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The effective treatment of unconventional oil and gas (UOG) wastewater is a promising and potentially necessary strategy of wastewater management in the UOG industry. While tremendous efforts have ...

Projected climate change impacts on the hydrological regime and corresponding flood risks were examined for the years 2030 (near-term) and 2050 (long-term), under representative concentration pathways (RCP) 4.5 (moderate) and 8.5 (high) emission scenarios. The United States Army Corps of Engineers' (USACE) Hydrologic Engineering Center's Hydrologic Modeling System was used to simulate the complete hydrologic processes of the various dendritic watershed systems and USACEs' Hydrologic Engineering Center's River Analysis System hydraulic model was used for the two-dimensional unsteady flow flood calculations. Climate projections are based on recent global climate model simulations developed for the International Panel on Climate Change, Coupled Model Inter-comparison Project Phase 5. Hydrographs for frequent (high-recurrence interval) storms were derived from 30-year historical daily precipitation data and decadal projections for both time frames and RCP scenarios. Since the climate projections for each scenario only represented ten years of data, 100-year or 500-year storms cannot be derived. Hence, this novel approach of identifying frequent storms is used as an indicator to compare across the various time frames and climate scenarios. Hydrographs were used to generate inundation maps and results are used to identify vulnerabilities and formulate adaptation strategies to flooding at 43 locations worldwide.

Leveraging waste heat has been considered to have significant potential for promoting the economic feasibility of wastewater treatment in unconventional oil and gas (UOG) production. However, its availability near well sites has not been fully understood and other energy sources may be also feasible. In this work, we quantitatively investigate the viability of using waste heat and well-pad natural gas to power on-site wastewater treatment by membrane distillation (MD) for twenty randomly selected wells located in the Denver-Julesburg (DJ) Basin, U.S. Results show that waste heat produced from on-site electrical loads is insufficient for MD treatment of all the wastewater generated during UOG production (2.2–24.3% of thermal energy required for MD treatment). Waste heat from hydraulic fracturing, which persists only for a short timeframe, is able to meet the full or partial energy requirement during the peak period of wastewater production (17–1005% of thermal energy required for MD treatment within the first two months of production), but this scenario varies among wells and is dependent on the energy efficiency of MD. Compared to waste heat, natural gas is a more consistent energy source. The treatment capacity of MD powered by natural gas at the well pad exceeds full wastewater treatment demands for all the twenty wells, with only two wells requiring short-term wastewater storage. Our work indicates that although waste heat has the potential to reduce the electricity consumption and cost of UOG wastewater treatment, it is unlikely to supply sufficient thermal energy required by MD for long-term treatment. Natural gas can serve as an alternative or complementary energy resource. Further investigations, in particular techno-economic analyses, are needed to identify the best suitable energy source or combination for on-site UOG wastewater treatment.

Extensive efforts have been made to tailor membrane surface wettability in order to mitigate fouling and wetting in membrane distillation (MD), but the developed membranes have rarely been challenged with real industrial wastewater. This study compared three membranes – a hydrophobic PVDF membrane, a superhydrophobic PVDF membrane, and a composite PVDF membrane with hydrophilic coating – in MD desalination of shale oil and gas produced water from the Wattenberg field in northeast Colorado. Two produced water samples with varied chemical compositions were collected and used as the feedwater. In a single treatment cycle, the composite membrane showed the best fouling resistance for the first sample, while all the tested membranes experienced similar flux decline with the second sample. Thus, the relationship between membrane surface wettability and fouling propensity in MD treatment of real produced water was influenced by feedwater composition. This effect was reflected by distinct features of fouling layers resulting from the two produced water samples, revealed by detailed microscopic and spectroscopic characterization. In three treatment cycles with physical membrane cleaning, the hydrophobic and composite membranes suffered from accelerated membrane fouling after each cycle, whereas a decelerated flux decline was observed for the superhydrophobic membrane. The better reusability of the superhydrophobic membrane, however, was achieved at the expense of initial water vapor flux. Our study suggests that one should comprehensively consider fouling/wetting resistance, water productivity, and reusability in the design and selection of appropriate membranes for MD treatment, and that long-term testing with multiple treatment cycles should be performed to assess MD membrane performance more accurately.

