The response of a mid- and high latitude peat bog to predicted climate change: methane production in a 12-month peat incubation

There are fears that global warming will lead to degradation of peatlands, higher emissions of greenhouse gases from peat, and accelerated warming. Anaerobic decomposition of organic soils produces methane (CH₄), a potent greenhouse gas. Two peat bogs differing in mean annual temperature, Velke Darko (VD, Czech Republic, 7.2 °C), and Stor Åmyran (SA, Sweden, 4.0 °C), were selected for a comparative study of how organic soils in different climatic zones will respond to warmer and drier conditions. Twenty peat cores from each bog were incubated in growth chambers. Under present-day summer conditions, VD produced 14 times more CH₄ than SA. Two different warming scenarios were used. Peat-core replicates were kept at temperatures of 11 versus 16 °C, and 11 versus 22 °C. From 11 to 16 °C, the CH₄ production slightly decreased at SA, and slightly increased at VD. From 11 to 22 °C, the CH₄ production increased 9 times at SA, but slightly decreased at VD. After an 8-month incubation, peat cores under drying conditions (water table at ?14 cm) were compared to samples with original water table (?2 cm). Drying conditions led to a steeper reduction in CH₄ production at VD, compared to SA. The CH₄ production decreased more than 100 times at VD. Then, the combined effect of simultaneous warming and drying at 11 and 22 °C was studied. We did not find any significant effect of interactions between increasing temperature and decreasing water table level. Overall, the warmer site VD responded more strongly to the simulated climate change than the colder site SA.     

Delignification of disposable wooden chopsticks waste for fermentative hydrogen production by an enriched culture from a hot spring

Hydrogen(H2) production from lignocellulosic materials may be enhanced by removing lignin and increasing the porosity of the material prior to enzymatic hydrolysis. Alkaline pretreatment conditions,used to delignify disposable wooden chopsticks(DWC) waste, were investigated. The effects of NaOH concentration, temperature and retention time were examined and it was found that retention time had no effect on lignin removal or carbohydrate released in enzymatic hydrolysate. The highest percentage of lignin removal(41%) was obtained with 2% NaOH at 100℃, correlated with the highest carbohydrate released(67 mg/gpretreated DWC) in the hydrolysate. An enriched culture from a hot spring was used as inoculum for fermentative H2 production, and its optimum initial pH and temperature were determined to be 7.0 and 50℃, respectively. Furthermore, enzymatic hydrolysate from pretreated DWC was successfully demonstrated as a substrate for fermentative H2 production by the enriched culture. The maximum H2 yield and production rate were achieved at 195 mL H2/g total sugarsconsumedand 116 mL H2/(L·day), respectively.     

Enhanced nitrogen removal upon the addition of volatile fatty acids from activated sludge by combining calcium peroxide and low-thermal pretreatments

This study investigated a combined low-thermal and CaO₂ pretreatment to enhance the volatile fatty acid (VFA) production from waste activated sludge (WAS). The fermentative product was added to a sequencing batch reactor (SBR) as an external carbon source to enhance nitrogen removal. The results showed that the combined pretreatment improved WAS solubilization, releasing more biodegradable substrates, such as proteins and polysaccharides, from TB-EPS to LB-EPS and S-EPS. The maximum VFA production of 3529 ± 188 mg COD/L was obtained in the combined pretreatment (0.2 g CaO₂/g VS + 70 °C for 60 min), which was 2.1 and 1.4-fold of that obtained from the sole low-thermal pretreatment and the control test, respectively. Consequently, when the fermentative liquid was added as an external denitrification carbon source, the effluent total nitrogen decreased to Class A of the discharge standard for pollutants in rural wastewater treatment plants in most areas of China.     

Der atmosphärische Kreislauf von Methan

Present methane concentrations in the northern troposphere average 1.65 ppm. Most CH₄ is of recent biogenic origin. ¹⁴C analyses indicate that no more than 10% is released by fossil sources. The various CH₄-producing ecosystems are described and the total annual production is estimated to lie between 5.9×10¹⁴ and 9.3×10¹⁴ g/y. CH₄ is destroyed through photochemical oxidation mainly in the troposphere. In this process CH₂O, H₂, and CO are produced as intermediates. Tropospheric CH₄ provides an important source of stratospheric water vapor.     

