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When wood-based activated carbon was tailored with quaternary ammonium/epoxide (QAE) forming compounds (QAE-AC), this tailoring dramatically improved the carbon's effectiveness for removing perfluorooctanoic acid (PFOA) from groundwater. With favorable tailoring, QAE-AC removed PFOA from groundwater for 118,000 bed volumes before half-breakthrough in rapid small scale column tests, while the influent PFOA concentration was 200 ng/L. The tailoring involved pre-dosing QAE at an array of proportions onto this carbon, and then monitoring bed life for PFOA removal. When pre-dosing with 1 mL QAE, this PFOA bed life reached an interim peak, whereas bed life was less following 3 mL QAE pre-dosing, then PFOA bed life exhibited a steady rise for yet subsequently higher QAE pre-dosing levels. Large-scale atomistic modelling was used herein to provide new insight into the mechanism of PFOA removal by QAE-AC. Based on experimental results and modelling, the authors perceived that the QAE's epoxide functionalities cross-linked with phenolics that were present along the activated carbon's graphene edge sites, in a manner that created mesopores within macroporous regions or created micropores within mesopores regions. Also, the QAE could react with hydroxyls outside of these pore, including the hydroxyls of both graphene edge sites and other QAE molecules. This latter reaction formed new pore-like structures that were external to the activated carbon grains. Adsorption of PFOA could occur via either charge balance between negatively charged PFOA with positively charged QAE, or by van der Waals forces between PFOA's fluoro-carbon tail and the graphene or QAE carbon surfaces.

Positively charged polypyrrole (Ppy) was grafted into coconut-based activated carbon (AC), and this increased trifluoroacetate (TFA, CF3COO−) removal from a groundwater source. For batch i...

This research reports an integrated method for synthesizing a quaternary nitrogen-grafted activated carbon that is derived from a subbituminous coal source. The protocol employed nitric acid oxidation, thermal ammonia treatment and methyl iodide quaternization. The quaternized product greatly increased trifluoroacetate (TFA, CF3COO−) removal from a groundwater source. This quaternary nitrogen-grafted carbon (designated AWNQ) exhibited the highest TFA adsorption capacity of 32.9 mg/g and exhibited high energy of adsorption for TFA. Also, when processing groundwater that had been spiked with 200 ppb TFA, this quaternary nitrogen-grafted carbon removed TFA to 3 ppb breakthrough for 1860 BV, which was twelve times longer than the 150 BV for the pristine carbon. The enhanced sorption was attributed to its high quaternary nitrogen ratio (1.30, at.%), which offered 0.69 meq/g positive charge. Furthermore, high regeneration efficiency (89.5%) was achieved by the proposed regeneration protocol. The mixed regenerant (ethanol and NaCl solution) effectively stripped off the loaded TFA and regenerated the quaternary nitrogen sites. This quaternary nitrogen-grafted carbon with its fast and high uptake capacity offered technical promise for TFA removal from groundwater.

Unconventional oil and gas residual solid wastes are generally disposed in municipal waste landfills (RCRA Subtitle D), but they contain valuable raw materials such as proppant sands. A novel process for recovering raw materials from hydraulic fracturing residual waste is presented. Specifically, a novel hydroacoustic cavitation system, combined with physical separation devices, can create a distinct stream of highly concentrated sand, and another distinct stream of clay from the residual solid waste by the dispersive energy of cavitation conjoined with ultrasonics, ozone and hydrogen peroxide. This combination cleaned the sand grains, by removing previously aggregated clays and residues from the sand surfaces. When these unit operations were followed by a hydrocyclone and spiral, the solids could be separated by particle size, yielding primarily cleaned sand in one flow stream; clays and fine particles in another; and silts in yet a third stream. Consequently, the separation of particle sizes also affected radium distribution - the sand grains had low radium activities, as lows as 0.207 Bq g-1 (5.6 pCi g-1). In contrast, the clays had elevated radium activities, as high as 1.85-3.7 Bq g-1 (50-100 pCi g-1) - and much of this radium was affiliated with organics and salts that could be separated from the clays. We propose that the reclaimed sand could be reused as hydraulic fracturing proppant. The separation of sand from silt and clay could reduce the volume and radium masses of wastes that are disposed in landfills. This could represent a significant savings to facilities handling oil and gas waste, as much as $100 000-300 000 per year. Disposing the radium-enriched salts and organics downhole will mitigate radium release to the surface. Additionally, the reclaimed sand could have market value, and this could represent as much as a third of the cost savings. Tests that employed the toxicity characteristic leaching protocol (TCLP) on these separated solids streams determined that this novel treatment diminished the risk of radium mobility for the reclaimed sand, clays or disposed material, rendering them better suited for landfilling.

