Browsing by Subject "Wastewater"
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Item Balancing ammonia and alkalinity for nitrification at Walnut Creek Wastewater Treatment Plant(2014-05) Weidner, Austin David; Lawler, Desmond F.The Walnut Creek Wastewater Treatment Plant in Austin, Texas, has recently experienced increasing influent ammonia concentrations. Nitrification, the biological process used to treat ammonia, consumes alkalinity, which makes it difficult to properly treat ammonia while still maintaining the pH above the required discharge level of pH 6. Operators have looked to the addition of chemicals to supplement alkalinity; one creative alkalinity source was CaCO₃ solids, which are generated by the lime-softening process at Davis Water Treatment Plant. In 2011, the utility began transferring solids to Walnut Creek and immediately noticed improvements in both the nitrification efficiency and the effluent pH. However, undissolved solids accumulated at Walnut Creek and had a detrimental effect on the biosolids treatment efficiency at Hornsby Bend Biosolids Management Plant. Ultimately the costs of the poor biosolids treatment forced the utility to examine an alternative alkalinity source. The objective of this thesis is to help Walnut Creek optimize the use of various alkalinity sources to find a long-term solution that will improve the alkalinity and ammonia balance for adequate nitrification. Analysis of the plant’s influent characteristics suggested that industrial users, especially the semiconductor industry, are major contributors of ammonia and sulfate to the wastewater. A theoretical modeling based on chemical equilibrium predicted that using the CaCO₃ solids would provide a maximum alkalinity benefit of 47 mg/L as CaCO₃. Experimental dissolution jar tests were conducted to verify the model predictions and estimate the kinetics of dissolution. Results from these tests showed no significant dissolution of CaCO₃, and that the solids remained unchanged throughout the test. These results indicate that CaCO₃ solids are not recommended to provide alkalinity at Walnut Creek. Finally, the use of Mg(OH)₂ for alkalinity was employed at Walnut Creek and allowed operators to reduce the blowers that provide aeration. To quantify this observation, bubbling column tests were conducted to measure differences in the oxygen transfer rate at various Mg(OH)₂ concentrations. However experimental results did not match the expectations, so future work is required.Item The energy-water nexus : energetic analysis of water and wastewater treatment, distribution and collection(2014-12) Kjellsson, Jill Blosk; Webber, Michael E., 1971-The water sector is responsible for a significant portion of energy use. Energy is required for water treatment, water distribution, wastewater collection and wastewater treatment. There is significant benefit to water utilities that can be gained by understanding how much energy, what type of energy, and at what time of day energy is being used. The Austin Water Utility (AWU) is a useful testbed for examining the energy use for each specific step of the process due to the availability of data and the fact that the majority of Texas (both in terms of population and land area) is serviced by a single electric grid. This research examines the type and quantity of energy used by AWU. From an electricity supply perspective, electric utilities work year round to ensure that there is enough electricity in their generation portfolios to meet the high loads that their customers demand, and to assure that the electric distribution grid is capable of providing the transmission requirements of that electricity. System peak demand is the largest amount of electricity consumed by a utility's customers at any given time. Therefore electric utilities, such as Austin Energy, create and market their energy efficiency programs to help reduce this peak and avoid the need to build new generation capacity which can be expensive. Because AWU is one of Austin Energy's largest customers, AWU's ability to shift its energy use from on-peak to mid-peak and off-peak time periods can contribute towards reducing the peak, and can help avoid the need for new generation capacity. This analysis finds that AWU can reduce its electricity demand during peak periods by making use of reservoir capacity, i.e. by filling its reservoirs prior to peak time and draining them during peak periods. This proposed pumping schedule could save AWU up to 29% of its monthly electricity costs under current Austin Energy time-of-use rate (as opposed to flat rate) structures at the specific pump station analyzed as part of this research. Together, state-wide water utilities provide even more opportunities for the interconnected Electric Reliability Council of Texas' (ERCOTs) grid that are also evaluated in this research.Item Enzymes : the new water/wastewater treatment chemical(2011-05) Garcia, Hector A.; Lawler, Desmond F.; Kinney, Kerry A.; Kirisits, Mary J.; Malina, Joseph F.; Kitto, George B.Pharmaceuticals and personal care products (PPCPs) are detected routinely in raw and treated municipal wastewater. Conventional wastewater treatment processes are not effective in removing PPCP; therefore, treated wastewater discharges are one of the main entry points for PPCPs into the aquatic environment, and eventually into drinking water supplies. The use of laccase-catalyzed oxidation for removing low concentrations of