Analysis of temperature effects on seasonal and interannual variation in CH4 emission from rice-planted pots

Rice (Oryza sativa L.) paddies are one of the major sources of atmospheric methane (CH₄), a greenhouse gas. To elucidate the quantitative relationship between CH₄ emission from rice paddies and temperature, 6 years data of CH₄ emission from pot experiments were analyzed in terms of the sum of effective temperature (∑(T−15); T is the daily mean air temperature (°C)). The base temperature of 15 °C was adopted as the 0 °C physiological temperature for methanogens. Significant positive correlations between total CH₄ emission throughout the rice growth period and ∑(T−15) were observed for pots with rice straw (RS) application at a rate of 6 g kg⁻¹ soil, which corresponds to 6 t ha⁻¹ (r=0.830⁷¹), and those without RS application (r=0.818⁷¹). It was confirmed that temperature is a major factor affecting the interannual variation in CH₄ emission. For the 1993 and 1995 data sets that include seven and four levels of RS application, the relationship between seasonal CH₄ emission and RS application rate could be expressed using linear functions (r=0.988⁷¹, 0.996⁷¹), the slopes of which were similar to each other. Based on these findings, we confirmed that the dependence of seasonal CH₄ emission on both temperature and RS application rate can be described by a single linear equation.     

瓦里关山大气CH4本底变化

利用 1991 0 5— 2 0 0 2 0 5期间实测资料 ,分析了瓦里关全球基准站 (36°17′N ,10 0°5 4′E ,海拔 3816m)大气CH4本底特征 ,并探讨了与源汇过程的关系 .结果表明 ,瓦里关山大气CH4体积分数本底范围和增长趋势与 6 0°N— 30°N平均水平大致相符 ,但本底体积分数季节变化与所处纬度带基本特征和季节振幅的地理分布差异较大 ,年增长值波动也与全球平均状况并不完全一致 ,是所在地区多种CH4源汇和大气输送共同作用的结果 .瓦里关站提供的大气CH4本底观测资料 ,既能体现亚洲内陆地域特点又具有全球代表性 ,辅以其它相关资料 ,还可进一步揭示中国内陆高原大气CH4本底特征的成因     

A comparative study on the alternating mesophilic and thermophilic two-stage anaerobic digestion of food waste

An alternating mesophilic and thermophilic two stage anaerobic digestion(AD) process was conducted. The temperature of the acidogenic(A) and methanogenic(M) reactors was controlled as follows: System 1(S1) mesophilic A-mesophilic M;(S2) mesophilic A-thermophilic M; and(S3)thermophilic A-mesophilic M. Initially, the AD reactor was acclimatized and inoculated with digester sludge. Food waste was added with the soluble chemical oxygen demand(SCOD) concentrations of41.4–47.0 g/L and volatile fatty acids of 2.0–3.2 g/L. Based on the results, the highest total chemical oxygen demand removal(86.6%) was recorded in S2 while S3 exhibited the highest SCOD removal(96.6%). Comparing S1 with S2, total solids removal increased by 0.5%; S3 on the other hand decreased by 0.1 % as compared to S1. However, volatile solids(VS) removal in S1, S2, and S3was 78.5%, 81.7%, and 79.2%, respectively. S2 also exhibited the highest CH4 content, yield, and production rate of 70.7%, 0.44 L CH4/g VSadded, and 1.23 L CH4/(L·day), respectively. Bacterial community structure revealed that the richness, diversity, evenness, and dominance of S2 were high except for the archaeal community. The terminal restriction fragments dendrogram also revealed that the microbial community of the acidogenic and methanogenic reactors in S2 was distinct. Therefore,S2 was the best among the systems for the operation of two-stage AD of food waste in terms of CH4production, nutrient removal, and microbial community structure.     

Enhancement of thermophilic anaerobic digestion of thickened waste activated sludge by combined microwave and alkaline pretreatment

Pretreatment of thickened waste activated sludge (TWAS) by combined microwave and alkaline pretreatment (MAP) was studied to improve thermophilic anaerobic digestion efficiency. Uniform design was applied to determine the combination of target temperature (110–210°C), microwave holding time (1–51 min), and NaOH dose (0–2.5 g NaOH/g suspended solids (SS)) in terms of their effect on volatile suspended solids (VSS) solubilization. Maximum solubilization ratio (85.1%) of VSS was observed at 210°C with 0.2 g-NaOH/g-SS and 35 min holding time. The effects of 12 different pretreatment methods were investigated in 28 thermophilic batch reactors by monitoring cumulative methane production (CMP). Improvements in methane production in the TWAS were directly related to the microwave and alkaline pretreatment of the sludge. The highest CMP was a 27% improvement over the control. In spite of the increase in soluble chemical oxygen demand concentration and the decrease in dewaterability of digested sludge, a semi-continuous thermophilic reactor fed with pretreated TWAS without neutralization (at 170°C with 1 min holding time and 0.05 g NaOH/g SS) was stable and functioned well, with volatile solid (VS) and total chemical oxygen demand (TCOD) reductions of 28% and 18%, respectively, which were higher than those of the control system. Additionally, methane yields (L@STP/g-CODadded, at standard temperature and pressure (STP) conditions of 0°C and 101.325 kPa) and (L@STP/g VSadded) increased by 17% and 13%, respectively, compared to the control reactor.     