High volumes of flowback and produced water are generated everyday as a byproduct of hydraulic fracturing operations and shale gas developments across the United States. Since most shale gas developments are located in semi-arid to arid U.S. regions close to agricultural production, there are many opportunities for reusing these waters as potential alternatives or supplements to fresh water resources for irrigation activities. However, the impacts of high salinity and total organic content of these types of water on crop physiological parameters and plant growth needs to be investigated to determine their utility and feasibility. The aim of the present study was to evaluate the response of switchgrass and rapeseed to treated produced water as an irrigation water source. In this greenhouse study, the influence of produced water at four total organic carbon (TOC) concentrations [1.22, 38.3, 232.2 and 1352.4 mg/l] and three total dissolved solids (TDS) levels [400,3,500, and 21,000 mg/l] on rapeseed (Brassica napus L.) and switchgrass (Panicum virgatum L.), two relatively salt-tolerant, non-food, biofuel crops, was studied. Seedling emergence, biomass yield, plant height, leaf electrolyte leakage, and plant uptake were evaluated. Irrigation water with the highest salinity and TOC concentration resulted in significantly lower growth health and physiological characteristics of both crop species. The organic content of the produced water had a negative impact on biomass yield and physiological parameters of both species. The results of this study could be valuable for regulators and stakeholders in development of treatment standards in which organic matter should be removed to less than 50 mg/l to keep leaf EL (cell damage) to less than 50% and a TOC concentration of less than 5 mg/l required to keep a sustainable biomass production rate.

Currently, only a few states in the U.S. (e.g. Colorado and Ohio) require mandatory baseline groundwater sampling from nearby groundwater wells prior to drilling a new oil or gas well. Colorado is the first state to regulate groundwater testing before and after drilling, requiring one pre-drilling sample and two additional post-drilling samples within 6 - 12 months and 5 - 6 years of drilling, respectively. However, the monitoring method is limited to ex-situ sampling, which offers only a snapshot in time. To overcome the limitations and increase monitoring effectiveness, a new groundwater monitoring system, Colorado Water Watch (CWW), was introduced as a decision-making tool to support the state’s regulatory agency and also to provide real-time groundwater quality data to both industry and the public. The CWW uses simple in-situ water quality sensors based on surrogate sensing technology that employs an event detection system to screen the incoming data in near real-time. This objective of this study was to improve the understanding of groundwater quality in Wattenberg field and assess event detection methods. The data obtained from 5 sites (the earliest monitoring sites in the CWW network) for 3 years of the regional monitoring network in Wattenberg field is used to illustrate the background information about groundwater quality and its changing trend, and make comparisons between two outlier detection methods, CANARY and simple moving median.

Flowback/produced water reuse cannot be optimized without a thorough understanding of the quality of the water that needs to be treated for reuse, including the temporal variability. Samples for flowback/produced water were collected over a 200-day period (day 0 refers to when flowback began) from two wells. One of the frac fluids had an initial pH greater than 10 and used a guar-based gel and the second fluid contained a non-guar polysaccharide based polymer with an initial pH of less than 6. Total dissolved solids (TDS) and total organic carbon (TOC) were used as macro-indicators and key ions (barium, calcium, chloride, magnesium, sodium, strontium, boron and iron) were compared to TDS with the different frac fluids and there were significant positive correlations observed between the key ions and TDS with relatively high values of the coefficient of determinant (over 0.85). The concentrations of calcium, chloride, sodium and strontium are statistically equivalent between the two fluids. A mass balance approach was applied to evaluate the quantity of mass of injected additives that was recovered over the 200-day period. Recoveries of zirconium, potassium and aluminum ranged from 3% to 33% after 200 days, and notable differences were observed between frac fluids.

