Proportion Of CH4 Research Articles

Evaluation of Suitability of Buffer to Induce Acidosis on Rice (Oriza sativa) based Diet in RUSITEC

Background: Rice feeding followed in Tamil Nadu for dairy cattle induces acidosis and the effect of acidosis studies through in vitro techniques is desirable to reduce the animal experiment. Since Mc Dougall Buffer neutralizes acidity produced on incubation with rice (Oriza sativa) in semi continuous culture, it is difficult to mimic acidosis in RUSITEC. Hence a study was conducted in RUSITEC with cooked rice incubated for 24 hours to evaluate the effect of diluting Mc Dougall buffer to establish rumen acidosis (pH less than 5.8). Methods: Two treatments were followed with undiluted Mc Dougall Buffer (MDB) and diluting Mc Dougall Buffer (MMDB) as per Mickdam et al. (2016) in RUSITEC experiments with six replicates for each treatment. This experiment was conducted with equivalent weight of test material (Cooked rice on DMB). The pH of artificial buffer was maintained at 7.4 during start of incubation for both buffers. Result: The rumen fermentation pattern for establishment of onset of acidosis due to over feeding of cooked rice was evinced by the onset of acidosis ( less than 5.8 pH) recorded at 3 hours of incubation in MMDB infusion and at 18 hours of incubation in MDB infusion. The concentration of NH3-N declined after acidosis induction; however, it reached its minimum in MMDB at significant difference (p less than 0.05) than MDB at all incubation hours. Total gas production (Methane and Carbon dioxide) was reduced with MMDB incubation. The CH4 proportion declined strongly (p less than 0.01) at all incubation hours in MMDB than MDB. The production of volatile fatty acid was reduced significantly (p less than 0.05) in MMDB at all incubation period compared with MDB. This was based on a significant decrease in the acetate production (p less than 0.05), an increase in the propionate and butyrate production (p less than 0.05). Acidosis challenge resulted in significantly (p less than 0.01) elevated lactate levels in MMDB at all incubation hours which remained high at 24 hours of incubation. Compared to MDB condition, the LPS concentration was largely elevated (p less than 0.01), by 36% on average till 12 hours of incubation, due to severe acidosis condition (pH 4.9) created by MMDB. The early occurrence of acidosis condition in MMDB, increased significantly (p less than 0.01) gram positive organisms in the rumen. The MMDB infusion showed a strong effect on degradation of DM, OM and N and it was decreased, similarly the degradation rate of DM and N was lowest. This study proves that the MMDB is the suitable acidosis inducing buffer for establishing the in vitro models to cooked rice.

Transformation mechanism of polycyclic aromatic hydrocarbons and hydrogen production during the gasification of coking sludge in supercritical water

In this study, the characteristic of hydrogen production and polycyclic aromatic hydrocarbons (PAHs) transformation during supercritical water gasification (SCWG) of coking sludge (400 °C - 450 °C, 1 min–30 min) were explored. The total gas yield was between 0.62 mol/kg OM and 1.05 mol/kg OM (on dry basis), and the proportion of CH4 and H2 was only between 5.41% and 6.44%. PAH content were increased from 194.92 mg/kg to 326.04 mg/kg, and mainly high molecular weight PAHs, which were formed from the Diels-Adler reaction of single aromatic hydrocarbon and the addition reaction of low molecular weight PAHs. High reaction temperature favored more active PAH formation than reaction time. The possible control methods for PAH formation during SCWG of coking sludge was proposed. H2O2 and KOH addition effectively reduce PAHs amount in solid residues by 46.67% and 38.33%, and KOH performed positive effect on hydrogen production. The work revealed that the inhibition of PAHs and hydrogen production were achieved from SCWG of coking sludge with KOH addition.

