Ubonratchathani, Thailand
Ubonratchathani, Thailand

Time filter

Source Type

Mattaraj S.,Environmental Engineering Program | Mattaraj S.,Ubon Ratchathani University | Phimpha W.,Environmental Engineering Program | Hongthong P.,Environmental Engineering Program | Jiraratananon R.,King Mongkut's University of Technology Thonburi
Desalination | Year: 2010

This paper describes the effect of operating conditions and solution chemistry on model parameters in crossflow reverse osmosis of natural organic matter. Mathematical fouling model based on the combined osmotic pressure and cake filtration model was used to evaluate model parameters (i.e. steady-state flux, J* and specific cake resistance, αcake). In addition, the empirical equation for steady-state flux (J* = 9.12 × 10- 8ΔP1.04v0.223R- 1.18I- 0.590) was successfully determined to characterize reverse osmosis operation. Steady-state flux increased with increased operating pressure, indicating a pressure-dependent steady-state flux under laminar flow condition. The specific cake resistance (αcake = 7.943 × 1012ΔP- 2.03v- 0.739R6.29I1.37) was inversely related to increased operating pressure and crossflow velocity, while the specific cake resistance increased linearly with recovery effects and ionic strength. Recovery effects with high ionic strength resulted in the highest flux decline, corresponding to high specific cake resistance (i.e. lowering cake porosity) due to combined salt concentration polarization and NOM cake compaction near the membrane surface. © 2009 Elsevier B.V. All rights reserved.

Chen H.,Taiyuan University of Technology | Chen Y.-C.,Environmental Engineering Program
Journal of Residuals Science and Technology | Year: 2013

The aim is to optimize a rapid DNA extraction protocol for biosolids that provides high recovery and purity, and to evaluate potential biases on both quantitative and qualitative microbial analyses. A protocol with 3-step sequential DNA extractions using a modified lysis buffer and purification by a commercial DNA kit was developed and compared to a previously known high recovery solvent-based extraction method, a commercial soil DNA kit with single extraction, and the same commercial kit protocol except extracted with the modified lysis buffer. The developed protocol showed more than 7 times DNA recovery compared to the commercial kit, and comparable E. coli concentrations to the solvent-based method. Direct adoption of the commercial soil kit showed significantly lower recovery and underestimation of E. coli compared to the high recovery protocols. A simple switch of the lysis buffer also improved the DNA recovery by 5 times. Species diversity indexes from pyrosequencing analysis on the other hand showed scatter results from all protocols and only as much as 76% similarity was observed among any paired protocols. Phylogenetic analysis showed a shift of dominance as DNA recovery increases. Overall, this work shows that the developed protocol allows extraction of high quality and quantity DNA within 3 hr. However, qualitative comparisons of species structure may still vary. © 2013 DEStech Publications, Inc.

Chen Y.-C.,Environmental Engineering Program | Higgins M.J.,Bucknell University | Beightol S.M.,Bucknell University | Murthy S.N.,DC Water and Sewer Authority | Toffey W.E.,Effluential Synergies LLC
Water Research | Year: 2011

The objective of this research was to investigate whether a preferential stimulation of microorganisms in anaerobically digested biosolids can occur after dewatering and if it can lead to pathogen indicator regrowth and odor generation upon storage. Laboratory incubation simulating biosolids storage indicates that both odorant generation, based on total volatile organic sulfur compound concentrations (TVOSCs) and pathogen indicator regrowth, based on fecal coliform densities follow similar formation and reduction patterns. The formation and reduction patterns of both odor compounds and fecal coliforms imply that groups of microorganism are induced if shearing disturbance is imposed during dewatering, but a secondary stabilization can be achieved soon after 1-2 weeks of storage. The occurrence of the induction is likely the microbial response to substrate release and environmental changes, such as oxygen, resulting from centrifuge shearing. The new conditions favor the growth of fecal coliforms and odor producing bacteria, and therefore, results in the observed fecal coliforms regrowth and odor accumulation during subsequent storage. However, when both substrate and oxygen deplete, a secondary stabilization can be achieved, and both odor and fecal coliforms density will drop. © 2011 Elsevier Ltd.

