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Author: Natalia Fischer Publisher: ISBN: Category : Carbon, Activated Languages : en Pages : 156
Book Description
Granular activated carbon (GAC) is effectively used to remove natural organic matter (NOM) and to assist in the removal of disinfection byproducts (DBPs) and their precursors. However, operation of GAC is cost- and labor-intensive due to frequent media replacement. Optimizing the use of GAC is necessary to ensure treatment efficiency while reducing costs. This dissertation presents four strategies to reduce improve GAC usage while reducing formation of DBPs. The first part of this work adopts Rapid Small Scale Tests (RSSCTs) to evaluate removal of molecular weight fractions of NOM, characterized using size exclusion chromatography (SECDOC). Total trihalomethanes (TTHM), haloacetic acids (HAA5) and haloacetonitriles (HAN) formation were quantified after treatment with GAC. Low MW NOM was removed preferentially in the early bed volumes, up until exhaustion of available adsorption sites. DBP formation potential lowered with DOC removal. Chlorination prior to GAC is investigated in the second part of this work as a strategy to increase removal of NOM and DBP precursors. Results showed lower TTHM formation in the effluent of the GAC treatment when pre-chlorination was adopted, meaning this strategy could help optimize and extend the bed life if GAC filters. The third part of this work investigates in-situ GAC regeneration as an alternative to recover adsorption capacity of field-spent GAC that could potentially offer new modes of operation for water treatment facilities while savng costs with reactivation of spent GAC in an external facility. Field-spent GACs were treated with different oxidant solutions and recovery in adsorption capacity was evaluated for NOM and for two micro pollutants. Recovery of GAC adsorption capacity was not satisfactory for most of conditions evaluated. This indicates that in-situ GAC regeneration could be more effective when the adsorbates are present at high concentrations. Lastly, this work investigates the impact of low molecular weight polyDADMAC on N-nitrosodimethylamine (NDMA) formation. Water treatment facilities rely on polyDADMAC as a coagulant aid to comply with NOM removal and turbidity requirements. Since polymer-derived NDMA precursors are not removed by GAC, it is essential to optimize the use and synthesis of polyDADMAC to reduce NDMA precursors during water treatment.
Author: Natalia Fischer Publisher: ISBN: Category : Carbon, Activated Languages : en Pages : 156
Book Description
Granular activated carbon (GAC) is effectively used to remove natural organic matter (NOM) and to assist in the removal of disinfection byproducts (DBPs) and their precursors. However, operation of GAC is cost- and labor-intensive due to frequent media replacement. Optimizing the use of GAC is necessary to ensure treatment efficiency while reducing costs. This dissertation presents four strategies to reduce improve GAC usage while reducing formation of DBPs. The first part of this work adopts Rapid Small Scale Tests (RSSCTs) to evaluate removal of molecular weight fractions of NOM, characterized using size exclusion chromatography (SECDOC). Total trihalomethanes (TTHM), haloacetic acids (HAA5) and haloacetonitriles (HAN) formation were quantified after treatment with GAC. Low MW NOM was removed preferentially in the early bed volumes, up until exhaustion of available adsorption sites. DBP formation potential lowered with DOC removal. Chlorination prior to GAC is investigated in the second part of this work as a strategy to increase removal of NOM and DBP precursors. Results showed lower TTHM formation in the effluent of the GAC treatment when pre-chlorination was adopted, meaning this strategy could help optimize and extend the bed life if GAC filters. The third part of this work investigates in-situ GAC regeneration as an alternative to recover adsorption capacity of field-spent GAC that could potentially offer new modes of operation for water treatment facilities while savng costs with reactivation of spent GAC in an external facility. Field-spent GACs were treated with different oxidant solutions and recovery in adsorption capacity was evaluated for NOM and for two micro pollutants. Recovery of GAC adsorption capacity was not satisfactory for most of conditions evaluated. This indicates that in-situ GAC regeneration could be more effective when the adsorbates are present at high concentrations. Lastly, this work investigates the impact of low molecular weight polyDADMAC on N-nitrosodimethylamine (NDMA) formation. Water treatment facilities rely on polyDADMAC as a coagulant aid to comply with NOM removal and turbidity requirements. Since polymer-derived NDMA precursors are not removed by GAC, it is essential to optimize the use and synthesis of polyDADMAC to reduce NDMA precursors during water treatment.