Dose-response effects of Poncirus trifoliata extract on in vitro ruminal methane production, fermentation, and microbial abundance

The effects of different inclusion rates of Poncirus trifoliata (PT) extract on in vitro ruminal fermentation parameters were investigated. Six dose levels were referred to as follows: PT0, control (without PT); PT1, (3 mg/L); PT3, (9 mg/L); PT5, (15 mg/L); PT7, (21 mg/L); PT9, (27 mg/L), each incubated with 50 mL of buffered rumen fluid and 300 mg of timothy hay as a substrate for 72 h of incubation using an in vitro batch culture system. The in vitro dry matter digestibility (IVDMD) was significantly affected by the PT dose, except after 6 and 48 h of incubation. Total volatile fatty acids (VFAs) increased quadratically (12 h of incubation) within the range of PT1–PT7, whereas decreased at PT9 dose. Methane (CH4) production and the proportion of CH4 in the total gas produced decreased linearly after 12 h of incubation. The relative abundance of Ruminococcus albus and Ruminoccocus flavefaciens was greater at the doses PT1 than PT0, whereas that of Fibrobacter succinogenes was greater at PT0 than at PT9 after 24 h of incubation. Methanogenic archaea decreased linearly with increasing PT dose after 12 h of incubation. The abundance of ciliate-associated methanogens decreased linearly over 24 h of incubation under PT7 and PT9 treatments. These results suggest that the dose of PT can modulate ruminal fermentation to alter VFA concentration and reduce CH4 production by altering ruminal bacterial abundance. Highlights This study evaluated the dose-response effects of Poncirus trifoliata as a methane mitigation agent in ruminants. Inclusion of Poncirus trifoliate lowered in vitro dry matter digestibility and total volatile fatty acid concentration. Inclusion of Poncirus trifoliata extract reduced methane production after 12 h of incubation but did not maintained. Inclusion of Poncirus trifoliata extract reduced methanogenic archaea and ciliate-associated methanogens abundance

Can flushing gas distort the rumen in vitro experiment results?

To test whether the type of flushing gas could alter rumen in vitro experimental results, effects of three flushing gases (Ar, CO2, and N2) were compared with or without hypothetic experimental treatment (monensin supplementation) in a batch culture system. Rumen fluids obtained from three cannulated Holstein heifers were incubated for 3, 6, 12, 24, and 48 h according to 3 × 2 factorial arrangements. Total gas production was decreased, and CH4 proportion was increased by CO2 flushing regardless of incubation time. The effects of monensin on CH4 proportion were not shown in CO2 flushed group. After 3 h incubation, ammonia nitrogen was increased by N2 flushing, and interaction between flushing gas and monensin was observed in iso-butyrate. Total volatile fatty acids production was not influenced by the type of flushing gases regardless of incubation time. However, after 48 h incubation, by CO2 flushing, the valerate without monensin decreased while it increased with monensin, implying the interaction effect between flushing gas and monensin. The pH elevation effect of monensin was delayed by CO2 flushing compared to Ar and N2 flushing. This study demonstrated whether the type of flushing gas can confound experimental results. Since N2 flushing can influence rumen nitrogen parameters in early incubation and CO2 flushing affected pH results while Ar flushing did not show noticeable results, we suggest that Ar could be used as a new alternative flushing gas for rumen in vitro studies.

Mechanism analysis of gas products from catalytic pyrolysis of tire rubber based on reaction thermodynamics and kinetics

In this paper, the gas products from pyrolysis of tire rubber was respectively studied by fixed bed pyrolysis experiments—gas chromatography analysis and molecular dynamics simulations. The results of experiments showed that the main gas products of pyrolysis were CH4, H2, and C2H4. The simulation results showed that the long rubber chain broke into four main rubber monomers at low temperature: isoprene, styrene, 1,3-butadiene and uncondensated C4H6·. And at higher temperature, the generated monomers were pyrolyzed into small molecule gases. Fe2O3 reduced the final pyrolysis temperature and increased the pyrolysis rate with a good catalytic reactively. And it changed the gas products distribution, in which the proportion of CH4 and H2 were promoted while the proportion of C2H4 was reduced. In order to obtain the thermodynamic and kinetic data of each reaction path, DFT calculation was carried out. The reaction paths of three major radicals H·, CH3·, and CH2 = CH· were further discussed. The results showed that Fe2O3(commercial) promoted the release of CH3· from isoprene monomer and CH3· attack on isoprene monomer and 1,3-butadiene to produce CH4. Moreover, Fe2O3 promoted H· attacking styrene monomer to generate H2.

