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EVALUATION OF PREFERMENTATION AS A UNIT PROCESS UPON BIOLOGICAL NUTRIENT REMOVAL INCLUDING BIOKINETIC AND WASTEWATER PARAMETERS
Title
EVALUATION OF PREFERMENTATION AS A UNIT PROCESS UPON BIOLOGICAL NUTRIENT REMOVAL INCLUDING BIOKINETIC AND WASTEWATER PARAMETERS.
Creator
McCue, Terrence, Randall, Andrew, University of Central Florida
Abstract / Description
The objective of this dissertation was to provide a controlled comparison of identical continuous flow BNR processes both with and without prefermentation in order to provide a stronger, more quantitative, technical basis for design engineers to evaluate the potential benefits of prefermentation to EBPR in treating domestic wastewater. In addition, the even less understood effect of prefermentation on denitrification kinetics and anoxic phosphorus (P) uptake was studied and quantified. Other...
Show moreThe objective of this dissertation was to provide a controlled comparison of identical continuous flow BNR processes both with and without prefermentation in order to provide a stronger, more quantitative, technical basis for design engineers to evaluate the potential benefits of prefermentation to EBPR in treating domestic wastewater. In addition, the even less understood effect of prefermentation on denitrification kinetics and anoxic phosphorus (P) uptake was studied and quantified. Other aspects of BNR performance, which might change due to use of prefermentation, will also be addressed, including anaerobic stabilization. Potential benefits to BNR processes derived from prefermentation are compared and contrasted with the more well-known benefits of primary clarification. Finally, some biokinetic parameters necessary to successfully model both the activated sludge systems and the prefermenter were determined and compared for the prefermented versus the non-prefermented system. Important findings developed during the course of this dissertation regarding the impact of prefermentation upon the performance of activated sludge treatment systems are summarized below: • For a septic COD-limited (TCOD:TP < 40:1) wastewater, prefermentation was found to enhance EPBR by 27.7% at a statistical significance level of alpha=0.05 (95% confidence level). • For septic P-limited (TCOD:TP > 40:1) wastewaters, prefermentation was not found to improve EBPR at a statistical significance level of alpha=0.05 (95% confidence level). • The increased anaerobic P release and aerobic P uptakes due to prefermentation correlated with greater PHA formation and glycogen consumption during anaerobiosis of prefermented influent. • Improvements in biological P removal of septic, non-P limited wastewater occurred even when all additional VFA production exceeded VFA requirements using typical design criteria (e.g. 6 g VFA per 1 g P removal). • Prefermentation increased RBCOD content by an average of 28.8% and VFA content by an average of 18.8%, even for a septic domestic wastewater. • Prefermentation increased specific anoxic denitrification rates for both COD-limited (14.6%) and P-limited (5.4%) influent wastewaters. This increase was statistically significant at alpha=0.05 for COD-limited wastewater, but not for P-limited wastewater.
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Date Issued
2006
Identifier
CFE0001418, ucf:47052
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0001418
REMOVAL OF REFRACTORY TKN FROM AN EFFLUENT WASTEWATER USING SODIUM FERRATE
Title
REMOVAL OF REFRACTORY TKN FROM AN EFFLUENT WASTEWATER USING SODIUM FERRATE.
Creator
Lettie, Lucia, Reinhart, Debra, University of Central Florida
Abstract / Description
This research addresses refractory forms of nitrogen that, even with advanced biological nitrification-denitrification systems are not removed completely from domestic wastewater. TKN (Total Kjeldahl Nitrogen), ammonia plus organic nitrogen, is one of the forms to measure the levels of nitrogen present in effluent wastewaters. Ferrate, a strong oxidant, was used for the treatment of these nitrogen forms with the objective of producing nitrogen compounds that can be removed by subsequent...