Curcumin-Mediated Photodynamic Inactivation of Norovirus Surrogates

Photodynamic inactivation (PDI) is extensively used to inactivate different type of pathogens through the use of photosensitizers (PS). Curcumin has been identified as an excellent natural photosensitizer with some potential applications in the food industry. The aim of this study was to assess the antiviral activity of photoactivated curcumin on norovirus surrogates, feline calicivirus (FCV), and murine norovirus (MNV). Initially, different concentrations of curcumin (13.5–1358 µM) were individually mixed with each virus at titers of ca. 6–7 log TCID₅₀/ml and photoactivated by LED blue light with light dose of 3?J/cm². Results showed that photoactivated curcumin at 50 µg/mL reduced FCV titers by almost 5 log after incubation at 37 °C for 30 min. Lower antiviral activity (0.73 log TCID₅₀/mL reduction) was reported for MNV. At room temperature, curcumin at 5 µg/mL reduced FCV titers by 1.75 log TCID₅₀/mL. These results represent a step forward in improving food safety using photoactivated curcumin as an alternative natural additive to reduce viral contamination.     

Biogas production from maize and dairy cattle manure—Influence of biomass composition on the methane yield

There is an increasing world wide demand for energy crops and animal manures for biogas production. To meet these demands, this research project aimed at optimising anaerobic digestion of maize and dairy cattle manures. Methane production was measured for 60 days in 1 l eudiometer batch digesters at 38 °C. Manure received from dairy cows with medium milk yield that were fed a well balanced diet produced the highest specific methane yield of 166.3 Nl CH₄ kg VS⁻¹. Thirteen early to late ripening maize varieties were grown on several locations in Austria. Late ripening varieties produced more biomass than medium or early ripening varieties. On fertile locations in Austria more than 30 Mg VS ha⁻¹ can be produced. The methane yield declined as the crop approaches full ripeness. With late ripening maize varieties, yields ranged between 312 and 365 Nl CH₄ kg VS⁻¹ (milk ripeness) and 268–286 Nl CH₄ kg VS⁻¹ (full ripeness). Silaging increased the methane yield by about 25% compared to green, non-conserved maize. Maize (Zea mays L.) is optimally harvested, when the product from specific methane yield and VS yield per hectare reaches a maximum. With early to medium ripening varieties (FAO 240–390), the optimum harvesting time is at the “end of wax ripeness”. Late ripening varieties (FAO ca. 600) may be harvested later, towards “full ripeness”. Maximum methane yield per hectare from late ripening maize varieties ranged between 7100 and 9000 Nm³ CH₄ ha⁻¹. Early and medium ripening varieties yielded 5300–8500 Nm³ CH₄ ha⁻¹ when grown in favourable regions. The highest methane yield per hectare was achieved from digestion of whole maize crops. Digestion of corns only or of corn cob mix resulted in a reduction in methane yield per hectare of 70 and 43%, respectively. From the digestion experiments a multiple linear regression equation, the Methane Energy Value Model, was derived that estimates methane production from the composition of maize. It is a helpful tool to optimise biogas production from energy crops. The Methane Energy Value Model requires further validation and refinement.     

Effect of long-term fertilization on C mineralization and production of CH4 and CO2 under anaerobic incubation from bulk samples and particle size fractions of a typical paddy soil

Impacts of nutrient management on C mineralization and greenhouse gas (GHGs) emission from soils have been of much concern in global change. Using laboratory incubation, the production of CH₄ and CO₂ were studied from both bulk samples and the particle size fractions (PSF) of topsoil from a paddy under a long-term different fertilization trial (including non (NF), chemical without (CF) and with manure (CFM) fertilization, respectively) in the Tai Lake Region, China. Four PSFs (2000–200, 200–20, 20–2, <2 μm) were separated from undisturbed samples collected after rice harvest by a low-energy ultrasonic dispersion procedure. Both the bulk samples and PSFs were incubated under submerged condition for 72 days. The concentration of CH₄ and CO₂ evolved during incubation were determined by gas chromatography. C mineralization rates ranged from 0.13 to 0.52 mg C g⁻¹ C day⁻¹, with different fertilizations and size of the PSFs, and were not correlated with C/N ratio. While CO₂ production predominated over CH₄ from C mineralization from both bulk samples and the size fractions, CH₄ production played a predominant role in the total global warming potential (GWP) under all treatments. C mineralization of bulk soil was significantly higher under CF than under CFM and NF. CH₄ production, however, was 3 times as under CFM and 27 times as under NF, indicating a tremendous effect of chemical fertilization alone on the total GWP. CO₂ production from the PSFs differed from CH₄ under a single treatment, which was notably from the coarse PSFs larger than 200 μm. Higher C mineralization and CH₄ production with a higher metabolic quotient under CF implicated a vulnerability of soil functioning of GHGs mitigation in the paddy receiving chemical fertilizers only. Thus, rational organic amendments should be undertaken for mitigating the climate change.     