Wastewater from shale oil and gas wells contains high levels of organic and inorganic compounds, and the beneficial reuse of produced water requires some level of treatment to remove emulsified oil and grease, suspended solids, and multivalent ions. It is important to identify the quantity and makeup of solids in produced water, so that an optimized reuse or treatment approach can be achieved. This study provides a qualitative and quantitative characterization of solids in frac flowback and produced water from five horizontal wells at two separate sites in the Wattenberg field of Northern Colorado. Difference in solids from wells fractured with fresh water and recycled water is compared in this study, and their distribution and characterization are identified by particle size distribution measurement and X-ray photoelectron spectroscopy (XPS). Results show that particle sizes were smaller and more uniform in produced water samples collected during the first week of production from the wells fractured with recycled water, suggesting that the recycled water was more compatible with the shale formation and wells fractured with recycled water tend to clean out faster.

In an effort to determine impacts of the increased use of treated produced water in new fracs, the rheology of two fracturing fluids was observed for varying water qualities. Specific ions of interest were spiked at varying concentrations into tap water that was used as a base for the fluids. Apparent viscosities were measured using a Chandler 5500 viscometer once fluids were formulated. Empirically, it was determined that at the chosen concentrations for this study, aluminum, iron, phosphorous, potassium, and sodium all have negative impacts on fracturing fluid stability. Calcium and magnesium improved fluid stability until a critical concentration was reached, resulting in lowered viscosities and a less stable fluid. The carboxymethyl cellulose (CMC) fluid was more resilient to aluminum, potassium, and sodium, and other ions that negatively impacted stability than the guar based fluid. The guar based fluid also benefited from divalent cations more than the CMC fluid. The effect of using concentrated gel hydrated with fresh water and then diluted with concentrated ion solutions was also evaluated and did not show any improvement in fluid stability. It appears that specific cations compete for crosslink sites on the gel polymer either through shielding or complexing with active sites that the crosslinker metal would normally complex with. This results in less crosslink sites available for the quatrovalent metal and a less stable fluid. In addition to crosslinked sites that an added crosslinker would complex with, hydrogen bonds can also make a weak crosslink. In the case of calcium and magnesium, the added cations displace hydrogen bonds and form a slightly stronger crosslink. However, this crosslink is not as strong as the ones made by the added crosslinker, and when a critical concentration of calcium or magnesium is reached, the cation competes with the added crosslinker as well, reducing fluid stability.

This paper presents studies on modeling and algorithms for groundwater anomaly detection. Specifically, conductivity along with four other surrogates are used for identifying anomaly in groundwater, the one-class support vector machine (1-SVM) technique is utilized for model training, and real data from Colorado Water Watch is used for testing the model and algorithms. Design of code modules in Python is briefly discussed. Since groundwater contamination rarely happens in reality, we also use synthetic data from numerical simulations of flow and transport in porous media to test this model for anomaly detection.

Currently, only a few states in the USA (e.g., Colorado and Ohio) require mandatory baseline groundwater sampling from nearby groundwater wells prior to drilling a new oil or gas well. Colorado is the first state to regulate groundwater testing before and after drilling, which requires one pre-drilling sample and two additional post-drilling samples within 6-12 months and 5-6 years of drilling. However, the monitoring method is limited to the state's regulatory agency and to ex situ sampling, which offers only a snapshot in time. To overcome the limitations and increase monitoring performance, a new groundwater monitoring system, Colorado Water Watch (CWW), was introduced as a decision-making tool to support the state's regulatory agency and also to provide real-time groundwater quality data to both the industry and the public. The CWW uses simple in situ water quality sensors based on the surrogate sensing technology that employs an event detection system to screen the incoming data in near real-time.

The occurrence of micropollutants in agricultural wastes is an emerging area of interest due to the potential impact of these compounds on the environment. A sensitive and reliable analytical method using liquid chromatography-electrospray tandem mass spectrometry has been developed and validated for the determination of three β-lactam and three polyether ionophore antibiotics in lagoon water and animal manure matrices. The method was applied to evaluate the occurrence of these compounds from participating farms in northern Colorado. Seven of the 19 lagoon water samples and two of the six animal manures showed detectable. The three targeted β-lactams (cephapirin, penicillin G, cloxacillin) were found at 0.97–43.31 μg/L in the lagoon water samples. Of the three targeted polyether ionophores, only monensin (94 to 1077 μg/L) was detected in the beef runoff pond water samples. Only cloxacillin was measured in the dairy animal manure samples at levels from 8.09 to 45.20 μg/kg. No cephapirin, penicillin G, cloxacillin, salinomycin, or narasin A were detected in any solid animal manure sample. These results indicate that elevated concentrations of β-lactam and ionophore compounds might be found in lagoon or runoff pond waters and solid animal manures compared to surface waters, which these compounds are used in veterinary applications.