Radium measurements in high total dissolved solids (TDS) fluids from oil and gas extraction can have unfavorable precision and accuracy, in part because these high-level impurities incur attenuation. γ spectroscopy is often recommended for determining radium activities in these fluids, but even this method can produce a range of reported activities for the same sample. To reduce measurement duration and to maintain or improve accuracy, we propose a method to rapidly assess both

Acid/base/oxidant pretreatment influenced subsequent quaternary ammonium epoxide compounds modified carbon (QAE-AC) and hence PFOA and nitrate removal. This work discerned that the most favorable QAE-AC protocol for PFOA removal was achieved when the wood carbon pretreated with HNO3 to adjust the carbon’s slurry pH to 4.77, and tailored with the QUAB188. For nitrate removal, the most favorable when the carbon was pretreated with NaOH to raise the carbon’s slurry pH to 9.34, and then loaded with the QUAB360. Based on experimentally results and molecular model, we found that pore volume, phenolic groups and the surface charge were the main factors affecting the PFOA removal, while the only factor affecting nitrate removal was surface charge. The QUAB’s epoxide functionalities have cross-linked with phenolics along the activated carbon’s graphene edge sites. QAE is preferentially reacted with the phenolic in the micropores and mesopores of carbon, and some QAE molecules form new “pore-like structures” outside the pores with the graphene planes or other QAE molecules. This pore-like structure hosted adsorption capacity by the quaternary ammonium. The favorable PFOA adsorption sites were in smaller mesopores via both hydrophobic interaction and electrostatic interaction; and nitrate sorption was occurring in the smaller micropores via anion exchange. Therefore, it can be considered that QAE-AC can simultaneously adsorb PFOA and nitrate in water.

Beneficial reuse and resource recovery of produced water often require treatment to remove radium before valuable products are extracted. The radium content of the treatment waste solids and beneficial products must be accurately determined when evaluating the efficacy and social validity of such treatments. While gamma spectroscopy remains the recommended method for radium measurements, these measurements can be impacted by the composition/mineralogy of the solids, which influence the attenuation of the gamma decay energy – with denser sediments incurring greater degrees of attenuation. This self-attenuation must be accounted for when accurately measuring radium, otherwise radium measurements are found to be inaccurate, sometimes by as much as 50%. To meet industry needs, measurements should be both accurate and rapid, even for small sample sizes. Consequently, we propose a rapid method for accurate radium measurements with an empirical technique to account for sample attenuation in well-detector gamma spectroscopy. This technique utilizes the sample density and sample volume in the measuring vial. These corrections are relevant to a wide range of solid samples and sediment densities that may be encountered during treatment and management of oil and gas solids, including clays, environmental sediment samples, sand grains, and precipitated salts. These corrections can also be applied for situations were low volumes of material are present, as in bench scale studies, thereby rendering this technique applicable to a wider range of scenarios.

Concentrations of naturally occurring radioactive material (NORM) in Marcellus Shale produced water presents a challenge for effective management and treatment, because of the vast fluid volumes generated. With an increased emphasis on beneficial reuse and resource recovery from the produced waters, a rapid, yet reliable, method for quantifying radium in these produced waters is needed. The high total dissolved solids (TDS) concentration introduces difficulties when measuring 226Ra by recommended EPA methods that were specifically developed several decades ago for drinking water. While other techniques for measuring radium in these high-TDS fluids have since been developed, these newer techniques often require extensive and complicated pre-concentration steps; and they thus require extensive analytical chemistry skills, utilize hazardous chemicals like hydrofluoric acid, demand long holding times or measurement times, and require high sample volumes. We present a rapid method for 226Ra measurements in high-TDS produced waters by liquid scintillation counting, which has been corroborated herein by concurrent gamma spectrometry analyses. Samples were prepared for analysis by evaporating the fluid and re-suspending the evaporate with acidified distilled deionized water prior to liquid scintillation counting for 1 h. This protocol yielded radium recoveries ≥93%. Per this protocol, the alpha and beta spectra of 226Ra and its daughters were computationally separated by alpha-beta discrimination and spectrum deconvolution. The minimum detectable activities of 226Ra was 0.33 Bq/L (9.0 pCi/L) when the counting time was 60 min and the sample volume was 4 mL. Nine produced waters of varying TDS and radium concentrations from the Marcellus Shale Formation were analyzed by this method and compared with gamma spectroscopy; and these yielded comparable results with an R2 of 0.92. The reduced sample preparation steps, low cost, and rapid analysis position this as a well-suited protocol for field-appraisal and screening, when compared to comprehensive radiochemical analysis. We offer that for a given produced water region, routine and local liquid scintillation analyses can be compared and calibrated with infrequent gamma spec analyses, so as to yield a near-real time protocol for monitoring 226Ra levels during hydrofracturing operations. We present this as a pragmatic and efficient protocol for monitoring 226Ra when produced water samples host low levels of 228Ra—since the progeny of 228Ra can significantly confound the LSC analyses.

