Solid Organic Carbon Research Articles

The promising Cu/graphene composites in situ fabricated by solid organic carbon sources

Copper/graphene composites have attracted extensive attention in electrical materials due to their excellent electrical and mechanical properties. However, graphene is easy to agglomerate and poorly bonded with copper, leading to its performance failing to meet expectations. In this paper, an in-situ fabrication method using solid organic compounds (malic acid, maleic acid, and melamine) as the carbon sources is adopted to achieve the uniform dispersion of graphene and the strong interface bonding between Cu and graphene, and further explore the rules of selecting different carbon sources. The morphology and quantity of graphene and the interfacial structure are deeply analyzed. The three-dimensional high-quality graphene and the strong copper/carbon interface due to the Cu-O-C chemical bond facilitate the Cu/graphene composite fabricated by malic acid to exhibit the best comprehensive performance, the electrical conductivity is 96.40% International Annealed Copper Standard (IACS) and the hardness is 75.13HV..

Organic Matter Matters—The Imaginary Conductivity of Sediments Rich in Solid Organic Carbon

AbstractSolid organic matter (OM) is a biogeochemically relevant constituent of soils and sediments. It also affects sediments' geophysical properties, but is often overlooked in hydro‐ and biogeophysical approaches for the characterization of the shallow subsurface. Here, we explore the potential of spectral induced polarization (SIP) to delineate OM‐rich zones in the subsurface and provide insights into the mechanisms that drive OM‐polarization using measurements on both field cores and artificial OM‐sand mixtures. Both, field samples and artificial mixtures showed a linear relationship between the total organic carbon (TOC) content and charge storage (imaginary conductivity). The high cation exchange capacity of OM drives the increase in polarization and can help in delineating potentially microbially active OM‐rich zones in cores or field surveys. To avoid misinterpretation of SIP data in unconsolidated media, we strongly suggest quantifying TOC content in sediment samples to accompany the interpretation of field surveys.

Biochar-based fertilizer under drip irrigation: More conducive to improving soil carbon pool and promoting nitrogen utilization

In order to explore a resource-saving and environmentally friendly approach to reduce nitrogen fertilizer and increase soil carbon pool in crop production. There are 5 treatments in the experiment namely CK: conventional fertilization and irrigation methods (pure nitrogen 30 kg/hm2); T1: drip irrigation fertilization method (pure nitrogen 15 kg/hm2); T2: drip irrigation fertilization method (pure nitrogen 15 kg /hm2), biochar-based fertilizer 600 kg/hm2; T3: drip irrigation method (pure nitrogen 15 kg/hm2), biochar-based fertilizer 1200 kg/hm2; T4: drip irrigation method (pure nitrogen 15 kg/hm2), biochar-based fertilizer is 1800 kg/hm2. The results showed that the microbial carbon content of the biochar-based fertilizer treatment under the condition of drip irrigation to reduce nitrogen was increased by 39.9%-68.4% as compared with the control. All treatments of the biochar-based fertilizer can significantly increase the soil easily oxidizable carbon in the early and mid-term growth. The content of solid carbon and soluble organic carbon increased by 31.3%-148.31% and 12.2%-63.92%, respectively. The application of biochar-based fertilizers significantly increased the net photosynthetic rate and stomatal conductance in the early and mid-transplanting period, as well as the transpiration rate and intercellular CO2 concentration throughout the growth period, and the SPAD, NDVI value, and dry matter accumulation. Under the condition of reducing nitrogen by 50%, drip irrigation combined with biochar-based fertilizer can significantly increase the soil microbial biomass carbon content, oxidizable carbon and soluble carbon content, promote the photosynthetic effect and dry matter accumulation of tobacco plants, and it is beneficial to promote crop planting.