Show moreThis research addresses refractory forms of nitrogen that, even with advanced biological nitrification-denitrification systems are not removed completely from domestic wastewater. TKN (Total Kjeldahl Nitrogen), ammonia plus organic nitrogen, is one of the forms to measure the levels of nitrogen present in effluent wastewaters. Ferrate, a strong oxidant, was used for the treatment of these nitrogen forms with the objective of producing nitrogen compounds that can be removed by subsequent biological processes. Bench-scale experiments were performed on effluent samples taken prior to chlorination from an Orlando, FL wastewater treatment facility, using a biological nutrient removal process. The samples were treated with doses of ferrate ranging from 1 to 50 mg/L as FeO4–2 under unbuffered conditions. TKN removal as high as 70% and COD removal greater than 55% was observed. The TSS production after ferrate treatment was in a range of 12 to 200 mg/L for doses between 10 and 50 mg/L FeO4-2. After an optimum dose of ferrate was determined, three bench-scale reactors were operated under anoxic conditions for 10 to 12 days, two as duplicates containing the treated effluent and one as a control with untreated sample. Two different doses of ferrate were used as optimum dose for these experiments, 10 and 25 mg/L as FeO4-2. The purpose of these reactors was to determine the potential for biological removal of remaining nitrogen after ferrate oxidation of refractory nitrogen. Treated and raw samples were analyzed for Total Kjeldahl Nitrogen (TKN) (filtered and unfiltered), chemical oxygen demand (COD) (filtered and unfiltered), total suspended solids (TSS), nitrate (NO3-N), nitrite (NO2-N), and heterotrophic plate count (HPC). As a result, more than 70% of the soluble TKN was removed by chemical and biological oxidation for a sample treated with a dose of 25 mg/L FeO4-2, and less than 50% when treated with 10 mg/L FeO4-2. For the control samples run parallel to the ferrate treated samples, a maximum of 48% of soluble TKN and a minimum of 12% was removed. A three-log increase was observed in heterotrophic bacteria numbers for both doses during the operation of the reactors. Sodium ferrate was found to be an effective oxidant that can enhance the biodegradability of recalcitrant TKN present in municipal wastewaters. As mentioned before this research was develop using batch reactor units at bench-scale, therefore it is recommended to follow the investigation of the biodegradability of recalcitrant TKN of a ferrate treated sample under continuous flow conditions so that results can be extrapolated to a full-scale treatment facility.
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Date Issued
2006
Identifier
CFE0001247, ucf:46936
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0001247
Biological Nutrient Removal (BNR) Process Optimization and Recovery of Embedded Energy Using Biodiesel By-product
Title
Biological Nutrient Removal (BNR) Process Optimization and Recovery of Embedded Energy Using Biodiesel By-product.
Creator
Salamah, Sultan, Randall, Andrew, Duranceau, Steven, Chopra, Manoj, University of Central Florida
Abstract / Description
Enhanced biological phosphorus removal (EBPR) as well as biological nitrogen removal require a carbon source to be carried out. Volatile fatty acid (VFAs) (mainly acetic and propionic acids) are the major driving force for EBPR. Many domestic wastewaters have an insufficient amount of VFAs. However, carbon sources such as acetic and propionic acids can be produced using primary solids fermentation process. Due to the cost of VFA production, an external carbon source can be added to the...
Show moreEnhanced biological phosphorus removal (EBPR) as well as biological nitrogen removal require a carbon source to be carried out. Volatile fatty acid (VFAs) (mainly acetic and propionic acids) are the major driving force for EBPR. Many domestic wastewaters have an insufficient amount of VFAs. However, carbon sources such as acetic and propionic acids can be produced using primary solids fermentation process. Due to the cost of VFA production, an external carbon source can be added to the biological nutrient removal (BNR) system that can be fermented to provide the desired VFAs. Glycerol (biodiesel by-product) offers a solution to reduce carbon addition cost if can be fermented to acetic and propionic acid or can be used directly as an external carbon substrate for EBPR and denitrification. Using glycerol in wastewater treatment can also offset the biodiesel plant disposal cost and reduce the BNR chemical cost. The main objective of this study was to optimize the prefermentation process and optimize the BNR system using glycerol as an external carbon source. In this work, Optimization of the prefermentation process using glycerol, mixing, and hydrogen gas addition was evaluated. EBPR performance within an A2O-BNR system was evaluated using either a direct glycerol method to the anaerobic zone or by co-fermentation with primary solids. Also, optimization of the nitrogen removal (specifically denitrification) efficiency of a 5-stage BardenphoTM BNR system using either a direct glycerol method to the second anoxic zone or by co-fermentation with primary solids was evaluated. It was found in this study that glycerol was an efficient external carbon substrate for EBPR as well as biological nitrogen removal. The prefermentation experiment showed that glycerol co-fermentation with primary solids produced significantly higher (p(<)0.05) VFAs than primary solids fermentation alone, even more than the possible value from the added glycerol (427 mg-COD/L). The increased VFAs imply that the glycerol addition stimulated additional fermentation of primary solids. Lowering the prefermenter mixing energy (50 to 7 rpm) resulted in a significant increase in VFAs production (80%). Also, purging the headspace of the prefermenter with hydrogen gas did not lead to more VFAs, but significantly (p(<)0.05) increased the propionic acid to acetic acid ratio by 41%. In the A2O-BNR pilot plant experiment, it was found that glycerol is a suitable renewable external substrate to drive enhanced EBPR as well as denitrification. The results from both locations of glycerol addition (direct vs. fermented) were beneficial to the BNR system. Both systems had similar effluent quality and achieved total nitrogen (TN) and total phosphorus (TP) removals up to 86% and 92% respectively. The 5-stage BardenphoTM BNR experiment investigated the location of glycerol addition (direct vs. fermented) on the performance of denitrification in the second anoxic zone and the overall performance. The results from both systems were that glycerol was beneficial to the BNR system and had virtually similar effluent quality. Both systems achieve complete denitrification and excellent removal of TN and TP up to 95% and 89% respectively. Also, the pilot that received fermented glycerol had significantly higher VFAs loading and lower observed yield. The side-stream prefermenter effluent flowing to the second anoxic reactor did not cause high effluent ammonia (NH3) concentration. In summary, the location at which glycerol was added did not affect effluent quality for nitrogen and phosphorus. However, glycerol addition and mixing energy did impact prefermenter performance and effluent quality.
