固体废弃物处理与产氢技术

氢气能作为一种清洁能源和工业上的原料所使用。目前国际上氢气的获得主要有化学制取和电解水制取两种方法, 但这些方法都需要耗费大量的能源, 特别是化学制取法在耗能的同时还极易对环境造成污染。相比之下, 生物制氢有着极大的优势, 它主要是通过微生物发酵或者光合微生物的作用, 将有机废弃物进行分解从而获得氢气。利用废弃物制氢即可以低廉的获得氢能源同时又能资源化利用废弃物。以下对固体废弃物的类型、产氢的方法等进行了综述。     

微生物制氢技术研究进展

氢气是一种清洁高效的可再生能源.该文比较分析了常用于氢气制取的方法,讨论了生物制氢的微生物种类以及发酵产氢的诸多影响因素,对目前生物制氢的研究进展进行了综述.     

废水中“淘”出新能源

该项目开发的乙醇型发酵生物制氢技术,实际上是一项生物发酵产氢和高浓度有机废水处理的集成技术,在治理废水污染的同时,制取了大量的清洁能源氢气。从废弃物资源化与综合利用的角度看,该技术符合我国废水循环利用和污染物资源化的迫切需求。     

生物质制氢技术研究进展

氢能以其清洁,来源广泛及用途广等优点成为最有希望的替代能源之一,用可再生能源制氢是氢能发展的必然趋势。由于生物质制氢具有一系列独特的优点,它已成为发展氢经济颇具前景的研究领域之一。生物质制氢技术可以分为两类,一类是以生物质为原料利用热物理化学方法制取氢气,如生物质气化制氢,超临界转化制氢,高温分解制氢等热化学发制氢,以及基于生物质的甲烷、甲醇、乙醇的化学重整转化制氢等;另一类是利用生物转化途径转换制氢,包括直接生物光解,间接生物光解,光发酵,光合异养细菌水气转移反应合成氢气,暗发酵和微生物燃料电池等技术。本文综述了目前主要的生物质制氢技术及其发展概况,并分析了各技术的发展趋势。     

暗发酵-光发酵两阶段联合生物制氢技术研究进展

随着能源紧缺的日益加剧,以及化石燃料燃烧引起的环境问题逐渐突显,氢能作为一种清洁可再生能源越来越受到青睐。生物制氢与热化学及电化学制氢相比其反应条件温和、低耗、绿色,是一项非常有应用前景的技术。生物制氢从广义上可以分为暗发酵和光发酵产氢两种,其中暗发酵微生物可以利用有机废弃物产生氢气以及有机酸等副产物,光合细菌在光照和固氮酶的作用下可以将暗发酵产生的有机酸继续用于产氢,因此两种发酵产氢方式相结合可以提高有机废物的资源化效率。将近年来暗发酵-光发酵两阶段生物制氢技术进行整理分析,从其产氢机理、主要影响因素、暗发酵-光发酵产氢结合方式(两步法、混合培养产氢)几个方面进行阐述,最后指出该技术面临的挑战。     

微藻光生物水解制氢技术

氢气是未来人类社会可持续发展的理想能源。介绍微藻太阳能光生物水解制氢的研究现状,重点讨论微藻光水解制氢的生物学原理。重点讨论微藻光解水制氢的酶学机理、工艺过程以及当前的主要研究方向。通过比较微藻固氮酶制氢、可逆产氢酶直接光水解制氢、可逆产氢酶间接光水解制氢等技术路线的优缺点,指出利用微藻可逆产氢酶两步法间接光水解制氢最具发展潜力,可望为21世纪的“氢能经济社会”提供大量的氢源。该技术成功的关键在于相关的基因工程和代谢调控研究取得重大突破。     

