Chlorella pyrenoidosa is a unicellular green alga that grows in fresh water. C. pyrenoidosa contains much more protein and chlorophyll than other plants. Spirulina, like any blue-green algae, can be contaminated with toxic substances called microcystins. It can also absorb heavy metals from the water where it is grown . Chlamydomonas is the algae from genus of microscopic, unicellular green plants (algae) which live in fresh water. It has been found that they can be used to generate hydrogen from light, water, and basic nutrients. The possibility of generating large quantities of hydrogen, which is a renewable fuel, from cheap and abundant sources is produced by Chlamydomonas .A critical growth‐limiting factor is the carbon, usually supplied as CO 2 that occurs in enriched environments.
This section presents a model for the MEC in a fed-batch reactor, which is a modified model from Pinto et al. (2010). The mathematical models presented here aim to simulate the competition of microbial in the MEC. The model represents competition between anodophilic, acetoclastic methanogenic and hydrogenotrophic methanogenic microorganisms for the substrate (Pinto et al., 2011). The dynamic mass balance equations in the reactor system are given below as follows:
develop a large-scale, economically attractive way  . Bio-hydrogenproduction is a complex, multiphase biological, chemical and physical process with many internal interactions between gas, liquid and solid phases. Present researches on bio-hydrogenproduction have focused on the chemical and biological aspects which affect the efficiency of hydrogenproduction. While, the physical characteristics such as reactor configuration and hydrodynamics have received very little attention  . Light supply, biomass concentration, mixing pattern, cell shear, temperature control and mass transfer rate all influence the photo-bioreactor performance  . However, few studies elucidated the heat transfer in the process of bio-hydrogenproduction [12-15] .
comparable to the 0.24s (at the optimal condition) used by Bimbela et al. , therefore ensuring that the catalytic reforming took place completely. Bio-oil was fed continuously into the reactor at a mass flow rate of 0.3g min -1 . High-purity nitrogen was supplied as carrier gas at 150 ml min -1 . A thin layer of quartz wool was placed on a mesh support in the middle of the catalytic stage to hold the catalyst particles. 0.5g of catalyst was loaded evenly between two layers of quartz wool. After pyrolysis and catalytic reforming, the gas product was passed through a two-stage ice-water condenser for condensable vapors condensing. The non-condensable gas was periodically sampled and analyzed on-line, while liquid in the condenser was collected for further analysis. Experiments were repeated twice to ensure the reliability of the results. Blank experiments were carried out with quartz sand as a control experiment.
Anaerobic fermentation decreases the total mass of waste, makes solid or liquid fertilizer, and yields energy. In the first step of hydrolysis, or liquefaction, fermentative bacteria change the insoluble complex organic matter, such as cellulose, into soluble molecules, such as sugars, amino acids, and fatty acids. The complex polymeric matter is hydrolyzed to monomers. For example, hydrolytic enzymes buried by microbes transform cellulose into sugars, or alcohols and proteins into peptides or amino acids. The hydrolytic action is importance waste has high organic content that might develop rate limiting. Some industrial operations overcome this limitation by using chemical reagents to improve the hydrolysis process. The use of chemicals to increase the first stage has been found to shorten digestion time and increase methane yields [Molino et al., 2012]. 2.3.2. Four important steps in this process
catalysis seems to be a good pretreatment of WAS for enhancing its biodegradability by accelerating the hydrolysis of specific macromolecular components such as proteins . Iraq uses unfavorable sources of fuel in gas turbine engines as a heavy fuel oil which is produced from refinery columns because of long years of suffering from the insufficient electricity production. The use of these fuels decreases the efficiency of gas turbine around 60-70%. But the use of biogas as a fuel of gas turbine increases the efficiency of engines, in addition, it can decrease the mass of pollutants produced from waste water treatment, and greenhouse gases. This study mainly focused on investigating the effected strategy to increase the biohydrogen production from effected microorganisms in WAS by loaded to DFPBR, and the effect of photo-catalysis (TiO 2 ) nano-particle as a photo-catalyst on the
A conventional fixed bed reaction apparatus is used to evaluate the steam reforming of bio-ethanol over nickel-based catalysts. The reaction apparatus consists of a flow system, the reactor unit and the analysis system. Steam reforming of bio-ethanol is carried out for the reactor operated isothermally. All experiments have been performed under atmospheric pressure. This acquisition system allows obtaining detailed information of the catalytic process since all reaction parameters are measured and controlled in real time. The reactor is made with a Pyrex glass tube of 8.0 mm inner diameter, and it is placed into an electric oven. The flow system is equipped with a set of mass-flow controllers (MFCs), which accurately control the flow of the inlet gases, and a set of valves which allow selection of gas feed composition and introduction of the gas mixture to the reactor or to a by-pass stream. A high pressure pump is used for feeding the liquid reagents. Bio-ethanol and water are fed by means of a carrier nitrogen stream flowing through a saturator. Bio-ethanol would react with steam over the catalyst to produce a mixture of hydrogen and other compounds, such as hydrogen, carbon monoxide, carbon dioxide, methane, ethylene, and acetaldehyde. In some experiments, acetaldehyde or ethylene are used as a reactant, instead of bio-ethanol, and oxygen is added together with nitrogen. The water-to-ethanol molar ratio is controlled by adjusting both the saturator temperature and the input nitrogen flow rate. Carbon monoxide is poisonous to the noble-metal catalysts, and thus the formation of carbon monoxide is typically reduced by performing the reaction in excess steam. The reaction temperature is measured with a sliding thermocouple placed inside the catalyst bed. Heating of the reactor is provided by an electric furnace, controlled by a proportional-integral-derivative (PID) temperature controller, which is connected with a thermocouple placed in the middle of the furnace. A pressure indicator is used to measure the pressure drop in the catalyst bed.
