Bio Gas

Biogas

Photo. Biogas plant

Biogas is very similar to natural gas by properties .

Synonyms for biogas are such words as methane, sewage

gas, marsh gas. Biogas caloric value if from 6000 to 9500

ccal/m3.

Biogas is gas with 50-70% of methane (CH4) and 50-30% of

carbon dioxide (CO2) content. It is produced while

anaerobic decomposition of organic matter and as is a

product of bacteria metabolism. Anaerobic digestion -

the process of organic matter decomposition

Biogas can be

burned in boilers as natural gas;

burned with the purpose of electric and heat power production;

after its treatment up to methane it can be used as fuel for vehicles or fed into the grid like

natural gas.

Substrate Biogas yield m3/t

Cattle manure (natural, 85-88% wet) 60

Pig manure (natural, 85% wet) 65

Chicken dung 80-140

Corn s i lage 180-220

Fresh grass 250

Mi lk whey 50

Gra in 550

Frui t pulp (80% wet) 70

Sugar beet pulp (77% wet) 100

Molasses 430

Sugar beet tops 200

Dis tillery gra in (93% wet) 45

Dis tillery molasses wastewater 50

Brewer’s spent grains (80% wet) 110

Fat 1300

Fat from grease trap 250

Slaughter house waste 300

Root crop vegetables 100

Technical glycerin 500

Fish processing wastes 300

Biogas technology:

Four steps of fermentation

Scheme 1. Metabolism products of the anaerobic fermentation in biogas technology process

Bacteria decompose the organic matter in anaerobic environment. Biogas is an intermediate

product of their metabolism.

The decomposition process can be divided into 4 steps (see scheme 1) each of those accompanied

by different bacteria groups:

In the first stage aerobic bacteria reconstructs high-molecular substances (protein,

carbohydrates, fats, cellulose) by means of enzymes to low-molecular compounds like

monosaccharide, amino acids, fatty acids and water. Enzymes assigned by hydrolysis bacteria

decompose substrate components to small water-soluble molecules. Polymers turn into monomers

(separate molecules). This process called hydrolysis.

Then decomposition is made by acid-forming bacteria. Separate molecules penetrate into

bacteria cells where further transformation takes place. This process is partially accompanied

by anaerobic bacteria that consume rest of oxygen hence providing suitable anaerobic environment

for methane bacteria.

This step produces:

acids (acetic acid, formic acid, butyric acid, propionic acid, caproic acid, lactic acid),

alcohols and ketones (methanol, ethanol, propanol, butanol, glycerin and acetone),

gases (carbon dioxide, carbon, hydrogen sulfide and ammonia).

The step is called oxidation.

Afterwards acid-forming bacteria form initial products for methane formation: acetic acid,

carbon dioxide and hydrogen). These products are formed from organic acids. For vital

functions of these bacteria that consume hydrogen, stable temperature mode is very important.

The last step is methane, carbon dioxide and water formation. 90% of methane yield takes

place at this stage, 70% from acetic acid. Thus acetic acid formation (3rd step) is the factor that

defines the speed of methane formation .

One and two stages biogas technology process

Scheme 2. One and two stages biogas technology process.

In most cases such processes take place simultaneously it means that there is no boundaries for

place and duration of decomposition. Such technology is called two stages technology. For

fermentation of rapidly decomposable raw materials in pure state two stage technology required.

For example chicken dung, distillery slop shouldn’t be recycled in one digester. In order to process

those substrates hydrolysis reactor is needed. Such reactor allows control over the acidity and

alkalinity level in order to avoid bacteria collapse and increase methane yield. (Scheme 2.)

For successful lifecycle of all microorganisms inside the digester special conditions must be secured.

Mandatory factors for that are the following:

Anaerobic environment - active functioning of bacteria is possible only in oxygen-free conditions.

Biogas plant design takes that into consideration.

Humidity - bacteria can live, feed and propagate only in moist conditions.

Temperature - the optimum temperature for mode for all bacteria groups is 35-40о С range. Human

is not able to control this, that is why it is done by automatic control system.

Fermentation period - The quantity of produced biogas is different within the fermentation period.