Preparation and characterization of boron-doped corn straw biochar: Fe (Ⅱ) removal equilibrium and kinetics

Nowadays, iron ions as a ubiquitous heavy metal pollutant are gradually concerned and the convenient and quick removal of excessive iron ions in groundwater has become a major challenge for the safety of drinking water. In this study, boron-doped biochar (B-BC) was successfully prepared at various preparation conditions with the addition of boric acid. The as-prepared material has a more developed pore structure and a larger specific surface area (up to 897.97 m²/g). A series of characterization results shows that boric acid effectively activates biochar, and boron atoms are successfully doped on biochar. Compared with the ratio of raw materials, the pyrolysis temperature has a greater influence on the amount of boron doping. Based on Langmuir model, the maximum adsorption capacity of 800B-BC_1:2 at 25 °C, 40 °C, 55 °C are 50.02 mg/g, 95.09 mg/g, 132.78 mg/g, respectively. Pseudo-second-order kinetic model can better describe the adsorption process, the adsorption process is mainly chemical adsorption. Chemical complexation, ions exchange, and co-precipitation may be the main mechanisms for Fe²⁺ removal.     

Temperature Effects for High-Pressure Processing of Picornaviruses

Investigation of the effects of pre-pressurization temperature on the high-pressure inactivation for single strains of aichivirus (AiV), coxsackievirus A9 (CAV9) and B5 (CBV5) viruses, as well as human parechovirus-1 (HPeV) was performed. For CAV9, an average 1.99 log₁₀ greater inactivation was observed at 4 °C after a 400-MPa–5-min treatments compared to 20 °C treatments. For CBV5, an average of 2.54 log₁₀ greater inactivation was noted after 600-MPa–10-min treatments at 4 °C in comparison to 20 °C treatments. In contrast, inactivation was reduced by an average of 1.59 log₁₀ at 4 °C for HPeV. AiV was resistant to pressure treatments of 600 MPa for as long as 15 min at 4, 20, and 30 °C temperatures. Thus, different pre-pressurization temperatures result in different inactivation effects for picornaviruses.     

Trends of tropospheric CO,N2O and CH4 as observed at cape point,South Africa

The results of CO, CH₄ and N₂O measurements performed over several years at the station Cape Point (34°21′S, 18dg29′E), South Africa, are presented. The analytical technique and data filtering procedure are described. The results indicate seasonal variations of the CO and CH₄ mixing ratios with maximum values around October and minimum values in February/March. The patterns and the amplitudes of the seasonal variations of both gases compare suprisingly well, indicating interrelations between the source-sink and/or transport mechanisms of CH₄ and CO in the Southern Hemisphere. CO measurements performed over a period of 9 years do not show any significant trend of the mean annual CO mixing ratios while the N₂O mixing ratios increase at a rate of 0.2% per year for the observation period from 1983 to 1987. The data obtained for CH₄ between 1983 and 1987 yield an increase rate of 0.7% per year indicating a reduction of the CH₄ increase in the Southern Hemisphere during recent years.     

农垦与放牧对内蒙古草原N2O、CO2排放和CH4吸收的影响

利用优选静态箱/气相色谱法(GC),首次对我国内蒙古草原典型地区进行了人类活动对N₂O、CO₂和CH₄交换通量影响的实验观测结果表明,农垦麦田N₂O平均排放通量比原始草原高出3倍,并改变了草甸草原为CO₂汇的性质,使其季节排放净通量以C计增加14.3 mg·(m²·h).随放牧强度的增加CO₂排放通量呈线性增长,轻牧会引起草原对CH₄吸收的大幅增加,而随着放牧压力的增大,增加值迅速回落.农垦麦田与草甸草原相比地-气间CH₄交换无显著变化,放牧强度对N₂O排放影响无显著规律.土壤湿度和温度是影响草原排放N₂O和CO₂、吸收CH4季节变化形式的关键因子,而人类活动仅影响排放强度.排放和吸收量年际间差异很大,但主要受降水的影响.N₂O和CO₂排放与CH₄吸收峰值相反现象普遍存在.     