Treese D.P.,Environmental Engineering Program | Clark S.E.,Environmental Engineering Program | Baker K.H.,Life science Program
Advances in Civil Engineering | Year: 2012

Subsurface infiltration and surface bioretention systems composed of engineered and/or native soils are preferred tools for stormwater management. However, the disturbance of native soils, especially during the process of adding amendments to improve infiltration rates and pollutant removal, may result in releases of nutrients in the early life of these systems. This project investigated the nutrient release from two soils, one disturbed and one undisturbed. The disturbed soil was collected intact, but had to be air-dried, and the columns repacked when soil shrinkage caused bypassing of water along the walls of the column. The undisturbed soil was collected and used intact, with no repacking. The disturbed soil showed elevated releases of nitrogen and phosphorus compared to the undisturbed soil for approximately 0.4 and 0.8m of runoff loading, respectively. For the undisturbed soil, the nitrogen release was delayed, indicating that the soil disturbance accelerated the release of nitrogen into a very short time period. Leaving the soil undisturbed resulted in lower but still elevated effluent nitrogen concentrations over a longer period of time. For phosphorus, these results confirm prior research which demonstrated that the soil, if shown to be phosphorus-deficient during fertility testing, can remove phosphorus from runoff even when disturbed. Copyright © 2011 Daniel P. Treese et al.

Rodriguez Serrezuela R.,Antonio Nariño University | Carvajal Pinilla L.A.,Environmental Engineering Program
International Journal of Ecology | Year: 2015

Lutzomyia longiflocosa is considered the most likely vector of cutaneous leishmaniasis in the sub-Andean region of the upper valley of the Magdalena River between 1,000 and 2,000 meters in the Department of Huila, Colombia. L. longiflocosa is anthropophilic, has endophagic behavior, and is especially important since its dominance in epidemics recorded in the last decade in the departments of Huila, Tolima, and the outbreak in Norte de Santander. The aim of our work is to identify ecological determinants in forest microhabitat level defining the abundance of L. longiflocosa. We use sampling; this was performed in 56 microhabitats of 28 forests with CDC traps for two consecutive nights from 18:00 to 06:00 hours. Each microhabitat (favorable and unfavorable) was located 10 m from the ecotone, with an approximate area of 10 m2. Thirty-five variables were examined as potential explanatory variables which were recorded in each microhabitat. Regression models were used to identify ecological determinants. Our results confirm that there are favorable microhabitats in the forest with specific ecological determinants that define the aggregated distribution of the species and provide the conditions necessary for survival and abundance of L. longiflocosa. © 2015 Ruthber Rodríguez Serrezuela and Luis Alexander Carvajal Pinilla.

Brooke Anderson G.,Environmental Engineering Program | Bell M.L.,Yale University
Environmental Health Perspectives | Year: 2011

Background: Devastating health effects from recent heat waves, and projected increases in frequency, duration, and severity of heat waves from climate change, highlight the importance of understanding health consequences of heat waves. Objectives: We analyzed mortality risk for heat waves in 43 U.S. cities (1987-2005) and investigated how effects relate to heat waves' intensity, duration, or timing in season. Methods: Heat waves were defined as ≥ 2 days with temperature ≥ 95th percentile for the community for 1 May through 30 September. Heat waves were characterized by their intensity, duration, and timing in season. Within each community, we estimated mortality risk during each heat wave compared with non-heat wave days, controlling for potential confounders. We combined individual heat wave effect estimates using Bayesian hierarchical modeling to generate overall effects at the community, regional, and national levels. We estimated how heat wave mortality effects were modified by heat wave characteristics (intensity, duration, timing in season). Results: Nationally, mortality increased 3.74% [95% posterior interval (PI), 2.29-5.22%] during heat waves compared with non-heat wave days. Heat wave mortality risk increased 2.49% for every 1°F increase in heat wave intensity and 0.38% for every 1-day increase in heat wave duration. Mortality increased 5.04% (95% PI, 3.06-7.06%) during the first heat wave of the summer versus 2.65% (95% PI, 1.14-4.18%) during later heat waves, compared with non-heat wave days. Heat wave mortality impacts and effect modification by heat wave characteristics were more pronounced in the Northeast and Midwest compared with the South. Conclusions: We found higher mortality risk from heat waves that were more intense or longer, or those occurring earlier in summer. These findings have implications for decision makers and researchers estimating health effects from climate change.

Clark S.E.,Environmental Engineering Program | Pitt R.,University of Alabama
World Environmental and Water Resources Congress 2012: Crossing Boundaries, Proceedings of the 2012 Congress | Year: 2012

Stormwater treatment is entering a new phase with stormwater management systems being required to meet specific numeric objectives, as opposed to the historic approach of meeting guidance-document-provided percent removal rates. Meeting numeric discharge requirements will require designers to better understand and apply the physical, chemical, and biological processes underpinning these treatment technologies. This paper focuses on the potential unit treatment operations available for stormwater treatment and how this theoretical information can be applied to stormwater control practice design. © 2012 ASCE.