In the beginning of fermentation it is more intensive then at the en of it. Then comes the moment

when further biomass presence in the digester is economically unfeasible. Our specialists rest upon

long-term experience while calculating fermentation period efficiency.

рН level - hydrolysis and oxidation bacteria can live in acid environment with pH level 4.5-6.3 while

methane and acetic acid formation bacteria can exist only in low alkalinity environment with pH 6.8-

8. All the bacteria kinds have tendency to suspend their activity in case pH level is higher of the

optimum hence the biogas production suspends as well. That is why the best pH level 7 should be

maintained.

Even substrate feed - the by-products of each group of bacteria lifecycle are the nutrients for other

bacteria group. The all work with different speed. The bacteria should not be overfeed as they

hardly be able to produce nutrients for another group. That is why the substrate feed is calculated

and programmed for each project carefully.

Nutrients supply - bacteria provided with all necessary nutrients that are contained in substrate so

the only thing is needed is constant substrate supply. Substrate contains vitamins, soluble ammonia

compounds, microelements and heavy metals in small quantities. Nickel, cobalt, molybdenum,

wolfram and ferrum are required by bacteria for enzyme formation and are also present in

substrates.

Particle size - The smaller the better rule is working here. Bacteria size 1/1000 mm the smaller the

substrate particles the easier the decomposition made by bacteria. Fermentation period becomes

shorter and biogas production faster. If necessary additional substrate disintegration should be done

before substrate feed into reactor.

Mixing - is important not only to avoid floating cork and sediment formation but also for biogas

extraction (mixers help bubbles to go up the digester). Mixers work constantly in a bacteria

preserving mode.

Process stability - microorganisms are used to certain feed other modes.

Any changes should be done smoothly.

Avoid getting into reactor antibiotics, chemical and disinfection means, big quantities of heavy

metals. Our specialists can advice you on that.

The end product of biological treatment are:

biogas (methane not less then 55%, carbon dioxide not more then 45%, hydrogen sulfide

not more then 2%, hydrogen not more then 1%);

Fermented substrate as fermentation residue, consisting of water, cellulose residues, small

quantity of bacteria and organic nutrients (nitrogen, phosphorus, potassium etc.).

Increase of biogas plant efficiency

Photo. Impact of additves application on biogas production

Application of additives in biogas production allows achievement of considerable results at low

expenses. Here are the main advantages of enzymes application:

increase in biogas yield up to 40% without any changes in plant design;

more easy plant operation due to stability of the process;

increase of methane concentration in biogas.

With the purpose of economic viability most of the biogas plants are designed for 70% digestion

efficiency. Thanks to enzymes application it is possible to collect almost complete volume of biogas from

main digesters without post digesting stage.

ZorgEnzym additive is a smashing mixture consisting of enzymes, probiotics and microelements. In case

only enzymes are used, biogas production intensification is often of an accidental character.

When ZorgEnzym is used biogas production increase is guaranteed.

Enzymes – are natural proteins that play key role in plants, animals and human metabolism. These

substances can be called biological catalyst that intensifies organic substance conversion. Main purpose

of enzymes is destruction. Syntheses or integration is done only by three or five percent of existing

enzymes. Such enzymes called anabolic and destructive enzymes are called catabolic. Bacteria and

moulds produce enzymes for destruction of organic substances. Our product is the result of special

technology for combination of different enzymes, which makes it highly efficient biological catalyst.

Application of that product considerably increases biogas plant profitability at expense of higher biogas

yield and intensification of biological feed stock recycling.

Anaerobic digestion process in biogas plant is performed by microorganisms. For optimum biomass

destruction process microorganisms require energy, which can be obtained from polysaccharides, lipids,

and fats. Those substances can be released only after destruction of more complicated substances like

polymers (cellulose, starch).

But natural enzymes quantity is not always enough for optimum microorganism nutrition. With the help

of our product microorganisms constantly receive nutrients in the form of mono and polysaccharides. As

a result reproductive level and biological activity are increased, which leads to considerable reduction of

substrate viscosity and its higher homogeneity. Thanks to that processes biogas production and process

stability can be increased by 30-40%. Accordingly biogas plant energy output is increased.

