Greeley and Hansen Inc.
Greeley and Hansen Inc.
Cooper B.E.,Greeley and Hansen Inc. |
Cooper B.E.,Virginia Polytechnic Institute and State University |
Dymond R.L.,Virginia Polytechnic Institute and State University |
Shao Y.,Virginia Polytechnic Institute and State University
Photogrammetric Engineering and Remote Sensing | Year: 2017
To address accuracy concerns of the National Land Cover Dataset (NLCD), this case study compares impervious surface from the NLCD to a Detailed Land Cover Dataset (DLCD) for the Town of Blacksburg, Virginia over two time periods (2005/2006 and 2011) at spatial aggregation scales (30 m and 90 m) and scopes (site-specific to area-extent). When comparing the total impervious surface area, the NLCD overestimated significant amounts (12 to 27 percent) for the entire town and across all specified land use zones (single family, multi-family, and non-residential) for both time periods examined. A binary pixel-wise accuracy assessment of impervious surface revealed that the NLCD performed well for the multi-family and non-residential land use zones. However, accuracy level was quite low (user’s accuracy <40 percent) for the single family land use zone. Percent impervious surface of NLCD and DLCD was further compared at 30 m and 90 m spatial scales. The spatial aggregation of pixels to 90 m led to improved agreement between the two datasets, although NLCD still showed an underestimate of high values and an overestimate of low values. An empirical normalization equation was successfully applied to the NLCD to further reduce such data skewness. © 2017 American Society for Photogrammetry and Remote Sensing.
Wilson C.A.,Greeley and Hansen Inc. |
Novak J.,Virginia Polytechnic Institute and State University |
Takacs I.,Dynamita |
Wett B.,University of Innsbruck |
Murthy S.,District of Columbia Water and Sewer Authority
Water Research | Year: 2012
Advanced anaerobic digestion processes aimed at improving the methanization of sewage sludge may be potentially impaired by the production of inhibitory compounds (e.g. free ammonia). The result of methanogenic inhibition is relatively high effluent concentrations of acetic acid and other soluble organics, as well as reduced methane yields. An extreme example of such an advanced process is the thermal hydrolytic pretreatment of sludge prior to high solids digestion (THD). Compared to a conventional mesophilic anaerobic digestion process (MAD), THD operates in a state of constant inhibition driven by high free ammonia concentrations, and elevated pH values. As such, previous investigations of the kinetics of methanogenesis from acetic acid under uninhibited conditions do not necessarily apply well to the modeling of extreme processes such as THD. By conducting batch ammonia toxicity assays using biomass from THD and MAD reactors, we compared the response of these communities over a broad range of ammonia inhibition. For both processes, increased inhibitor concentrations resulted in a reduction of biomass growth rate (rmax = μmax.X) and a resulting decrease in the substrate half saturation coefficient (KS). These two parameters exhibited a high degree of correlation, suggesting that for a constant transport limited system, the KS was mostly a linear function of the growth rate. After correcting for reactor pH and temperature, we found that the THD and MAD biomass were both able to perform methanogenesis from acetate at high free ammonia concentrations (equivalent to 3-5 g/L total ammonia nitrogen), albeit at less than 30% of their respective maximum rates. The reduction in methane production was slightly less pronounced for the THD biomass than for MAD, suggesting that the long term exposure to ammonia had selected for a methanogenic pathway less dependent on those organisms most sensitive to ammonia inhibition (i.e. aceticlastic methanogens). © 2012 Elsevier Ltd.
