City of Greeley WPCF
Greeley, Colorado
The prime objective of the work described in this paper was to determine the correct half saturation dissolved oxygen coefficients, KDO,AOB and KDO,NOB for the ammonia oxidizing and nitrite oxidizing bacteria, respectively for accurately simulating the Greeley WPCF, using the Biowin 3™ software. These parameters are often considered to be constants, whose values are generally accepted to be the default values embedded in the Biowin 3™ software. However, they are in fact not constants, and unless care is taken in the assignment of the proper values, errors in predicted air quantities or the required DO concentrations to achieve the necessary effluent ammonia concentrations will result. Determining the specific KDO value for a given application is important because it impacts the rate of nitrification achieved for a given oxygen concentration, the SRT, the consequent size of the aeration reactors, and the energy required to maintain required DO levels. Our other experiences subsequent to the work described in this paper showed that simulation results achieved by using the half saturation coefficients determined in this paper provide a much better goodness of fit than the current Biowin 3™ default values. For future plant simulations, the same type of stress tests carried out for this work are recommended as part of the wastewater characterization and calibration exercises. However, if this is not possible, adjusting the default values in Biowin 3™ to the values presented in this paper is recommended. The work presented in this paper can only be accomplished using a properly calibrated dynamic model. A steady state modeling approach would not produce the required results and would not be suitable to confirm nitrifier growth rates with plant scale measurements. Source: WEFTEC 2009 Proceedings
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Indian Creek Middle Basin , Blue River and Sherwood Wastewater Treatment Plants
Kansas
The fate and removal of triclosan (TCS), an antimicrobial agent and emerging surface water pollutant, was studied in three full-scale activated sludge plants. The performance of the activated sludge wastewater facilities evaluated in this study reflected consistently high removal efficiencies for TCS, and consistent secondary effluent TCS concentrations. The mean overall removal of TCS ranged from 94.4% to 96.1% for the facilities evaluated. Consistently low residual concentrations of soluble TCS were found to be achieved by activated sludge effluent examined in this study with average concentrations ranging from 0.00098 to 0.0013 mg/L and a relative standard deviation of 26% or less. General chemical fate model results indicated that biodegradation was likely to be the dominant mechanism in the TCS removal (79 to 90%) versus sorption to waste activated sludge solids and effluent particulate matter (7 to 18%) or volatilization (less than 0.0002%). Source: WEFTEC 2009 Proceedings
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San Jose/Santa Clara Water Pollution Control Plant
San Jose, California
Results showed no serious effluent quality deterioration when continuously air-mixed anaerobic and anoxic quadrants of the San Jose/ Santa Clara Water Pollution plant’s secondary aeration systems were operated in pulse aeration mode. Ammonia concentrations in pulse aerated and continuously aerated tanks were, on average, 0.73 mg/l and 0.63 mg/l, respectively. Such a slight increase in ammonia concentration in pulse aerated tanks was inevitable with reduction in air flow to Quad 3, although the final effluent quality was never affected. Nitrite concentrations were on average 0.15 mg/l and 0.17 mg/l in the pulse aerated and non pulsed tanks, respectively. Nitrate was significantly reduced from an average concentration of 7.26 mg/l in continuously aerated tanks to 4.45 mg/l in the pulse aerated tanks. Phosphate levels in the effluents of pulse aerated experimental tanks were found to be higher than those in continuously aerated control tanks with averages of 2 mg/l and 1.5 mg/l, respectively. No significant difference was observed in mixed liquor suspended solids concentrations between pulse aerated and continuously aerated tanks, signifying that the chosen pulse aeration cycle of 1.5 min ON/10.5 min OFF was, indeed, sufficient to keep solids in suspension. Tanks with pulse aerated anaerobic and anoxic compartments produced final effluent as superior in quality to the NPDES permit requirements as those that were not pulse aerated. The study demonstrated implementation of pulse aeration in anaerobic and anoxic quadrants would result in 13% less total aeration demand with associated annual energy saving potential close to $430,000. Source: WEFTEC 2009 Proceedings
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Stable N-removal and successful enrichment of anammox bacteria was achieved over a period of one year in continuous flow granular sludge bioreactor. C. Brocadia was the dominant anammox community in the reactor, likely by virtue of operating conditions including not maintaining excessive control over nitrite concentrations and the possible influx and utilization of volatile fatty acids in the influent centrate. In general, granulation led to a significant improvement in reactor stability and N-removal performance and was paralleled by a significant increase in bacteria related to the Bacteroidetes/Chlorobi phylum. Based on data obtained to date, expression of both hzo and ISR appear to be suitable biomarkers of anammox activity and have potential as predictive tools for anammox monitoring and control. Source: WEFTEC 2009 Proceedings
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Blue Plains AWTP
Washington, District of Columbia
The MBBR process is a relatively new biological attached growth treatment system for denitrification. The results of this research should improve the understanding and quantification of the important kinetic and stoichiometric parameters of the MBBR system. The following conclusions can be drawn from overall test results:
i. Biomass density test indicated an increase in biomass density with decrease in temperature. Observed values ranged widely from 6 – 22 g/m2 for R1 and 5-17 g/m2 for R2 throughout the test period (January through June, 2008) for temperatures ranging from 11oC to 24oC.