In order to obtain a high adsorption capacity for perchlorate, the epoxide-forming quaternary ammonium (EQA) compounds were chemically bonded onto granular activated carbon (GAC) surface by cationic reaction. The optimum preparation condition of the cationic GAC was achieved while applying softwood-based Gran C as the parent GAC, dosing EQA first at a pH of 12, preparation time of 48 h, preparation temperature of 50 °C, and mole ratio of EQA/oxygen groups of 2.5. The most favorable cationic GAC that had the QUAB360 pre-anchored exhibited the highest perchlorate adsorption capacity of 24.7 mg/g, and presented the longest bed volumes (3000 BV) to 2 ppb breakthrough during rapid small scale column tests (RSSCTs), which was 150 times higher than that for the pristine Gran C. This was attributed to its higher nitrogen amount (1.53 At%) and higher positive surface charge (0.036 mmol/g) at pH 7.5. Also, there was no leaching of the quaternary ammonium detected in the effluent of the RSSCTs, indicating there was no secondary pollution occurring during the perchlorate removal process. Overall, this study provides an effective and environmental-friendly technology for improving GAC perchlorate adsorption capacity for groundwater treatment.

A novel method has been developed for anchoring quaternary ammonium/epoxide-forming compounds (QAEs) within bituminous based granular activated carbons (GACs). This modified GAC was then used to remove perchlorate from groundwater. The effect of the preparation temperature (T), solution pH (pH) and the dry mass ratio of QAE-to-GAC (R) over the perchlorate adsorption capacity (Qe) were studied by the Response Surface Methodology. The combined effects of these variables were fitted to a quadratic model to determine the more favorable preparation protocol for perchlorate removal. Statistical analysis revealed that: (1) the interaction of T and pH incurred the most effect on Qe; and (2) two of the more favorable preparation protocols became apparent: one was at 75 °C, pH 11 and R of 1.73 g QAE/g GAC (U17), the other was at 35 °C, pH 14 and R of 4.00 g QAE/g GAC (U2). Rapid small scale column tests were further employed to evaluate the performance of the QAE-anchored GACs for perchlorate removal. U17 and U2 exhibited 18–20 times longer bed life (BV) to 6 ppb breakthrough than did the Pristine GAC (900 BV), when processing groundwater that had been spiked with 30–35 ppb perchlorate. This indicated the statistical method enhanced GAC’s perchlorate removal efficiency.

Polypyrrole modified activated carbon was used to remove sulfate from acid mine drainage water. The polypyrrole modified activated carbon created positively charged functionality that offered elevated sorption capacity for sulfate. The effects of the activated carbon type, approach of polymerization, preparation temperature, solvent, and concentration of oxidant solution over the sulfate adsorption capacity were studied at an array of initial sulfate concentrations. A hardwood based activated carbon was the more favorable activated carbon template, and this offered better sulfate removal than when using bituminous based activated carbon or oak wood activated carbon as the template. The hardwood-based activated carbon modified with polypyrrole removed 44.7 mg/g sulfate, and this was five times higher than for the pristine hardwood-based activated carbon. Various protocols for depositing the polypyrrole onto the activated carbon were investigated. When ferric chloride was used as an oxidant, the deposition protocol that achieved the most N+ atomic percent (3.35%) while also maintaining the least oxygen atomic percent (6.22%) offered the most favorable sulfate removal. For the rapid small scale column tests, when processing the AMD water, hardwood-based activated carbon modified with poly pyrrole exhibited 33 bed volume compared to the 5 bed volume of pristine activated carbons.

Studies on arsenic removal by zero-valent iron (ZVI)–based system have focused mostly on batch or small scale tests. In this research, pilot-scale studies were carried out on arsenic removal by technologies developed in rapid small-scale column tests (RSSCTs). Pilot-scale studies can provide significant information on final scale-up to full-scale operation, which RSSCT inherently was not able to provide. In addition, comparison between pilot column and RSSCT breakthrough profiles could help validate RSSCT design, especially RSSCT for arsenic. Results from pilot studies indicate that arsenic removal by a system of ZVI plus iron-tailored granular activated carbon showed significant promise for practical applications. The best performance was achieved when ZVI worked together with carbon pretailored by an iron-salt evaporation method. In addition, the similarity in arsenic breakthrough curves between RSSCTs and pilot studies serves to confirm that it is appropriate to assume proportional diffusivity...