High-efficiency gas storage via methane-tetrahydrofuran hydrate formation: Insights from hydrate structure and morphological analyses

Hydrate-based gas storage and transportation is limited by harsh hydrate formation conditions and low formation rate, which cannot be used in large-scale commercial applications. In this work, based on the good thermodynamic properties of tetrahydrofuran (THF), we systematically studied the hydrate formation kinetics of CH4–THF (5.56 mol%) hydrate under static conditions (4 MPa and 282.2–288.2 K). The experimental results showed that CH4 storage was greatest at 288.2 K within 5 h, reaching a value of 0.0483 ± 0.005 mol/mol, which was 19.85% higher than that at 282.2 K. Based on the quantitative results of Raman spectroscopy, the proportion of CH4 in the small cages of sII hydrates increased by approximately 11.63% with an increase in temperature from 282.2 to 288.2 K. In addition, by observing the growth behavior and morphology of CH4-THF hydrate, it was found that the morphology of CH4-THF hydrate became looser with the decrease of undercooling (ΔTsub), which effectively promoted the formation of hydrate. Furthermore, the energy consumption during CH4-THF hydrate formation was greatly decreased with the increase of temperature, saving about 98.62% at 288.2 K. This study provides a theoretical basis for the storage and transportation of natural gas via the solid hydrate method.

Removal of hydrogen sulfide from a binary mixture with methane gas, using IRMOF-1: a theoretical investigation.

The natural gas is mainly composed by methane, ethane, propane, and contaminants. Among these contaminants, the H2S gas has some specific characteristics such as its toxicity and corrosion, besides reducing the combustion power efficiency of natural gas. In this context, metal-organic frameworks appear as promising materials for purification of natural gas by adsorption, due to their large surface area and pore volume. In this work, Grand Canonical Monte Carlo method was used to study the adsorption and separation of CH4:H2S mixture by IRMOF-1. The adsorption isotherms were computed for the pure components, and at different compositions of binary mixture (90:10, 75:25, 50:50, 25:75, and 10:90). Interaction energy obtained with the semiempirical method confirmed that the inorganic unit is the preferred site for CH4 and H2S adsorption. Moreover, in a gas mixture with 50:50 proportion of CH4:H2S mixture, methane adsorbs preferentially in the inorganic unit only at pressures close to 20bar. Non-covalent interaction (NCI) analyses indicated that the interactions involving H2S are more effective than that for CH4, due to an electrostatic character in the H2S interaction. The simulations also showed that the separation of gases occurs in all compositions and pressures studied, suggesting that IRMOF-1 has a promising potential for this application.

Synergistic effects from fast co-pyrolysis of lignin with low-rank coal: On-line analysis of products distribution and fractal analysis on co-pyrolysis char

Synergistic effects from fast co-pyrolysis of low-rank coal with lignin via on-line mass spectrometry were explored. Iso-conversional method was used to obtain frequency factor and activation energy of main gaseous products. The morphology evolution of both individual and co-pyrolysis char was analyzed via fractal theory quantificationally. The results indicated that various synergistic effects were found from the distribution and composition of products. CO and CO2 were the main content of the gaseous products, and the content of CO from lignin increased with the temperature. Lignin promoted the generation of tar and inhibited the formation of gaseous products during fast co-pyrolysis, which reflected different synergistic effects, respectively. Positive synergistic effects were observed from the component proportion of CH4 as the temperature increasing higher than 600 °C. Kinetic analysis indicated that activation energy for H2 from lignin and low-rank coal was 32.21 and 59.90 kJ/mol, and higher temperature would be beneficial for H2 formation. Fractal analysis indicated that lignin promoted the surface morphology of co-pyrolysis char to become more complicated, with the fractal dimension of individual char less than those of co-pyrolysis char.

Study on Mechanisms Underlying Changes in Agricultural Carbon Emissions: A Case in Jilin Province, China, 1998-2018.