News Article | November 21, 2016
CHICAGO, Nov. 21, 2016 /PRNewswire/ -- Greeley and Hansen, a global environmental engineering and consulting firm, announced that Val S. Frenkel, PhD, has joined the firm as Vice President of Process Engineering. A prominent industry expert with over 25 years of vast experience in water and wastewater treatment and water reuse process design, Dr. Frenkel is recognized as an international authority on desalination and membrane technologies. In this key role at Greeley and Hansen, Dr. Frenkel will lead efforts to expand the firm's process engineering capabilities and opportunities for future growth in this area. He will also serve as the global leader of the firm's Water Reuse Technical Center of Excellence. "The strategic addition of Dr. Frenkel to the Greeley and Hansen team, will even better position our firm to meet the increasingly complex challenges within the water and wastewater industry today," said Greeley and Hansen President, John C. Robak. "Val's impressive technical knowledge and expansive experience on major water and wastewater projects worldwide will be valuable assets for providing our clients with innovative and effective process configurations and sustainable solutions to meet their long-term needs." Dr. Frenkel most recently served as a Principal Project Manager for CH2M. He is a licensed professional engineer in the State of California and Ontario, Canada and is also certified as a Diplomate, Water Resources Engineer (D.WRE) by the American Academy of Water Resources Engineers. Dr. Frenkel is an active member of numerous industry organizations, including the American Water Works Association, American Society of Civil Engineers, and the Water Environment Federation, among others. In addition, he is a Fellow of the International Water Association and has served on multiple water reuse and membrane processes committees for various industry organizations. The author of more than 100 articles and presentations on a wide range of water reuse and treatment process topics, Dr. Frenkel has also contributed chapters to several industry-wide Manuals of Practice. He is the author of a number of patents for his work and is the recipient of numerous professional awards. Greeley and Hansen is a leader in developing innovative engineering, architecture, and management solutions for a wide array of complex water, wastewater, and related infrastructure challenges. The firm has built upon over 100 years of proven civil and environmental engineering experience in all phases of project development and implementation to become a premier global provider of comprehensive services in the water sector. Greeley and Hansen is dedicated to designing better urban environments worldwide. http://www.greeley-hansen.com/new.htm
McNamara P.J.,University of Minnesota |
Wilson C.A.,Greeley and Hansen Inc. |
Wogen M.T.,University of Minnesota |
Murthy S.N.,District of Columbia Water and Sewer Authority |
And 2 more authors.
Water Research | Year: 2012
The presence of micropollutants can be a concern for land application of biosolids. Of particular interest are nonylphenol diethoxylate (NP 2EO), nonylphenol monoethoxylate (NP 1EO), and nonylphenol (NP), collectively referred to as NPE, which accumulate in anaerobically digested biosolids and are subject to regulation based on the environmental risks associated with them. Because biosolids are a valuable nutrient resource, it is essential that we understand how various treatment processes impact the fate of NPE in biosolids. Thermal hydrolysis (TH) coupled with mesophilic anaerobic digestion (MAD) is an advanced digestion process that destroys pathogens in biosolids and increases methane yields and volatile solids destruction. We investigated the impact of thermal hydrolysis pretreatment on the subsequent biodegradation of NPE in digested biosolids. Biosolids were treated with TH, anaerobic digestion, and aerobic digestion in laboratory-scale reactors, and NPE were analyzed in the influent and effluent of the digesters. NP 2EO and NP 1EO have been observed to degrade to the more estrogenic NP under anaerobic conditions; therefore, changes in the ratio of NP:NPE were of interest. The increase in NP:NPE following MAD was 56%; the average increase of this ratio in four sets of TH-MAD samples, however, was only 24.6±3.1%. In addition, TH experiments performed in pure water verified that, during TH, the high temperature and pressure alone did not directly destroy NPE; TH experiments with NP added to sludge also showed that NP was not destroyed by the high temperature and pressure of TH when in a more complex sludge matrix. The post-aerobic digestion phases removed NPE, regardless of whether TH pretreatment occurred. This research indicates that changes in biosolids processing can have impacts beyond just gas production and solids destruction. © 2012 Elsevier Ltd.
Nelson D.,Greeley and Hansen Inc.
Journal - American Water Works Association | Year: 2014
The Envision™ sustainable infrastructure rating system provides planning and design guidance, performance evaluation, and award recognition to infrastructure projects that contribute to a sustainable future. As a rating system, Envision joins the ranks of LEED, Green Globes, SITES, and hundreds of other regional sustainable metric systems. Envision is currently available for use during planning and design phases. Within each phase, sustainability objectives are summarized in 60 credits organized in five categories, quality of life, leadership, resource allocation, natural world, and climate and risk. The Envision system offers three tools for project assessments, Envision checklist, Envision rating system, and Envision verification and award. ISI offers training and accredition for using the Envision tools the Envision rating system and mandatory for verification and award.
