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PREDICTIVE MODELING OF SULFIDE REMOVAL IN TRAY AERATORS
Title
PREDICTIVE MODELING OF SULFIDE REMOVAL IN TRAY AERATORS.
Creator
Faborode, Jumoke, Reddi, Lakshmi, University of Central Florida
Abstract / Description
Hydrogen sulfide is commonly found in many Florida potable groundwater supplies. Removing sulfur species, particularly hydrogen sulfide is important because if left untreated, sulfide can impact finished water quality, corrosivity, create undesirable taste and odor, and oxidize to form visible turbidity and color. This document presents the results of a study designed to investigate the removal efficiencies of a variety of tray aerators in Central Florida in order to develop a predictive...
Show moreHydrogen sulfide is commonly found in many Florida potable groundwater supplies. Removing sulfur species, particularly hydrogen sulfide is important because if left untreated, sulfide can impact finished water quality, corrosivity, create undesirable taste and odor, and oxidize to form visible turbidity and color. This document presents the results of a study designed to investigate the removal efficiencies of a variety of tray aerators in Central Florida in order to develop a predictive mathematical model that could be used to determine tray effectiveness for sulfide removal. A literature review was performed that indicated there was limited information regarding the removal of hydrogen sulfide using conventional tray aerators, and no information regarding the removal of total sulfide from tray aerators. There was significantly more information available in the literature regarding the usefulness of sulfide removal technologies from water supplies. Consequently, the lack of literature regarding sulfide removal using tray aerators suggested that there was a need for additional research focused on sulfide removal from water flowing thru tray aerators. Several water purveyors that relied on tray aerators as a part of their water treatment operations were contacted and requested to participate in the study; three water purveyors agreed to allow the University of Central Florida (UCF) to enter their secured sites to collect samples and conduct this study. The three facilities included the UCFÂÂ's water treatment plant located in Orlando and situated in eastern Orange County, the City of Lake HamiltonÂÂ's water treatment plant located in west-central Polk County, and the Sarasota-Verna water treatment plant located in western Sarasota County. An experimental plan was developed and field sampling protocols were implemented to evaluate sulfide removal in commonly used tray aerators at the three drinking water treatment facilities. Total sulfide concentrations passing through the trays were determined in the field at each site using a standard iodometric analytical technique. In addition, other water quality parameters collected included dissolved oxygen, pH, temperature, conductivity, turbidity, alkalinity, hardness, total dissolved solids and total suspended solids; these samples were collected and analyzed either in the field or at the UCF laboratory. A first-order empirical model was developed that predicted sulfide removal in tray aerators. The modelÂÂ's constant was evaluated with respect to the waterÂÂ's proton concentration , the tray aeratorÂÂ's surface area, and hydraulic flow rate thru the trays. The selected model took the form of Cn=C0 (10-kn) where Cn is the sulfide remaining after aeration in mg/L, C0 is the sulfide entering the distribution tray in mg/L, n is the number of tray stages in the aerator, and k=(0.00248)(H^+ )^(-0.397) (Area)^0.584 (Flow)^(-1.17). From the empirical model, it was shown that sulfide removal was negatively impacted as the proton concentration (H+) decreased, and flow increased. Conversely, it was observed that increased sulfide removal occurred as the available tray aerator surface area increased. The combined parameters of proton concentration, flow rate, and area were statistically evaluated and used to develop an empirical constant that could be used in a first order model to predict sulfide removal in tray aerators. Using a site-specific derived experimental (empirical) constant, a water purveyor could use the developed model from this work to accurately predict sulfide removal in a tray aerator by simply measuring the total sulfide content in any raw groundwater supply and then providing the desired number of tray stages available for treatment.
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Date Issued
2010
Identifier
CFE0003518, ucf:48980
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0003518
Disinfection By-Product Reduction Study of a Small Central Florida Public Water System
Title
Disinfection By-Product Reduction Study of a Small Central Florida Public Water System.
Creator
Staubus, Paul, Duranceau, Steven, Sadmani, A H M Anwar, Randall, Andrew, University of Central Florida
Abstract / Description
The disinfection of water for potabilization has proven to be one of the most significant public achievements of the 20th century. Although chemical disinfectants are successfully utilized to inactivate acute pathogenic organisms, they may react with natural organic matter (NOM) to produce potentially-harmful disinfection by-products (DBPs). As a result, the United States Environmental Protection Agency regulates DBPs such as total trihalomethanes (TTHMs) and haloacetic acids (HAAs). The...
