Investigation of the chlorine dioxide disinfection in terms of disinfection by product (DBP) formation of Omerli raw water in Istanbul

Chlorine which is nowadays the most commonly used disinfectant, interacts aquatic organic matter and causes formation of harmful disinfection by products. For this reason, number of researches on chlorine dioxide as a disinfectant alternative to chlorine, increased in recent years. After disinfection via the chlorine dioxide, chlorite and chlorate which defines as inorganic by products are formed. Chlorite total maximum concentration in water is limited as 1 mg/L as by USEPA. WHO limits total maximum chlorite concentration as 0.7 mg/L in water. There is no detailed study has been conducted for determination of the limit value yet in our country. In this study; after 0.25; 0.50; 0.75; 1; 1.25 and 1.5 mg/L chlorine dioxide had been dosed to Omerli raw water samples taken in December, and February; disinfection by products: chlorite, chlorate, THMs, HAAs and water quality parameters such as TOC, chloride, floride, bromide, sulphate and nitrate were analyzed and effect of the pH and contact time also investigated

Modeling the formation of chlorination by-products during enhanced coagulation

Because of increasing need to balance health risks for pathogen control and disinfection by-products (DBP) formation in drinking water supplies, water utilities are forced to closely examine and optimize their disinfection practices. This research was designed to investigate the effects of independent variables of dissolved organic carbon (DOC), ferric chloride dosage, chlorine dose, and reaction time on trihalomethanes (THMs) formation in Terkos Lake Water (TLW) of Istanbul City. A statistically-based empirical model was developed for predicting THM formation during enhanced coagulation. The R-2 and F value of model were 0.762 and 460, respectively. The model was found to be statistically significant for all four variables, and model predictions appear to be most accurate for this study. A multiple linear model exhibited the best fit of data. It was observed that THM formation depended primarily on DOC removal. Model calibration, testing and validation were accomplished by using independent data set

Disinfection by-product precursors reduction by various coagulation techniques in Istanbul water supplies

Coagulation process can be used to control natural organic matter (NOM) during drinking water production. The effectiveness of the coagulation process appeared to depend on the pH of coagulation rather than coagulant dosages. Jar tests conducted with depressed pH levels at different coagulation conditions removed more dissolved organic carbon (DOC) than those at moderate pH levels. For low DOC waters, like Omerli Lake Water (OLW), additional treatment would be necessary to achieve enhanced removal of NOM. In this study, three different coagulation techniques were used to remove disinfection by-products (DBP) precursors from three Istanbul surface water supplies. Jar test results indicate that optimize coagulation (OC) can enhance the removal of DBP precursors, and the removal of DOC could be improved from the current average of 15% to an average of 56% at the three sites tested. At lower pH, ferric coagulants generally performed better for removal of DBP precursors than did alum. (c) 2006 Elsevier B.V. All rights reserved

Multiple linear regression modeling of disinfection by-products formation in Istanbul drinking water reservoirs

Oxidation of raw water with chlorine results in formation of trihalomethanes (THM) and haloacetic acids (HAA). Factors affecting their concentrations have been found to be organic matter type and concentration, pH, temperature, chlorine dose, contact time and bromide concentration, but the mechanisms of their formation are still under investigation. Within this scope, chlorination experiments have been conducted with water reservoirs from Terkos, Buyukcekmece and Omerli lakes, Istanbul, with different water quality regarding bromide concentration and organic matter content. The factors studied were pH, contact time, chlorine dose, and specific ultraviolet absorbance (SLTVA). The determination of disinfection by-products (DBP) was carried out by gas chromatography techniques. Statistical analysis of the results was focused on the development of multiple regression models for predicting the concentrations of total THNI and total HAA based on the use of pH, contact time, chlorine dose, and SUVA. The developed models provided satisfactory estimations of the concentrations of the DBP and the model regression coefficients of THM and HAA are 0.88 and 0.61, respectively. Further, the Durbin-Watson values confirm the reliability of the two models. The results indicate that under these experimental conditions which indicate the variations of pH, chlorine dosages, contact time, and SUVA values, the formation of THM and HAA in water can be described by the multiple linear regression technique. (c) 2007 Elsevier B.V. All rights reserved