Public concerns related to the fast-growing shale oil and gas industry have increased during recent years. The major concern regarding shale gas production is the potential of fracturing fluids being injected into the well or produced fluids flowing out of the well to contaminate drinking water resources such as surface water and groundwater. Fracturing fluids contain high total dissolved solids (TDS); thus, changes in TDS concentrations in groundwater might indicate influences of fracturing fluids. An increase of methane concentrations in groundwater could also potentially be due to hydraulic fracturing activities. To understand the possible contamination of groundwater by fracturing activities, real-time groundwater monitoring is being implemented in the Denver-Julesburg basin of northeast Colorado. A strategy of monitoring of surrogate parameters was chosen instead of measuring potential contaminants directly, an approach that is not cost effective or operationally practical. Contaminant surrogates of TDS and dissolved methane were proposed in this study, and were tested for correlation and data distribution with laboratory experiments. Correlations between TDS and electrical conductivity (EC), and between methane contamination and oxidation–reduction potential (ORP) were strong at low concentrations of contaminants (1 mg/L TDS and 0.3 mg/L CH4). Dissolved oxygen (DO) was only an effective surrogate at higher methane concentrations (≥2.5 mg/L). The results indicated that EC and ORP are effective surrogates for detecting concentration changes of TDS and methane, respectively, and that a strategy of monitoring for easy to measure parameters can be effective detecting real-time, anomalous behavior relative to a predetermined baseline.

The objective of this study was to develop models that could be used to predict frac flowback and produced water volumes considering the unique decline rates that exist for different types of oil and gas wells. Specifically, water production data from the Colorado Oil and Gas Conservation Commission (COGCC) and Noble Energy Inc. were used to develop models for water production for vertical and horizontal wells, a distinction made largely due to the different amounts of water used for each. If centralized water treatment and handling facilities are going to be designed and constructed, it is important to have a reliable estimate of the water that will be produced in the future as wells are completed and brought on line. An Excel-based tool was developed utilizing the horizontal and vertical well models for predicting total volume of water production by current and future wells in Wattenberg Field. Two case studies have been conducted including one with all of the Noble wells in Wattenberg Field and one with a subset assuming a regional treatment center might be established. Uncertainty of the predictions was determined using standard error calculations on the two modeling parameters for water flow decline rates. An interactive Excel-based spreadsheet has been developed to allow predictions of water production based on the number of horizontal and vertical wells drilled in the future.

The development of unconventional resources in tight shales has stimulated considerable growth of oil and gas production in Northeastern Colorado, but has led to concerns about added demands on the region’s strained water resources. Northeastern Colorado’s semi-arid environment, population growth, competing water demands and uncertainty about drilling and hydraulic fracturing water requirements have resulted in scrutiny and conflict surrounding water use for tight shales. This study collects water use data from wells in Northeastern Colorado to improve water estimates and to better understand important contributing factors. Most water resource studies use estimates for the number of future wells to predict water demands. This study shows that the number of hydraulic fracturing stages is a better measure of the future water demands for horizontal wells. Vertical wells use significantly less water than horizontal wells and will be less prevalent in the future.