Vertical distribution of pH in the top ~10 m of deep-ocean sediments: Analysis of a unique dataset

We analyze, for the first time in the oceanographic literature, pH over the top ~10 m of the sediment (down to 11.9 m) in a deep-sea environment, together with the oxidation/reduction potential and concentrations of solid organic carbon (OC) and CaCO3. A total of 1157 sediment cores were collected from years 2000 to 2011 over >300,000 km2 in the South China Sea, at water depths up to 3702 m. We found that there were marked downward pH increases in the upper 2 m of the sediment (first 20-40 ka, corresponding to the geochemically active period). In deeper, older sediment (up to 200 ka), pH was generally less variable with depth but not uniform, and solid OC may have been consumed down to ≥10 m depth. This reflected interactions between in situ geochemical diagenetic processes, which tended to create vertical variations, and vertical diffusion of ions, which tended to even out vertical variability. In other words, there were slow diagenetic geochemical processes in the sediment layer below 2 m, and the effects of these in situ processes were partly offset by vertical diffusion. Overall, our study identified a previously unknown consistent pH difference between the upper 2 m of the sediment and the underlying layer down to ≥10 m, and suggested combinations of geochemical diagenetic processes and vertical diffusion of ions in the porewater to explain it. These results provide a framework for further studies of pH in the top multi-meter layer of the sediment in the World Ocean.

Comprehensive distribution characteristics and risks of heavy metals in typical intertidal zones and their relationship with urban economic indicators

Human activities have increased heavy metal pollution in intertidal environments. However, the comprehensive ecological risks of heavy metals in the active zones and their relationship with urban economic indicators are still poorly understood. This study investigated the multiphase distribution characteristics of heavy metals (Cr, Ni, Cu, Zn, Pb, and Cd) in 14 typical intertidal zones in the Guangdong–HongKong–Macao Greater Bay Area. The results showed that the concentrations of heavy metals varied greatly among different cities, and the highest average concentrations in Dongguan city were 695.27, 243.79, 1482.36, 980.24, 66.36 and 4.95 mg.kg−1, respectively. The proportion of bioavailable state Cd was the highest as 54.20%, followed by Zn > Cu > Pb > Ni > Cr. The comprehensive ecological risks (RCER) of the two intertidal zones in Dongguan were 1.45 ∼ 7.70 times higher than those of other sampling areas, indicating a very high ecological risk. Correlation analysis showed that total organic carbon in surface water, ammonia nitrogen in pore water, and solid organic carbon and the proportion of clay in sediments were significantly correlated with RCER values, and the linear regression coefficients were 0.784, 0.919, 0.962 and 0.914, respectively. The modified environmental Kuznets curve (EKC) model was used to describe the relationship between RCER values and urban economic indicators, and an inverted U shaped curve relationship was found, indicating that regional heavy metal pollution seemed to have reached a peak and entered a period of emission reduction. Nevertheless, given the increasing proximity of the intertidal zone to human daily life, long-term follow-up assessments are recommended.

Controls on sulfide accumulation in coastal soils during simulated sea level rise

A likely consequence of sea level rise during the next century will be progressive inundation of seawater through the current unsaturated zone in coastal-margin soils. It is unclear how this will change the biogeochemical cycling of iron, sulfur and carbon over different time scales and soil types. A long-term (540 day) laboratory experiment, slowly inundating intact coastal soil cores with seawater from the ‘bottom up’, was conducted to observe how coupled iron and sulfur dynamics change in different soil types. Pore water was extracted from the 60 cm cores at 10 cm depth intervals every 90 days and analysed for pH, electrical conductivity (EC), Fe2+, HS− and dissolved metals (Fe, Mn, As, Cd, Cu, Ni, Pb, Co, Zn) as well as stable sulfur (34S/32S) and radiogenic strontium (87Sr/86Sr) isotopes. Destructive solid phase analyses (for reactive Fe, acid volatile and chromium reducible sulfur (AVS and CRS) and total organic carbon (TOC)) were made at the start and end of the experiment. Iron and sulfate reduction was induced in soils with readily available TOC as anoxic conditions established, evidenced by statistically significant increases (P < 0.001) in dissolved Fe2+ and sulfide concentrations in porewaters, as well as simultaneous and progressive increase in the sulfur isotope (34S/32S) ratios. An increase in AVS indicated formation of metastable iron sulfide (FeS) minerals resulting from Fe2+ and sulfide in porewaters post inundation. This was supported by PHREEQC modelling of local mineral saturation states/indices in the system. Overall, the Fe2+ concentration increased to a peak at between 270 and 360 days, and then began decreasing at some depths, indicating slowing iron reduction, presumably because reactive iron (oxyhydro)oxides became progressively consumed by microbially driven reductive processes. However, microbially mediated sulfate reduction continued as abundant sulfate was still available from seawater. In the absence of free Fe2+, sulfide accumulated in the porewater, but only in those soils inundated the longest (>360 days), and with greater than 5% TOC. The combined use of sulfur (34S/32S) and strontium (87Sr/86Sr) isotopes supported the observed results, and represents a new and robust technique to quantify progressive sulfate reduction and seawater mixing phenomena in coastal soils. This study gives new insights into the biogeochemical cycling of sulfur and iron in soils experiencing seawater inundation from sea level rise over longer timescales. It is likely that sulfidisation (due to in-situ sulfate reduction) will begin to affect coastal wetland soils, especially in areas where TOC is high and where reactive iron depletes over time. This has potential consequences for sulfide toxicity in coastal soils and environments globally.