Reducing agricultural carbon emissions (ACE) is a key point to achieve green and sustainable development in agriculture. Based on the ACE statistics of Jilin Province in China from 1998 to 2018, this article considers the sources of ACE in depth, and fourteen different carbon sources are selected to calculate ACE. Besides, the paper explores the variation characteristics of ACE in Jilin Province, their structure, and the relationship between the intensity and density of the dynamic changes in ACE in the province in terms of time. Finally, this paper uses the Kaya identity and logarithmic mean Divisia index (LMDI) to analyze the influential factors in ACE. The results show the following: (1) During 1998–2018, the amount of ACE in Jilin Province increased, with an average annual growth rate of 1.13%. However, the chain growth rate has been negative in recent years, which reflects that carbon emission reduction has been achieved to a certain extent. (2) The characteristics of ACE in Jilin Province during the years is that of the low-intensity, high density category. Furthermore, agricultural resource input is the main source of the planting industry’s carbon emissions. From the perspective of animal husbandry, the proportion of CH4 decreased, while the proportion of N2O is relatively stable. (3) Based on the LMDI decomposition model, production efficiency, industrial structure, and labor are the three main factors that reduce ACE in Jilin Province. The economic level is the main factor of ACE, and it will be the most important factor leading to an increase in ACE in the short term. On the basis of comprehensive analysis, this article puts forward reasonable suggestions in terms of policy improvement, production mode and industrial structure adjustment, technological innovation, and talent introduction.

Enhanced 2,4,6-trichlorophenol degradation and biogas production with a coupled microbial electrolysis cell and anaerobic granular sludge system

A coupled microbial electrolysis cell - anaerobic granular sludge system (MEC-AGS) was established to explore the degradation efficiency of 2,4,6-trichlorophenol (TCP) with synchronous biogas production. Results showed that MEC-AGS yielded a higher proportion of CH4 than MEC (83.8 ± 0.4% vs 82.0 ± 1.0%, P < 0.05) with sodium acetate (NaAc) as the only carbon source. Moreover, MEC-AGS had higher tolerance to the addition of TCP, with the highest TCP degradation efficiency of 45.5 ± 0.5% under 5 mg L−1 of TCP addition in 24 h. Furthermore, microbial community structures were significantly changed based on community composition, hierarchical cluster and PCoA analysis, which proved that MEC-AGS favored the enrichment of dechlorination-related microbes such as Pseudomonas, Desulfovibrio and Longilinea, as well as their syntrophic bacteria of Anaerolineacea, Syntrophobacter, Arcobacter, etc. The coupled system provides a promising strategy for biogas production from wastewater with recalcitrant organics.

Treatment and valorisation of fruit juice wastewater by aqueous phase reforming: Effect of pH, organic load and salinity

Abstract This work analyses the application of aqueous phase reforming as a treatment and valorisation method for fruit juice wastewater enabling production of H2 and alkanes from renewable source. The variables considered were pH, organic load and salinity of wastewater, since they are fluctuant and can affect the performance of biological treatments most commonly used. The experiments were carried out in batchwise, at 493 K and 24–28 bar for 4 h using a 3% Pt/C catalyst. Single compounds (glucose, fructose, citric acid, ascorbic acid, galacturonic acid) and fruit juice wastewater were tested as feedstocks. Organic carbon removal from wastewater was higher in the reforming of glucose and fructose within 7–10 pH range, while for organic acids and fruit juice wastewater a higher removal was obtained at pH 2. H2 yield and selectivity increased at increasing pH, due to better conditions for water-gas shift reaction and abstraction of CO2. H2 production by aqueous phase reforming of fruit juice wastewater was little affected by pH, yielding around 6.6 mmol H2/g initial chemical oxygen demand, in the pH range tested. Alkanes were also produced, with higher proportion of CH4 than other alkanes at high pH (10–12). A wide operation window was observed regarding organic load of fruit juice wastewater, although organic carbon removal declined slightly at the highest loads tested. Salinity did not affect organic carbon removal, while H2 yield decreased from 7.8 to 4.2 mmol H2/g initial chemical oxygen demand at high salinity, probably due to catalyst deactivation. Aqueous phase reforming is proved to be an alternative to biological treatment methods with low sensibility to fluctuations in the characteristics of wastewater.

Influence of Selected Synthesis Gas Component on Internal Parameters of Combustion Engine

Abstract The paper deals with the influence of selected component of synthesis gas on internal parameters of combustion engine that is planned to be used in micro-cogeneration unit. The aim is to better understand the mechanism of combustion of carbon monoxide mixed with methane and as a follow-up to optimize the operation of the Lombardini LGW 702 engine on change of fuel composition. Generally, an increasing proportion of carbon monoxide in methane mixture leads to a decrease in engine performance (mean indicated pressure) and the hourly fuel consumption in each of the operating modes of the engine increases. With growing proportion of CO in mixture with CH4, the maximum pressure in the cylinder increases together with pressure rise rate up to approximately 10 % vol. of CH4. With further increasing proportion of CH4, there is a significant decrease of the before-mentioned engine parameters. The optimum ignition angle for pure methane, or carbon monoxide, does not change significantly and it is about 27° CA BTDC.

