Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7148
Browse
2 results
Search Results
Article Citation - Scopus: 6An Experimental Study on Release Mechanism of Iron and Manganese From Sediments To the Water Column in Reservoirs(Yildiz Technical University, 2021) Vural,B.; Elçi,Ş.; Ökten,H.E.Iron and manganese accumulation in drinking water reservoirs is a challenging issue and should be controlled to prevent their adverse effects on human health. Accumulation of these elements not only clogs pipeline systems but also causes stains on fixtures and laundry. Also, high concentrations of iron and manganese may lead to various health problems when ingested. This study focuses on the release mechanism of iron and manganese from sediments to the water column in reservoirs and investigates methods to prevent this release. Effects of hypoxia, hypolimnetic aeration, alkalinity of water, and thermal stratification on iron and manganese concentrations were investigated through laboratory experiments. Experiments done simulating the water column showed that hypoxia caused more dissolution of ferrous iron when compared with that of manganese. Accordingly, aeration of the water column in hypoxic conditions lead to a significant decrease in ferrous iron concentrations (in our case reaching zero). However, manganese and total iron levels were not affected by the aeration of the water column. Alkalinity level of the water column was observed to have a great effect on the solubility of iron and manganese. Concentrations of total Fe and total Mn measured for acidic (pH = 5) conditions were considerably greater than concentrations measured at neutral conditions. As for alkaline (pH = 11) conditions, the opposite was observed with measured concentrations of total Fe and total Mn being lower than the ones measured for neutral conditions. Thermal stratification had an enhancing effect on the solubility of both iron and manganese ions. While aeration of the stratified water column slightly decreased the concentrations of Total Fe and Mn, it had a greater impact on decreasing Fe2+ concentrations. Copyright 2021, Yıldız Technical University.Conference Object Design of an Artificial Destratification System To Control Cyanobacteria Growth in Reservoirs(Iahr-int Assoc Hydro-environment Engineering Research, 2022) Hazar, Oguz; Bahadiroglu, Nisa; Karakaya, Derya; Elci, SebnemThis study aims at designing an artificial destratification system to control cyanobacteria growth in the reservoirs. Previous applications for artificial destratification in reservoirs were based on trial and error on site, where neither the effect of air bubble size and configuration nor the effect of air density in the bubble plume could be investigated. This study seeks for the optimized design. We have tackled this task at four steps. Firstly, we setup an experimental system that mimics a thermally stratified reservoir experiencing hypoxia and oxygenate/mix the water column. We maintain a stable stratification by a novel setup designed for this study enabling to form consistent and desired stratified layers along the water column. Next, we investigate the effects of bubble size, bubble slip velocity and other parameters on destratification efficiency. Nondimensional numbers involving bubble diameter, bubble diffusing area, air rate and stratification rates are used to quantify destratification efficiency for the best design of aeration systems. Then, we simulate the hydrodynamics during the mixing of thermally stratified water columns by air diffusers via a 3-D numerical model. The Eulerian multiphase model and k-. turbulence model are found to be suitable for the purposes of the study. In the final part, the numerical model is validated with the experiments. Based on the error analysis of comparisons of the model and observations, the best configuration of air diffuser is proposed, and the numerical model is found to be successful in simulating the destratification of thermally stratified water columns by air diffuser.