Multiphase Spatial Distribution Characteristics of Cd Morphology in Typical Intertidal Zones in the Guangdong-Hong Kong-Macao Greater Bay Area and Its Influencing Factors

Simultaneous sampling and observation were conducted at 14 stations in typical intertidal zones of the Guangdong-Hong Kong-Macao greater bay area. The spatial distribution characteristics of Cd morphology in surface water, pore water, suspended matters, and sediments at each sampling site were analyzed, and the influencing factors of Cd morphology changes in each medium were discussed using statistical analyses based on environmental factors. The results showed that the total contents of Cd in surface water, pore water, suspended matters, and sediments in each intertidal zone ranged from 0.41-15.03 μg·L-1, 0.41-27.54 μg·L-1, 0.41-4.88 mg·kg-1, and 0.20-5.30 mg·kg-1, respectively. The contents of Cd in Shajiao Bay were significantly higher than those in other sampling sites, which should be related to the developed electronics and manufacturing industries in Dongguan. The concentration of Cd in surface water was slightly lower than that in pore water, whereas the content of Cd in suspended matter was comparable to that in sediment at the same sampling site. The results of morphological analysis showed that the ionic-state Cd was dominant in both surface water and pore water, accounting for 67.23%-97.56% and 33.33%-97.16%, respectively. In suspended matter and sediment, Cd was mainly in the residual state, accounting for 45.45%-96.36% and 45.80%-97.27%, respectively. Pearson correlation analysis showed that the complex-state Cd in the aqueous phase was negatively correlated with oxidation reduction potential (ORP) and pH and positively correlated with total organic carbon. The bioavailable Cd in solid sediment was significantly positively correlated with the proportion of clay, ORP, and solid organic carbon and significantly negatively correlated with pH. The single factor linear regression analysis showed that ORP had the greatest effect on the complex-state Cd in the aqueous phase, with regression coefficients of 0.864 and 0.824, respectively. The bioavailable Cd in solid sediment at different depths was significantly affected by the proportion of clay, and the regression coefficients were 0.968, 0.980, 0.977, and 0.877, respectively. The above results indicate that the distribution of total Cd content in the typical intertidal environment of the Greater Bay Area was affected by the characteristics of urban economic development, whereas the allocation of Cd morphology was closely related to environmental factors.

Remediation of nitrate-contaminated groundwater by a combined treatment method of novel Mass Bio System and solid organic carbon sources: In-depth study

In recent years, one of the most pervasive groundwater (GW) contaminants worldwide is nitrate. Traditional technologies for the remediation of nitrate-contaminated GW are usually expensive, lengthy, and often only partly effective. Of the emerging technologies for nitrate remediation, biological denitrification technologies are more economical, timely, and more efficient means of reducing nitrate contamination to standard levels. The present study investigates the roles of combined treatment method of novel Mass Bio System (MBS), an advanced nontoxic immobilized biologically activated water purification product and solid organic carbon sources (SOCS) for the removal of nitrate from GW to meet the drinking water standards. Natural organic rice straws and commercially available paper plates rich in cellulose were used as SOCS. Effects of various parameters such as nitrate nitrogen concentration, hydraulic retention time, pH and temperature on denitrification process were studied. In the present study, four batch tests are conducted to evaluate two common solid organic carbons and their combination with MBS for nitrate removal from GW. Overall, the reactor with MBS particles and SOCS exhibited clear advantages over reactor inoculated with activated sludge and SOCS with respect to better denitrification, stable operation, strong environmental adaptability and complete nitrate removal. At last, the concentrations of nitrate and nitrite were lowest in the combined system. Kinetic analysis by Monod model showed good agreement with the experimental results. MBS particles are responsible for the main denitrification and the reaction kinetic model conforms to Monod equation of double substrate. Static carbon release test and degradation mechanism of solid carbon sources were carried out. It showed the slow-release carbon source by their own hydrolysis and contain easily soluble organic matter that can be quickly dissolved into water, which substantiated the analysis of the results further. All the results demonstrate that this combined method is a potentially nontoxic, cleaner and sustainable technology for remediation of nitrate-contaminated GW.

