沼气中硫化氢气体的生物处理法

沼气中硫化氢的存在限制了沼气能源的推广。文章阐述了沼气生物脱硫法的原理、方法和可行性,介绍了该方法在国内外的研究发展现状。     

The removal of heavy metals in anaerobic upflow sludge blanket reactors

The continuous removal of heavy metals by the biological solids in an anaerobic reactor has been examined. The metals used were chromium (III), zinc and lead. Both competitive and non-competitive removal was studied. The results were evaluated in terms of adsorption isotherms and were compared with earlier batch studies. This suggested that the sludge acted as a cation-exchange material, with chromium having a much lower binding intensity than lead and zinc. The data also suggest that the nature of the sludge surface is of considerable significance in determining the capacity and intensity of binding. The effect of the metals on biogas formation was also examined. This showed that inhibition of the gas formation was a function of the metal concentration and that the relative toxicities appeared to be zinc > lead > chromium.     

Enhancement of Anaerobic Digestion Using Duckweed (Lemna minor) Enriched with Iron

ABSTRACT This paper describes the enhancement of biogas production in laboratory-scale anaerobic digesters (with batch and semi-continuous operation) using iron-enriched duckweed as a supplement to the digestion of feedstock. The relationship between the level of enhancement achieved and the retention period of the digesters was also investigated. The trials demonstrated that, in batch digesters, iron-enriched duckweed significantly improved the rate of microbial succession. Batch digesters receiving no duckweed took 40 days to reach peak methane production compared to 15 days when duckweed was added. In the semi-continuous digesters, an increase in gas production of about 44% was observed.     

Gaseous fuel production from fungal lignocellulose degradation

Anaerobic biodegradation of lignocellulose from elephant grass by cellulolytic fungi was carried out at optimum operational conditions: reactor volume of 50 cm³, slurry concentration of 2:5 w/v lignocellulose (g): water (cm³), and degradation temperature of 33 °C. Four cellulolytic fungi and a bacterium, which were harnessed from the air, were isolated in pure form and identified. Two species, Curvularia and Penicillium, were responsible for the biodegradation of lignocellulosic material, to yield biogas. The other two, Fusarium species and Aspergillus niger, including the bacterium, gave no gaseous products. Three gaseous products, namely methane, propane and carbon dioxide, were identified and measured. The rates of formation of these products were found to be first order with respect to the concentration of lignocellulose and the concentration of the microorganism, respectively. The distribution of the gaseous products suggests that the mechanism involves reductive decomposition of the cellulose monomeric unit, by the microorganism, to the gaseous products formed. Major heavier hydrocarbons produced in the degradation were also identified as mainly saturated polycyclic hydrocarbons, probably formed from the reductive degradation of the polyaromatic portions of the lignocellulose.     

The Main Technology of Solid Waste Treatment

This essay illustrated the three main solid waste trealment,biogas technology,landfill and incineration.Limitations and improvements Of each technology were discussed.     

Monitoring and control of biogas desulphurization using oxidation reduction potential under denitrifiying conditions

BACKGROUND: Hydrogen sulphide (H₂S) present in biogas can be oxidized to elemental sulphur (S₀) or sulphate (SO₄^2?) using nitrate and nitrite. Both nitrate and nitrite are normally available in most wastewater treatment plants and could be used to oxidize H₂S depending on the molar loading ratio of wastewater and biogas. A control approach is required in order to minimize the fluctuations in inlet and outlet H₂S concentrations in biogas, and the oxidation potential of the wastewater used. RESULTS: A control scheme has been developed for biogas desulphurization using oxidation reduction potential under industrial conditions. The redox potential was maintained at about + 50 to + 100 mV in the activated sludge plant to monitor the performance of the nitrification process. The redox potential in the bioscrubber was related to sulphide removal from biogas. More than 90% of the hydrogen sulphide was removed from the biogas. CONCLUSION: The oxidation reduction potential can be used as a key parameter for monitoring and controlling biogas cleaning. Fluctuations of the inlet H₂S concentration in biogas can be compensated by manipulating the flowrates of wastewater used in order to achieve consistent and desired H₂S concentrations in treated biogas. Copyright © 2011 Society of Chemical Industry     