Abstract—During the past decade, major studies have identified hydrogen as the safest fuel and its demand has been on the rise ever since. This paper looks into the different biological methods of hydrogenproduction and the economics involved in-order to identify the most economical and environment friendly method of biohydrogen production. A detailed study has been conducted regarding the methods of production, the types of reactors and raw-materials required. The cost requirement of each of the aspects involved in the processes have been looked into. The study proves the Direct Biophotolysis method to be the least favourable in-terms of land requirement and costs and Indirect Biophotolysis and Photofermentation to be amongst the better options available.
A partially broader bio-economy concept appears in the European Commission Com- munication of February 2012 on the «Bio-economy for Europe» and especially in the related Staff Working Document (2012d), which incorporates views from the public con- sultation and the expert impact assessment. The latter document mentions that the bio- economy strategy will support ecosystem-based management and that it will seek syner- gies with the Common Agriculture Policy (CAP) Common Fisheries Policy (CFP), Inte- grated Maritime Policy (IMP), the Water Framework Directive (WFD) and the Marine Strategy Framework Directive (MSFD). Mentioned also are the EU environmental policies on resource efficiency, sustainable use of natural resources, protection of biodiversity and habitats and provision of ecosystem services. However the full potential of an integrated bio-economy needs to be developed more through linkages with public goods and a more prominent role for farmers.
the increase of the mass ratio of DME and steam. The energy efficiency of hydrogenproduction system using reactor as heat source and hydrogenproduction system using engine exhaust gas as heat source is compared, and energy efficiency of using reactor as heat source (57.96117%, 63.89651%, 69.0002%) is higher than that using engine exhaust gas as heat source (54.4913%, 60.11311%, 66.25342%).
Bioreactors for cyanobacterial hydrogenproduction Bioreactors are essential for large-scale production of hydrogen. Since light is an essential parameter for cyano- bacterial growth so all such bioreactors must be transpar- ent and hence are called photobioreactors [41,55]. All photobioreactors require adequate entry of light, which usually is sunlight but in some photobioreactors other artificial sources of light is also used for providing control- led light. Inside photobioreactor there should be a photic zone, close to the illuminated surface and a dark zone, fur- ther away from this surface. The dark zone is due to light absorption by the cells and mutual shading. The hydrogen productivity of a photobioreactor is light limited and tends to decrease at higher light intensities (Photosynthe- sis diverts the hydrogenproduction pathway) hence the light regime is determined by the light gradient (must be diluted and distributed as much as possible; absolute dark condition responsible for highest production). Liquid cir- culation time or aeration (hydrogen producing enzymes are oxygen susceptible; anaerobic condition or inert gas environment is preferred) rate has something to do with hydrogen productivity. It has followed that cyanobacteria absorb preferentially red light around 680 nm. To fulfill this demand Red light panels are constructed in special- ized bioreactors to provide red light to the culture systems. As a result of mixing, cells will circulate between the light and the dark zone of the reactor at a certain frequency and regular intervals, which is dependent on reactor design and gas input. The position of the light source as well as gas liquid hydrodynamics also affects cyanobacterial growth as well as hydrogenproduction .