Certain Soil Surfactants Could Become a Source of Soil Water Repellency after Repeated Application.

Repeated application of soil surfactants, or wetting agents, is a common practice for alleviating soil water repellency associated with soil organic coatings. However, wetting agents are organic compounds that may also coat soil particle surfaces and reduce wettability. For this experiment, hydrophobic sands from the field and fresh, wettable sands were collected and treated with either a polyoxyalkylene polymer (PoAP) or alkyl block polymer (ABP) wetting agent, or water only treatments served as a control. Following repeated treatment application and sequential washings, dissolved and particulate organic carbon (OC) were detected in the leachates of both sand systems. The total amount of OC recovered in leachates was 88% or less than the OC introduced by the wetting agents, indicating sorption of wetting agent monomers to soil particle surfaces regardless of soil hydrophobicity status. While ABP treatment did not alter solid phase organic carbon (SOC) in the sands studied, PoAP application increased SOC by 16% and 45% which was visible in scanning electronic microscopy images, for hydrophobic and wettable sands, respectively. PoAP application also increased the hydrophobicity of both sands that were studied. In contrast, ABP treatment increased the wettability of hydrophobic sand. Our results provide strong evidence that certain wetting agents may increase soil hydrophobicity and exacerbate wettability challenges if used repeatedly over time.

Exploration and verification of the feasibility of the sulfur-based autotrophic denitrification integrated biomass-based heterotrophic denitrification systems for wastewater treatment: From feasibility to application

The sulfur-based autotrophic denitrification (SAD) and the solid organic carbon-based denitrification processes are both efficient techniques to remove nitrate from wastewater, and the hydrogen ions generated by the SAD process would be consumed in the heterotrophic denitrification process. Therefore, it is possible to improve the denitrification capacity when the solid organic carbon was added into a SAD reactor. In this study, corncob powder and sawdust powder were selected as solid organic carbon sources, and the sulfur-based autotrophic denitrification integrated biomass-based heterotrophic denitrification system was formed (SBD). The laboratory and field experiments showed that SBD could shorten the start-up period, decrease the sulfate productivity, and maintain a good denitrification performance when treated wastewater. According to the field experiment results, when the HRT was 1 h, the effluent total nitrogen (TN) concentration was always lower than 15 mg L−1. In addition, nitrite inhibition was observed when the concentration of nitrite in the reactors reached above 30 mg L−1. The mixture of elemental sulfur powder, shell powder, corncob powder, and sawdust powder with a mass ratio of 6:2:1:1 was the optimal filter for the SBD system, with an average nitrate reduction rate (NAR) of 420 mg NO3–N·L−1·d−1 obtained at the end of the study. During the whole operation, the major autotrophs in the SBD systems were Thermomonas, Ferritrophicum, and Thiobacillus, while the major heterotrophs were Saprospiraceae, Ferruginibacter, Dokdonella, and Simplicispira. Overall, the SBD system was a feasible and practically favorable way to remove nitrate from wastewater.