Park C.,University of Massachusetts Amherst |
Fang Y.,Greeley and Hansen Inc. |
Murthy S.N.,DC Water and Sewer Authority |
Novak J.T.,Virginia Polytechnic Institute and State University
Water Research | Year: 2010
The effects of floc aluminum (Al) on activated sludge performance and 17-α-ethinylestradiol (EE2) removal were studied using bench-scale activated sludge systems. The results showed that higher Al-fed activated sludge led to better settling, dewatering, and effluent quality with better EE2 removal. EE2 concentrations in the effluent revealed correlations with effluent suspended solids and large particulate/colloidal effluent biopolymer (protein + polysaccharide). Furthermore, a significant correlation existed between effluent proteins and EE2 for all size fractions, indicating that hydrophobic proteinaceous colloids provide binding sites for EE2 and washout together into the effluent. These results suggest that aluminum plays a crucial role in bioflocculation of activated sludge and the efficacy of flocculation influences the removal of endocrine disrupting compounds (EDCs) from wastewater treatment systems. © 2009 Elsevier Ltd. All rights reserved.
Knocke W.R.,Virginia State University |
Zuravnsky L.,Greeley and Hansen Inc. |
Little J.C.,Virginia Polytechnic Institute and State University |
Tobiason J.E.,University of Massachusetts Amherst
Journal / American Water Works Association | Year: 2010
Many water utilities historically have produced highly effective manganese (Mn) removal by maintaining an active manganese dioxide (MnOx(S)) surface on their filter media that adsorbs soluble Mn. This process requires the presence of free chlorine to regenerate the media or the system fails, and some utilities have ceased adding free chlorine before their filters to pursue treatment goals such as disinfection by-product control or biological filtration. Often the result is elevated Mn levels in the finished water and a corresponding increase in consumer complaints. This research demonstrated the use of MnOx(S)-coated media as a postfiltration adsorptive contactor to provide cost-effective, efficient soluble Mn removal across a range of hydraulic loading rates, solution pH, influent Mn levels, and hypochlorous acid concentrations. Integration of the technology into treatment plants-via either new design or retrofit-could provide effective Mn control, especially at facilities seeking to eliminate free chlorine application to dualmedia filters and/or establish biofiltration across the filters.
Parks J.,Virginia Polytechnic Institute and State University |
Edwards M.,Virginia Polytechnic Institute and State University |
Vikesland P.,Virginia Polytechnic Institute and State University |
Dudi A.,Greeley and Hansen Inc.
Journal of Materials in Civil Engineering | Year: 2010
Autogenous healing can occur when hairline cracks in concrete repair themselves through reactions with water and/or constituents in water. The chemistry of water contacting the cement affects whether the crack heals autogenously or propagates until leaks occur. The strength testing on concrete specimens demonstrates that appreciable healing can occur at a pH of 9.5 when there is sufficient magnesium and silicon in the water. Scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS) analyses indicate that a magnesium silicate material is present within the crack surfaces when higher strength healing has occurred. Calcium does not appear to promote the sealing of cracks. A carbonation of internal concrete surfaces was not detected when cracks were sealed via autogenous healing. Chloride diffusion rates do not return to levels seen in virgin concrete when cracks are autogenously healed. However, the water permeability and chloride diffusion are impeded by any filling of cracks regardless of the strength attained. © 2010 ASCE.
News Article | November 29, 2016
CHICAGO, Nov. 29, 2016 /PRNewswire/ -- Greeley and Hansen, a leading global civil and environmental engineering, architectural, and management consulting firm in water infrastructure, recently opened a new office location in San Francisco, California to further advance the expansion of...
News Article | November 21, 2016
CHICAGO, Nov. 21, 2016 /PRNewswire/ -- Greeley and Hansen, a global environmental engineering and consulting firm, announced that Val S. Frenkel, PhD, has joined the firm as Vice President of Process Engineering. A prominent industry expert with over 25 years of vast experience in water...