The inhibitory action mode of nitrocompounds on in vitro rumen methanogenesis: a comparison of nitroethane, 2-nitroethanol and 2-nitro-1-propanol

AbstractNitroethane (NE), 2-nitroethanol (NEOH) and 2-nitro-1-propanol (NPOH) were investigated in order to determine their inhibitory effects on in vitro ruminal fermentation and methane (CH4) production of a hay-rich substrate (alfalfa hay: maize meal = 4:1, w/w). The rumen liquor collected from cannulated Holstein dairy cows was incubated at 39 °C for 72 h. The addition of NE, NEOH and NPOH slowed down the fermentation process and notably decreased molar CH4 proportion by 96.8, 96.4 and 35.0%, respectively. The abundance of total methanogen and methanogens from the order Methanobacteriales were all decreased with NE, NEOH and NPOH supplementation. Meanwhile, the nitrocompound addition reduced mcrA gene expression, coenzyme F420 and F430 contents. The correlation analysis showed that CH4 production was correlated positively with the population abundance of total methanogens, Methanobacteriales, mcrA gene expression, coenzyme contents of F420 and F430. The nitrocompound addition decreased acetate concentration and increased propionate and butyrate concentrations in the culture fluid. In summary, both NE and NEOH addition presented nearly the same inhibitory effectiveness on in vitro CH4 production; they were more effective than NPOH. The results of the current study provide evidence that NE, NEOH and NPOH can dramatically decrease methanogen population, mcrA gene expression and the coenzyme content of F420 and F430 in ruminal methanogenesis.

Effect of temperature on the physicochemical characteristics of pine nut shell pyrolysis products in a screw reactor

ABSTRACT Pyrolysis experiments of pine nut shells (PNSs) were carried out in a screw reactor at 300–700°C with approximately 98% energy yields. The analysis results showed that higher temperatures result in elevated heating values (HVs) of products but reduced biochar and bio-oil yields. The HVs of pyrolytic gas were remarkably influenced by proportions of CH4 and H2. Bio-oil of PNSs consisted primarily of phenols, acids, aldehydes, ketones, furans, and aromatic hydrocarbons. Five hundred degree Celsius was considered as optimal temperature for PNS pyrolysis, and biochar was the primary product with a yield of 37.11% and better Cu2+, Ni2+, and Zn2+ adsorption properties.

Spatial and Temporal Distribution of Greenhouse Gas Emissions From Municipal Wastewater Treatment Plants in China From 2005 to 2014

AbstractMunicipal wastewater treatment plants (MWWTPs) are considered significant artificial sources of greenhouse gas (GHG) emissions, in the forms of methane (CH4) and nitrous oxide (N2O), during their normal operations. In this study, we used an emission factor method to determine the spatial and temporal distribution characteristics of GHG emissions from MWWTPs in China during the period 2005–2014; influencing factors and uncertainties were also analyzed. Our results show that total GHG emissions from Chinese MWWTPs increased from 326.54 to 1294.03 Gg CO2‐eq between 2005 and 2014, and that regional distribution was extremely variable. During this decade, the proportion of CH4 in the total GHG emissions decreased from 74.1 to 59.4% while that of N2O increased from 25.9 to 40.6%. The observed increase in N2O was probably due to the enhancement of wastewater discharge standards for nitrogen discharge, resulting in lower waterborne but higher atmospheric levels of nitrogen oxides. Our comparison of GHG emissions from wastewater discharging directly to the aquatic environment with that treated at MWWTPs in 2014 indicate that the latter disposal method resulted in an 18‐fold drop in GHG emissions. Regional economic development level and wastewater treatment capacity were the factors most closely related to GHG emissions from MWWTPs; the per‐capita protein supply was closely related to N2O emissions.