Two typical animal waste management practices, composting and stockpiling, were evaluated for their effect on the degradation of three veterinary antibiotics (VAs), chlortetracycline (CTC), tylosin (TYL), and monensin (MNS). The VAs were applied to horse manure plots subject to composting or stockpiling, and core samples were collected over a period of time. Selected buffer solutions were used to extract the VAs and analysis for concentration was conducted with solid phase extraction (SPE) followed by high performance liquid chromatography tandem mass spectrometry (HPLC/MS/MS) technique. The VAs demonstrated rapid dissipation within ten days followed by a gradual decrease in concentration until the end of the experimental period (141 days). All three VAs degraded more rapidly in the composting samples than in the stockpiling samples, particularly between 20 and 60 days of the observation period. Degradation of the three VAs generally followed a first-order kinetic model, and a fitted model with a calculated rate constant was determined for each treatment. TYL in composting showed the fastest degradation, with a calculated rate constant of 0.91 day -1 ; the slowest degradation was exhibited by MNS in stockpiling, with rate constant of 0.17 day -1 . Calculated correlation coefficients ranged from 0.89 to 0.96, indicating a strong correlation between measured concentrations and fitted values in this study. Although concentration of TYL in composting treatment showed below detection limit during the test period, this study suggests that composting can reduce animal waste contaminants prior to field application as fertilizer.

A reactive stream stabilization (RS2) system based on aluminum as the adsorbent and garden mulch as the organic matter source was designed to minimize release of agricultural nonpoint source pollutants and installed along the bank of the Little Bogue Creek, MS in 2008. The scope of this research was to design, install and assess the performance of a field scale RS2 structure based on results from previous lab scale studies. Concentrations of alum and total organic carbon (TOC) in the RS2 test barrier and surrounding area were measured to evaluate design parameters of RS2 and the removal effectiveness was examined from soils and monitoring wells that were sampled in 2009. The mean concentration of Al from the reactive barrier was 2.1 mg/g and organic matter from the monitoring wells was 4.7 mg/L, values significantly greater than the surrounding area (p < 0.05). Soil Mehlich-3 P and total phosphorus (TP) were decreased by 55% and 30%, and 40% of the TN and 51% of the nitrate in the ground water were removed through the RS2. The design objectives have been satisfied with the installed RS2 system and the initial sampling data shows effective nutrient removal.

Veterinary antibiotics, leached from contaminated manure that is applied as fertilizer, could be transported to surface water as runoff or infiltrated to groundwater after a significant rainfall. The main objective of this study was to evaluate the transport behaviour of ten antibiotics belonging to four different groups in soil through the column leaching study under biotic and abiotic conditions. Among compared antibiotic groups, tetracyclines (TCs) were found to have no residual in the leachate and mainly remained sorbed to the fixed column soil ranging 34~81% of initially applied mass. In contrast, sulfamethazine(SMTs), one of the sulfonamides (SAs) group, was mostly recovered in the leachate at the ranges of 74~83% of the total mass applied. Also, colloidal-facilitated transport of antibiotics was observed. Depending on the antibiotics, recovered mass of colloidal-facilitated transport was 0.4~22.7% for biotic and 0.2~62.5% for abiotic treatment as compared to total mass applied in soil. In general, a less mass was recovered in biotic leachate and soil columns indicating that microorganism activity might be a minor attenuation mechanism. Results indicated that phase partitioning of antibiotics would be a major factor to be assessed in evaluation of fate and transport of antibiotics in soil.

An analytical method was developed and tested for four different groups of veterinary antibiotics in both river water and sediment matrices. Solid phase extraction (SPE) was used to enrich and to clean up the aqueous sample. Also, Mcllvaine and ammonium hydroxide buffer solutions were used to extract the compounds from the sediment matrix. High performance liquid chromatography (HPLC) equipped with tandem mass spectrometry (MS/MS) was used to separate and quantify the samples. The range of recoveries (in percent) for tetracyclines (TCs), sulfonamides (SAs), macrolides (MLs), and ionophore polyethers (IPs) in the water matrix were 102.2-124.8, 76.6-124.3, 89.5-114.7, 82.7-117.5 with 1-13 (%) of relative standard deviation respectively with three different concentrations. For sediment, the percent recovery ranges were 32.8-114.8, 62.4-108.9, 53.4-128.4 and 51.3-105.4 for TCs, SAs, MLs and IPs, respectively. The relative standard deviation ranged from 16 - 27 (%) over three different concentrations. The limit of quantification (LOQ) was determined by two different methods and calculated to be in the range of 0.01-0.04 microg/l and 0.3-2.5 microg/kg for TCs, SAs, and MLs in water and sediment, respectively. For IPs, the LOQ was 0.001-0.003 microg/l in river water and 0.4-3.6 microg/kg for sediment. The sediment concentration measured in an agriculture-influenced river was much higher than in the overlying water matrix, indicating a high degree of sediment partitioning for these compounds.