Ogburn O.,University of Alabama | Pitt R.,University of Alabama | Clark S.,Environmental Engineering Program
World Environmental and Water Resources Congress 2012: Crossing Boundaries, Proceedings of the 2012 Congress | Year: 2012

The primary objective of this research was to examine how different drainage system and tank materials, water characteristics, and exposure time affect contaminants leaching into stormwater runoff. Static leaching tests for eight pipe and gutter materials were conducted over a three month period during which pipe and gutter test materials were immersed in containers with roof runoff water buffered to pH 5 and pH 8. New research was conducted on the same eight gutter and pipe materials using water from Mobile Bay and Black Warrior River in Alabama. In this research, the release of heavy metals is being studied under naturally occurring pH conditions. Water samples were periodically analyzed for a wide range of metallic constituents. As pH decreased, copper concentrations in the copper gutter samples increased. The highest copper release was observed in bay water samples. Galvanized materials resulted in the highest concentrations of zinc. At lower pH conditions, zinc releases from galvanized steel materials increased during the first day of exposure. Zinc releases from galvanized materials were lower in river water samples compared to the bay water samples during short exposure time, however, during long time exposure, zinc concentrations in the river water samples exceeded those in the bay water samples. Galvanized materials were the only source of lead releases. © 2012 ASCE.

Pitt R.,University of Alabama | Clark S.E.,Environmental Engineering Program
World Environmental and Water Resources Congress 2011: Bearing Knowledge for Sustainability - Proceedings of the 2011 World Environmental and Water Resources Congress | Year: 2011

Bioretention has been promoted as a stormwater management technique that can reduce the loads of solids, heavy metals, and nutrients to surface waters. Many researchers have reported the treatment effectiveness of bioretention both in terms of percent removal and periodically in terms of effluent concentration. No studies, however, have evaluated the ability of carefully-selected bioretention media to treat pollutants to meet specific permit limits for certain organic toxicants and radionuclides. This project focused on the selection of a bioretention media mixture from pre-selected components - a granular activated carbon (GAC), two zeolites, two sands, and a peat moss - with the goal of treating numerous constituents, including dioxins, mercury, perchlorate, oil and grease, and radioactive components, along with numerous conventional constituents, to numeric permit limits. Two series of column tests, one focusing on long-term pollutant removal behavior and the other on the effect of depth/contact time on removal and using stormwater as the base test fluid, showed that a bioretention media containing a virgin coconut-hull granular activated carbon (GAC) was able to treat these constituents to the very low permit limits under a wide range of likely site conditions. © 2011 ASCE.

Clark S.E.,Environmental Engineering Program | Pitt R.,University of Alabama
World Environmental and Water Resources Congress 2011: Bearing Knowledge for Sustainability - Proceedings of the 2011 World Environmental and Water Resources Congress | Year: 2011

To address water quality concerns and numeric effluent limits, the designers of bioinfiltration/bioretention systems will need to integrate water and soil chemistry into the selection of filtration media mixtures. For the "dissolved" metals, designers will need to consider the ratio of valence states of the metals as they consider the proportion of ion exchange resins versus organic-based media in the final media mixture. As the correlations between pollutant capacity and soil/media chemistry showed, metals' capacity is directly related to organic matter content and the effective cation exchange capacity of the soil. Available stormwater treatment organic media provides a wide range of treatment sites, but possibly smaller numbers of each site type, compared to ion exchange resins such as zeolites. An activated organic media, such as granular activated carbon (GAC), will have an increased number of surface active sites potentially available for treatment, but this media may not sustain plant growth and may not be desired as a component of bioretention media. Other trade-offs also have to be considered in a complete analysis of a potential media component, such as the trade-off between organic content for plant growth versus nutrient leaching. Finally, there is a lower limit to treatment, after which no further pollutant removal occurs, especially given the contact time requirements based on draindown times required for many bioretention devices. Slightly improved removals for many metals may be achieved with much longer contact times, but the substantial increase in surface area devoted to bioinfiltration may not be cost-effective (given the draindown time requirements). This paper uses "dissolved" copper as an example of how to use both soil and water chemistry to design an optimal bioretention media from a subset of potential mixture components. © 2011 ASCE.

Loading Environmental Engineering Program collaborators
Loading Environmental Engineering Program collaborators