Equipment for tempering the substrate

For continuous processing the heating method is important. The heat requirement results on the one hand from the volume flow of the substrate, its specific heat capacity and the temperature difference between the substrate and the processing temperature. On the other hand, heat requirements result from heat losses at the bioreactor surface. In Table 1.5, the energy consumption of a mesophilic bioreactor is shown as an example. The smaller the biomass concentration in the substrate the lower is...

Adsorption with pressure swing technology VPSA under vacuum

Vacuum pressure swing adsorption plants Figure 3.6' work in principle like the pressure swing adsorption plants and use the same adsorbents. The special economy of the VPSA technology is derived from the lower operating pressure. The biogas is only slightly compressed lt 1 bar' by a ventilator and does not need to be pretreated or precleaned. Thus, the difficult oil and water separation is avoided. The pressure swing is achieved with a vacuum pump. The substantial advantage of these plants is...

Combined fermentation of sewage sludge and bio waste

Sludge Load

Experience92' on the combined fermentation of sewage sludge and bio waste has been obtained in a plant in Germany Figure 5.1 .93' The daily throughputs per inhabitant of processed waste water and bio waste are listed in Table 5.1. The bio waste from different origins is collected separately and dumped together into a flat hopper from where a wheel loader transports it to a screw mill, from where it is then transported to the liquid preparation stage, consisting of two steps dissolving the...

Reinforced concrete tanks

How Will Field Concrete Tanks

The reinforced concrete must be free of cracks and resistant under the special conditions during fermentation over the entire period of utilization. With reinforced concrete, the acidic substrate can penetrate to the reinforcement and corrode it if carbon dioxide-containing air also permeates to the Figure 1.1 Reinforced concrete in Europe top left , Heating and agitation devices inside a vertical bioreactor top right , Construction of a basin middle left , Uncovered basin middle right , Thoeni...

Low pressure biogasholder

Biogasholder

Most i.e. 80 of the installed biogasholders are of the low-pressure type. Many consist of a biogas bag of plastic foil. Others are constructed of steel. Biogas from Waste and Renewable Resources. An Introduction. Dieter Deublein and Angelika Steinhauser Copyright 2008 WILEY-VCH Verlag GmbH amp Co. KGaA, Weinheim ISBN 978-3-527-31841-4 Bioreactor cover or biogas bag of foil The plastic foils used are manufactured from plastics resistant to UV, weather, fungus, microbes, and biogas, e.g.,...

Landfill for residual waste

Until the 1990s, residual waste i.e. household waste was discarded on landfills, by default. Biological components of the waste were degraded quite slowly and the fermentation process took about 20-40 years. The landfill gas produced during the process was gathered by using horizontal drainages and gas pits for disposal. About 12-300m3 oflandfill gas was produced in total per Mg ofresidual waste, but it contained quite a high level of toxic and corrosive organic components, so that damage to...

Acidogenic genera

Nearly all acidogenic microorganisms also participate in hydrolysis. The genera Clostridium, Paenibacillus and Ruminococcus appear in all phases of the fermentation process but are dominant in the acidogenic phase. The cluster Cytophaga - Flavobacterium - Bacteroides is the second largest group of microorganisms during the first two phases of decomposition, but represents in the methanogenic phase less than 5 of all microorganisms. This is an indication that species of these groups are mainly...

Utilization of biogas for the generation of electric power and heat

Biogas can be used either for the production of heat only or for the generation of electric power. When current is obtained, normally heat is produced in parallel. Such power generators are called combined heat and power generation plants CHP and are normally furnished with a four-stroke engine or a Diesel engine. A Stirling engine or gas turbine, a micro gas turbine, high- and low-temperature fuel cells, or a combination of a high-temperature fuel cell with a gas turbine are alternatives....

Process engineering and equipment construction

Flowsheet Biogas

Figure 4.41 shows the flow sheet ofa biogas plant for bio waste. The biomass is continuously dehydrated by centrifuges applied during the hydrolysis stage. In this process the liquid phase is transferred into the methane reactor while the solid phase is recirculated for continuous hydrolysis. A series arrangement of several tanks allows the use of cultures of special bacteria and optimization of the degradation of organic substances. Usually about 40-50 of the organic substances dissolve easily...

General aspects of the recovery of biomass in the future

In developed countries it is difficult for an agriculturist to decide how to best use his land. If the object is to use the land in the best ecological way possible, a slow downcycling of the biomass will be recommended in the first place. The agriculturist should decide to do silviculture. For example, wood can be used to build houses. After the house has been deconstructed, the quality of the wood is still good enough to serve as material for wardrobes or rail tracks and then to make boxes or...