An evaluation on mechanisms of miscibility development in acid gas injection for volatile oil reservoirs

Produced gas containing the acid gas reinjection is one of the effective enhanced oil recovery methods, not only saving costs of disposing acid gases and zero discharge of greenhouse gases but also supporting reservoir pressure. The subsurface fluid from the Carboniferous carbonate reservoir in the southern margin of the Pre-Caspian basin in Central Asia has low density, low viscosity, high concentrations of H2S (15%) and CO2 (4%), high solution gas/oil ratio. The reservoir is lack of fresh water because of being far away onshore. Pilot test has already been implemented for the acid gas reinjection. Firstly, in our work a scheme of crude oil composition grouping with 15 compositions was presented on the basis of bottomhole sampling from DSTs of four wells. After matching PVT physical experiments including viscosity, density and gas/oil ratio and pressure–temperature (P–T) phase diagram by tuning critical properties of highly uncertain heavy components, the compositional model with phase behavior was built under meeting accuracy of phase fitting, which was used to evaluate mechanism of miscibility development in the acid gas injection process. Then using a cell-to-cell simulation method, vaporizing and/or condensing gas drive mechanisms were investigated for mixtures consisting of various proportions of CH4, CO2 and H2S in the gas injection process. Moreover, effects of gas compositions on miscible mechanisms have also been determined. With the aid of pressure-composition diagrams and pseudoternary diagrams generated from the Equation of State (EoS), pressures of First Contact Miscibility (FCM) and Multiple Contact Miscibility (MCM) for various gases mixing with the reservoir oil sample under reservoir temperature were calculated. Simulation results show that pressures of FCM are higher than those of MCM, and CO2 and H2S are able to reduce the miscible pressure. At the same time, H2S is stronger. As the CH4 content increases, both pressures of FCM and MCM are higher. But incremental values of MCM decrease. In addition, calculated envelopes of pseudoternary diagrams for mixtures of CH4, CO2 and H2S gases of varying composition with acid gas injection have features of bell shape, hourglass shape and triangle shape, which can be used to identify vaporizing and/or condensing gas drives. Finally, comparison of the real produced gas and the one deprived of its C3+ was performed to determine types of miscibility and calculate pressures of FCM and MCM. This study provides a theoretical guideline for selection of injection gas to improve miscibility and oil recovery.

Phase Equilibria of the CH4-CO2 Binary and the CH4-CO2-H2O Ternary Mixtures in the Presence of a CO2-Rich Liquid Phase

The knowledge of the phase behavior of carbon dioxide (CO2)-rich mixtures is a key factor to understand the chemistry and migration of natural volcanic CO2 seeps in the marine environment, as well as to develop engineering processes for CO2 sequestration coupled to methane (CH4) production from gas hydrate deposits. In both cases, it is important to gain insights into the interactions of the CO2-rich phase—liquid or gas—with the aqueous medium (H2O) in the pore space below the seafloor or in the ocean. Thus, the CH4-CO2 binary and CH4-CO2-H2O ternary mixtures were investigated at relevant pressure and temperature conditions. The solubility of CH4 in liquid CO2 (vapor-liquid equilibrium) was determined in laboratory experiments and then modelled with the Soave–Redlich–Kwong equation of state (EoS) consisting of an optimized binary interaction parameter kij(CH4-CO2) = 1.32 × 10−3 × T − 0.251 describing the non-ideality of the mixture. The hydrate-liquid-liquid equilibrium (HLLE) was measured in addition to the composition of the CO2-rich fluid phase in the presence of H2O. In contrast to the behavior in the presence of vapor, gas hydrates become more stable when increasing the CH4 content, and the relative proportion of CH4 to CO2 decreases in the CO2-rich phase after gas hydrate formation.

