Average Total Organic Carbon Concentration Research Articles

Characterizing Various Produced Waters from Shale Energy Extraction within the Context of Reuse

Environmental concerns with unconventional oil and gas development are frequently centered on elevated water usage and the induction of seismic events during waste disposal. Reuse of produced water for subsequent production well stimulation can effectively address these concerns, but the variability among such samples must be well understood. Twenty-four samples of wastewater from unconventional oil and gas development were collected from south and west Texas to assess their variability and feasibility for direct reuse. Bulk metrics were collected, including total organic carbon, total nitrogen, as well as total dissolved and suspended solids. The profiles of pertinent inorganic constituents were also evaluated. Variations were not only seen between regions but also among samples collected from the same region. For example, the average total organic carbon for Eagle Ford samples collected was 700 ± 500 mg/L, while samples collected from the Permian Basin featured an average total organic carbon concentration of 600 ± 900 mg/L. The Permian Basin total organic carbon ranged from 38 to 2600 mg/L. The total dissolved solids levels had the same variability between regions, with an average value for Eagle Ford of 20,000 ± 10,000 mg/L and a Permian Basin value of 150,000 ± 40,000 mg/L. However, samples were more reproducible within a given region. Collectively, the data indicate that the direct reuse of raw produced water for subsequent production well development without treatment is not feasible based on the reported reuse thresholds. Unconventional development wastewater samples from the Permian Basin were also compared to produced water values from conventional oil and gas wells in the same region, as reported by the United States Geological Survey. Samples collected in the Permian Basin consistently demonstrated lower ionic strength compared to conventional produced water data.

The in situ treatment of Basic Violet 16 synthetic dye in groundwater

AbstractSynthetic dyes have been shown to be micropollutants in various aquatic and groundwater systems, often occurring at milligram per liter (mg/L) concentrations. Synthetic dyes are typically introduced into the environment either as a continuous stream from wastewater or as episodic events related to the disposal of residues or spills generated during the manufacturing process. Various studies for the treatment of synthetic dyes have been undertaken for wastewater but studies for the in situ treatment of synthetic dyes in groundwater are limited. A pilot‐scale test was conducted to determine if the use of colloidal activated carbon (CAC) could effectively reduce dissolved concentrations of the synthetic dye Basic Violet (BV16) in groundwater using in situ methods. The pilot test was carried out downgradient of a textile manufacturing facility where historic disposal practices resulted in the release of various chemicals of concern including BV16 to an unconfined silty sand aquifer. A 10‐weight percent CAC solution was injected into a series of temporary direct push injection points to target the synthetic dye that was present at concentrations of up to 1,640 micrograms per liter (μg/L) during the 738‐day study. The results from the pilot test indicated that the CAC was effectively delivered to the target injection zone resulting in a three order of magnitude increase in total organic carbon (TOC) concentrations compared to preinjection TOC concentrations within the aquifer. Distribution of the CAC within the targeted injection zone indicated that heterogeneity affected the distribution with a zone of higher horizontal hydraulic conductivity (KH) having an average TOC concentration approximately 100 percent greater than the mean TOC concentration within the surrounding aquifer targeted by the CAC injection. Analyses of the groundwater chemistry before and postinjection indicated that the CAC had no detrimental impact on the groundwater quality while reducing the concentration of dissolved BV16 within the plume to below the method detection limits within 62 days of injection. The concentration of BV16 remained below the method detection limit of 10 µg/L for the 738‐day duration of the study apart from one detection of 180 µg/L at Day 183 within groundwater sampled from one monitoring well suggesting that the CAC was effective in attenuating the BV16 over the short and moderate term.

