Sharif Digital Repository

Membrane bioreactors (MBRs) which are commonly understood as the combination of membrane filtration and biological treatment using activated sludge have several advantages, but membrane fouling reduces the membrane efficiency, permeability and lifetime. An alternative is replacing a moving bed biofilm reactor (MBBR) with the activated sludge system which may reduce the effect of membrane fouling. The sludge produced in MBBRs has poor settling characteristics, therefore, their efficiency is limited by the sedimentation tank performance and they require a larger settling surface. The combination of moving bed biofilm reactors and membrane bioreactors can compensate for the drawbacks of both of... 

The application of membranes for separate of particles in mainly microbial flacs , are fast growing in biological treatment systems. Membrane bioreactors are now considered as one of the major new processes in wastewater treatment. However , membranes are expensive and costly. This study is carried out to test an innovative , locally made filters for separation of flocs in an MBBR reactor. This innovative filter is replacing a traditional settling tank. This type of filters is made very cheaply and has important advantages in installing and operation. Experiments were carried out in a laboratory scale MBBR unit. A filter unit consisting of 3 innovative filter tubes were placed and the... 

Removing nitrogen, as one the most surface and ground water contaminant is very important and in order to achieve this aim,nitrification and denitrification are effective and economical methods. In this work, moving bed biofilm reactor (MBBR) with initial denitrification structure, adapted from modified LUDZACK-ETTINGER (MLE) method used in order to industrial wastewater treatment with COD value in range of 900-2100 mg/lit and ammonium in range of 150-430 mg/lit in 3 hydrolic retention time of 18 , 12 and 8 hours.Aerobic reactor volume is 14.4 liter and anoxic reactor volume is 7.2 liter and reflux flow amount from aerobic reactor to anoxic reactor has considered being 3 times of anoxic... 

Nitrogen compounds are becoming increasingly important in wastewater management, because of the many effects that nitrogenous material can have on the environment that need nitrogen removal. In this study, the performance of a submerged fixed bed reactor in nitrogen removal, constructed two anoxic and aerobic sections under Modified Ludzack-Ettinger process was investigated. Laboratory experiments were conducted at a constant COD concentration of 350 mg/lit, hydraulic retention times of 8, 12 and 18 hours and influent ammonia loading rate between 0.128 and 0.955 g NH3/m2.day. Nitrogen removal efficiency was obtained between 80.4 and 97.3%, and COD removal efficiency was achieved between 88.9... 

Eutrophication and algae growth is one of the consequences of high concentration of nutrients in surface water bodies; therefore, both phosphorus and nitrogen existing in wastewater or at least one of them should be decreased to a standard amount before entering water to rivers. This can prevent eutrophication and detriment to the ecosystem of rivers. An investigation on both biological and chemical phosphorus and carbon removal in low loading rate influent ( below 100) has been carried out in this research. Investigated topics includes aerobic COD removal in IFAS reactor, comparison of biological nutrient removal to the combination of chemical and biological method, effect of the order of... 

Heavy metals, present in many industrial wastewaters, are considered as major pollutants of environment. Various methods to removal heavy metals effectively from effluents have been used in industry, yet more efficient and economical methods are required. Magnetic iron nanoparticles are known for their superior adsorption, ion exchange and electro-static forces characteristics.The aim of this study was to evaluate the efficiency of magnetic nanoparticles for removal of hexavalent chromium (VI) and Divalent nickel from wastewater and the parameters that influence the removal.The magnetite nanoparticles were prepared by co-precipitation method where produced Fe3O4 nanoparticle’s average size... 

Growing rate of eutrophication in receiving waters has made the enhancement of wastewater treatment plants to advanced methods of nutrients removal as necessary. Nitrogen and Phosphorus as the nutrients can reduce the quality of water and even make it unusable. Phosphorus is known to be one of the main reasons of eutrophication and creation of algal bloom. In this study, chemical-biological method for phosphate removal from the municipal wastewater is studied. Experiments are implemented for hydraulic retention times of 4, 8 and 16 hours, total intake concentration of phosphorus 7 ppm, COD 400 ppm and Nitrogen 25 ppm. Ferric Chloride as the precipitator chemical substance injected into the... 

There are a lot of industry, including refineries with saline wastewater. Biological wastewater treatment saline pose particular problems and leads to plasmolysis microorganisms in the presence of salt. Remove salt from the wastewater before biological treatment by reverse osmosis or ion exchange and other methods are expensive and often impossible. Remove nutrients from wastewater before disposal and give up their saline for nature is essential. Because the these materials, especially nitrogen and phosphorus can degrade water quality and even make it unusable. So that by increasing the concentration of the algae production is also too much and cause eutrophication of water tanks are grown.... 

In this research, MBBR was used to study petrochemical and gas refinery industry's low strength wastewater COD removal for reuse purposes. Reactor's feed was synthesized based on data analysis conducted by fourth wastewater treatment facility operating in phases 6,7 and 8. Inlet COD was 70 mg/L and this COD was provided by different portions of Mono ethylene glycol and Tri ethylene glycol. COD removal was studied under 1, 2 and 3 hours hydraulic retention time. Reactor's feed was provided with COD ratio of ( 〖COD〗_MEG/〖COD〗_total ) 65%, 60% and 50%. For the first time, hybrid combination of activated sludge system and MBBR was carried out and recycle stream was used in this system. The... 