CH4 emission model from the waste of Sus Domesticus and Gallus Domesticus in Nigerian local farms: environmental implications and prospects

The potential of CH₄ (methane) greenhouse gas (GHG) emissions based on a model of prevailing behavioural pattern of livestock waste management in Nigerian local farms was investigated in this paper. Livestock waste, from Sus domesticus, pig, and Gallus domesticus, poultry, were employed as substrates in the study which uses water from a fish rearing farm as the matrix medium to simulate wastewater pool/river environment. A substrate to fish-water ratio of 1:3 by mass was used in developed laboratory-size digesting reactor system with U-tube water displacement, to facilitate volumetric readings of gas production, for each mix of the livestock waste. Volumetric readings from these, at ambient temperature conditions in the retention time of 32 days, follow the Normal probability density function, in accordance with Kolmogorov-Smirnov goodness-of-fit criteria. These readings showed that CH₄-containing gas as high as 67.3?×?10^?3 dm³ was produced on the 14th day from the pig and 86.8?×?10^?3 dm³ on the 13th day from the poultry substrates. The overall CH₄-containing gas productions of 255.4?×?10^?3 dm³/kg and 323.58?×?10^?3 dm³/kg were observed for the pig and the poultry substrates, respectively. A 70% scale-up analysis, modelled from these results, for the nation yield potential emission of about 4 kg CH₄ (that could be as potent as 84 kg CO₂-equivalent) annually. The environmental implications on global warming and possible prospects of recoverable domestic benefits from the waste through the adoption of sustainable policy of livestock waste managements for mitigating the CH₄ emissions in Nigerian local farms are presented.     

NaOH处理对互花米草高温干式厌氧发酵的影响

为了解NaOH处理对互花米草厌氧发酵的影响,在高温（55℃±1℃）和互花米草初始干物质含量为20％条件下,考察了NaOH处理对互花米草厌氧发酵产气特性、物质结构和组成以及发酵后互花米草水浸提液理化特性的影响．结果表明,互花米草经5％NaOH处理后,产气受到明显的抑制,累积产气量仅为CK的76．68％;碱处理配合水洗可有...     

Preliminary report on methane emissions from the Three Gorges Reservoir in the summer drainage period

Considerable variations may exist in CH4 emissions from the Three Gorges Reservoir.     

玉米秸秆干式厌氧发酵乙酸产生规律及其对发酵的影响

为解决玉米秸秆干式厌氧发酵系统因乙酸积累而致发酵失败、工程运行不稳定等问题,利用气相色谱仪对玉米秸秆干式厌氧发酵过程中w(乙酸)和w(CH₄)进行检测,结合相关性分析和回归分析等方法,研究了乙酸动态产生趋势、w(TS)(TS为总固体)与w(乙酸)的相关性,以及w(乙酸)对CH₄产生的作用机制. 结果表明:发酵过程中w(乙酸)先增后降,w(TS)由20%增至30%,w(乙酸)增加的持续时间由5 d延至15 d. Pearson相关性分析结果表明,w(TS)与w(乙酸) 呈极显著负相关(R<-0.979,P<0.01). 一元线性回归分析得到拟合方程y=-1 214.8w(TS)+668.2,由斜率(-1 214.8)可知,w(TS)对产乙酸过程具有较明显的抑制作用. 玉米秸秆干式厌氧发酵系统内w(乙酸)为160~451 mg/g,随着w(乙酸)的增加,底物CH₄产率经历上升、稳定、下降后再稳定和下降4个阶段,其中w(乙酸)为212~312 mg/g时,底物CH₄产率(大于120 m3/t,以秸秆干质量计)最大,其次为w(乙酸)在>312~410 mg/g时的80~120 m3/t.      

Synthesis, characterization and experimental investigation of Cu-BTC as CO2 adsorbent from flue gas

Porous Cu-BTC material was synthesized by the solvothermal method. Powder X-ray diffraction (PXRD) was used to test the phase purity of the synthesized material and investigate its structural stability under the influence of flue gas components. The thermal stability of the material was determined through thermal gravimetric (TG) analysis. Scanning electron microscopy (SEM) was employed to study the microstructure of the material. Cu-BTC was demonstrated not only to have high CO₂ adsorption capacity but also good selectivity of CO₂ over N₂ by means of packed bed tests. The adsorption capacity of Cu-BTC for CO₂ was about 69 mL/g at 22°C. The influence of the main flue gas components on the CO₂ capacity of the material were discussed as well.