Author: T. Karanfil Publisher: IWA Publishing ISBN: 9781843398141 Category : Science Languages : en Pages : 0
Book Description
Powdered or granular activated carbon adsorption has been widely used in drinking water treatment plants primarily for taste, odor, and synthetic organic contaminant (SOC) removal. However, carbon adsorption has not been widely used for controlling DOM due to the low equilibrium capacities and slow adsorption kinetics. The main reason for these drawbacks is that the majority of commercial activated carbons have been developed primarily to remove small molecular weight hydrophobic SOCs from water. As a result, many commercial carbons do not provide feasible engineering solutions for removing large molecular weight and heterogeneous mixtures of DBP precursors. This research was undertaken to develop a fundamental understanding of tailoring activated carbons for DBP control. The main objectives of this project were to (1) conduct a systematic investigation for developing a fundamental understanding of how activated carbons should be tailored for enhanced removal of dissolved organic matter (DOM) from natural waters; and (2) investigate the effectiveness of some carbon tailoring approaches for disinfection by-products (DBP) formation control at typical drinking water treatment conditions. This project showed that the removal of DBP precursor by GAC adsorption can be significantly improved. GAC adsorption, using modified GACs, can provide another alternative to some water utilities for meeting the Stage 2 requirements of the Disinfectant/Disinfection By-Products Rule.
Author: Allyson Junker Publisher: ISBN: Category : Languages : en Pages : 103
Book Description
The addition of chlorine disinfectant to drinking water during the treatment process results in the formation of disinfection by-products (DBPs). The United States and several other nations regulate for DBPs in drinking water because studies have linked exposure to these compounds to increased incidence of cancers as well as birth and developmental defects. Incorporation of activated carbon(AC) into the drinking water treatment process may reduce the formation of DBPs through the adsorption of natural organic matter (NOM) precursors and formed DBPs. The goal of this research project is to investigate how AC can be better used by small-scale drinking water plants as a feasible option for reducing the DBPs formed in their systems, which would allow them to consistently achieve compliance with the Environmental Protection Agency’s latest regulation Stage 2 D/DBP Rule. This research compared the factors of AC particle size, carbon source material, and concurrent coagulant addition in NOM sorption experiments. Although concurrent chemical addition and carbon source had no significant differences on AC performance, the performance of powdered activated carbon (PAC) was notably greater than granular activated carbon(GAC). Characterization of NOM in source water showed preferential adsorption of hydrophilic NOM compounds onto the AC. Finally, a pilot studied was designed to investigate the potential of granular activated carbon (GAC) to adsorb formed DBPs before entering the distribution system.
Author: David Hanigan Publisher: ISBN: Category : Electronic Dissertations Languages : en Pages : 76
Book Description
The objective of this research was to investigate NOM removal with activated carbon and MIEX®. Hydrophilic (HPI), hydrophobic (HPO), and transphilic (TPI) NOM was fractionated and subsequent DBP formation from these fractions was studied. Several new adsorptive materials (greensand, carbon nanotubes, iron impregnated activated carbon) were tested for DBP reduction potential. Reductions by the materials were poor and therefore the materials were not investigated further. Activated carbons, although similar in structure, perform differently from each other. Aqua Nuchar® and Hawkins Sabre Series® had greater than 30% difference in TTHM FP reduction under the same test conditions. None of the activated carbons investigated were found to have potential for brominated DBP precursor removal. When MIEX® (magnetic ion exchange) was compared to activated carbon with respect to NOM fraction removal, it was found that MIEX® removed more of the HPI and TPI fractions. This was represented well in DBP FP reductions specifically derived from reactions with NOM in these fractions. In particular, MIEX® decreased NOM in the HPI fraction only 10% more than activated carbon but decreased TTHM FP 34% greater than activated carbon. This suggests that MIEX® preferentially removes DBP precursors to a greater extent than activated carbon. MIEX® was also found to decrease formation of brominated DBPs. SUVA, UV254, DOC, and chlorine demand were all investigated as surrogate parameters for DBPs. UV254 was found to correlate best with DBP formation with 0.56
Author: Natalia Fischer
Author: Natalia Fischer
Author: T. Karanfil
Author: Karen Blake Burnett Carter
Author: Allyson Junker
Author: John Clark Maness
Author: Stuart M. Hooper
Author: David Hanigan
Author: 
Author: Leon S. Directo
Author: Michael J. McGuire