Two wastewater treatment plants (WWTPs) of northern Colorado were monitored for anhydroerythromycin and tylosin. An analytical method has been developed and validated for the trace determination and confirmation of these compounds in the raw influent and final effluent water matrices. This method was used to evaluate the occurrence and fate of these compounds in WWTPs. The method uses solid-phase extraction and liquid chromatography-tandem mass spectrometry with positive electrospray ionization. Detection and quantification was performed using selected reaction monitoring, and a method detection limit of between 0.01 and 0.06 microg/L was obtained. Unequivocal confirmation analysis of analyte identity according to the criteria (based on the use of identification points) of the 2002/657/EC European Commission Decision was possible with satisfactory results. Average recoveries for the two compounds ranged from 89.2+/-9.7% for raw influent to 93.7+/-6.9% for effluent wastewaters. The within-run precision of the assay was found to be always less than 14.1% for the two analytes. The overall precision was always less than 13.7%. The relative uncertainty of the present assay was also evaluated and the combined relative uncertainty ranged from 6.4 to 15.5% over three days of the validation study. These compounds were partially removed in the WWTPs with a removal efficiency of >50%. The measured concentrations in raw influents and effluents ranged from 0.09-0.35 and 0.04-0.12 microg/L for anhydroerythromycin to 0.06-0.18 and ND-0.06 microg/L for tylosin, respectively. The results indicate that WWTP effluents are relevant point sources for residues of these compounds in the aquatic environment. These occurrence results were compared with those in WWTP wastewaters of other countries.

This four-page summary provides a general overview of the complete text of this article, which is available online in e-JOURNAL AWWA at www.awwa.org/communications/journal/2005/july.

The vulnerability of drinking water distribution systems, combined with the heightener risk of an attack designed to producce mass casualities, has stirred a great amount of interest in designing adequate defenses for these resources.

Chlorite ion is a by-product of chlorine dioxide and is typically present at concentrations ranging from 0.3 to 1.0 mg/L in the finished water of systems using this oxidant in the treatment process. When combined with free chlorine, these two reactive ions have been shown to react to form chlorine dioxide. Chlorine dioxide concentrations formed in tap water (either in the distribution system or during domestic use of tap water, such as laundry bleaching) can off-gas in a home and react with volatile organic compounds associated with new carpets and furniture fabrics, resulting in cat-urine type odors and customer complaints. The objective of this study was to determine if chlorine dioxide is formed when the high concentrations of hypochlorite ion that are used in laundry bleaching operations are contacted with residual chlorite ion that is present in tap water of systems using chlorine dioxide at the treatment plant. If chlorine dioxide is forming under these circumstances, it could be a cause of seemingly random odor complaints periodically received by water utilities using chlorine dioxide. The formation of chlorine dioxide was found to be negligible under simulated laundry bleaching conditions. The key factor in chlorine dioxide formation was found to be pH. When chlorine is added as a base (e.g., sodium hypochlorite), the resulting pH is high enough to suppress chlorine dioxide formation.Key words: chlorine dioxide, chlorite ion, hypochlorite ion, re-formation, odors.

This study examined the effect of initial manganous ion (Mn 2+ ) concentration and oxidant dose on the oxidation of Mn 2+ to Mn oxide during water treatment. The oxidants studied were chlorine dioxide (ClO 2 ), potassium permanganate (KMnO 4 ), and ozone. Initial Mn 2+ concentrations were 60, 200, and 1,000 μg/L, and the goal of the treatment was a final Mn 2+ 20 μg/L after 5 min, with the formation of permanganate ion in many cases. For low Mn 2+ concentrations, 90% oxidation by KMnO 4 required 15-30 min.