In Situ Carbon Stable isotope Analysis of Organic Carbon by Laser Ablation-Isotope Ratio Mass Spectrometry

An interface of laser ablation (LA) and stable isotope ratio mass spectrometry (IRMS) was developed to provide high spatial resolution organic carbon stable isotope analysis. Based on this, a LA-IRMS 13 C/ 12 C analytical method for organic carbon in standards and rice leaf was developed. The results showed that this system could carry out continuous on-line analysis of solid samples with high sensitivity, and the sampling amount was as low as tens of nanograms, which was 10000 times lower than that of traditional element analyzer (EA)-IRMS analysis. This method avoided many fractionation factors effectively in the process of sampling, transmission and ionization, and obtained repeatable and high-precision results. Combined with the advantages of laser ablation technique in situ sampling, the high-resolution carbon isotope distribution information of solid samples was obtained by using this method. This in-situ solid organic carbon isotope measurement technique was stable, reliable with high accuracy, and it would have a broad application prospect in the fields of environment, agriculture, forestry and ecology in the future. An interface of laser ablation and stable isotope ratio mass spectrometry was developed to provide high spatial resolution organic carbon stable isotope analysis. On the surface of rice leaves (about 1 mm wide), 8 samples were taken successively for 13 C analysis, and repeat twice.

Effect of Feeding Rate on the Reduction of Total Volatile Solids and Organic Carbon during Combined Composting and Vermicomposting of Elephant Dung

One of the methods of treatment of animal waste to conserve our nature is vermicomposting in which waste-feeding rate is one of the important parameters to be considered. This paper is concerned with studying and analyzing the effect of feeding rate on the reduction of total volatile solid and total organic carbon during vermicomposting of elephant dung.&#x0D; The raw dung collected from the Central Zoo, Jawalakhel, Nepal was composted in a heap on the open ground after removal of inorganic substances by hand sorting and manually breaking of lumps. Composted dung only after two weeks was feed in the circular earthen flower pots having average diameter of 0.15 m and surface area of 0.017 m2 each with small holes at the bottom. The adult healthy Eiseniafetida with a stocking density of 1.6 kg-worm/m2 with feeding rates of 0.75, 1, 1.5 and 2kg-feed/kg worms/day in the batch basis were used in the separate sets for vermicomposting in moisture content of 70 to 80% at normal room condition in two cycles of eight weeks after two weeks of normal composting in a room.&#x0D; It was revealed from the experiment that the combined composting and vermicomposting system with feeding rate of 0.75 kg-feed/kg worms/day was more effective in reducing total volatile solids and total organic carbon content to 42.52% and 23.62% respectively after ten weeks.

Assessment of coastal turbidity improvement potential by terrigenous sediment load reduction and its implications on seagrass inhabitable area in Banate Bay, central Philippines

This paper demonstrates the effects of terrigenous sediment load reduction by watershed managements on coastal turbidity in Banate Bay, Iloilo located in central Philippines, using field observations and numerical simulations. Measurements of the total suspended solid and particulate organic carbon indicated that the bulk component of the coastal turbidity comprised terrigenous mineral particles rather than phytoplankton at the rise of the river after heavy rain. The suspended sediment concentration and underwater light intensity were simulated by an atmosphere-watershed-coastal ocean model to investigate the contribution of the terrigenous sediment load to the coastal turbidity in rainy season. The coastal sediment simulation indicated that the turbidity in Banate Bay is highly impacted by terrigenous sediment inputs from distant watersheds, which are transported to the bay by coastal currents. In contrast, the contributions of sediment loads from the adjacent watersheds to the bay turbidity were limited. The simulation also indicated that the majority of the bay is not inhabitable for seagrasses due to limited light availability caused by the high turbidity. Scenario analysis of the sediment load reduction demonstrated that significant reduction of turbidity and improvement of light penetration are conditionally expected only when the remediation is implemented with cooperative management of a series of neighboring watersheds because of the significant contributions of sediment loads from multiple basins.