A series of pilot-scale tests were conducted with a continuous system composed of a stirring tank reactor, settling tank, and sand filter. In order to treat acidic drainage from a Pb–Zn mine containing high levels of heavy metals, the potential use of coal-mine drainage sludge (CMDS) was examined. The pilot-scale tests showed that CMDS could effectively neutralize the acidic drainage due to its high alkalinity production. A previous study revealed that calcite and goethite contained in CMDS contributed to dissolutive coprecipitation and complexation with heavy metals. The continuous system not only has high removal efficiencies (97.2–99.8%), but also large total rate constants (Ktotal, 0.21–10.18 h−1) for all heavy metals. More specifically, the pilot system has a much higher Zn(II) loading rate (45.3 g m−3 day−1) than other reference systems, such as aerobic wetland coupled with algal mats and anoxic limestone drains. The optimum conditions were found to be a CMDS loading of 280 g L−1 and a flow rate of 8 L day−1, and the necessary quantity of CMDS was 91.3 g L−1 day−1, as the replacement cycle of CMDS was determined to be 70 days.

Removal of perchlorate (ClO4−) while using granular-activated carbon (GAC) that had been preloaded with cetylpyridinium chloride was appraised using Rapid Small-Scale Column tests (RSSCT) and pilot-scale demonstration. ClO4− competed with nitrate, sulfate, chloride, and other anions for ion exchange sites on the preloaded carbon. Tests used native groundwater from Fontana, CA, which contained nitrate of 32 mg/L as NO3−, 7 μg/L as ClO4−, and 1.9 μg/L (as U) of uranyl carbonate species (predominantly UO2(CO3)34−) species. RSSCT with Fontana groundwater exhibited ClO4− breakthrough at 25,000 bed volumes. When the same groundwater was spiked to three times the native NO3− concentration, ClO4− breakthrough occurred at 12,000 bed volumes. When the total dissolved solids (TDS) increased from the native 250 mg/L up to 660–810 mg/L TDS, by adding magnesium sulfate, sodium bicarbonate, or sodium chloride, the bed-life for removing ClO4− increased by 10%–30%. This result was attributed to perchlorate's comp...

Thiosulfate (S2O32−) hosts redox stability in time frame of days, rendering it a candidate ion exchange competitor in anoxic groundwaters during the brief time frames of treatment processes. Indeed, this research determined that the oxyanion thiosulfate (S2O32−) competed with perchlorate (ClO4−) for sorption onto activated carbons that had been preloaded with a quaternary ammonium surfactant. Moreover, this research showed that when proper prechlorination oxidized this S2O32− to sulfate (SO42−), this competition was diminished. When rapid small-scale column test employed Redlands, CA, groundwater that contained a native 30 μg/L ClO4−, this exhibited a 6 μg/L ClO4− breakthrough after 33,000 bed volumes (BVs) when processed through bituminous-based granular-activated carbon that had been preloaded with a quaternary ammonium surfactant, namely, 0.24 g/g dicocoalkyldimethylammonium chloride (Arquad 2C-75). When this same water was spiked with 1,000 μg/L S2O32−, 6 μg/L of ClO4− broke through at 17,000...

Temporal changes in the pore structure of granular activated carbons (GACs) were investigated for two reactivated and one virgin GAC during water treatment. One reactivated GAC had experienced five cycles of treatment and reactivation (5xReac), whereas the other had experienced twelve cycles (12xReac). For the virgin GAC that became loaded with natural organic matter (NOM), nearly all pore volume loss occurred in pores 40 A. For the 5xReac, the greatest loss of pore volume occurred in the 100–500 A pores. The 12xReac GAC experienced some loss of pore volume in the 100–500 A pores. For each GAC, NOM adsorption initially caused pore volume loss in pores that were only slightly wider than the NOM itself. Subsequent to this initial stage, NOM was mostly retained in the 20–40 A pores for the virgin GAC and in the 100–500 A pores for the 5xReac GAC. This was followed by gradual migration of the NOM into smaller pores. A lull in NOM loading revealed distinctions in ho...