Policy impact analysis of penalty and reward scenarios to promote flowering cover crops using a business simulation game

Due to an increasing number of biogas plants and the positive qualities of maize as a biogas substrate, the cultivation of silage maize has risen in Germany. However, there are still various reasons for the limitation of the cultivation area of silage maize. Hence, policymakers are currently discussing various alternative biogas substrates and ways to promote their cultivation. One possible alternative is the use of special flowering cover crops with additional ecological benefits. Using a business simulation game conducted with farmers, the present study investigates whether the implementation of a reward and penalty policy will improve the uptake of flowering cover crops in the production programs of farmers. The results indicate that the implementation of these policy measures was followed by a significant increase in the cultivation area of flowering cover crops. The penalty policy leads to a stronger increase in the size of the cultivation area of flowering cover crops than the reward policy, even though the policies have the same income effect for farmers. Furthermore, the results reveal that the cultivation of flowering cover crops is influenced by various socio-demographic variables.     

The PCDD/PCDF Dioxin Releases in the Climate of Environment of Jordan in the Period （2000-2008）

Many environment problems of the full using of several categories of processing include mining, heat generators, direct combustion of forest fires, cement production, power plant, transport, medical waste. Dioxin/furan releases from these categories are one of these environment problems. Possible lines of reducing the PCDD/ PCDF （Polychlorinated dibenzo-para-dioxins/Polychlorinated dibenzofurans） releases from these categories are eluci- dated. The contribution of this paper is present the identification and estimation of the latest figure of dioxin/furan releases in the climate of environment of Jordan in the period 2000-2008 from the following categories （cement, aluminum, ceramic, medical waste, power plant, land fill, ferrous and non- ferrous metals, uncontrolled combustion process （biomass burning, waste burning, accidental fires in house, transport）. These finding shows the sign of growth of estimated PCDD/PCDF releases from categories which did not calculated and followed after 2003. The result shows the highest PCDD/PCDF release from landfill fires （62.75 g TEQ/year）, medical waste （8.8264 g TEQ/year）, and transport （3.0145 g TEQ/year）. Jordan seeks by next years, a reduction in total releases of dioxins and furans from sources resulting from human activity. This challenge will apply to the aggregate of releases to the air nationwide and of releases to the water within the Jordan area. Jordan should conduct air monitoring for dioxin in order to track fluctuations in atmospheric deposition levels.     

Effect of reformed biogas as a low reactivity fuel on performance and emissions of a RCCI engine with reformed biogas/diesel dual-fuel combustion

Biogas can be used as a less expensive continuance renewable fuel in internal combustion engines. However, variety in raw materials and process of biogas production results in different components and percentages of various elements, including methane. These differences make it difficult to control the combustion, effectively, in internal combustion engines. In this research, under cleaning and reforming process, biogas components were fixed. Then the effect of reformed biogas (R.BG) was investigated, numerically, on the combustion behavior, performance and emissions characteristics of a RCCI engine. A 3D-computational modeling has been performed to validate a single-cylinder compression ignition engine in conventional diesel and dual-fuel operations at 9 bar IMEP, 1300 rpm. Then, the combustion model of the RCCI engine was simulated by replacing diesel fuel with 20%, 40% and 60% of R.BG as a low reactivity fuel while remaining constant input total fuel energy per cycle. The results demonstrated that when the R.BG substitution ratio increases with a constant equivalence ratio of 0.43, the mean combustion temperature decreases to 1354 K, 1312 K, 1292 K which are about 3.5%, 6.6%, 7.9% lower than the conventional diesel combustion, respectively. The maximum in-cylinder pressure increases up to 22.63%. Instead, it results in 2.3%, 7.9%, and 14.5% engine power output losses, respectively. Also, the NOx emission, against CO, is decreased by 50%. Soot and UHC emissions were found to be slightly decreased while was used R.BG more than 40%.