Bio waste plants

In Germany, 70 of the biogas plants for bio waste, operate based on wet fermentation with suspension of the wastes, while in 30 of the plants, stacked waste is leached by means of percolation. Most plants work in batch mode Table 5.2 . In all current processes, the bio waste is first accepted and then pretreated and subjected to a single-phase or multi-stage bioreactor plant. The biogas is utilized for power generation and the fermentation residue aerobically decomposed, while waste water is...

Index

ABBR see anaerobic baffled reactors absorbents, based on glycol and - carbon dioxide removal 345-348 - ferric chelate solution 340 access door 252 acetate, methane formation 99 acetic acid - inhibition 122 acetobacter 129 acetogenic bacteria 134-135 acetogenic phase 96-97 acid detergent fiber ADF 213 acid detergent lignin ADL 213 acid value, of the feed and discharge 216 acoustic processes, for degradation 232 - long-chain hydrocarbon compounds 53 - sodium alginate 344 ADF see acid detergent...

Plant installations

Schwarting Uhde Process

Contact Process CP Figure 4.36 In the contact process, the bioreactor, a degassing device, and a clarifier with biomass recycling are combined. This process is characterized by a low volume load and a residence time of 0.5-5 days. The procedure can be used for waste water with high concentrations of suspended solids up to 40 without risk of clogging. Clarification of the overflow could be difficult, because the biomass washed out does not have good sedimentation properties. The contact process...

Generation of electricity in a micro gas turbine

Biogas Gas Turbine

Micro gas turbines are small high-speed gas turbines with low combustion chamber pressures and temperatures. They are designed to deliver up to ca. 200 kWei electrical power. Nearly all micro gas turbine manufacturers offer turbines of radial design with combustion air compressor, combustion chamber, generator, and heat exchanger Figure 5.13 . Micro gas turbines are characterized by a single shaft on which the compressor, the turbine, and the generator are fixed. The turbine propels the...

Parameter cultivation mixing and volume load

The start-up phase ofan anaerobic plant often lasts 2-4 months Figure 2.17 . The start-up of the plant usually has a long-term effect on the biocenosis. The start up even can fail completely i.e., the bioreaction does not work and biogas is not produced. To avoid these problems, the hydrolyzer and the methane reactor 15 Degree of disintegration As decrease in relative to the BOD of untreated sewage BOD due to breakdown of microorganisms sludge are often inoculated with anaerobic sludge from...

Ammonium NH and ammonia NH

Www Anastrip Net

Ammonia and ammonium result from the anaerobic biological degradation of nitrogen compounds. Ammonia forms ammonium ions in the substrate, the extent of this depending on the pH value. Ammonia has an inhibiting effect, and with larger concentrations can even be toxic, while ammonium is innocuous. It can only have an inhibiting effect at concentrations NH4 -N gt 1500 mgMg-1, where its inhibiting effect is predominantly due to the species whose concentration depends on the pH value. Ammonium...

Acidogenic phase

Isovaleric Degradation

The monomers formed in the hydrolytic phase are taken up by different facultative and obligatorily anaerobic bacteria and are degraded in the second, the acidogenic phase, to short-chain organic acids, C1-C5 molecules e.g., butyric acid, propionic acid, acetate, acetic acid , alcohols, hydrogen, and carbon dioxide. The concentra- tion of the intermediately formed hydrogen ions affects the kind of the products of fermentation. The higher the partial pressure of the hydrogen, the fewer reduced...

Generation of electricity in a fourstroke gas engine and a Diesel engine

Disgin Engine Piston

Today's four-stroke biogas engines were originally developed for natural gas and are therefore well adapted to the special features of biogas. Their electrical efficiency normally does not exceed 34-40 , as the nitrogen oxide output NOx has to be kept below the prescribed values. There are, for example, four-stroke engines with electrical offi-ciencies above 40 working with a recuperator Figure 5.5 . The capacity of the engines ranges between 100KW and 1MW and the lifetime is given as ca. 60...

Utilized biomass

The German law of bio waste regulates the circulation of bio wastes in agriculture, in forestry, and in horticulturally used ground Table 1.2 . Bio waste recycling includes all plants which ferment biological waste, even if the fermented substances are only partly of biological origin. The residue is called bio waste and is the subject of the bio waste regulations. Bio waste is, for example, the content of the grease removal tank in catering establishments, mash from Table 1.2 Restrictions when...

Generation of electricity in a fuel cell

Solid Waste Generation Flow Chart

Compared to combustion engines, the fuel cell converts the chemical energy of hydrogen and oxygen directly to current and heat. Water is formed as the reaction product Figure 5.8 . In principle, a fuel cell works with a liquid or solid electrolyte held between two porous electrodes - anode and cathode Figure 5.9 . The electrolyte lets pass only ions and no free electrons from the anode to the cathode side. The electrolyte is thus electrically non-conductive. It separates the reaction partners...