In order to drive the electrochemical reactions, the solution temperature was set at 55 o C, followed by applying 0.900 V across the stack using a DC power supply (TDK-Lambda, GENH6- 100). As a result, water reduction at the cathode side produced hydrogen gas and ammonia oxidation at the anode side produced nitrogen gas. A lab-view® based program was used to record the data from the power supply. The ammonia concentrations in KOH were measured in the beginning and end of each electrolysis cycle.
the biomass structure, after which pressure is released causing water to explode. This procedure opens the plant cells and increases the biomass surface area leading to biomass digestibility enhancement [Ballesteros et al., 2000; Monlau et al., 2013b]. The problem with steam explosion is the incomplete disruption of the lignin-carbohydrate matrix [Kumar et al., 2009]. Chemical methods such as acid and alkaline pretreatments are used efficiently for breaking ether and ester bonds in lignin/phenolics-carbohydrates complexes. Acid pretreatment is used to convert glucan in the biomass into glucose with a conversion efficiency that can reach 90% [Monlau et al., 2013a]. Acid pretreatment is the most commonly used method for treating substrates of fermentation processes and is considered the most efficient and easiest method for releasing simple sugars [Mosier et al., 2005]. However, acid pretreatment can produce inhibitory compounds and fermentation can be inhibited by acid residues [Nissila et al., 2014]. In addition, acid recovery and hydrolysates neutralization are sometimes required after pretreatment [Akobi, 2016]. Pan et al.  investigated the effect of acid pretreatment of wheat bran on H 2 production. Soluble saccharides contents in the acid pretreated biomass increased
Several valuable products are generated through the development of renewable means utilizing biomass. Acidogenic fermentation is one of the processes that use acidogens to convert organic matter to volatile fatty acids (VFAs). VFAs are very essential substrates for diverse applications, including, the biological removal of nutrients (nitrogen and phosphorus) from wastewater (Zheng et al., 2010), biofuels (Uyar et al., 2009; Choi et al., 2011), and the manufacturing of biodegradable plastics (Mengmeng et al., 2009). The commercial production of VFAs is generally through chemical processes that usually require high amounts of raw materials as non-renewable petrochemicals. Acidogenic fermentation can relatively enhance the recycling of organics and at the same time produce VFAs. Among the VFAs, acetate, and propionate have been observed to be the most essential substrates that buttress enhanced biological phosphorus removal (EBPR)(Randall et al., 2003; Gerber et al., 1986; Chen et al., 2004). Mengmeng et al., (2009) reported that 6 – 9 mg of VFAs is required to biologically remove 1 mg of phosphorus. However, in wastewater especially when the influent chemical oxygen demand (COD) is very low, these levels of VFAs are not always available. Moreover, the removal of phosphorus is determined by the available VFAs supply as they are being
When the inhibitors were divided into two equal portions and added in a 24 hour interval, methane production was significantly reduced. Both sets of LA and BES cultures that received two inhibitor additions showed remarkably similar methane production over the duration of the experiment. In fact, there was never more than a 2 µmol/bottle difference at each sampling time interval. The culture sets of LA and BES which received one injection also showed remarkably similar methane production. All the cultures reached peak methane concentrations 12 hours after glucose was injected. The methane concentration was 95 and 50 µmol/bottle after 12 hours for cultures containing 2000 mg/l LA and 1000 mg/l LA + 1000 mg/l LA, respectively. Moreover, the methane concentration was 90 and 50 µmol/bottle after 12 hours for cultures containing 50 mM BES and 25 mM BES + 25 mM BES, respectively. These represent a 45% and 43% decreases in methane production, for LA and BES, respectively; exclusively by splitting the inhibitor injections into two equal amounts separated by 24 hours. No methane was produced during the second glucose injection.
waste. Bio-oil is one of the promising renewable energy where raw materials are sourced from agricultural waste and industrial waste. There are many methods to produce bio-oils such as using fast pyrolisis or hydrothermal liquefaction. Fast pyrolysis is designed to maximize bio-oil yield by the rate of heating used potential. However, there are many issues of bio-oil like high water content in bio-oil affects the value of heating and viscosity, while high acidity causes bio-oil to become highly corrosive and unstable and high oxygen content causes low energy density and insoluble with hydrocarbons. The problems of low quality bio-oil as fuel becomes main issues, but the quality bio-oil can be improved through several efforts, known as upgrading bio-oil. There are several methods to improve the quality of bio-oil to be better including hydro- cracking, supercritical fluids (SCFs), esterification process, and emulsification .