Physical Characterisation of Natural Organic Matter and Determination of Disinfection By-Product Formation Potentials in Istanbul Surface Waters

Natural organic matter (NOM) is a complex mixture of various organic molecules mainly originating from aquatic organisms, soil and terrestrial vegetation which enters surface and ground waters. Through the different reaction reactivity of the NOM components with disinfectants, isolation and fractionation of NOM into more homogenous components is the better way of determining the DBP formation potential of the waters. Within the aim and scope of this paper, raw water samples were taken from Buyuk-cekmece (BC) and Omerli (OM) surface water sources which supply drinking water to Istanbul, in eight different months between February 2010 and February 2011. At first water quality parameters were analysed. Then, the physical structure of the waters' dissolved organic matter (DOM) content, seasonal variations of this structure, reactivity of DOM by means of DBP production and the effects of the seasonal variations on this reactivity were investigated. In terms of specific reactivity of the OM and BC physical fractions, 5kDa fraction was also determined as the most reactive part of the DOM in terms of SAOXFP for both waters. Both of the waters SUVA values were increased due to the increase of DOM molecular weight but there was no similar trend in the formation of by-products. The main reason for this situation is the lower SUVA and DOM values of the waters investigated. In this context, it can be said that OM and BC waters have special characteristics

Investigation of the Usability of Automotive Industry Chemical Wastewater Treatment Sludge as An Additive to Brick Raw Material in Terms of Firing Process Stack Gas Emissions

The gradual decrease in the capacity of landfill sites necessitates the use of alternative disposal methods instead of the storage for disposal of industrial treatment sludges, which are not classified as hazardous and non-combustible wastes. The use of these wastes in other industrial areas as a raw material or raw material additive is an important research area, at the present time. By this usage, disposal cost reduction and landfill usage period increments will be provided. In this study, firing process stack emissions are investigated when using automotive industry treatment sludge as an additive to brick raw material. Chemical treatment sludge, which is categorized as non-hazardous. according to the General Fundamentals Relating to Waste Management Regulation (GFRWMR) Appendix-3-B, does not adversely affect the product quality, with additive rates of 5% and 10 to raw material, according to experimental studies on field-scale experimental brick production. During the firing process, stack gas emissions were sampled and measured according to the Industry Originated Air Pollution Control Regulation (IOAPCR), and the Hazardous Waste Control Regulation (HWCR). According to the measurement results, chemical treatment sludge as an additive to the raw material was determined as a useful recycling option; however, it should be monitored according to variable process conditions

Investigation of the usability of automotive industry chemical wastewater treatment sludge as an additive to brick raw material in terms of firing process stack gas emissions

The gradual decrease in the capacity of landfill sites necessitates the use of alternative disposal methods instead of the storage for disposal of industrial treatment sludges, which are not classified as hazardous and non-combustible wastes. The use of these wastes in other industrial areas as a raw material or raw material additive is an important research area, at the present time. By this usage, disposal cost reduction and landfill usage period increments will be provided. In this study, firing process stack emissions are investigated when using automotive industry treatment sludge as an additive to brick raw material. Chemical treatment sludge, which is categorized as non-hazardous according to the General Fundamentals Relating to Waste Management Regulation (GFRWMR) Appendix-3-B, does not adversely affect the product quality, with additive rates of 5% and 10 to raw material, according to experimental studies on field-scale experimental brick production. During the firing process, stack gas emissions were sampled and measured according to the Industry Originated Air Pollution Control Regulation (IOAPCR), and the Hazardous Waste Control Regulation (HWCR). According to the measurement results, chemical treatment sludge as an additive to the raw material was determined as a useful recycling option; however, it should be monitored according to variable process conditions