Estimación del potencial de emisión de CO2 en suelos agrícolas de dos cuencas en el estado de Durango

El sector agrícola genera impactos en el medio ambiente por la liberación de gases efecto invernadero (GEI), considerados factores potenciales para el aumento del calentamiento global. El carbono orgánico del suelo tiene una importante repercusión sobre las emisiones de GEI, debido a que la pérdida de materia orgánica del suelo repercute en la liberación de CO2, principal gas emitido a la atmósfera. El objetivo de este trabajo fue predecir el potencial de emisión de CO2 a partir del carbono orgánico total (COT) del suelo de algunas zonas agrícolas pertenecientes a las cuencas “Arroyo La India”, “Arroyo Cerro Gordo” y “Arroyo de Naitcha” del estado de Durango, mediante estimaciones basadas en los modelos del IPCC. La concentración promedio de COT en los sitios de estudio fue de 1.33 %, mientras que el potencial de emisión de CO2 fue de 0.032 Gg correspondiente a un 1.03 % del total de emisión de suelos del estado de Durango.

Analysis of the Energetic Potential Generable from an Hybrid Bioreactor Landfill for Waste Organic Fraction

The analysis of the amount of landfill gas generable from a full scale hybrid bioreactor landfill was investigated. The waste disposed in the landfill biocells was constituted by the waste organic fraction (WOF) arising from the mechanical pre-treatment of the residual municipal solid waste. The average humidity of the WOF was of about 40% by weight on wet basis whereas the volatile solids (VS) where about 50% by weight on total solids. The average total organic carbon concentration was of about 20% by weight of TS. The landfill gas generation potential of WOF was investigate by a standardized anaerobic test shows an average value of about 180 NL/kgVS. The construction of two full scale hybrid bioreactor landfill biocells was followed and the evolution of the composition of the landfill gas generated investigated. Results shows that in about 12 weeks the gas generated shows a methane concentration that rise rapidly from about 20% by vol. up to 55-60% by vol. In about 4 month of collection for energy recovery the amount of landfill gas generated results of about 36 Nm3/tonne significantly higher than the one detected for other traditional landfills.

Organic Carbon Concentration in the Northern Coastal Baltic Sea between 1975 and 2011

Boreal coastal seas are reported to be subject of high carbon load from land, yet actual published results on the trends in carbon concentration in coastal waters are scarce. We examined a unique time series of total organic carbon (TOC) concentration at 20 sites along the Finnish coast of the northern Baltic Sea to identify linkages between TOC and other key environmental parameters. Over the last 27 years, TOC concentration has increased in the northernmost Bothnian Bay and Quark sub-basins and in parts of the eutrophic southern Gulf of Finland sub-basin. In the entire coast, the average TOC concentration varied between 3 mg l−1 (at southwestern sites) and 6 mg l−1 (at northern and eastern sites), despite the fact that average TOC concentrations in the adjacent rivers were up to fourfold greater than in the seawater. Coastal and adjacent riverine TOC concentration correlated positively demonstrating the effect of terrestrial input, yet salinity-based mixing analysis proposes effective carbon removal at low salinities. TOC correlated negatively with salinity, which in turn decreased over the study period at 10 coastal sites. Total P increased in the southwestern mosaic-like Archipelago and Aland Sea sub-basin, but decreased in the northern sub-basins. TOC was not shown to be a major contributor to water clarity, but instead Secchi depth was observed to correlate frequently to Fe and chlorophyll a.

Advanced treatment of dyeing wastewater towards reuse by the combined Fenton oxidation and membrane bioreactor process

The performance of combined Fenton oxidation and membrane bioreactor (MBR) process for the advanced treatment of an effluent from an integrated dyeing wastewater treatment plant was evaluated. The experimental results revealed that under the optimum Fenton oxidation conditions (initial pH 5, H 2O 2 dosage 17 mmol/L, and Fe 2+ 1.7 mmol/L) the average total organic carbon (TOC) and color removal ratios were 39.3% and 69.5% after 35 min of reaction, respectively. Results from Zahn-Wallens Test also represented that Fenton process was effective to enhance the biodegradability of the test wastewater. As for the further purification of MBR process, TOC removal capacity was examined at different hydraulic retention times (HRT) of 10, 18 and 25 hr. Under the optimum HRT of 18 hr, the average TOC concentration and color of the final MBR effluent were 16.8 mg/L and 2 dilution time, respectively. The sludge yield coefficient was 0.13 g MLSS/g TOC and TOC degradation rate was 0.078 kg TOC/(m 3·day). The final effluent of MBR can meet the reuse criteria of urban recycling water - water quality standard for miscellaneous water consumption GBT18920-2002.