There is a growing demand for efficient treatment plans which can deal with high loading of organic pollutant, considering the population growth in communities. Our country is going toward industrialization; hence, it requires more effective and efficient treatment plans as well as innovative ones. Moving Bed Biological Reactors are accounted amongst appropriate methods in removing various pollutant which has been used in recent decades. In regard to increasing demand for new treatment plans, one of the options can be upgrading of existing activated sludge systems. Two bioreactors with 10 liter volume each in parallel lines were used in this work. One of them was a regular MBBR as a blank... 

Recent advances suggest that many of the issues involving in improving water quality could be solved by using nano particles. Aquifer and groundwater remediation are also critical issues. Becoming more important as water supplies steadily decrease and demand continues to increase. Although some of the remediation technologies available today are , they are costly and time-consuming, especially pump and treat methods. A wide range of nano particles have been used for the removal of organic and inorganic contaminants. In the first part of this work, zero-valent Iron nano particles was synthesized and was covered with nickel as catalyst. Diameter of the synthesized nano particles was... 

One of the most significant consequents of industrial world is environmental pollutions which displays its mortal effects in all aspects of human life including water, atmosphere and soil. After different applications of water, variable substances like organic and mineral components, toxics, heavy metal, etc is added to the water and wastewater. One of these organic components which appear in runoff and industrial wastes specially refinery companies’ is Ethylene Glycol (EG). It is used in Poly ethylene Glycol, Poly Viniles and Resin product industries, etc. In this research the effect of EG on COD removal and performance of an Anaerobic Baffled Reactor during treating Ethylene Glycol... 

In the modern societies, wastewater treatment is essential in achieving high level of standard in environmental protection and disposal. Recently, many researches are performed to study the surfactants’ biological decomposition in wastewater treatment process. In this project, fixed bed aerobic reactors are used in order to remove surfactant from wastewater. Integrated fixed film activation sludge reactor (IFAS) is used to remove surfactants and organic matters. It also used to study the capability of micro organisms in organic load removal in fixed bed biofilm for biological treatment of industrial wastewater. Pumice stone were used as the support in the reactor. The pumice stone is a... 

Air entering in to the water supply systems and occurrence of two-phase flow makes several problems in design and operation of these systems by damaging the structures and making indefinite and complicated conditions. Existence of some singularities like contractions in pipelines makes the conditions more indefinite. So an experimental study is performed in order to investigate the two-phase flow hydraulic properties in a rectangular channel in presence of an area contraction. The contraction ratio is σ=0.44, whereby the test section is included two different rectangular channels from 60 × 100 mm to 40 × 67 mm. Four series of experiments are performed using four types of transitions with... 

One of the common and frequent problems in sewer systems is sediment deposit in the pipes and conduits. In a sewer system, most of the pipes experience extensive fluctuations of flow rate during their operation. There could be high and low flows of fluids passing through the pipe. In the former, solid particles will pass through the pipe because of the high velocity of the flow, while in the latter, velocity of the flow is lower than the self cleaning velocity. Lower velocities of flow lead to deposition of solid particles inside the pipe. As a result, several problems such as decrease of pipe capacity, lower velocity and system over flow happen. A promising solution to overcome this problem... 

Sharp crested weirs are one of the main and oldest means of measuring discharge in water conveyance systems. Many studies have been done on sharp rectangular weirs and have provided many relationships regarding the effect of geometric parameters and various factors on discharge coefficient of the weirs.In some places, due to existence of obstacles or barriers in the channel, it is impossible to create a symmetrical continuous weir some other cases, multiple or asymmetric or curved weirs should be used, which is the main concept of this project. Since it seems unlikely that a purely mathematical model can review the impact of the multiplicity and asymmetry of these weirs without using... 

In this text to find the answer of the question “ what is it to be physical” in a definition form or a scheme of the term physical, firstly we sought for a possible consensus among recent physicists and philosophers. But from their answers not only we did not find any clear consensus but also most of them confess that the term is ambiguous and unclear. In a general aspect, we can categorize the answers to two theoretical and realistic perspective. The theoretical perspective, beside circularity and Hempel’s triviality, seems not to present any criteria for being physical. In realistic perspective, it seems that there is no ontologic constraint for being physical, that is from “being... 

This thesis addresses the problem of dynamic security assessment in power sys-tems with an emphasis on its application in restructured power systems and issues arising in its applications. The new electric utility environment has an immedi-ate consequence of emphasis on reliability and secure operation of power systems. This requires faster and more precise methods to assess the dynamic aspect of se-curity. On the other hand, this issue is becoming challenging when the determined dispatch might not be accommodated due to violation of the limits.This thesis addresses the problem of dynamic security assessment in power sys-tems with an emphasis on its application in restructured power systems...