necessary to attest its exergetic viability. The exergetic efficiency and cost of hydrogenproduction are factors that determine the profitability of the hydrogenproduction plant (Madeira et al., 2017a). Many authors have used the exergetic analysis to quantify the technical viability of an energy production process (Orhan et al., 2010; Tsatsaronis et al., 2008; Kalinci et al., 2011). Costs associated to the products generated in a small effluent treatment plant applying the thermoeconomic method based on the functional diagram was obtained by (Lamas et al., 2009). Effluents are considered as a source of energy in the form of heat for the operation of systems that operate as heat pumps, in this sense a review of studies that consider energy, exergic, economic and environmental aspects was developed by (Hepbasli et al., 2014). The aims of this study is the exergetic analysis of each equipment of the plant of production of H 2 by steam reforming
Hydrogen fuel is believed that it will be a promising candidate to lead a new hy- drogen economy. In this review paper, the hydrogenproduction key technolo- gies are reviewed. The hydrogenproduction different technologies from both fossil and non-fossil fuels such as (water electrolysis, biomass, steam reforming, partial oxidation, auto thermal, pyrolysis, and plasma technology) are reviewed. The reforming and gasification technologies are the most mature hydrogenproduction technology. Water electrolysis can be combined with the renewable energy to get eco-friendly technology. Additionally, it is important to produce hydrogen from a wide range of feedstock. Currently, the maximum hydrogen fuel productions are registered from the steam reforming, gasification, and par- tial oxidation technologies using fossil fuels. The hydrogenproduction technol- ogy efficiencies are summarized in Table 13. These technologies still have chal- lenges such as the total energy consumption and carbon emissions to the envi- ronment are too high. Ammonia decomposition using plasma technology with- out and with a catalyst to produce pure hydrogen is considered as a compared
waste with three hydrogen-producing strains viz., Butti- auxella sp. 4, Rahnella sp. 10, and Raoultella sp. 47 using each single strain and mixed three strains together significantly increased the hydrogen yield (HY) and the hydrogenproduction rate (HPR) in comparison to non- bioaugmentation. Bioaugmentation would not only improve the hydrogenproduction process but also can be used to overcome the inhibition occurred in the hydro- gen production process. Goud et al.  reported that the bioaugmentation of native acidogenic microflora with Bacillus subtilis, Pseudomonas stutzeri, and Lysinibacillus fusiformis could increase substrate degradation rate and enhance fermentative hydrogenproduction from real- field food wastewater at elevated organic load. In addi- tion, the bioaugmentation strategies could shorten the digestion time in a bioreactor. For example, Ma et al.  found that the bioaugmentation of the activated sludge with mixed cultures of specialized bacteria consisting of Pseudomonas, Bacillus, Acinetobacter, Flavobacterium, and Micrococcus in a contact oxidation process decreased the chemical oxygen demand (COD) and ammonia nitro- gen (NH 4+ -N) from 320–530 mg/L and 8–25 mg/L to
biohydrogen production from water through the use of cyanobacteria species such as blue green algae, cyanophyceae or cyanophytes (Kapdan and Kargi, 2006). Biological water- gas shift reaction is another method of generating hydrogen from water through the use of photoheterotrophic bacteria, belong to the Rhodospirillaceae family which use carbon monoxide as the carbon source (Ni et al., 2006). The biohydrogen production by Enterobacter aerogenes and Rhodobacter sphaeroides using Calophyllum inophyllum oil cake under dark and photo fermentation conditions was studies by Arumugam et al. (2014). Cyanobacteria and green algae produce both hydrogen and oxygen by light-driven biophotolysis processes involving both nitrogenase and hydrogenase enzymes. The oxygen produced in biophotolysis inactivates the hydrogen producing conditions which leading to lower yields of biohydrogen. Fermentative bacteria can produce hydrogen from organic compounds using hydrogenase throughout the day in dark fermentation process but at lower yields. On the other hand, purple non-sulfur photosynthetic bacteria can decompose organic acids by using light energy and nitrogenase in a photofermentation process. The hybrid system is a combination of dark fermentation by fermentative bacteria followed by photofermentation by purple non-sulfur photosynthetic bacteria, wherein the overall hydrogen yield can be enhanced to a great extent (Basak and Das, 2006). Various species like Rhodospirillum rubrum (Piyawadee et al., 2005), Rhodobium marinum (Anam et al., 2012), Rhodobacter sphaeroides (Pattanamanee et al., 2012; Eroglu et al., 2011), Chlorella vulgaris (Bala Amutha and Murugesan, 2011), Clostridium butyricum (Pattra et al., 2011; Wang et al., 2008), Enterobacter cloacae (Namita et al., 2011; Ghosh et al., 2011), Clostridium saccharoperbutylacetonicum (Shorgani et al., 2013), Bacillus coagulans (Ghosh et al., 2011),