Distribution of total organic carbon and total nitrogen in deep-sea sediments from the southwestern Gulf of Mexico

The temporal and spatial variations of total organic carbon (TOC) and nitrogen (TN) contents, and the carbon-nitrogen ratio in superficial sediments collected at 115 locations at depths between 1,025 and 3,795 m in the Gulf of Mexico during the SIGSBEE, PROMEBIO and DGoMB cruises are herein reported. The average TOC concentration was 0.9 ± 0.3%, the TN 0.12 ± 0.03% and the C/N ratio 8.0 ± 1.7. None of the typically hemipelagic sediment samples recorded any sulfur. In contrast, chemosynthetic sediment samples from the immediate area of the Chapopote asphalt volcano in the Campeche Bay (3,300 m deep) were significantly higher both in their TOC and TN values than hemipelagic samples, and were characterized by high sulfur contents with local variations associated with bathymetric features in the lower continental slope and the abyssal plain. This study shows that the elemental composition of the abyssal sediments is controlled by depth and follows a parabolic pattern for both TOC and TN. Average values for the continental slope were TOC = 0.8 ± 0.2%, TN = 0.11 ± 0.0 4% (n=39), and for the abyssal plain TOC = 1.0 ± 0.3%, TN = 0.12 ± 0.03% (n=44). The C/N ratio suggests that the organic matter in the superficial sediments has a mixed hemipelagic-terrigenous origin, and it depends on the distance from the coast. This is a major contrast to open-coast gradients where C/N ratios remain constant, and thus it is characteristic of a marginal sea. The bathymetry affects TOC and TN, causing significant differences among the physiographic regions. TOC and TN recorded in a long-term time series station in the abyssal plain displayed changes with time, showing alternating periods of high terrigenous and photoautotrophic input. This study provides evidence of the inter-yearly variability in the origin of the organic matter in the abyssal plain. TOC and TN decrease with depth in the sediment due to the changing sedimentation conditions.

Climate's control of intra‐annual and interannual variability of total organic carbon concentration and flux in two contrasting boreal landscape elements

Large spatial and temporal variations in stream total organic carbon (TOC) concentration and export occurred during an 11‐year observation period (1993–2003) in a boreal headwater catchment. TOC flux and concentration patterns from mire‐ and forest‐dominated subcatchments differed (mean annual flux 8.2 g m−2 a−1 versus 5.8 g m−2 a−1). Temporal variations in stream TOC concentrations in both landscape types were primarily driven by variations in streamflow, with the mire stream generally diluting by half with increased runoff during spring flood and TOC from the forested landscape increasing during runoff peaks irrespective of season. Average TOC concentration in the mire stream in the snow‐free season increased with increased seasonal precipitation from around 20 to 40 mg L−1 but then dropped to around 35 mg L−1 during very wet years. Average snow‐free season TOC concentration at the forested site remained stable when summer precipitation was below average but then increased from 10 to around 25 mg L−1 during exceptionally wet years. For both the forested subcatchment and the whole catchment, TOC concentrations increased during the warm summer months during wet years, but no such increase occurred during dry years. Interannual variations in TOC flux were primarily driven by variations during the snow‐free period. Wet years decreased the relative TOC export from the mire and favored the relative export of TOC from areas dominated by forest, an observation that also held true on a larger scale when similar landscape types were considered. Predicted climate change in rainfall and temperature patterns will affect the amount and character of TOC exported downstream from boreal landscapes with a mix of forest and mire.