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Date Issued
2017
Identifier
CFE0006788, ucf:51826
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0006788
The effect of glycerol on readily biodegradable chemical oxygen demand (RBCOD) in a wastewater stream
Title
The effect of glycerol on readily biodegradable chemical oxygen demand (RBCOD) in a wastewater stream.
Creator
Rawut, Rojina, Sadmani, A H M Anwar, Lee, Woo Hyoung, Duranceau, Steven, University of Central Florida
Abstract / Description
This study evaluated the short-term effects of glycerol addition on readily biodegradable (RB) chemical oxygen demand (COD) in a carbon limited wastewater influent. The presence of an RB fraction provides with a suitable substrate for microorganisms to produce volatile fatty acids (VFA). The oxygen utilization rate (OUR) has been used to evaluate the oxygen consumption for RB substrate in wastewater. Wastewater with low organic content contains limited RB substrate, and thus, additional...
Show moreThis study evaluated the short-term effects of glycerol addition on readily biodegradable (RB) chemical oxygen demand (COD) in a carbon limited wastewater influent. The presence of an RB fraction provides with a suitable substrate for microorganisms to produce volatile fatty acids (VFA). The oxygen utilization rate (OUR) has been used to evaluate the oxygen consumption for RB substrate in wastewater. Wastewater with low organic content contains limited RB substrate, and thus, additional carbon source is required to improve biological treatment capability. Acetate, propionate, methanol, and glycerol are the commonly available carbon sources for biological treatment process. However, the cost of acetate and propionate are relatively high, and it is not economical to use these carbon sources in the wastewater plant. The use of methanol as a carbon source inherently poses safety issues in field applications due to its toxic and flammable properties. On the other hand, crude glycerol is the byproduct of biodiesel, which is an excellent carbon source alternative. However, crude glycerol contains impurities and requires a certain degree of purification to enhance the performance. The samples for the study were collected from the Iron Bridge Wastewater Reclamation Facility (Oviedo, FL) designed for treating municipal wastewater. The total COD (TCOD) of the sample influent was in the range of 237 to 408 mg COD/L, and RBCOD value was between 38 and 80.5 mg COD/L, containing up to 10 mg COD/L of VFA. This study also demonstrates the relationship between the glycerol concentration and OURs during the diauxic growth phase from the addition of glycerol. The growth was due to the existence of RB substrate and availability of glycerol for the microorganisms. TCOD increased from 284 to 378 mg COD/L and from 284 mg COD/L to 323 mg COD/L by spiking approximately 30 and 15 mL of glycerol stock solution (6.67 g/L), respectively. RBCOD increased from 45 to 89 mg COD/L and 55 mg COD/ L by spiking 30 mL and 15 ml glycerol stock solution, respectively. The initial influent heterotrophic active biomass (ZBH) increased from 5.4 to 15.8 mg VSS/L (8 to 23.4 mg COD/L) due to the addition of glycerol, indicating that the glycerol may be an adequate carbon source. The COD of wastewater with limited VFA (e.g., 10 mg COD/L) increased up to 2,502 mg COD/L where propionic acid (2,468 mg COD/L) exists as the primary end product with a small quantity of acetic acid (34 mg COD/L). Propionic acid was the main VFA component fermented from the glycerol addition. Glycerol addition led to increased RBCOD accompanied by high VFA production. This research investigated the short-term effect of glycerol addition on existing RBCOD in wastewater. It is recommended to explore the effect of increased RBCOD by the addition of glycerol to the effluent N and P for future study.
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Date Issued
2016
Identifier
CFE0006543, ucf:51324
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0006543