Surfactant Chemistry Effects on Organic Matter Removal from Water Repellent Sand

Core Ideas Confirmed for the first time that certain wetting agents can remove organic coatings that cause soil hydrophobicity. A novel laboratory experiment was performed to precisely quantify this effect. Possible mechanisms regarding the removal of organic coatings following application of certain wetting agents were discussed. Soil surfactants, which represent a wide range of wetting agent chemistries, have been used as the primary tool for mitigating drought issues caused by soil water repellency (SWR). However, the residual effects of soil surfactants are often short‐lived, requiring repeated applications. Alternatively, certain groups of wetting agents may remove hydrophobic organic matter for extended control of SWR. This laboratory study investigated the effects of selected wetting agent chemistries, including products of alkyl block polymer (ABP), nonionic surfactant + acidifiers (NIS), and polyoxyalkylene polymer (PoAP), for removing organic matter and reducing SWR. Naturally‐occurring hydrophobic sand was packed into sand columns and subjected to wetting agent application. The treated columns were then washed three times with deionized water, and the volume of the leachates from each wash event was determined. Sand treated by PoAP showed enhanced water‐holding capacity, although the effect diminished after the second wash. In comparison, ABP resulted in 2.3‐fold greater output of combined dissolved organic carbon (DOC) and particulate organic carbon (POC) in the leachates than PoAP, and made the hydrophobic sand completely wettable. Alternatively, NIS showed similar effects compared with the control. Although PoAP reduced SWR to a minimum level, it was sorbed strongly to the sand, which resulted in 27% greater solid phase organic carbon (SOC) in treated sand, compared with the untreated control. However, the exact mechanisms underlying surfactant effects on DOC and POC are unclear and the long‐term effects of surfactants following repeated application in the field are yet to be determined.

Plastic carrier polishing chamber reduces pollution swapping from denitrifying woodchip bioreactors

Denitrifying bioreactors with solid organic carbon sources (i.e., “woodchip bioreactors”) have proven to be relatively simple and cost effective treatment systems for nitrate-laden agricultural and aquacultural waters and wastewaters. However, because this technology is still relatively new, design modifications, such as the addition of a post-bioreactor polishing chamber filled with inert media, may offer potential to increase nitrate removal and mitigate unintended bioreactor by-products. Paired-column configurations filled with woodchips followed by plastic biofilm carrier media showed significant nitrate removal within the woodchip bioreactor columns (37, 26, and 88% nitrate removal efficiencies at woodchip column retention times of 7.1, 18, and 52 h), but no significant additional nitrate removal benefit of the post-processing plastic media chamber (41, 22, and 89% nitrate removal efficiencies, respectively). Releases of chemical oxygen demand from the woodchips were likely not sufficient to fuel significant nitrate removal in the polishing chamber. However, the polishing chamber significantly reduced nitrite releases from the bioreactor columns, and provided some mitigation of reduced sulfate during the 52-h retention time testing period (influent, woodchip effluent, and plastic chamber effluent sulfate concentrations of 23.6, 18.8, and 20.7 mg SO42− L−1, respectively). A full-scale post-woodchip polishing chamber filled with inert plastic media generally may not be worth the added cost unless the receiving waters are particularly sensitive to nitrite or hydrogen sulfide.

The influence of coring method on the preservation of sedimentary and biogeochemical features when sampling soft-bottom, shallow coastal environments

It is frequently assumed that taking samples of soft marine sediments using surface-based gravity coring equipment causes minimal disruption to their sedimentological, biogeochemical, and biological condition. This assumption was evaluated by examining the potential disturbances caused when obtaining soft-sediment samples either by SCUBA or Craib-coring, comparing sediment oxygen microprofiles, benthic oxygen flux rates and sediment solid phase analyses (chlorophyll a (Chl a), organic carbon, and porosity) between both methods and against reference values measured in situ by benthic lander. The two sampling methodologies were tested in shallow coastal environments on the west coast of Scotland and generally the results obtained from cores collected using SCUBA exhibited values closest to those observed in situ. Oxygen penetration depth was significantly shallower in cores obtained by Craib-corer compared with the SCUBA cores. Craib cores also produced higher oxygen uptake rates which could be caused by greater levels of sediment disturbance during sampling. In addition, more homogenous levels of Chl a in the top 1 cm of the Craib cores, compared with the SCUBA samples, may indicate either resuspension or compression during gravity coring. Using SCUBA for shallow-water soft-sediment sampling permits steady and controlled core-tube insertion and extraction, and more measured retrieval of the cores to the surface; this probably accounts for the observed differences. Whereas benthic lander-based in situ measurement would be the preferred method for analyzing sediment parameters in detail in this type of environment, SCUBA-based sampling offers a more accurate alternative to surface-based gravity coring.

Multi-Response Optimization of Process Parameters for Imidacloprid Removal by Reverse Osmosis Using Taguchi Design.