History and status to date in Europe

Biogas Reusch

Very old sources indicate that using wastewater and so-called renewable resources for the energy supply is not new, but was already known before the birth of Christ. Even around 3000 BC the Sumerians practiced the anaerobic cleansing of waste. The Roman scholar Pliny described around 50 BC some glimmering lights appearing underneath the surface of swamps. In 1776 Alessandro Volta personally collected gas from the Lake Como to examine it. His findings showed that the formation of the gas depends...

Methanotropic species

Methanomicrobium Paynteri

Methanotropic species methane-consuming microorganisms Figure 3.4 are everywhere. They are undesired in biogas plants, but very importend for our climate. Most of them are aerobics. They use oxygen to split methane and to get their energy. The metabolic products are water and carbon dioxide. M. Defluvii M. Oryzae M. Thermoflexum Mbr. Arboriphilus Mbr. Ruminantium dominant type in stomachs of cattle Mbr. Smithii sewage-sludge and mammalian colons j Mbr. Curvatus Mbr. Cuticularis Mbr. Filifomiis...

Benefits of a biogas plant

Like natural gas, biogas has a wide variety of uses, but, as it is derived from biomass, it is a renewable energy source. There are many other benefits to be derived from the process of converting substrates in a biogas plant. The economic pressure on conventional agricultural products always continues to rise. Many farmers are forced to give up their occupation, since their land no longer brings sufficient yield. However, the production of biogas is subsidized in many countries, giving the...

Valorga process Figure

The Valorga process was specifically developed for the treatment of communal bio waste, food waste, and sewage sludge. The process is based on dry anaerobic fermentation with a DM content of 25-35 . The fermentation process - starting with hydrolysis and up to methanation -takes place under anaerobic conditions in only one vertical cylindrical bioreactor. Preparation Preparation Because of the vertical arrangement of the bioreactor, the fermentation residues can be discharged by gravity without...

Biochemical reaction

The formation of methane1' from biomass follows in general the equation CcHhO0NnSs y H2O x CH4 n NH3 s H2S c - x CO x 1 8- 4c h - 20 - 3n - 2s y 1 4- 4c - h - 20 3n 3s The products include, for example, the following Carbohydrates C6H12O6 3CO2 3CH4 Fats C12H24O6 3H2O 4.5CO2 7.5CH4 Proteins C13H25O7N3S 6H2O 6.5CO2 6.5CH4 3NH3 H2S Because the sulfur remains in the residue and part of the CO2 binds to NH3, the result in general is a biogas composition of The ratio of CO2 to CH4 is determined by...

B br Brs X

Uasb Reactor

The sludge age d is calculated from VR, X, the volumetric flow of excess sludge Vs, m3 d and the biomass concentration in the excess sludge cS kgCOD m3 . Table 4.18 summarizes all available findings for sludge- bed reactors with pellet-ized and flocculated sludge. For only slightly contaminated sewage COD value lt 1000 mg L-1, gt 25 C , the required reactor volume is derived from the required residence time. The surface load wet surface of the separators can also be decisive for the calculation...

Biological desulfurization

H2s Biogas

Biological desulfurization is mostly applied for the reduction of the H2S content. The process is effective at concentrations up to 3000 mg Nm-3.14 ,15 In the biological desulfurization process, the hydrogen sulfide is absorbed in water and then decreased biologically. Microorganisms of the species Thiobacillus and Sulfolobus, which are omnipresent and therefore do not have to be inoculated especially, degrade the hydrogen sulfide. Table 3.2 Decision-making aid for the selection of procedures...

Agitators Figure

Paddelgigant

Mixing by filling in of new substrate, by thermal convection flow, and by raising of gas bubbles is mostly not sufficient for agricultural biogas plants. Only small plants can be operated without agitators. The mixing operation is done mechanically by devices moving in the bioreactor, hydraulically by pumps located outside of the tank, or pneumatically either by pumping in biogas or by using the autonomously generated gas- pressure for pump work, potentially with two-component nozzles Table 4.4...

Energy supply in the future scenarios

Shell International4' has published a projection for different energy sources for the years 1990 up to 2100 Figure 2.1 . Assuming the Sustainable Growth scenario, energy consumption will increase by 7 times at most during this period. Applying the Dematerialization scenario much lower consumption driven by sustained economic use , the amount of energy will increase by a factor of 3 at least . Both scenarios can be explained and are driven by the assumptions of an increase in population from...

Residues

In most biogas plants the retention time of the biomass is ca. 20 days in the anaerobic reactor. As mentioned above, only part of the organic matter is degraded within this time. A certain amount of residue remains Table 1.1 . This residue contains more or less water depending on the applied technology. Residues from a wet thermophilic fermentation have a higher water content than those from mesophilic or dry processes. Before the residue can be distributed as valuable fertilizer on...