Sharif Digital Repository

Water hammer is a pressure surge or wave resulting when a pressurized fluid in motion is forced to stop or change direction suddenly. This phenomenon can cause great amount of damage to the system and should be considered in designing of pipe systems. So, researchers have derived and proposed numerous models using different approaches. In this study a one-dimensional model using Time Splitting Method (TSM) and Double Sweep Method (DSM) are proposed to simulate transient flow in deformable pipes in networks. To solve the equations of momentum and continuity TSM is applied. In addition Brunone model is used to study the effect of unsteady friction on water hammer wave shape and attenuation. To... 

Selective withdrawal from water and settlement reservoirs and tanks is necessary for water and environmental systems. Perforated pipes can be used for selective withdrawal within the length of these reservoirs. In this method, the lateral inflow through perforations leads to the outlet of the pipe that is placed in a depth of fluid. In relation to the hydraulics of perforated pipes, most studies are about drainage pipes and perforated pipes that are used as wellbores in horizontal wells, but application of these pipes have not been investigated in submerged situations. Capacity estimation of perforated pipes based on inside diameter of the pipe, material of the pipe, perforations of the... 

In this study, the effect of submerged vanes on the bed scouring and deposition pattern at a 90̊ open-channel junction was investigated. First, the bed formation without submerged vanes were studied under the effect of hydraulic variables like the discharge ratio of tributary to main channel and the ratio of mean approach velocity to the threshold velocity. The results show that scour holes enlarge with time while they move towards the downstream and the outer wall in the main channel. Also, by increasing the ratio of mean approach velocity to the threshold velocity about 0.5, the maximum scour depth occurred at the downstream junction corner with time. In the second stage, the proper vane... 

Slug Flow is one of the most important schemes of two-phase air/water flow, which is quite complex and quite different to a single-phase flow. Also one of the common water conveyance systems is a rectangular tunnel which may have adverse slope at some parts of the tunnel. In this study the hydraulic of slug flow in rectangular tunnels with variable slope from horizontal to adverse have been considered using experimental setup. About 150 tests were carried out for different air/water discharge ratios and adverse slopes, and dynamic pressure fluctuations together with the slug period were measured. It was observed that the pressure fluctuations increase as the air to water ratio increases and... 

In this study, the effect of submerged vanes on the flow pattern and dimensions of separation zone at a 90˚ open-channel Junction were investigated. The experiments were conducted in three stages. First, for validity of data with the results of webber et al, using ADV, velocities was teken without submerged vanes.in the second stage, experiments with dye injection was performed at confluence for several initial arrangement of vanes. From 54 different arrangements, two arrangements were selected. In three stage, three dimensional velocities was teken in two arrangement selected. Due to the significant reduction the size of separation zone in one of these arrangements, with moving this... 

Based on the air entrainment, the water conveyance tunnels can be categorized as pressurized, two-phase flow. When the flow is controlled by gates, sudden closure of gates would produce unsteady two-phase flow. The most important effect of such an event is the sudden change in the pressure which can be a function of channel slope, air and water inflow and their ratio. In this thesis the pressure change in unsteady two-phase in an experimental set up using rectangular tunnel is studied. About 100 tests were carried out for single and two-phase flow with various water and air discharges causing unsteady flow with different slopes. It was observed that in a defined slope the ratio of the... 

Fluid transient in a conduit is an unsteady flow, which is followed by the change in the flow rate condition. Pressure transients in pipeline systems are caused by fluid flow interruption from operational changes such as starting/stopping of pumps, sudden changes to valve setting, etc. Fluid transient analysis is commonly based on the assumption of no air in the liquid. However, air entrainment, trapped air pockets, free gas, and dissolved gases frequently are present in the pipeline. In fact, Air changes flow properties and transient pressure peaks in comparison with single-phase flow. Experimental study has been carried out to verify characteristics of transient pressure inside a... 

Resources management is essential duo to sustainable development and marine resources limitations. There are several ways to restore coastal damaged ecosystems, one of the best and most cost effective solution is establishment of artificial reefs. A popular type of artificial reef is named Reef ball, a hollow hemisphere. In some regions these habitats has also been used as submerged breakwater. These structures recover and protect endangered species ecosystem although they provide aesthetic view to a beach. Main application of these structures is to provide a safe environment for marine creature. In this study initially Transmission coefficient variation in two-dimensional model experiments... 

In this study biological denitrification method by moving bed biofilm reactor is investigated. The main advantage of MBBR reactor is due to their capacity for high removal rates and low operational problems such as clogging. Two MBBRs in series with 3 liter volume each, were designed in experimental set up and used in this research. Nitrification reactor worked under aerobic conditions and denitrification reactor operated under anaerobic conditions. Methanol was used as carbon source in the reactors throughout the study. Fifty percent of each reactor volume was occupied with KMT1 packing. To finding the optimum nitrate loading rate, the concentration of ammonium and nitrate were changed from... 