Temporal and Spatial Distributions of Sediment Total Organic Carbon in an Estuary River

Understanding temporal and spatial distributions of naturally occurring total organic carbon (TOC) in sediments is critical because TOC is an important feature of surface water quality. This study investigated temporal and spatial distributions of sediment TOC and its relationships to sediment contaminants in the Cedar and Ortega Rivers, Florida, USA, using three-dimensional kriging analysis and field measurement. Analysis of field data showed that large temporal changes in sediment TOC concentrations occurred in the rivers, which reflected changes in the characteristics and magnitude of inputs into the rivers during approximately the last 100 yr. The average concentration of TOC in sediments from the Cedar and Ortega Rivers was 12.7% with a maximum of 22.6% and a minimum of 2.3%. In general, more TOC accumulated at the upper 1.0 m of the sediment in the southern part of the Ortega River although the TOC sedimentation varied with locations and depths. In contrast, high concentrations of sediment contaminants, that is, total polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs), were found in sediments from the Cedar River. There was no correlation between TOC and PAHs or PCBs in these river sediments. This finding is in contradiction to some other studies which reported that the sorption of hydrocarbons is highly related to the organic matter content of sediments. This discrepancy occurred because of the differences in TOC and hydrocarbon source input locations. It was found that more TOC loaded into the southern part of the Ortega River, while almost all of the hydrocarbons entered into the Cedar River. This study suggested that the locations of their input sources as well as the land use patterns should also be considered when relating hydrocarbons to sediment TOC.

Products Identified at an Alternative Disinfection Pilot Plant

Many drinking water utilities have recently changed or are seriously considering changing their disinfection practice from chlorine to some alternative treatment process. However, most of these utilities are changing their disinfectants without evaluating chemical impacts. Therefore, a research cooperative agreement was developed with Jefferson Parish, LA, to evaluate four parallel streams treated with four different disinfectants (chlorine, monochloramine, chlorine dioxide, and ozone.) These streams, along with a fifth parallel stream, which was not treated with a disinfectant (control), were passed through both sand and granular activated carbon (GAC). Ozonation reduced the total organic carbon (TOC) and total organic halide (TOX) concentration by 0.3 mg/L and 10 micrograms/L, respectively. The average concentration of TOC for the other disinfectants was comparable to that associated with the nondisinfected stream (3.3 mg/L). The average instantaneous TOX concentration for chlorine dioxide, chloramine, and chlorine disinfection after 30 min contact time increased by 60, 92, and 238 micrograms/L, respectively, from a nondisinfected concentration of 25 micrograms/L. The volatile organics most affected by disinfection (chlorination) were the trihalomethanes. No significant change in concentration was noted after disinfection for the other volatile organics evaluated, such as 1,2-dichlorethane, dichloromethane, trichloroethylene, 1,1,2-trichloroethane, and carbon tetrachloride. Ozonation produced an average concentration reduction of 11 to 84% for most of the nonvolatiles evaluated. Conversely, a concentration increase of 43 to 100% was noted, after chlorination, for some of the nonvolatile organics.

Products identified at an alternative disinfection pilot plant.

Many drinking water utilities have recently changed or are seriously considering changing their disinfection practice from chlorine to some alternative treatment process. However, most of these utilities are changing their disinfectants without evaluating chemical impacts. Therefore, a research cooperative agreement was developed with Jefferson Parish, LA, to evaluate four parallel streams treated with four different disinfectants (chlorine, monochloramine, chlorine dioxide, and ozone.) These streams, along with a fifth parallel stream, which was not treated with a disinfectant (control), were passed through both sand and granular activated carbon (GAC). Ozonation reduced the total organic carbon (TOC) and total organic halide (TOX) concentration by 0.3 mg/L and 10 micrograms/L, respectively. The average concentration of TOC for the other disinfectants was comparable to that associated with the nondisinfected stream (3.3 mg/L). The average instantaneous TOX concentration for chlorine dioxide, chloramine, and chlorine disinfection after 30 min contact time increased by 60, 92, and 238 micrograms/L, respectively, from a nondisinfected concentration of 25 micrograms/L. The volatile organics most affected by disinfection (chlorination) were the trihalomethanes. No significant change in concentration was noted after disinfection for the other volatile organics evaluated, such as 1,2-dichlorethane, dichloromethane, trichloroethylene, 1,1,2-trichloroethane, and carbon tetrachloride. Ozonation produced an average concentration reduction of 11 to 84% for most of the nonvolatiles evaluated. Conversely, a concentration increase of 43 to 100% was noted, after chlorination, for some of the nonvolatile organics.