ii. SDNR was estimated between 1.3 to 2.0 g N/m2/d expressed in terms of total biofilm carrier area. The SDNR expressed as g/m2.d had very little relationship with temperature suggesting a resilience of the overall process to temperature changes. The SDNR expressed as g-NOx- N/g biomass-d was observed to decrease with decreasing temperature. This suggested an Arrhenius relationship, and the Arrhenius constant was calculated as 1.09 for R1 and 1.07 for R2 for a temperature range of 11 – 18 oC, similar to those observed for the activated sludge process using methanol as a substrate. The biomass accumulation at colder temperatures may have contributed to temperature-stable SDNRs when expressed as g/m2.d. This is of practical significance for use of MBBRs in colder climates.
iii. Stoichiometric COD/N ratio was observed in the range of 4.6 mg COD/mg NO3-N to 5.3 mg COD/mg NO3-N and 4.4 mg/mg to 6.1 mg/mg for R1 and R2 respectively. This range is similar to the range observed for denitrification in suspended growth processes.
iv. A model was developed to predict half saturation constant for the MBBR biofilm. The model was based on the non-linear Monod kinetic model and operated on a Microsoft Excel Platform. The model predicted a similar range of KsNOx-N between 0.6 and 2.6 mg N/L for R1 and R2. These values seemed insensitive to changes in temperature with a weak relationship with biomass density. Source: WEFTEC 2009 Proceedings
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Valued qualities such as portability, small footprint, fast start up, and high effluent quality have made package membrane bioreactor (MBR) systems a preferred technology for decentralized wastewater treatment applications. Package MBR systems have many advantages which make them ideal for decentralized wastewater treatment applications, particularly those looking for high effluent quality including total nitrogen removal. However, the selection of a package MBR system can be overwhelming for decision makers given the wide variety in available package MBR systems today and if not evaluated properly can lead to selection of a system that cannot meet the low flow challenges often encountered by decentralized wastewater treatment applications. Therefore it becomes important for decision makers to recognize whether the package MBR system is designed with features that allow it to maintain treatment conditions during low flows. This includes a properly designed flow equalization system capable of handling low influent flows which can be done using multiple pumps with VFDs or an influent flow splitter configuration. The package MBR system should also be designed with system turndown through the use of multiple treatment trains and/or use of multiple pumps and blowers. Lastly the package MBR system must be able to maintain control of oxygen delivery during low flows. Selecting a system which incorporates these low flow design methods into the design of the package MBR system will lead to selection of a system that will reliable meet total nitrogen limits at low flow conditions. Source: WEFTEC 2009 Proceedings
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Gippsland Water Factory
Gippsland, Victoria (Australia)
The Gippsland Water Factory (GWF) will be one of Australia’s most innovative wastewater treatment and recycling systems. With the advent of a carbon constrained economy, infrastructure projects will be required to demonstrate reduced greenhouse gas emissions (GHGe) compared to existing practice. Placing a GHGe constraint on the GWF project drove innovation: in the conceptual stages of design; in research conducted through the pilot plant facility; in determining operational electricity and chemical input requirements; in sourcing electricity inputs; and in carbon accounting techniques. An unambiguous target to reduce GHGe by 20% off a theoretical benchmark of 52,102 tonnes CO2-e/year was set, to ensure that the project was well placed for the introduction of an emissions trading scheme in Australia. A 13,681 tCO2-e per year (29% reduction) from the original concept design (June 2006) to final design (June 2009) was achieved. The GHG assessment included scope 1, 2 and 3 emissions which was important for minimising both onsite and offsite emissions with particular emphasis on reducing chemical consumption. The most significant process design features and characteristics that minimised GHGe were: anaerobic reactors for treatment of the industrial pulp and paper wastewater; methane recovery; membrane bioreactors; cogeneration and micro-hydro energy generation; and biological odour and H2S treatment systems. Source: WEFTEC 2009 Proceedings