The authors monitored hydrogen peroxide (H2O2), ozone (O3), and apparent hydroxyl radical (OH·) concentrations in the liquid phase, along with gas phase ozone when operating an advanced oxidation (AO) system that included H2O2, O3, sonication, and underwater plasma (UWAP). The OH· radical converted non-fluorescent terephthalic acid to fluorescent hydroxyterephthalic acid (HTA). As determined from HTA formation, when a 500 ppm H2O2 dose in tap water was combined with O3 and sonication, nearly twice as much OH· (0.72 ppm) accumulated than with H2O2 alone. When UWAP accompanied H2O2, O3, and sonication, these together generated 15–35% more OH· than when UWAP was excluded. When ozone was introduced into this AO system, the AO system decomposed almost all the O3. This research has been conducted as a part of a study that has appraised this advanced oxidation system (Sonoperoxone) in green sand foundries, where it has diminished volatile organic compound (VOC) and hazardous air pollutant (HAP) emissions by 20–7...

Analytical pyrolysis was conducted to study a relative comparison of the hydrocarbon and greenhouse gas emissions of three foundry sand binders as follows: (a) conventional phenolic urethane resin, (b) biodiesel phenolic urethane resin, and (c) collagen-based binder. These binders are used in the metal casting industry for making cores that are used to create internal cavities within castings. In this study, the core samples were flash pyrolyzed in a Curie-point pyrolyzer at 920 degrees C with a heating rate of about 3000 degrees C/sec. This simulated some key features of the fast heating conditions that the core binders would experience at the metal-core interface when molten metal is poured into green sand molds. The core samples were also pyrolyzed in a thermogravimetric analyzer (TGA) from ambient temperature to 1000 degrees C with a heating rate of 30 degrees C/min, and this simulated key features of the slow heating conditions that the core binders would experience at distances that are further away from the metal-core interface during casting cooling. Hydrocarbon emissions from flash pyrolysis were analyzed with a gas chromatography-flame ionization detector, while hydrocarbon and greenhouse gas (CO and CO2) emissions from TGA pyrolysis were monitored with mass spectrometry. The prominent hazardous air pollutant emissions during pyrolysis of the three binders were phenol, cresols, benzene, and toluene for the conventional phenolic urethane resin and biodiesel resin, and they were benzene and toluene for the collagen-based binder. It was also found that volatile organic compound and polycyclic aromatic hydrocarbon emissions considerably decreased in order from conventional phenolic urethane resin to biodiesel resin to collagen-based binder. These results have shown some similarity with those for stack emission testing conducted at demonstration scale and/or full-scale foundries, and the similar trends in the two sets of results offered promise that bench-scale analytical pyrolysis techniques could be a useful screening tool for the foundries to compare the relative emissions of alternative core binders and to choose proper materials in order to comply with air-emission regulations.

Endocrine disrupting chemicals and pharmaceuticals represent two classes of emerging contaminants that are ubiquitously present in municipal wastewater effluents. Some of these contaminants have been shown to impact aquatic organisms at trace concentrations (i.e., ng/L). Moreover, the public has expressed human health concerns regarding the presence of emerging contaminants in water reuse projects. The primary objective of this investigation was to determine the efficacy of various membranes and activated carbons for the removal of endocrine disruptors, pharmaceuticals, and personal care products. A suite of structurally diverse target compounds was selected for evaluation based largely upon occurrence and molecular structure. Several membrane types and applications were evaluated at pilot- and/or full-scale, including: microfiltration, ultrafiltration, nanofiltration, reverse osmosis, electrodialysis reversal, membrane bioreactors, and combinations of membranes in series. Granular activated carbon was evaluated at bench-scale using rapid small scale column tests and at two full-scale utilities. Microfiltration and ultrafiltration were found to reject very few target compounds; however, some loss of steroidal type compounds was observed. Nanofiltration and reverse osmosis were capable of significant rejection of nearly all target compounds, though compounds were detectable at trace levels in permeates. Granular activated carbon was highly effective at removing all target chemicals. However, break-through curves clearly demonstrated that compounds with greater hydrophilicity breach activated carbon faster than hydrophobic compounds. In full-scale applications, the impact of regeneration was observed as activated carbon filters that received regular regeneration had minimal breakthrough of organic contaminants, while non-regenerated filters displayed no removal of target compounds. Findings confirm that membrane and carbon processes are capable of greatly reducing the concentrations of emerging contaminants; however, several compounds are detectable in membrane permeate and carbon effluent.

The effects of advanced oxidation (AO) processing on the properties of green sand were studied via pouring cast iron into green sand molds. Upon cooling, the green sand molds were autopsied at various distances from the metal−sand interface. Autopsy green sand samples collected from a mold that incorporated AO water were characterized and compared to controlled samples collected from a similar autopsied mold made with conventional tap water (TAP). It was found that the AO processing removed a coating of coal pyrolysis products from the clay surface that typically accumulated on the clay surface. As a result, the AO-conditioned green sand retained 10−15% more active clay as measured by the standard ultrasonic methylene blue titration than did the TAP-conditioned green sand. The AO processing also nearly doubled the generation of activated carbon from the normalized amount of coal composition of the green sand during the casting process. The AO-enhanced activated carbon generation and the AO-incurred clay s...

