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Tatiana Yuzhakova - One of the best experts on this subject based on the ideXlab platform.
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Simulation of the influence of industrial wastewater on a municipal sewage treatment plant—a case study
Environmental Science and Pollution Research, 2011Co-Authors: Ákos Rédey, Viola Somogyi, József Ányos, Endre Domokos, Péter Thury, Tatiana YuzhakovaAbstract:Purpose Industrial wastewater flow caused operational difficulties in the wastewater treatment plant in Debrecen, Hungary. Bioaugmentation was successfully applied to maintain effluent quality in the periods when wastewater of high starch content was accepted, but, at the end of 2008, the nitrification capacity of the plant decreased considerably due to improperly pre-treated pharmaceutical wastewater. Methods and material Dynamic simulations were carried out in a prototype programme developed by the Environmental Expert System Research Group at the University of Pannonia, Hungary. Several parameters for heterotrophic biomass were adjusted in function of time, and the specific growth rate of autotrophic biomass was altered in function of time and temperature in order to describe the effects of inoculation and toxic influence. Simulations were carried out with both constant and adjusted parameters. Results Though results on effluent COD of the different modelling versions were similar, the ammonia concentration fitted the measured data only when modified parameters were used. The study revealed that the autotrophic biomass had slowly adapted to the toxic compound. Different control strategies of aeration and decreased excess Sludge Removal rate were tested to enhance the nitrification in the critical time intervals. The amount of ammonia and inorganic nitrogen decreased in all cases while the oxygen demand increased to a maximum of 10.1%. Conclusions Reducing excess Sludge Removal rate gave satisfactory results even without changing aeration. Further improvement could be achieved by introducing aeration into the post-denitrification reactor. The combination of the two modifications can compensate for the effect caused by toxicity.
S. Fink - One of the best experts on this subject based on the ideXlab platform.
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OXALATE MASS BALANCE DURING CHEMICAL CLEANING IN TANK 6F
2011Co-Authors: M. Poirier, S. FinkAbstract:The Savannah River Remediation (SRR) is preparing Tank 6F for closure. The first step in preparing the tank for closure is mechanical Sludge Removal. Following mechanical Sludge Removal, SRS performed chemical cleaning with oxalic acid to remove the Sludge heel. Personnel are currently assessing the effectiveness of the chemical cleaning to determine whether the tank is ready for closure. SRR personnel collected liquid samples during chemical cleaning and submitted them to Savannah River National Laboratory (SRNL) for analysis. Following chemical cleaning, they collected a solid sample (also known as 'process sample') and submitted it to SRNL for analysis. The authors analyzed these samples to assess the effectiveness of the chemical cleaning process. Analysis of the anions showed the measured oxalate removed from Tank 6F to be approximately 50% of the amount added in the oxalic acid. To close the oxalate mass balance, the author collected solid samples, leached them with nitric acid, and measured the concentration of cations and anions in the leachate. Some conclusions from this work are: (1) Approximately 65% of the oxalate added as oxalic acid was removed with the decanted liquid. (2) Approximately 1% of the oxalate (added to the tank as oxalic acid) formed precipitates with compounds such as nickel, manganese, sodium, and iron (II), and was dissolved with nitric acid. (3) As much as 30% of the oxalate may have decomposed forming carbon dioxide. The balance does not fully account for all the oxalate added. The offset represents the combined uncertainty in the analyses and sampling.