Show moreThe disinfection of water for potabilization has proven to be one of the most significant public achievements of the 20th century. Although chemical disinfectants are successfully utilized to inactivate acute pathogenic organisms, they may react with natural organic matter (NOM) to produce potentially-harmful disinfection by-products (DBPs). As a result, the United States Environmental Protection Agency regulates DBPs such as total trihalomethanes (TTHMs) and haloacetic acids (HAAs). The research herein is focused on the formation, removal, and control of TTHMs and HAAs in a small public water system (PWS) in Polk County, Florida (County). Pilot-scale tests were implemented to determine the efficacy of stripping TTHMs using single-pass spray and recirculating tray aeration systems, both operating at flows of 3 gallons per minute. In the spray aerator evaluation, an average TTHM reduction of 29.5% was recorded. With tray aeration, a 46.7% reduction of TTHMs was observed after a single pass through the assembly. The benefits of additional recirculation appeared to decrease significantly after four passes, at a TTHM removal of 85.5%. A raw water blending effort was conducted to model bypass around granular activated carbon (GAC) adsorption vessels. The results demonstrated the feasibility of a 50% blend in full-scale treatment operations. With this blend, chlorine residuals and HAA concentrations were able to be controlled throughout 48 hours of incubation at 30(&)deg;C. From the data collected, a water quality plan was developed for the County's Waverly PWS. The plan to control the formation of DBPs integrated a recirculating tray aeration process for TTHM stripping complemented with GAC adsorption process for removing DBP precursors.The estimated conceptual operating cost was approximated at $24,000 annually. This cost considered carbon replacement as well as the recirculation pump operation. If the recommended 50% GAC bypass is applied, the conceptual operating cost reduces to approximately $15,250 annually.
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Date Issued
2018
Identifier
CFE0007249, ucf:52175
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0007249
Investigating Novel Water Treatment Methods and Monitoring Techniques for Sulfide-Laden Groundwater Supplies
Title
Investigating Novel Water Treatment Methods and Monitoring Techniques for Sulfide-Laden Groundwater Supplies.
Creator
Yoakum, Benjamin, Duranceau, Steven, Lee, Woo Hyoung, Sadmani, A H M Anwar, Moore, Sean, University of Central Florida
Abstract / Description
This dissertation reports on research related to novel water treatment and monitoring techniques for sulfide-laden groundwater supplies. The dissertation is divided into several chapters with four core chapters focused on investigations studying a novel water treatment method or monitoring technique. The first investigation assessed the efficacy of multi-pass spray aeration treatment to remove trihalomethanes (THMs) and to reduce the total THM formation potential (TTHMFP) of an aerated water...
Show moreThis dissertation reports on research related to novel water treatment and monitoring techniques for sulfide-laden groundwater supplies. The dissertation is divided into several chapters with four core chapters focused on investigations studying a novel water treatment method or monitoring technique. The first investigation assessed the efficacy of multi-pass spray aeration treatment to remove trihalomethanes (THMs) and to reduce the total THM formation potential (TTHMFP) of an aerated water column post-aeration. A recirculating spray aeration pilot unit was constructed to make this assessment. To assess the effect of multi-pass spray aeration on the TTHMFP, water was recirculated through a fabricated spray nozzle for various lengths of time. Results showed that multi-pass spray aeration can remove chloroform, dichlorobromomethane, dibromochloromethane and bromoform to below detection levels ((<) 0.7 ppb) for the waters investigated. Additionally, spray aeration reduced the TTHMFP of chlorinated water. Results suggest multi-pass spray aeration may be a viable treatment option for some bromide container waters. Results also indicate that multi-pass spray aeration removes bromide from the bulk water in the form of organically bound volatile compounds.The second investigation assessed the efficacy of using pre-existing tray aeration infrastructure to comply with disinfection by-product (DBP) regulations. To assess the efficacy of tray aerators to reduce the concentration TTHMs a pilot tray aerator was constructed. Results showed that after five tray passes (each pass consisting of water being passed over five trays) the concentration of TTHMs was below the detection limit ((<) 0.7 ppb) for the water investigated. To assess the efficacy of tray aeration at full-scale, a water treatment plant and the distribution system it serves were monitored for eight months. Results showed an approximate 40 ppb reduction in the TTHM concentration at two on-site monitoring locations and the one off-site monitoring location (initial concentrations being approximately 54 ppb, 60 ppb and 73 ppb, respectively). Results suggest that the utility managing the full-scale system could comply with DBP regulations by using the pre-existing tray aeration infrastructure to reduce formed THMs on-site where regulated haloacetic acids are not predominant.The third investigation assessed the efficacy of using biological activated carbon (BAC) to remove disinfection by-product precursor matter to comply with DBP regulations. To research this method, a pilot scale BAC filter was operated for three independent test runs. In addition, two full-scale WTPs using BAC were monitored over time. Results showed an approximate 40 percent removal of dissolved organic carbon (DOC) during the three pilot runs and an approximate 55 percent removal of DOC during full-scale monitoring. Results showed that the reduction in DOC reduced the TTHMFP of BAC treated water. Results suggest that BAC treatment could be a viable treatment option to comply with DBP regulations in the sulfide-laden water studied.The fourth investigation assessed the suitability of oxidation reduction potential (ORP) to monitor the effectiveness of an oxidizing media filter used to remove sulfur from a sulfide-laden groundwater. Results showed that ORP was more useful as a measurement technique as compared to free chlorine residual when assessing filter bed health and regeneration effectiveness. It was determined that when the ORP measurement taken from within the oxidative media layer was below 500 mV, the filter bed was not providing treatment, and manganese could be released. Results showed a significant increase in turbidity ((>) 2 NTU) and total manganese ((>) 0.05 mg/L) occurred when the ORP within the filter bed dropped below 400 mV. More frequent cycling of the filters was found to be an effective treatment option to maintain ORP values above an identified 400 mV operational threshold.
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Date Issued
2017
Identifier
CFE0007141, ucf:52317
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0007141