Prior full-scale foundry data have shown that when an advanced oxidation (AO) process is employed in a green sand system, the foundry needs 20-35% less makeup bentonite clay than when AO is not employed. We herein sought to explore the mechanism of this enhancement and found that AO water displaced the carbon coating of pyrolyzed carbonaceous condensates that otherwise accumulated on the bentonite surface. This was discerned by surface elemental analysis. This AO treatment restored the clay's capacity to adsorb methylene blue (as a measure of its surface charge) and water vapor (as a reflection of its hydrophilic character). In full-scale foundries, these parameters have been tied to improved green compressive strength and mold performance. When baghouse dust from a full-scale foundry received ultrasonic treatment in the lab, 25-30% of the dust classified into the clay-size fraction, whereas only 7% classified this way without ultrasonics. Also, the ultrasonication caused a size reduction of the bentonite due to the delamination of bentonite particles. The average bentonite particle diameter decreased from 4.6 to 3 microm, while the light-scattering surface area increased over 50% after 20 min ultrasonication. This would greatly improve the bonding efficiency of the bentonite according to the classical clay bonding mechanism. As a combined result of these mechanisms, the reduced bentonite consumption in full-scale foundries could be accounted for.

This research investigated methods for tailoring a commercial, lignite-based granular activated carbon (GAC) to enhance its adsorption of 2-methylisoborneol (MIB) from natural water. Tailoring efforts focused on heat treatments in gas environments comprising steam and/or methane, since these gases can alter GAC pore structure and surface chemistry. Heat treatments that combined methane and steam enhanced MIB adsorption considerably, causing a 4-fold improvement (over untreated GAC) in fixed-bed adsorption performance relative to initial MIB breakthrough. These favorable effects, observed in rapid small-scale column tests, occurred following simultaneous and separate (sequential) applications of methane and steam. Moderately low temperature steam treatments also improved MIB uptake in fixed-bed adsorption tests but to a lesser extent (approximately 1.5-fold). In contrast, methane treatments alone, at various temperatures, led to significant carbon deposition within the GAC pore structure. As a result, total pore volume was reduced and MIB adsorption performance declined.

The tetramethylammonium hydroxide (TMAH) thermochemolysis method was recently introduced for the qualitative characterization of organic matter from natural waters (NOM). Such characterizations were usually of a qualitative nature, and any semiquantitative assessments of individual compounds were often achieved by measuring relative areas and assuming unity as a response factor. In this paper we evaluate the quantitative measurement of many identified products characteristic of lignin and NOM using an internal standard approach. The relative standard deviation for most quantified compounds was between 1 and 10%. Four NOM samples, isolated by low-temperature, low-pressure evaporation and freeze-drying, were collected from temperate as well as tropical climates. Large variations were found between samples with respect to the distribution of compounds such as fatty acids, lignin-derived compounds, carbohydrate-derived compounds, and protein-derived compounds. We quantified most lignin-derived and aromatic TMAH products as well as fatty acids (as their methyl esters, FAME) that were found in this set of NOM samples. The contribution of lignin-derived compounds to the total quantified TMAH product distribution in these four samples varied between 21 and 35%. The contribution of FAMEs ranged from 32 to 51% whereas the contribution from non-lignin aromatic compounds was 24–32%. TMAH thermochemolysis potentially provides significant information about NOM sources, compared with other degradative techniques, since both lignin-derived compounds and lipids can be quantitatively and simultaneously investigated.

Copper removal to residual parts-per-billion (ppb) levels was achieved in an activated sludge system by employing iron bioflocculation and biosolids storage conditioning. Low copper residuals correlated to an increase in extracellular polysaccharides that were produced by microorganisms within activated sludge. In batch bench-scale tests, supernatant copper levels between 15 and 35 ppb were achieved when employing a coagulant dosage of 15 mg/L (as Fe) and when allowing 18 to 26 h of biosolids storage conditioning to enhance the production of exopolymers. These copper levels were less than half as much as when neither coagulant nor biosolids storage conditioning was employed. Minimum copper residuals occurred in a pH range from 6.5 to 8.8, and when at least half of the biosolids had been stored for a day. Biosolids that were conditioned under a closed-to-oxygen environment yielded the lowest copper residuals among the bench-scale conditions that were tested, and it also produced the largest amounts of extr...