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ANALYSIS OF SAMPLES FROM TANK 6F CHEMICAL CLEANING
2010Co-Authors: M. Poirier, S. FinkAbstract:Savannah River Remediation (SRR) is preparing Tank 6F for closure. The first step in preparing the tank for closure is mechanical Sludge Removal. In mechanical Sludge Removal, personnel add liquid (e.g., inhibited water or supernate salt solution) to the tank to form a slurry. They mix the liquid and Sludge with pumps, and transfer the slurry to another tank for further processing. Mechanical Sludge Removal effectively removes the bulk of the Sludge from a tank, but is not able to remove all of the Sludge. In Tank 6F, SRR estimated a Sludge heel of 5,984 gallons remained after mechanical Sludge Removal. To remove this Sludge heel, SRR performed chemical cleaning. The chemical cleaning included two oxalic acid strikes, a spray wash, and a water wash. SRR conducted the first oxalic acid strike as follows. Personnel added 110,830 gallons of 8 wt % oxalic acid to Tank 6F and mixed the contents of Tank 6F with two submersible mixer pumps (SMPs) for approximately four days. Following the mixing, they transferred 115,903 gallons of Tank 6F material to Tank 7F. The SMPs were operating when the transfer started and were shut down approximately five hours after the transfer started. SRR collected a sample of the liquid from Tank 6F and submitted it to SRNL for analysis. Mapping of the tank following the transfer indicated that 2,400 gallons of solids remained in the tank. SRR conducted the second oxalic acid strike as follows. Personnel added 28,881 gallons of 8 wt % oxalic acid to Tank 6F. Following the acid addition, they visually inspected the tank and transferred 32,247 gallons of Tank 6F material to Tank 7F. SRR collected a sample of the liquid from Tank 6F and submitted it to SRNL for analysis. Mapping of the tank following the transfer indicated that 3,248 gallons of solids remained in the tank. Following the oxalic acid strikes, SRR performed Spray Washing with oxalic acid to remove waste collected on internal structures, cooling coils, tank top internals, and tank walls. The Acid Spray Wash was followed by a Water Spray Wash to remove oxalic acid from the tank internals. SRR conducted the Spray Wash as follows. Personnel added 4,802 gallons of 8 wt % oxalic acid to Tank 6F through the spray mast installed in Riser 2, added 4,875 gallons of oxalic acid through Riser 7, added 5,000 gallons of deionized water into the tank via Riser 2, and 5,000 gallons of deionized water into the tank via Riser 7. Following the Spray Wash, they visually inspected the tank and transferred 22,430 gallons of Tank 6F material to Tank 7F. SRR collected a sample of the liquid from Tank 6F and submitted it to SRNL for analysis. Following the Spray Wash and transfer, Savannah River Site (SRS) added 113,935 gallons of well water to Tank 6F. They mixed the tank contents with a single SMP and transferred 112,699 gallons from Tank 6F to Tank 7F. SRR collected a sample of the liquid from Tank 6F and submitted to SRNL for analysis. Mapping of the tank following the transfer indicated that 3,488 gallons of solids remained in the tank. Following the Water Wash, SRR personnel collected a solid sample and submitted it to SRNL for analysis to assess the effectiveness of the chemical cleaning and to provide a preliminary indication of the composition of the material remaining in the tank.
Si Young Lee - One of the best experts on this subject based on the ideXlab platform.
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Analysis of Turbulent Mixing Jets in a Large Scale Tank
Journal of Fluids Engineering-transactions of The Asme, 2008Co-Authors: Si Young Lee, Robert A. Dimenna, Richard A. Leishear, David B. StefankoAbstract:Flow evolution models were developed to evaluate the performance of the new advanced design mixer pump for Sludge mixing and Removal operations with high-velocity liquid jets in one of the large-scale Savannah River Site waste tanks, Tank 18. This paper describes the computational model, the flow measurements used to provide validation data in the region far from the jet nozzle, and the extension of the computational results to real tank conditions through the use of existing Sludge suspension data. A computational fluid dynamics approach was used to simulate the Sludge Removal operations. The models employed a three-dimensional representation of the tank with a two-equation turbulence model. Both the computational approach and the models were validated with onsite test data reported here and literature data. The model was then extended to actual conditions in Tank 18 through a velocity criterion to predict the ability of the new pump design to suspend settled Sludge. A qualitative comparison with Sludge Removal operations in Tank 18 showed a reasonably good comparison with final results subject to significant uncertainties in actual Sludge properties.