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Eastern Treatment Plant
Bangholme, Victoria (Australia)
Use of ozone followed by biological media filtration has been shown in this comprehensive pilot and demonstration scale test to enhance secondary effluent for reclamation purposes. Some enhancements are desirable simply because of better public acceptance, including significant color reduction, and micro-contaminant reduction. However other enhancements like turbidity removal, additional disinfection and ammonia reduction improve effluent from a compliance perspective. Other technologies were trialed including membrane ultrafiltration and reverse osmosis. The ozone BMF treatment platform also improved downstream membrane filtration processes by significantly increasing stable filtration flux and extending “clean-in-place” intervals. The technology increased 5%ile UV transmissivity values from 34% to almost 60%, resulting in significant cost savings in UV disinfection equipment requirements. Lastly, preliminary results indicate ozone increases average BMF solids removal capacity by 46%. “This process delivers the best value for money now and into the future, as a platform for providing flexibility to further enhance recycled water treatment, as needed” (Melbourne Water, July 2009). Source: WEFTEC 2009 Proceedings
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Walton Wastewater Treatment Plant
Walton, New York
The CBUDSF tertiary treatment systems installed throughout the New York City water supply watershed have proven to be robust, reliable and easily maintained. The anticipated lifespan of the CBUDSF systems are 40-50 years with proper maintenance and replacement of supporting equipment (Delaware Engineering, 2008) and are in place at nine WWTP’s in the NYC water supply Catskill and Delaware watershed districts. Over the last 6 years, the CBUDSF system has met its design and operational objectives and continues to perform an integral role in optimizing the Walton WWTP effluent which in turn benefits water quality in the West Branch Delaware River, the Cannonsville Reservoir and the NYC water supply in general. Following installation of the system in January 2003, significant reductions in effluent turbidity (99.99%), total suspended solids (99.95%), phosphorus (99.98%) and fecal Coliform (99.99%) were realized. Plant discharge routinely meets discharge parameter limits for TSS, phosphorus and fecal Coliform. Improvements in water quality below the Walton WWTP as well as other WWTP’s discharging into the West Branch Delaware River have been detected following the regulatory upgrades. NYCDEP stream water quality monitoring operations has measured “drastic” reductions in nutrient loading in the West Branch Delaware River below the Walton WWTP since 2003 when the tertiary system became operational (NYCDEP, 2006). The increased TSS removal facilitated by the tertiary filtration system creates additional TSS loading at the head of the plant since the reject waste stream is directed there. This increase in influent TSS load resulted in a 30% net increase in the weight of residuals generated. Walton WWTP and other watershed WWTP’s operators find that the CBUDSF systems run with relative ease, tolerate variations in input flow composition and are not prone to malfunction (Delaware Operations, 2009). Source: WEFTEC 2009 Proceedings
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Tohopekaliga Water Authority
Tohopekaliga, Florida
Strategic planning is a key to being an effective utility, as described in the Effective Utility Attributes (U.S. EPA, 2007). When the City of Kissimmee divested its water department to form the Toho Water Authority, it was recognized that a strategic plan was needed to guide and align the organization to address its challenges and realize its opportunities. Five carefully and collaboratively selected key strategies were developed in the areas of customer service, water supply, workforce, infrastructure, and financial health. These strategies are also helping Toho to address the Attributes of an Effective Utility developed by the water sector in 2007 and 2008. Employing the Scan, Plan, Do approach has resulted in a viable Strategic Plan for Toho that is designed to accommodate continuous improvement. Toho used a proven process to develop a strong Strategic Plan that will serve to realize its vision for the future, consistent with the Ten Attributes of Effective Utilities. This Strategic Plan is proving to be a key to their success, now and in the future. Source: WEFTEC 2009 Proceedings
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