PPCPs from municipal wastewater after primary treatment is investigated. Oxybenzone was selected as a representative PPCP. Like many other PPCPs, oxybenzone is not recognized directly by the laccase enzyme. Therefore, mediators were used to expand the oxidative range of laccase, and the efficacy of this laccase-mediator system in primary effluent was evaluated. Eight potential mediators were investigated. The greatest oxybenzone removal efficiencies were observed when 2,2’-azino-bis(3-ethylbenzthiazoline-6sulphonic acid) (ABTS), a synthetic mediator, and acetosyringone (ACE), a natural mediator, were present. An environmentally relevant concentration of oxybenzone (10 µg/L) in primary effluent was removed below the detection limit after two hours of treatment with ABTS, and 95% was removed after two hours of treatment with ACE. Several mediator/oxybenzone molar ratios were evaluated at two different initial oxybenzone concentrations. Higher mediator/oxybenzone molar ratios were required at the lower (environmentally relevant) oxybenzone concentrations, and ACE required higher molar ratios than ABTS to achieve comparable oxybenzone removal. The oxidation mechanisms and kinetics of the ACE mediator was evaluated. A better understanding of the mediator oxidation process would lead to a better design of the laccase-mediator system. An alternative laccase-mediator treatment configuration, which allows the enzyme and mediator to react prior to coming in contact with the target PPCP, was investigated. This treatment configuration shows promise for further development since it might reduce laccase and mediator requirements. Oxidation byproducts generated by the laccase-mediator system were characterized and compared to those generated during ozonation. Enzymatic treatment generated byproducts with higher mass to charge (m/z) ratios, likely due to oxidative coupling reactions. The results of this study suggest that, with further development, a laccase-mediator system has the potential to extend the treatment range of laccase to PPCPs not directly recognized by the enzyme, even in a primary effluent matrix.Item Food service establishment wastewater characterization and management practice evaluation(Texas A&M University, 2006-04-12) Garza, Octavio ArmandoFood service establishments that use onsite wastewater treatment systems are experiencing hydraulic and organic overloading of pretreatment systems and/or drain fields. Design guidelines for these systems are typically provided in State regulations and based on residential hydraulic applications. For the purposes of this research, hydraulic loading indicates the daily flow of water directed to the wastewater system. Organic loading refers to the composition of the wastewater as quantified by five-day biochemical oxygen demand (BOD5), total fats, oils and greases (FOG), and total suspended solids (TSS). The first part of this study included an analysis of the central tendencies of analytical data of four wastewater parameters from 28 restaurants representing a broad spectrum of restaurant types. Field sampling consisted of two sets of grab samples collected from each restaurant for six consecutive days at approximately the same time each day. These sets were collected approximately two weeks apart. The numerical data included BOD5, FOG, and TSS. The fourth parameter evaluated was daily flow. Data exploration and statistical analyses of the numerical data from the 28 restaurants was performed with the standard gamma probability distribution model in ExcelTM and used to determine inferences of the analytical data. The analysis shows higher hydraulic and organic values for restaurant wastewater than residential wastewater. The second part of the study included a statistical analysis of restaurant management practices and primary cuisine types and their influence on BOD5, FOG, TSS, and daily flow to determine if management practices and/or cuisine types may be influencing wastewater composition and flow. A self-reporting survey was utilized to collect management practice and cuisine type information. Survey response information and analytical data were entered into an ExcelTM spreadsheet and subsequently incorporated into SASTM statistical software for statistical analysis. Analysis indicated that the number of seats in a restaurant, use of self-serve salad bars, and primary cuisine types are statistically significant indicators of wastewater characteristics.Item Metagenomic investigation of the antibiotic resistance in coastal marine ecosystemsTallman, James Joseph IIIItem The potential for using energy from flared gas or renewable resources for on-site hydraulic fracturing wastewater treatment(2014-05) Glazer, Yael Rebecca; Webber, Michael E., 1971-The oil and gas well completion method of hydraulic fracturing faces several environmental challenges: the process is highly water-intensive; it generates a significant volume of wastewater; and it is associated with widespread flaring of co-produced natural gas. One possible solution to simultaneously mitigate these challenges is to use the energy from flared natural gas to power on-site wastewater treatment, thereby reducing 1) flared gas without application, 2) the volumes of wastewater, and 3) the volumes of freshwater that need to be procured for subsequent shale production, as the treated wastewater could be reused. In regions with minimal flaring a potential solution is to couple renewable electricity (generated from solar and wind energy) with on-site wastewater treatment, thereby 1) reducing the volumes of wastewater, 2) reducing the volumes of freshwater that need to be procured for subsequent shale production, and 3) displacing fossil fuel energy for treatment. This study builds an analytical framework for assessing the technical potential of these approaches. In this research, the hydraulic fracturing wastewater characteristics (such as quality, quantity, and flow rates) were considered along with various treatment technologies best suited to utilizing natural gas and renewable electricity, using the Permian Basin in west Texas as a geographic test bed for analysis. For the analysis looking at using flared natural gas energy for on-site treatment, the required volume of gas to meet the thermal energy requirements for treatment was calculated on a per-well basis. Additionally, the volume of product water (defined here as the treated water that can be reused) based on the technology type was determined. Finally, the theoretical maximum volume of product water that could be generated using the total volume of natural gas that was flared in Texas in 2012 as a benchmark was calculated. It was concluded that the thermal energy required to treat wastewater that returns to the surface over the first ten days after a well is completed is 140–820 Million British Thermal Units (MMBTU) and would generate 750–6,800 cubic meters of product water depending on the treatment technology. Additionally, based on the thermal technologies assessed in this study, the theoretical maximum volume of product water that can be generated statewide using the energy from the flared gas in 2012 is 180–540 million cubic meters, representing approximately 3–9% of the state’s annual water demand for municipal purposes or 1–2.4% of total statewide water demand for all purposes. This is enough gas to treat more water than was projected would be used for the entire mining sector in 2010 in Texas. For the analysis coupling renewable electricity with on-site treatment, the necessary energy for water management upstream and downstream of a well site was calculated and compared with the current energy requirements and those of a proposed strategy where a portion of the wastewater is treated on-site and reused on a subsequent well. Through this analysis, it was determined that implementing on-site treatment using renewable electricity could reduce freshwater requirements by 11–26%. Finally, it was calculated that this approach could displace approximately 16% of the fossil fuel energy requirements for pumping freshwater, trucking that water to the well site, and trucking wastewater to a disposal well.Item Removal of Chloride from Wastewater by Advanced Softening Process Using Electrochemically Generated Aluminum Hydroxide(2014-07-23) Mustafa, Syed FaisalWastewater recycle and reuse is limited in many cases by high concentrations of dissolved solids. The majority of dissolved solids can be removed by precipitation. However, chloride is among ionic species that is difficult to remove due to its high solubility. Chloride can be removed from water and wastewater by precipitation as calcium chloroaluminate using advanced softening process. This research was conducted to evaluate chloride removal using electrochemically generated aluminum hydroxide and lime. Kinetics of chloride removal was investigated and the system reached equilibrium within two hours of reaction time indicating that removal kinetics is suitable for practical application of the process. Equilibrium characteristics of chloride removal were characterized. Good chloride removal was obtained at reasonable ranges of lime and aluminum doses. However, the stoichiometry of chloride removal deviated from the theoretical stoichiometry of calcium chloroaluminate precipitation. Analysis of experimental data indicated that this deviation was due to the formation of other solid phases such as tricalcium hydroxyaluminate and tetracalcium hydroxyaluminate. This research obtained the optimum doses of electrochemically produced aluminum hydroxide and lime which achieved maximum chloride removal. An attempt to regenerate and recycles precipitated solids was also investigated.Item Removal of Selenium from Wastewater using ZVI and Hybrid ZVI/Iron Oxide Process(2012-12-20) Yang, ZhenSelenium (Se), often in form of selenocyanate (SeCN-), which present in some of refinery process wastewater known as stripped sour water. As Se discharge is increasingly regulated, the industry struggles to find a cost-effective technology for SeCN- treatment. Zero-valent iron (ZVI) technology, with some successes in remediating toxic-metal contaminated groundwater remediation, emerges as a potential solution for addressing SeCN- problem. In this study, bench scale tests were conducted to investigate the removal of SeCN- from wastewater with ZVI. The removal efficiency was evaluated by a series of tests under different conditions such as initial pH, various ions, ZVI particle size, dissolved oxygen (DO) and iron oxide. Results showed that SeCN- was effectively removed from wastewater with ZVI and Fe(II) filings when the water pH was controlled at approximately 6 with sufficient DO. The further evaluate of treating SeCN- using hybrid zero valet iron (hZVI) system has also been conducted in this study. The hZVI system process is a novel chemical treatment that has shown valuable potential for removing several