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Mixing in Large Scale Tanks: Part I — Flow Modeling of Turbulent Mixing Jets
Volume 2 Parts A and B, 2004Co-Authors: Si Young Lee, Robert A. Dimenna, Richard A. Leishear, David B. StefankoAbstract:Flow evolution models were developed to evaluate the performance of the new advanced design mixer pump (ADMP) for Sludge mixing and Removal operations in one of the large-scale Savannah River Site (SRS) waste tanks, Tank 18. This paper is the first in a series of four that describe the computational model and its validation, the experiment facility and the flow measurements used to provide the validation data, the extension of the computational results to real tank conditions through the use of existing Sludge suspension data, and finally, the Sludge Removal results from actual Tank 18 operations using the new ADMP. A computational fluid dynamics (CFD) approach was used to simulate the Sludge Removal operations. The models employed a three-dimensional representation of the tank with a two-equation turbulence model, since this approach was verified by both test and literature data. The discharge of the ADMP was modeled as oppositely directed hydraulic jets submerged at the center of the 85-ft diameter tank, with pump suction taken from below. The calculations were based on prototypic tank geometry and nominal operating conditions. In the analysis, the magnitude of the local velocity was used as a measure of slurrying and suspension capability. The computational results showed that normal operations in Tank 18 with the ADMP mixer and a 70-in liquid level would provide adequate Sludge Removal in most regions of the tank. The exception was the region within about 1.2 ft of the tank wall, based on an historical minimum velocity required to suspend Sludge. Sensitivity results showed that a higher tank liquid level and a lower elevation of pump nozzle would result in better performance in suspending and removing the Sludge. These results were consistent with experimental observations.Copyright © 2004 by ASME
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Sludge Heel Removal Analysis for Slurry Pumps of Tank 11
2003Co-Authors: Si Young LeeAbstract:Computational fluid dynamics methods were used to develop and recommend a slurry pump operational strategy for Sludge heel Removal in Tank 11. Flow patterns calculated by the model were used to evaluate the performance of various combinations of operating pumps and their orientation. The models focused on Removal of the Sludge heel located at the edge of Tank 11 using the four existing slurry pumps. The models and calculations were based on prototypic tank geometry and expected normal operating conditions as defined by Tank Closure Project (TCP) Engineering. Computational fluid dynamics models of Tank 11 with different operating conditions were developed using the FLUENT(tm) code. The modeling results were used to assess the efficiency of Sludge suspension and Removal operations in the 75-ft tank. The models employed a three-dimensional approach, a two-equation turbulence model, and an approximate representation of flow obstructions. The calculated local velocity was used as a measure of Sludge Removal and mixing capability. For the simulations, a series of the modeling calculations was performed with indexed pump orientations until an efficient flow pattern near the potential location of the Sludge mound was established for Sludge Removal. The calculated results demonstrated that the existing slurry pumps running atmore » 1600 rpm could remove the Sludge mound from the tank with a 103 in. liquid level, based on a minimum Sludge suspension velocity of 2.27 ft/sec. In this case, the only exception is the region within about 2 ft. from the tank wall. Further results showed that the capabilities of Sludge Removal were affected by the indexed pump orientation, the number of operating pumps, and the pump speed. A recommended operational strategy for an efficient flow pattern was developed to remove the Sludge mound assuming that local fluid velocity can be used as a measure of Sludge suspension and Removal. Sensitivity results showed that for a given pump speed, a higher tank level and a lower pump nozzle elevation would result in better performance in suspending and removing the Sludge. The results also showed that the presence of flow obstructions such as valve housing structure were advantageous for certain pump orientations.« less
K Lorenzen - One of the best experts on this subject based on the ideXlab platform.
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Modeling nitrogen dynamics in intensive shrimp ponds: the role of sediment remineralization
Aquaculture, 2004Co-Authors: M.a Burford, K LorenzenAbstract:Abstract A mathematical model is used to investigate the role of sedimentation and remineralization in the sediment on nitrogen (N) dynamics in intensive shrimp culture ponds. The model describes the key processes involved in N cycling that underpin the dynamics of total ammoniacal N (TAN), nitrate/nitrite (NOX) and chlorophyll a (CHL) concentrations and the sediment N pool. These parameters may, in high concentrations, impact negatively on the shrimp or the adjacent aquatic environment when water is discharged from ponds. The model was calibrated for an Australian commercial shrimp ( Penaeus monodon ) pond. Most N enters the pond system as TAN from shrimp excretion of dietary N and decomposition of wasted feed, and is subsequently taken up by phytoplankton, which, on senescence, is sedimented and remineralized. Sediment remineralization is the dominant source of TAN in the water column for all but the beginning of the production cycle. The remineralization rate of sedimented N was estimated at 6% day −1 . Nonetheless, sediment acts as a net sink of N throughout the production cycle. The effect of management strategies, including increased stocking densities, water exchange and Sludge (=sedimented material) Removal, on water quality was examined. Model outputs show that using current shrimp farming techniques, with water exchange rates of 7% day −1 , an increase in stocking densities above 60 animals m −2 would result in unacceptably high TAN concentrations. Both Sludge Removal and water exchange provide effective ways of reducing TAN and NOX concentrations and may allow substantially higher stocking densities. However, Sludge Removal may be the more acceptable option, given the need to meet strict regulatory requirements for discharge loads in some countries and the desire to reduce water intake to improve biosecurity.