Biofiltration can be an effective drinking water treatment process when ozonation is practiced beforehand. The objectives and therefore the designs of these two processes are usually not related to biological treatment goals, and no effort has been made to determine the compatibility of the goals of these integrated treatment processes. The optimal application of ozone (O 3 ) for disinfection is the minimum dose that provides a target level of microorganism inactivation. This dose was equivalent to the optimal O 3 dose for biological treatment, defined as the minimum dose that would achieve the maximum relative BDOC rapid removal. Additionally, the O 3 process is limited with respect to controlling the formation of BDOC rapid Increasing the O 3 dose beyond the optimal dose will result in little additional BDOC rapid formation, little additional release of biodegradable dissolved organic carbon to the distribution system, and an increase in the cost of operation. A conceptual approach for optimizing the O 3 and biofiltration processes for biological treatment objectives is described for three case studies. The results indicate that biological treatment goals can be satisfied to a large degree while simultaneously meeting other drinking water treatment objectives such as disinfection and particle removal.

Pilot-scale biofiltration experiments were conducted to determine how empty bed contact time (BBCT) and hydraulic loading rate (HLB) the affected the removal of biodegradable organic matter (BOM). The removal of BOM formed during ozonation was measured as the reduction (resulting from biodegradation) of dissolved organic carbon in the filter; it was referred to as biodegradable dissolved organic carbon-filter (BDOC filter ). Ten ozone by-products were measured to understand the composition of BDOC filter and to assess whether these by-products might be used as a surrogate for BOM ; none sufficed. BOM formed during ozonation limited the removal of BDOC during biofiltration with two exceptions: nonsteady-state BOM loading conditions and inadequate EBCT. Both of these conditions were limited by biomass formation. HLR had no effect on BDOC filter even though markedly different biomass profiles were observed.

A series of filtration steps was used to separate iron (Fe) and manganese (Mn) into soluble, colloidal, and particulate fractions. Two case studies demonstrate how fractionation data can improve understanding of the origins and removal of Fe and Mn. The Mn species present in one water source were shown to be regulated by a biogeochemical cycle in which the natural oxidation and reduction of Mn appeared to be microbially mediated. Mn removal was improved by adjusting the application of potassium permanganate to account for this cycle. A groundwater treatment plant was suffering from high postfilter Fe and Mn concentrations. Fractionation data identified the problem as inadequate solids capture, not oxidant dosage, allowing a quick solution. The unexpected oxidation of Mn with chlorine (Cl 2 ) was attributed to Fe oxide surface catalysis. Without adequate particle removal (no coagulant added), applying Cl 2 on top of the filters exhibited superior removal to adding Cl 2 before a detention basin.

Pergolide, a synthetic ergoline with potent dopaminergic activity, is used to treat Parkinson disease. The low plasma concentrations of pergolide achieved during therapy complicate the development of a method for its analysis. Because radioimmunoassay successfully measures other structurally related ergolines in physiological fluids, we undertook the development of a radioimmunoassay of pergolide. The detection limit of the radioimmunoassay is 21 ng/L with an optimal working range from 100 to 1000 ng/L. We maximized assay specificity by using a monoclonal antibody that displayed low cross-reactivity with pergolide sulfoxide, a major metabolite found in animals. The radioimmunoassay has performed acceptably for > 2 years during toxicology studies with rats and rhesus monkeys and in clinical studies involving patients with Parkinson disease. We consider the radioimmunoassay a valid method for quantifying therapeutic concentrations of pergolide in plasma.

Currently, the first casualties after an intentional contamination event will be identified by physicians or other health care providers due to the onset of symptoms well after exposure. One approach to mitigating this potential disaster includes on-line monitoring of drinking water distribution systems. Four credible threat drinking water contaminants (aldicarb, sodium arsenate, sodium cyanide, and sodium fluoroacetate) were added to tap water and analyzed at different concentrations to determine their detectability in a drinking water distribution system. Bench top analysis and on-line monitoring equipment was used to measure pH, chlorine residual, turbidity, and total organic carbon values before and after introduction of these contaminants. Results indicate that all four contaminants can be detected at relatively low concentrations. Three of the four contaminants were detected below a concentration that will cause significant health impact.