固定化技术在促进光合细菌产氢中的应用

氢气是一种新型的清洁高效能源,制氢技术的创新是目前研究的热点。将新型的技术及材料应用到生物制氢工艺中,从而促进生物制氢技术的产氢效率和工程应用是研究的重点之一。该文阐述了光合细菌在固定化生长条件下发酵产氢的最新研究进展,从固定化技术的原理、固定化方法的应用进展及影响因素几个方面进行了综述,详细阐述了包括包埋、悬浮载体附着生长及固定生物膜法等几种固定化方法对光发酵产氢的作用,介绍了国内外用于固定化的新型材料,并对今后的研究重点及方向进行了展望。     

不同预处理条件对海水养殖废弃物发酵产氢的影响

【目的】利用海水养殖场有机废弃物厌氧发酵产氢,可在减少有机污染物的同时获取氢气。【方法】以海水养殖场有机废弃物为底物,比较嗜热酶(S-TE)、酸、碱、灭菌、微波不同预处理方法对厌氧发酵产氢效果的影响,并对发酵过程中底物性质变化[SCOD、可溶性蛋白质、可溶性糖、pH、VFAs(挥发性脂肪酸)和乙醇]进行探讨。【结果】灭菌预处理产氢效果最好,产氢率为22.0 mL/g VSS,酸处理的效果最差,产氢率为7.6 mL/g VSS。可溶性糖大量消耗之后,氢气不再产生。接种S-TE预处理污泥的底物能更多地释放营养物质,并在整个发酵过程中保持较为稳定的pH值。发酵过程中产生的VFAs主要成分是乙酸,在发酵后期出现乙醇。【结论】灭菌预处理是海水养殖场有机废弃物厌氧发酵产氢的最佳预处理方法,可溶性糖为这一过程主要的营养来源。     

衣藻生物制氢的研究进展

综述了利用衣藻生产氢气作为再生能源的研究进展。分别介绍了衣藻产氢的代谢机理、培养条件、衣藻氢化酶的特性以及利用分子生物学手段、生物信息学手段和生物工程技术提高衣藻生物制氢效率的方法,包括氢化酶的氧耐受性的改造、外源氢化酶基因的表达、影响衣藻产氢的关键基因的筛选、利用缺硫培养基和固定化培养方法提高氢气产量等。最后,还对利用衣藻生物制氢的可行性和经济性进行了分析,对其发展方向提出自己的看法。     

生物产氢研究进展

氢能是一种清洁高效的能源。氢气可以利用工农业废料通过微生物发酵制取 ,是一种可再生燃料。文中介绍了厌氧菌、兼性厌氧菌、好氧菌、光合细菌和蓝细菌等产氢的微生物种类 ,以及它们的产氢机理。从光合细菌利用废料产氢的效率和产氢设备的研究来看 ,无疑具有很大的潜力。以产氢技术作为下一代能源开发创新的技术已引起国际社会的重视 ,具有广阔的市场前景。     

Fermentative hydrogen production from low-value substrates

Hydrogen is a promising energy source that is believed to replace the conventional energy sources e.g. fossil fuels over years. Hydrogen production methods can be divided into conventional production methods which depend mainly on fossil fuels and alternative production methods including electrolysis of water, biophotolysis and fermentation hydrogen production from organic waste materials. Compared to the conventional methods, the alternative hydrogen production methods are less energy intensive and negative-value substrates i.e. waste materials can be used to produce hydrogen. Among the alternative methods, fermentation process including dark and photo-fermentation has gained more attention because these processes are simple, waste materials can be utilized, and high hydrogen yields can be achieved. The fermentation process is affected by several parameters such as type of inoculum, pH, temperature, substrate type and concentration, hydraulic retention time, etc. In order to achieve optimum hydrogen yields and maximum substrate degradation, the operating conditions of the fermentation process must be optimized. In this review, two routes for biohydrogen production as dark and photo-fermentation are discussed. Dark/photo-fermentation technology is a new approach that can be used to increase the hydrogen yield and improve the energy recovery from organic wastes.     