heavy metals from wastewater. This study concluded that at bench scale, the removal efficiency of SeCN- in the wastewater is over 99% with 2-steps of hZVI reactors and a HRT of 12 hours. In essence, this study concluded that ZVI is a highly valuable potential cost-effective treatment for SeCN- removal from wastewater and the results from bench scale hZVI system can be effectively used to scale up the system to serve the industrial needs in the future.Item Studies of the Performance, Stability and Reliability of Various Configurations of the Activated Sludge Process at Full-Scale Municipal Wastewater Treatment Plants(Engineering, Environmental, 2009-05-15T18:00:27Z)This research presents a performance, stability and reliability analysis of five configurations of activated sludge process, viz., conventional, contact stabilization, complete mix, extended aeration and sequencing batch reactor. Five years effluent records of carbonaceous biochemical oxygen demand (CBOD5), total suspended solids (TSS) and ammonia nitrogen (NH3-N) were used. The impact of hydraulic load classes (HLCes) and seasons on the performance of configurations were also examined. The Univariate General Linear Model with Tukey's Honestly Significant Difference was employed in the performance and stability studies. Performance was determined based on the observed lowest mean effluent concentrations, while the observed standard deviation from the mean effluent concentration was the basis for determining stability. Coefficient of Reliability and the Binary Logistic Regression (BLR) model were used to study reliability in terms of compliance with a daily average and single grab/daily max effluent values, and results were compared. Conventional aeration was the best performer with regard to CBOD5 removal, while sequencing batch reactor and extended aeration were the highest performers in TSS and NH3-N reduction, respectively. Contact stabilization was consistently observed to be the least performer under all effluent limitations examined. With the exception of NH3-N, where no statistical significance was observed, major HLCes were observed to perform better than minor hydraulic HLCes. Although, TSS and NH3-N reduction abilities were not affected by changes in seasons, the highest CBOD5 reduction was observed in summer and the least in winter. No statistical significance was observed with regard to effluent CBOD5 stability. However, sequencing batch reactors were observed to produce the most stable effluent TSS. Major HLCes showed more stability during NH3-N reduction. The Binary Logistic Regression model was compared to the COR and the BLR was found to be the better technique in determining reliability of wastewater treatment plants. Based on the BLR model prediction conventional, sequencing batch reactor and extended aeration were observed to be more reliable with regard to CBOD5, TSS and NH3-N, respectively. Major HLCes were more reliable than minor HLCes and daily average effluent limitations were more conservative compared to single grab/daily max effluent values.Item Treatment of shale gas wastewater in the Marcellus : a comparative analysis(2014-05) Yisa, Junaid Ololade; Spence, David B.; Nicot, Jean-Philippe, 1958-This analysis focused primarily on three main treatment methods which were re-use, recycle, and disposal wells. The re-use treatment option is when wastewater is mixed with source water in order to meet fracturing water requirements. With this option, the hope is that the wastewater for re-use will require little or no treatment at all. The second treatment option is the recycle option. This option provides high quality water for re-use or discharge to the environment using a recycling technology. The credibility of this option is heavily dependent on its ability to recycle almost all of the wastewater with little or none left for disposal or treatment. The third option is well disposal. This entails disposing all of the wastewater into a deep formation. The software used for building the model is called @Risk. The model’s costs were estimates from recent research to capture the risks and uncertainties associated with wastewater disposal. The model revealed that re-use option remains the most cost effective treatment method to reduce overall water management cost in the Marcellus. The re-use option is most viable when a hydraulic fracturing schedule is continuous (no significant storage requirement) and infrastructure is available to transport wastewater from one fracturing operation to the other. The recycle option is the second most viable disposal option. This option is most effective when the hydraulic fracturing schedule is staggered in both time and distance because distilled water from recycling facilities can be easily discharged into the environment or stored. The most unfavorable option for wastewater management at the Marcellus is the well disposal option due to the high cost of trucking wastewater to disposal wells in neighboring states or counties. It also requires the highest usage of fresh water. A well disposal option can be favorable at the onset of a hydraulic fracturing schedule when there are low levels of infrastructure, hydraulic fracturing programs are not continuous or localized in proximity, and the volume of wastewater does not exceed the capacity for injection. In this case, disposal wells can be more favorable than recycle or re-use if they are in close proximity to drilling sites.