Study Of Dynamic Membrane Engineering Structure System And Its Applications In Textile Dyeing Wastewater Treatment

Membrane filtration is one of the most common methods of separation used in water and wastewater treatment.Membrane filtration in water and wastewater treatment can be employed during primary,secondary as well as tertiary treatment processes;filtration can be either as solid-liquid or liquid-liquid separation.Membrane based on cake filtration is a process,which consists in deposition of solid particles on the supporting medium surface;this process results generally in the formation of a cake filter layer over the porous supporting medium capable to retain suspended particles and/or adsorb organic pollutants during filtration process.The driving force to perform membrane filtration is called trans-membrane pressure(TMP);and this driving force increases because of cake layer causing gradual to filtration resistance.As a new advanced sewage treatment process,dynamic membrane technology(DM)is particularly advantageous than traditional membrane bioreactor(MBR)when it comes to solve problems encountered during membrane filtration process including low filtration flux and the cleaning membrane system to control membrane fouling;making it a potential technology that may overcome shortage of conventional membrane bioreactor.The same is also true for its effluent quality and the decrease in permeate flux which resulted from the dynamic membrane layer formed on membrane support material in DM formation process;as the solute forming material and the membrane support material pores sizes ratio influences the stability of the formed dynamic membrane layer.Independently of the membrane support materials used,a dynamic membrane layer with average porosity was formed during DM formation step and it was acting as a filter layer to adsorb all organic pollutants in dyes wastewater.Different low cost membrane support materials of various pore sizes can be used to load the dynamic membrane layer as an alternative of conventional micro-filtration(MF)and ultrafiltration(UF)membranes;which makes dynamic membrane more advantageous and attractive in wastewater treatment and water reuse by reducing the membrane cost and low energy consumption.In this filtration of synthetic wastewater,the DM layer was formed by pre-depositing of certain quantity adsorbent material on the support membrane material,the dynamically formed membrane layer was therefore the main filtration screen;the more so as the membrane support material itself has no filtration ability.As more synthetic wastewater was passing through the supporting medium surface,the DM layer becomes more compact with low permeability.This effect enhanced the organic pollutants removal efficiency,but as TMP was increasing and becomes inhibited the DM was therefore performing at fouling potential behaviour.The filtration resistance increases as a result of DM layer compaction and membrane materials internal fouling while the permeate flow-rate decreases.Dynamic membrane removal efficiency was found to be directly affected by the DM formation process and the related hydrodynamic mechanisms.In this research,a dynamic membrane reactor device was designed and implemented to treat diluted textile wastewater.Dynamic membrane formation and filtration processes hydrodynamic mechanisms and interaction forces effects were investigated as well as the dynamic membrane fouling mechanism was identified.The study started by building up a continuous-flow dynamic membrane filter thin layer on the surface of the supporting medium with the use of new adsorbent for given conditions,12 g and 6g/L respectively the adsorbent mass and concentration,to be pre-deposited on different membrane support materials(MSMs)of various pore sizes;then evaluate the efficiency in removing organic pollutants.From this primarily adsorbent mass used,we come to predict the required DM thickness for the filtration of a known initial dyes concentration.Particles velocity speed second after second deposition on the supporting medium has been evaluated based on the balance forces of drag and gravity.Related hydrodynamic forces that influence as well as possible foster the DM filtration have been studied.The experimental results have shown that the incoming fluctuation flow was found to cause disturbances in the filtration unit,at Re ? 98 convection driving force was dominant then maintain a smooth flow.While at Re ? 100 shear stress at DM surface was more important to generate eddy circulation and then provoke particles erosion.Moreover,experimental results indicated that pre-depositing conditions determine the resulting DM layer,and that the thicker and more compact DM layer is;the stronger it can resist against vortices shedding and more efficiency it could remove high concentration of organic pollutants within the same filtration time.In contrast with conventional membrane filtration processes,low pressure dynamically formed membrane has proved to be a preferably approach in removing all organic pollutants,even at low biodegradability,from textile dyeing wastewater that cannot be achieved by conventional activated sludge process.The first used of the membrane material appeared to be a kind of pre-treatment process as regenerated MSMs have shown good compressibility characteristics and better filtration performance after each regeneration cycle.The obtained results also indicated that from a certain amount of PAC pre-deposited on different MSMs of various pore sizes,a flexible DM layer with different thickness was formed,which demonstrated that it was convenient to adjust the required DM layer for the filtration of known initial concentration.However,dynamic membrane performed a low fouling behaviour with the use of small pore size MSM;which resulted in an increase of the filtration pressure what have affected DM dyes adsorption performance.