastewater treatment meets (satisfies) the industrial standards, still these methods have significant disadvantages. Active sludge systems can not be effective enough due to the volatility and recalcitrance of styrene and ethylbenzene and a significant amount of volatile organic compounds exists in the discharging air. In order to reduce or totally remove this amount of pollutants in the discharging air, Membrane Bioreactors are used. One of the main problems of these systems is membrane fouling. In this thesis the... 

This study aims to investigate polysulfone (PSF) hollow fiber mixed matrix membranes (MMMs) properties containing Uio-66-NH2 and Mil-125-NH2 nanoparticles, groups of metal-organic frameworks (MOFs), for hemodialysis application. The nanoparticles were synthesized, and the membranes were produced by the phase inversion method. Membranes characterization conducted by ATR-FTIR, FE-SEM, EDX, TEM, and AFM was confirmed the presence of MOFs nanoparticles. Also, the evaluation of specific surface area of nanoparticles was done by BET. The water contact angle (WCA) results indicated the improvement of MMMs hydrophilicity, enhancing the pure water flux from 46.8 L/ m2h for the pristine membrane to... 

In the dairy industry, for the processing of raw milk, including the isolation of living bacteria and microorganisms from milk to increase the shelf life and improve the taste of milk, or the isolation of casein and whey proteins from milk for pHarmaceutical and medical purposes, as well as the production of low-lactose or lactose-free milk for patients with Digestive problems, use membrane processes, especially ultrafiltration and microfiltration, and the main problem in these methods is the fouling of the polymer membranes used, which results in the loss of flux or the reduction of product quality and system efficiency. With the help of bulk modification and surface modification of the...