In this study, a multi-response optimization method using Taguchi's robust design approach is proposed for imidacloprid removal by reverse osmosis. Tests were conducted with different membrane type (BW30, LFC-3, CPA-3), transmembrane pressure (TMP = 20, 25, 30 bar), volume reduction factor (VRF = 2, 3, 4), and pH (3, 7, 11). Quality and quantity of permeate are optimized with the multi-response characteristics of the total dissolved solid (TDS), conductivity, imidacloprid, and total organic carbon (TOC) rejection ratios and flux of permeate. The optimized conditions were determined as membrane type of BW30, TMP 30 bar, VRF 3, and pH 11. Under these conditions, TDS, conductivity, imidacloprid, and TOC rejections and permeate flux were 97.50 97.41, 97.80, 98.00% and 30.60 L/m2·h, respectively. Membrane type was obtained as the most effective factor; its contribution is 64%. The difference between the predicted and observed value of multi-response signal/noise (MRSN) is within the confidence interval.

MLA-Based Detection of Organic Matter with Iodized Epoxy Resin—An Alternative to Carnauba

Solid organic matter is an important constituent not only in coal, but also in black shale-hosted ore deposits. The reliable recognition and quantification of organic carbon—as well as its microfabric relation to associated inorganic minerals—plays a crucial role in characterization by scanning electron microscopy-based image analysis. However, the use of conventional epoxy resin in the preparation of grain mounts does not allow for recognition of solid organic carbon compounds. In this study we illustrate that the use of iodized epoxy resin readily overcomes this bottleneck. Best results are obtained with an addition of 15 wt% iodoform to the epoxy resin. With process samples of black shale-hosted polymetallic Kupferschiefer-type ore as a case study, it is shown that recognition and quantification of solid organic carbon are easily achieved and that tangible parameters such as particle and grain sizes, association and liberation for ore and gangue minerals can be determined in the presence of solid organic matter. Due to the inherent uncertainty of the exact chemical composition of the kerogen contained in Kupferschiefer, it was not possible to attain exact comparability between chemical Corg assays and assays calculated from MLA data. However, the results are still found to closely agree with one another. The strength of iodized resin lies in its ability to distinguish organic matter with high hydration ratios in addition to the easy integration in sample preparation. It could therefore be an attractive supplement in the analyses of other raw materials containing complex organic-matter.

Effect of Hydrodynamic Dispersion in Denitrifying Wood-Chip Stormwater Biofilters

AbstractStormwater biofiltration systems can include a submerged layer containing a solid organic carbon substrate, such as wood chips, to promote biological denitrification. The objective of this research was to evaluate the effect of biofilter depth and dispersion on the performance of submerged wood-chip biofilters. Tracer and reactive column studies were performed on biofilters with varying depths (30, 45, and 60 cm), which were evaluated with stormwater at varying hydraulic retention times. The results from every tracer test (n=9) indicated that dispersion affected constituent transport. Shorter columns and/or higher hydraulic retention times resulted in dispersion dominated transport, which contributed to greater constituent bypass through the biofilters. Even though a wood-chip biofilter is considered a porous medium, dispersivity values in this layer were an order of magnitude larger than dispersivities of natural porous media (e.g., sand). These results provide evidence that less media volume is ...

Optimum Position of Air Injection in Aerobic and Anaerobic Refuse Lysimeters

In order to determine the optimum air injection craftwork for the aerobic-anaerobic landfill method, three pilot-scale lysimeters were constructed. Through experiment in the lysimeters, it was concluded that air injection at bottom layer (in this research it’s 2.5 m) is the optimum position in terms of improving on the solid organic matters stabilization, amelioration on leachate quality, the restraint of GHE (Green House Effect) by CH4. For instance, air injected at bottom layer may get more TOC minimization in leachate under lower temperature (-4-10°C) and high temperature (20-35°C) compared with other conditions. NH4+-N content expressed similar advantages with air injected at bottom layer case. Meanwhile, accompanied with the high dissolved oxygen (DO) and higher TOC consumption in leachate, aerobic fermentation was activated in this case, and most organic carbon was transformed in term of CO2, in which the goal of restraint on GHE was realized. On basis of mechanism assumption, mathematical model was developed and according to the simulated results for 5 years, air injected at 2.5 m achieved improvements on stabilization of solid phase organic carbon and nitrogen for 34 % and 13 %, amelioration on leachate quality for 35 % and 62 % of TOC and T-N, and the restraint of GHE for 14 times compared with no air injection case.