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Modeling nitrogen dynamics in intensive shrimp ponds: the role of sediment remineralization
Aquaculture, 2004Co-Authors: M.a Burford, K LorenzenAbstract:A mathematical model is used to investigate the role of sedimentation and remineralization in the sediment on nitrogen (N) dynamics in intensive shrimp culture ponds. The model describes the key processes involved in N cycling that underpin the dynamics of total ammoniacal N (TAN), nitrate/nitrite (NOX) and chlorophyll a (CHL) concentrations and the sediment N pool. These parameters may, in high concentrations, impact negatively on the shrimp or the adjacent aquatic environment when water is discharged from ponds. The model was calibrated for an Australian commercial shrimp (Penaeus monodon) pond. Most N enters the pond system as TAN from shrimp excretion of dietary N and decomposition of wasted feed, and is subsequently taken up by phytoplankton, which, on senescence, is sedimented and remineralized. Sediment remineralization is the dominant source of TAN in the water column for all but the beginning of the production cycle. The remineralization rate of sedimented N was estimated at 6% day-1. Nonetheless, sediment acts as a net sink of N throughout the production cycle. The effect of management strategies, including increased stocking densities, water exchange and Sludge (=sedimented material) Removal, on water quality was examined. Model outputs show that using current shrimp farming techniques, with water exchange rates of 7% day-1, an increase in stocking densities above 60 animals m-2 would result in unacceptably high TAN concentrations. Both Sludge Removal and water exchange provide effective ways of reducing TAN and NOX concentrations and may allow substantially higher stocking densities. However, Sludge Removal may be the more acceptable option, given the need to meet strict regulatory requirements for discharge loads in some countries and the desire to reduce water intake to improve biosecurity.Griffith Sciences, Griffith School of EnvironmentFull Tex
B Bruce Martin - One of the best experts on this subject based on the ideXlab platform.
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HIGH-LEVEL WASTE MECHANCIAL Sludge Removal AT THE SAVANNAH RIVER SITE - F TANK FARM CLOSURE PROJECT
2008Co-Authors: R Jolly, B Bruce MartinAbstract:The Savannah River Site F-Tank Farm Closure project has successfully performed Mechanical Sludge Removal (MSR) using the Waste on Wheels (WOW) system for the first time within one of its storage tanks. The WOW system is designed to be relatively mobile with the ability for many components to be redeployed to multiple waste tanks. It is primarily comprised of Submersible Mixer Pumps (SMPs), Submersible Transfer Pumps (STPs), and a mobile control room with a control panel and variable speed drives. In addition, the project is currently preparing another waste tank for MSR utilizing lessons learned from this previous operational activity. These tanks, designated as Tank 6 and Tank 5 respectively, are Type I waste tanks located in F-Tank Farm (FTF) with a capacity of 2,840 cubic meters (750,000 gallons) each. The construction of these tanks was completed in 1953, and they were placed into waste storage service in 1959. The tank’s primary shell is 23 meters (75 feet) in diameter, and 7.5 meters (24.5 feet) in height. Type I tanks have 34 vertically oriented cooling coils and two horizontal cooling coil circuits along the tank floor. Both Tank 5 and Tank 6 received and stored F-PUREX waste during their operating service time before Sludge Removal was performed. DOE intends to remove from service and operationally close (fill with grout) Tank 5 and Tank 6 and other HLW tanks that do not meet current containment standards. Mechanical Sludge Removal, the first step in the tank closure process, will be followed by chemical cleaning. After obtaining regulatory approval, the tanks will be isolated and filled with grout for long-term stabilization.