Effects of pyrolysis temperature on the physicochemical properties of gas and biochar obtained from pyrolysis of crop residues

Pyrolysis of crop residues is an important method to promote the utilization of biomass energy. Pyrolysis experiments of wheat straw, rice straw, corn stover, rape stalk and cotton stalk were carried out under different temperatures. The results showed that the biochar yields decreased and the gas yields increased from 300 °C to 600 °C. Besides, the proportions of CO2 and CO decreased with temperature. Higher temperatures elevated the proportions of CH4, CnHm and H2 and the higher heating values. With increasing temperature, the biochars showed decreased contents of volatile matter, H, O and (O + N)/C ratios, while increased ash, fixed carbon, C, total P and K contents. The carbon and energy conversion efficiencies of biochars decreased with increasing temperature. Significant differences were observed in the pyrolysis products among different crop residues, and some high correlations were identified among the determination parameters in the gases and biochars. At the same temperature, rice straw had the highest biochar yield, and rape stalk showed the highest gas yield and proportions of CH4, CnHm and H2 among the five crop residues. In addition, rape stalk biochar showed higher C, H and S contents and higher heating value, and cotton stalk biochar exhibited a higher fixed carbon.

Fluid Inclusion Studies on Quartz Associated with Massive Ores of the Paleoproterozoic Carbonate-hosted Pb-Zn Deposit at Balaria, Rajasthan: Possible Evidence for Fluid-mixing

ABSTRACT Mixing of metal-rich connate waters derived from evaporative seawater with local sulfide-rich water is postulated as the mechanism of ore deposition in many Phanerozoic carbonate-hosted Pb-Zn deposits. The study of the Paleoproterozoic Balaria deposit of the Zawar belt of Rajasthan that hosts structurally-controlled, stratabound Pb-Zn mineralization, provides insight into the nature of fluids in quartz that is closely associated with massive Pb-Zn ore. The present study is focused on the massive-type ore which forms one of the major ore-types at Balaria. Massive-type ore consists predominantly of galena and sphalerite (with minor pyrite and pyrrhotite) that occur in shear-induced dilatational fractures. The ore is associated with clear, rounded to semi-rounded bodies of quartz that are embedded within the ore. The quartz bodies are inferred to be fragments of vein-quartz that underwent shear deformation along with enclosing massive galena-rich ore. Primary-biphase fluid inclusions in quartz belong to H2O-NaCl±CO2, H2O-NaCl-CH4-N2-CO2 and primary-monophase fluid inclusions to CH4-N2-CO2 types, while secondary fluid inclusions are biphase and belong to H2O-NaCl type. The salinity of primary-biphase H2O-NaCl type fluid inclusions range from 2 to 14 wt. percent NaCl equiv while that of secondary-biphase H2O-NaCl type fluid inclusions range from 3 to 5 wt. percent NaCl equiv. Homogenization temperatures for primary-biphase fluid inclusions range from 127 °to 217 °C while that of secondary-biphase fluid inclusions is 131 ° to 151 °C. The molecular proportions of of CH4, N2 and CO2 in primary-biphase (H2O-NaCl-CH4-N2-CO2) and primary-monophase (CH4-N2-CO2) as measured from Raman spectra are widely variable. Variability in molecular proportions of CH4, N2 and CO2 is interpreted as an evidence for mixing of pulses of a regional fluid with a local fluid and reactions with graphitic and carbonate rocks at the site of deposition. The low salinity of fluid inclusions in the quartz and the lack of any sulfur species in the aqueous or gaseous phase of the entrapped fluids indicates that although quartz occurs as entrained bodies within the massive ore, the fluids in them may not represent ore-forming fluids of the main ore-stage of massive-type ore.

Effect of Feedstock Concentration on Biogas Production by Inoculating Rumen Microorganisms in Biomass Solid Waste.

A methane production system with continuous stirred-tank reactor, rumen liquid as inoculate microorganisms, and paper mill excess sludge (PES) as feedstock was studied. The work mainly focused on revealing the effect of feedstock concentration on the biogas production, which was seldom reported previously for the current system. The optimal fermentation conditions were found as follows: pH=7, T=39±1°C, sludge retention time is 20days, sludge with total solids (TS) are 1, 2, 3.5, 5, 10, and 13% in weight. Daily gas yields were measured, and biogas compositions were analyzed by gas chromatograph. Under such conditions, the optimum input TS was 10wt%, and the biogas yield and volume gas productivity were 280.2mL/g·TS and 1188.4mLL-1·d-1, respectively. The proportions of CH4 and CO2 in the biogas were 65.1 and 34.2%. The CH4 yield reached 182.7mL/gVS (volatile suspended solid), which was higher than previously reported values. The findings of this work have a significant effect on promoting the application of digesting PES by rumen microorganisms and further identified the technical parameter.