Effluent copper concentrations from a pilot-scale conventional activated-sludge system (control) were compared with those from a conventional pilot treatment process that also integrated bioferric/selector units. The bioferric/selector units employed iron coagulation within the activated-sludge basin and also provided storage of activated sludge in a nonaerated selector for a period of 18–24 h. During pseudo-steady-state operation over a 30-day period, the systems employing the bioferric/selector treatment consistently yielded lower effluent copper concentrations than did the controls. Although influent copper concentration ranged from 126 to 723 pb (228 ppb average), the two bioferric/selector units achieved an average effluent copper concentration of 22 ppb, whereas the two conventional controls achieved an average of 40 ppb. The difference in copper concentrations between the bioferric/selector units and the controls was statistically significant to the 99.5% confidence level when comparing effluent copper concentrations as a function of mixed-liquor volatile suspended solids (MLVSS). For both conditions, lower effluent copper corresponded to higher MLVSS, and for equal levels of MLVSS, the bioferric/selector nits statistically achieved lower effluent copper concentrations than did the controls. Likewise, Freundlich isotherm plots indicated that the MLVSS (or MLSS) that had undergone the bioferric/selector treatment achieved statistically greater capture of copper than did their control counterparts.

Hydrous oxides of iron (HFO) and aluminum (HAO) were studied for their ability to reduce Cu (initially 4.3 mg/L) to microgram per liter levels typical of increasingly stringent wastewater discharge limits. Residual soluble Cu was compared following adsorption (ADS), where Cu was contacted with preformed oxide flocs, and coprecipitation (CPT), where Cu was added prior to HFO or HAO precipitation. For the HAO-ADS system, soluble Cu levels were markedly undersaturated with respect to homogeneous precipitation (PPT) of Cu(OH)2(s) over the pH 6−9 range. In contrast, soluble Cu was lowered by HFO-ADS for pH

The Pennsylvania State University is researching an advanced oxidation system, which includes an air-phase photolytic chamber, an air/water stripping tower, and granular activated carbon (GAC) beds, for controlling volatile organic compounds (VOCs). A laboratory-scale experimental procedure has been employed that simulated certain aspects of several full-scale installations. The apparatus has been used to characterize the loading capacity and mass transfer zone of selected VOCs on coconut shell GAC. The GAC bed has then been placed in series with an ultraviolet reactor, which generates ozone and advanced oxidants in order to regenerate the loaded GAC at intensities of advanced oxidants that were higher than full-scale installations. VOC loading tests revealed that the adsorption of methyl isobutyl ketone (MIBK) was characterized by a well-defined mass transfer zone. Upon exposure to UV/O3, desorption and/or destruction of the MIBK and other VOCs occurred most prominently within the first inch of the GAC bed. This correlated with the penetration of advanced oxidants into the GAC bed, which also occurred most significantly in the bed's first inch. However, the amount of oxidant penetration increased with time. The removal of oxidants from air by GAC was accompanied by a decrease in mass of the GAC. The ability of oxidants to penetrate a GAC bed was altered when the bed was loaded with a VOC.

The Pennsylvania State University is researching an advanced oxidation (AO) system for controlling volatile organic compounds (VOCs) (Cannon et al. 1994). The system includes an air‐phase photolytic chamber, an air/water stripping tower, and granular activated carbon (GAC) beds, and the work herein describes he evaluation of the GAC beds. Field GACs have been evaluated, which had previously been loaded with VOCs and regenerated with AO for several years at several full scale installations. Full scale response then was simulated in laboratory‐scale experiments. Results revealed that following 500 to 1000 daily loading and regeneration cycles, one field GAC lost 35% of its micropore volume, and 17–35% of its capacity to adsorb several VOCs. Under another condition, for a furniture coating GAC, 80% of the micropore volume was lost after several years of loading and reactivation cycles, and 23 to 63% of the VOC adsorption capacity was lost. Laboratory results revealed that prolonged AO regeneration d...

Demonstration-scale metal pouring emission tests and bench-scale Curie-point pyrolysis emission tests were conducted to identify and quantify the hazardous air pollutant (HAP) emissions of five kinds of casting materials, namely, bituminous coal, cellulose, conventional phenolic urethane binder (PUB), naphthalene-depleted PUB, and a collagen-based binder. For a given casting material, the major HAP species generated in Curie-point pyrolysis were essentially the same as those generated in demonstration-scale metal pouring. The 8-10 HAP species identified in the Curie-point pyrolysis tests comprised 65-98% (by weight) of the total HAP emissions quantified in the demonstration-scale pouring emission tests. Furthermore, with these two protocols, we appraised the relative emission changes that would be associated with (a) replacing conventional PUB with collagen-based binder, (b) replacing conventional PUB with naphthalene-depleted PUB, and (c) replacing bituminous coal with cellulose for making sand molds or cores in the casting process. The relative emission changes associated with the use of alternative casting materials exhibited similar trends for most of the major HAP species in the demonstration-scale pouring and Curie-point pyrolysis emission tests. The results indicated that Curie-point pyrolysis emission test could be employed as a convenient and cost-effective screening tool to identify the major HAP species and to compare the relative HAP emission levels for various casting materials.