Different strategies for the treatment and disposal of petroleum and biological sludge found in the treatment and reuse unit of Arak Petroleum Refinery have been studied in the present study. To this end, the resources found in the literature corresponding to the different fields of sludge treatment were studied and a summary of them which was required by this research was mentioned in the thesis. Considering the problems bound to the wastewater treatment unit of this refinery plant and the previous studies, two completely separate strategies were devised. The first one concerns petroleum and biological sludge being produced continuously. The method of aerobic fixation of petroleum sludge by... 

One of the most important methods of controlling discharge in water industry which is widely used in irrigation, water distribution, waste-water engineering, drainage, flood control and other water related projects, is side weir. The hydraulic behavior of flow over side weir is spatially varied flow with decreasing discharge. Various investigators have related the weir discharge coefficient as a function of main channel upstream Froude number and the fraction of weir height to upstream depth . Performance of sharp crested side weirs with extended length (as labyrinth side weir with asymmetric geometry) has been studied in this thesis. The variables for this study are height of weir ,... 

Given that the most polluting industries in the country there. A suitable treatment system for degradation of these compounds is necessary unless unexpected effect on environment will occur.Moving Bed Biofilm Reactor (MBBR) was developed to adopt the best features of the activated sludge process as well as those of the biofilter processes. MBBR has biomass growth on carriers that move freely in the water volume of the reactor. High surface area of carriers make a good condition for biomass attached growth. This system has had good operation in the urban and some industrial wastewaters.In this study, four reactor volume of approximately 16 litr and 6, respectively, in the aerobic, anoxic... 

Local scouring at the downstream of sluice gates in the erosive beds is one of the main concerns of hydraulic engineers because of the significant damage that it can cause to the hydraulic structures. It is important to control the local scour depth at downstream of hydraulic structures to ensure safety operation of these systems. Many researchers have conducted various studies to predict the maximum depth and diameter of scour hole and develop new methods in order to control this phenomenon. One way to overcome this problem is the use of apron, or non-erosive bed. In order to shorten the apron length or decrease the effect of the... 

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 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 empirical... 

In recent years,because of increasing problems that result from water shortage ,using of wastewater treated by high quality and entering them to water cycle is considered more than past.Large amount of waste waterare produced through cooling towers in industries per a day .Therefore ,cooling tower’s blow down is a most important source for reclamation and reuse of water .The purpose of this project was investigation ofefficiency of submerged aerated filter for treating low organic simulated blowdown water as a feed . The experimental unit consisted of 8/5 L filled with 70 percent of propylene media . After obtaining steady –state condition ,The SAF reactor was tested under... 

Phenolic compounds are hazardous pollutants that are released into environment through wastewater discharges from variety of industries. Although good biodegradability has been reported at low concentrations, but at higher concentrations phenols are known to be antibacterial. In this study the Membrane Biological Reactor (MBR) with submerged hallow fiber membrane was operated at 25±2 ºC and pH=7.5±0.5 to treat a synthetic wastewater containing high phenol concentration (up to 5.9 g/l). Removal efficiency of phenol and COD were evaluated at four various “Hydraulic Retention Times” (HRT) of 24, 12, 8 and 4 hours. To test the tolerance of the bioreactor to phenol concentration various loading... 

Discharging treated or raw waste water in to surface water may cause lots of serious problems, including growth of algae, as a result of the presence of nutrients in waste water.algae decrease the concentration of dissolve oxygen in water.phosphorus removal from waste water is of absolute necessity. according to the standards set by the environmental organization, discharge the untreated waster water in to the surface water is not allowed. on the other hand, given manager facilities of deprived area,effort is channeled to reach the desired result through designing the simplest treatment systems. anaerobic-aerobic systems have remarkably been used for many years in the treatment of urban and... 

Antibiotic medications are widely used in medicine and veterinary medicine. Since these drugs are extremely dangerous to the environment and specially to drinking water for humans and other organisms, the need to treat these wastewater is becoming increasingly important. One of the most commonly used antibiotics is oxytetracycline which is used for a wide range of infectious diseases Husbandry wastewater is one of the wastewaters that contains high diversity and large amounts of antibiotics. In this study, the performance of a Moving bed biofilm reactor (MBBR) was investigated for removal of oxytetracycline from synthetic wastewater with similar characteristics to Husbandry wastewater. A... 

Greywater accounts for about 70% of household consumption and can be returned to the consumption cycle if a sustainable system is built in residential areas and the treated water can be used for irrigation, flash tank filling, and even aquifer fillings. The purpose of this study was to establish a sustainable method in small treatment plants that could sufficiently recover the water used in households. In this study, chemical ways of wastewater treatment, as well as membrane filtrations, were investigated to reduce greywater pollution. The results show that the coagulants alone can remove 80% of COD. Membranes can also reduce COD by up to 83%. In addition, the best removal efficiency using...