Techno-economic comparison of a biological hydrogen process and a 2nd generation ethanol process using barley straw as feedstock

A process combining dark fermentation and photofermentation for production of hydrogen is interesting due to its potential of producing hydrogen at a high yields. In this study, the hydrogen process is compared to a 2nd generation ethanol process with respect to cost and with the aim of increasing our understanding of the pros and cons and giving a clear picture of the present status of the two processes. The hydrogen production cost was found to be about 20 times higher than the ethanol production cost, 421.7 €/GJ compared to 19.5 €/GJ. The main drawbacks of the hydrogen process are its low productivity, low energy efficiency, and the high cost of buffer and base required to control the pH.     

Hybrid electrosynthesis as non-genetic approach for regulating microbial metabolism towards waste valorization in circular framework

Biogenic waste (solid/liquid/gaseous) utilization in biological processes has disruptive potential of inclining towards carbon neutrality, while producing diverse products output. Anaerobic fermentation (methanogenesis and acidogenesis) routes are crucial bioprocesses for production of various renewable chemicals (carboxylate platform/organic acids, short/medium chain alcohols, aldehydes, biopolymers) and fuels (methane, hydrogen, hythane, biodiesel and electricity), while individual operations posing process limitations on their conversion efficiency. Advantageous benefit of using the individual bioprocess technicalities is of utmost importance in the context of sustainability to conceptualize and execute integrated waste biorefinery. The opinion article intends to document/familiarize the waste-fed biorefinery potential with application of hybrid advancements towards multiple product/energy/renewable chemical spectrum leading to carbon neutrality bioprocesses. Unique and notable challenges with diverse process integrations along with electrochemical/interspecies-redox metabolites-materials synergy/enzymatic interventions are specifically emphasized on application-oriented waste feedstock potential towards achieving sustainability.     

Economic and environmental assessment of automotive plastic waste end-of-life options: Energy recovery versus chemical recycling

Most automotive plastic waste (APW) is landfilled or used in energy recovery as it is unsuitable for high-quality product mechanical recycling. Chemical recycling via pyrolysis offers a pathway toward closing the material loop by handling this heterogeneous waste and providing feedstock for producing virgin plastics. This study compares chemical recycling and energy recovery scenarios for APW regarding climate change impact and cumulative energy demand (CED), assessing potential environmental advantages. In addition, an economic assessment is conducted. In contrast to other studies, the assessments are based on pyrolysis experiments conducted with an actual waste fraction. Mass balances and product composition are reported. The experimental data is combined with literature data for up- and downstream processes for the assessment. Chemical recycling shows a lower net climate change impact (0.57 to 0.64 kg CO₂e/kg waste input) and CED (3.38 to 4.41 MJ/kg waste input) than energy recovery (climate change impact: 1.17 to 1.25 kg CO₂e/kg waste input; CED: 6.94 to 7.97 MJ/kg waste input), while energy recovery performs better economically (net processing cost of −0.05 to −0.02€/kg waste input) compared to chemical recycling (0.05 to 0.08€/kg waste input). However, chemical recycling keeps carbon in the material cycle contributing to a circular economy and reducing the dependence on fossil feedstocks. Therefore, an increasing circularity of APW through chemical recycling shows a conflict between economic and environmental objectives.     

Microbial Production of Hydrogen by Mixed Culture Technologies: A Review

With its high energy content and clean combustion, hydrogen is recognized as a renewable clean energy source with enormous potential. Biological hydrogen production is a promising alternative with significant advantages over conventional petroleum‐derived chemical processes. Sustainable hydrogen production from renewable resources such as cassava, wastewater, and other agricultural waste is economically feasible for industrial applications. So far, the major bottlenecks in large‐scale biological hydrogen production are the low production rate and yield. This review discusses the various factors that affect the metabolic pathways of dark hydrogen production, and highlights the state‐of‐the‐art development of mixed culture technology. The aim of this review is to provide suggestions for the future directions of mixed culture technology, as well as by‐product valorization in dark fermentation.     