An alternative fuel to replace foundry coke in cupolas was developed from waste anthracite fines. Waste anthracite fines were briquetted with Si-containing materials and treated in carbothermal (combination of heat and carbon) conditions that simulated the cupola preheat zone to form silicon carbide nanowires (SCNWs). SCNWs can provide hot crushing strengths, which are important in cupola operations. Lab-scale experiments confirmed that the redox level of the Si-source significantly affected the formation of SiC. With zerovalent silicon, SCNWs were formed within the anthracite pellets. Although amorphous Si (+4) plus anthracite formed SiC, these conditions did not transform the SiC into nanowires. Moreover, under the test conditions, SiC was not formed between crystallized Si (+4) and anthracite. In a full-scale demonstration, bricks made from anthracite fines and zerovalent silicon successfully replaced a part of the foundry coke in a full-scale cupola. In addition to saving in fuel cost, replacing coke by waste anthracite fines can reduce energy consumption and CO2 and other pollution associated with conventional coking.

Analytical pyrolysis was conducted to identify and quantify the major pyrolysis products of a biodiesel phenolic urethane binder as a function of temperature. This biodiesel binder has been used in U.S. foundries recently to replace conventional phenolic urethane binders for making sand cores. Flash pyrolysis and thermogravimetric analytical (TGA) slow pyrolysis were conducted for the core samples to simulate some key features of the heating conditions that the core binders would experience during metal casting. Pyrolysis products from flash and TGA pyrolysis were analyzed with gas chromatography-mass spectrometry/flame ionization detection/thermal conductivity detection. The evolution profiles of the pyrolysis products during TGA slow pyrolysis were also monitored via thermogravimetry-mass spectrometry (TG-MS). The combination of TG-MS and TGA pyrolysis emission data facilitated a quantification of gaseous pyrolysis products of the biodiesel binder as a function of temperature. The major monitored carbonaceous pyrolysis products of the biodiesel binder included CO, CO2, CH4, and a variety of methyl esters such as dimethyl glutarate, dimethyl adipate, and methyl oleate. These latter species were the components of the biodiesel binder's solvent Pyrolysis of the biodiesel binder also generated a variety of hazardous air pollutants listed by the U.S. EPA, with benzene, toluene, xylene, phenol, and cresols being the prominent species. A considerable fraction of the binder's released mass did not appear as exhausted volatile carbonaceous species, but rather recondensed before they exhausted from the TGA. This represented mass that could likewise recondense within a green sand molding system during full-scale operations, as an environmentally favorable containment of air emissions.

Arsenic is of concern in water treatment because of its health effects. This research focused on incorporating hydrous ferric oxide (HFO) into granular activated carbon (GAC) for the purpose of arsenic removal. Iron was incorporated into GAC via incipient wetness impregnation and cured at temperatures ranging from 60 to 90 degrees C. X-ray diffractions and arsenic sorption as a function of pH were conducted to investigate the effect of temperature on final iron oxide (hydroxide) and their arsenic removal capabilities. Results revealed that when curing at 60 degrees C, the procedure successfully created HFO in the pores of GAC, whereas at temperatures of 80 and 90 degrees C, the impregnated iron oxide manifested a more crystalline form. In the column tests using synthetic water, the HFO-loaded GAC prepared at 60 degrees C also showed higher sorption capacities than media cured at higher temperatures. These results indicated that the adsorption capacity for arsenic was closely related to the form of iron (hydr)oxide for a given iron content For the column test using a natural groundwater, HFO-loaded GAC (Fe, 11.7%) showed an arsenic sorption capacity of 26 mg As/g when the influent contained 300 microg/L As. Thus, the preloading of HFO into a stable GAC media offered the opportunity to employ fixed carbon bed reactors in water treatment plants or point-of-use filters for arsenic removal.

Perchlorate's (C104] prevalent use as the propellant in rocket fuel has led to the C1O4contamination of considerable amounts of water thr6ughout the United states.' Perchlorate contamination is especially a problem in the arid Southwestern U.S. where alternate perchlorate-free water sources are not always readily available. Perchlorate, while thermodynamically unstable, is kinetically non-reactive at low concentrations,' as typically found in ground and surface water conditions where contamination has occurred. In addition, perchlorate is extremely soluble in water and is a poor complexing agent,' which makes it a very mobile, persistent contaminant in the environment.