Chemical Characterization of Natural Organic Matter and Determination of Disinfection By-Product Formation Potentials in Surface Waters of Istanbul (Omerli and Buyukcekmece Water Dam), Turkey

All surface and ground waters contain natural organic matter (NOM). NOM is a complex mixture of various organic molecules mainly originating from aquatic organisms, soil and terrestrial vegetation. When chlorine is applied to drinking water processes, it reacts with NOM and forms various types of chlorinated disinfection by-products (DBPs). These halogenated by-products are considered to be possible human carcinogens. Trihalomethanes (THMs) and haloacetic acids (HAAs) are the most widely known DBPs. Through the different reaction reactivity of the NOM components with disinfectants, the isolation and fractionation of NOM into more homogenous components is a better way to determine the DBP formation potential in the waters. Characterization of the NOM is also important for the selection of drinking water treatment processes because the US Drinking Water Regulations force water utilities to further increase DBP precursor removal by removing DOC to below 2 mg/L. In this study, using Omerli (OM) and Buyukcekmece (BC) surface water samples which were obtained over a 1-year period, the NOM content was isolated and chemically fractionated by means of XAD resins. In addition, each fraction was chlorinated separately and THMs and HAAs formation potential (THMFP and HAAFP) was investigated. The results indicated that both water chemical phases changed on a seasonal basis. This affects the DBPFP of waters. Hydrophobic (HPO) fraction was detected to be the highest percentage of the DOM in both OM and BC. But in terms of the DBPFP dominant phase, this changes seasonally. These results indicated that OM and BC surface waters include THM and HAA precursors and variations of these fractions are also effective for treatment process selection and attaining consistency in drinking water quality

Stabilization and solidification of electric arc furnace dust originating from steel industry by using low grade MgO

In this study, solidification/stabilization (S/S) of electric arc furnace dust (EAFD) which is generated during the production of steel from scrap metals and classified as hazardous waste were investigated by using different ratios of cement and low grade MgO (LG MgO) as binding agents. Type I PC 42.5 R portland cement and LG MgO which contains 70-80% MgO were used. S/S blocks that contain different ratios of binding agents which have 1/0.5 - 1/1 - 1/2 - 1/3 - 1/4 - 1/5 cement/LG MgO ratio and S/S blocks which contain only cement and no LG MgO agents were prepared. These blocks, which contain 3 different waste ratios according to weight, 20%, 30% and 40% respectively, were produced and exposed to 28-day water purification. At the end of the purification process, S/S blocks were extracted using TCLP (Toxicity Characteristic Leaching Procedure) tests in order to determine the leaching behavior of Zn, Pb, and Cd in S/S blocks. By the end of this study, it was concluded that the recovery of EAFD is possible and applicable by immobilization. The findings of the study concluded that environmental performances or structural properties of blocks contain 30% waste by weight are suitable. This method is a proper one for recovering and treatment of EAFD with mixture of cement and LG MgO

Disinfection by-products precursors removal by enhanced coagulation and PAC adsorption

Because of concerns over the health effects of disinfection by-products (DBPs), the removal of DBPs precursors from the Terkos Lake water (TLW) of the Istanbul City by enhanced coagulation and powdered activated carbon (PAC) adsorption was investigated. The results of this study clearly indicated that the effects of coagulation and PAC adsorption on the removal of dissolved organic carbon (DOC) and DBPs precursors from TLW were complementary. Maximum DOC removal efficiency of enhanced coagulation by ferric chloride was 45%, and this type of natural organic matter (NOM) is preferentially large organic molecules with negatively charged functional groups. However, supplementing enhanced coagulation with PAC adsorption increased the removal of DOC to 76%, and PAC adsorption removed mostly low molecular weight and uncharged NOM substances. This study shows that the combination of enhanced coagulation and PAC adsorption can be more effective than enhanced coagulation alone for meeting the Turkish trihalomethanes (THM) limit of 150 mu g/L