Dual purpose microalgae-bacteria-based systems that treat wastewater and produce biodiesel and chemical products within a Biorefinery

Excess greenhouse gas emissions and the concomitant effect on global warming have become significant environmental, social and economic threats. In this context, the development of renewable, carbon-neutral and economically feasible biofuels is a driving force for innovation worldwide. A lot of effort has been put into developing biodiesel from microalgae. However, there are still a number of technological, market and policy barriers that are serious obstacles to the economic feasibility and competitiveness of such biofuels. Conversely, there are also a number of business opportunities if the production of such alternative biofuel becomes part of a larger integrated system following the Biorefinery strategy. In this case, other biofuels and chemical products of high added value are produced, contributing to an overall enhancement of the economic viability of the whole integrated system. Additionally, dual purpose microalgae-bacteria-based systems for treating wastewater and production of biofuels and chemical products significantly contribute to a substantial saving in the overall cost of microalgae biomass production. These types of systems could help to improve the competitiveness of biodiesel production from microalgae, according to some recent Life Cycle Analysis studies. Furthermore, they do not compete for fresh water resources for agricultural purposes and add value to treating the wastewater itself. This work reviews the most recent and relevant information about these types of dual purpose systems. Several aspects related to the treatment of municipal and animal wastewater with simultaneous recovery of microalgae with potential for biodiesel production are discussed. The use of pre-treated waste or anaerobic effluents from digested waste as nutrient additives for weak wastewater is reviewed. Isolation and screening of microalgae/cyanobacteria or their consortia from various wastewater streams, and studies related to population dynamics in mixed cultures, are highlighted as very relevant fields of research. The species selection may depend on various factors, such as the biomass and lipid productivity of each strain, the characteristics of the wastewater, the original habitat of the strain and the climatic conditions in the treatment plant, among others. Some alternative technologies aimed at harvesting biomass at a low cost, such as cell immobilization, biofilm formation, flocculation and bio-flocculation, are also reviewed. Finally, a Biorefinery design is presented that integrates the treatment of municipal wastewater with the recovery of oleaginous microalgae, together with the use of seawater supplemented with anaerobically digested piggery waste for cultivating Arthrospira (Spirulina) and producing biogas, biodiesel, hydrogen and other high added value products. Such strategies offer new opportunities for the cost-effective and competitive production of biofuels along with valuable non-fuel products.     

生物制氢——能源、资源、环境与经济可持续发展策略

人类面临能源危机、资源短缺、环境污染的严峻挑战,开发新的能源,合理利用资源并保护生态环境势在必行。氢能具有清洁、高效、可再生的特点,是未来重要的新能源物质。生物制氢技术利用可再生资源,特别是可利用工农业有机废弃物产氢,效率高,能耗低,污染少,成本低,具有巨大的发展潜力。本文简要阐述生物制氢技术及其发展状况,提出我国发展生物制氢技术,实现能源、资源、环境与经济可持续发展的政策建议。     

Roles of microorganisms other than Clostridium and Enterobacter in anaerobic fermentative biohydrogen production systems--a review

Anaerobic fermentative biohydrogen production, the conversion of organic substances especially from organic wastes to hydrogen gas, has become a viable and promising means of producing sustainable energy. Successful biological hydrogen production depends on the overall performance (results of interactions) of bacterial communities, i.e., mixed cultures in reactors. Mixed cultures might provide useful combinations of metabolic pathways for the processing of complex waste material ingredients, thereby supporting the more efficient decomposition and hydrogenation of biomass than pure bacteria species would. Therefore, understanding the relationships between variations in microbial composition and hydrogen production efficiency is the first step in constructing more efficient hydrogen-producing consortia, especially when complex and non-sterilized organic wastes are used as feeding substrates. In this review, we describe recent discoveries on bacterial community composition obtained from dark fermentation biohydrogen production systems, with emphasis on the possible roles of microorganisms that co-exist with common hydrogen producers.