This additive has been used for 4 years at 80 biogas plants and secures guaranteed 40% biogas yield

increase. There are biogas plants where 260 m3/t biogas yield from corn silage is reached, which is 45%

yield increase.

Price 42 EUR /kg.

Consumption

50-100 grams per 1 ton of organic dry matter or 1-2 grams per 1 kW of installed plant power.

Example

Biogas plant with 60 t/day corn silageloading, 1MW installed electric power.

ODM content 20 t/day.

ZorgEnzyme requirement is 1-2 kg/day.

Additional biogas yield thanks to ZorgEnzyme application will make minimum 3000-4000 m3/day.

Glossary

Alternative energy

Alternative energy – is a sum of prospective methods of energy generation that are not so widespread as conventional energy sources. However they are very interesting due to economical feasibility and

environmental impact.

Anaerobic fermentation

Anaerobic fermentation – is the process of fermentation in anaerobic environment (oxygen free). End

products of such fermentation are methane, carbon dioxide and some other.

Algae recycling

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Biogas

Biogas – is gas produced by means of anaerobic fermentation of biomass. Biomass decomposition is

made by methanogenic bacterium. Gas composition: methane 50%-87%, 25%-45% CO2, and some

admixtures. Microorganisms metabolizing carbon from organic substrates in oxygen free conditions (anaerobically). This process is called rotten or oxygen free fermentation, and follows the food chain.

Synonyms for biogas are sewage gas, mine gas, marsh gas, and methane.

Biodiesel

Biodiesel – is fuel made of vegetable or animal fat, and their etherification products.

Biomass

Biomass – is organic substance of biological nature

Biomethane

Biomethane – is produced by means biogas treatment and CO2 extraction from. After such treatment

gas has homogeneous composition containing from 85 to 99% CH4. By composition biomethane is a complete analog of natural gas with only source difference. .

Biological wastes

Biological wastes – slaughterhouse wastes, fat, entrails, blood, ruminant content. Farm wastes: manure. Poultry wastes: chicken dung. Brewery and alcohol plants: distillery slop and brewers’ grains.

Household and factories with biological raw materials wastes.

Biofuel

Biofuel – is fuel made of biological raw materials.

Biogas plant

Biogas plant – produces biogas and bio-fertilizer from biological wastes of agricultural and food

industry by means of anaerobic fermentation.

Bioethanol

Bioethanol – ethanol produced from agricultural raw materials and used as biofuel. Today most part of

bioethanol produced from corn (USA) and sugarcane (Brasil). Cultures with high starch and sugar content like potato or fruits are also can be used as raw materials for bioethanol production

Bone crusher

Bone crusher – is set of mechanisms for crushing cattle and poultry bones for further utilization.

Brewers grains

Brewers’ grains – is a waste product of brewery plant in a form of lees after brewing. Brewers’ grains

contain barn coating and grain kernel parts. Brewers’ grains used for animal feed in dry and fresh state or for biogas production.

Or

Brewers grains – insoluble barley remnants obtained in the process of crushed grains filtration used for water mashing.

Butchering

Butchering – the process of animal killing.

Biogas storage

Biogas storage – biogas storage is made with the help of gasholders.

Biomass energy

Biomass energy – the quantity of energy that can be obtained in the process of biomass recycling.

Clamps

Clamps – piles of manure having round shape.

Cesspit

Cesspit – most primitive sewage storage facility.

Co-generator

Co-generator – is a generator based on gas or diesel engine. It is the source of electrical and heat power. The primary energy source is gas, biogas or diesel fuel. The mane advantage of co-generation

unit to be compared to conventional generators is in its efficiency as co-generator utilizes the heat

that usually is lost.

Co-generation

The process of energy conversion conserved in fuel into heat and electricity.

Compost

Compost – organic fertilizer that is the product of organic matter decomposition by microorganisms.

Composting

Composting – in the process of composting organic biomass is enriched with plant nutrients. Also in the process of composting pathogenic microflora and helminth ages neutralized, the quantity of

cellulose, hemicellulose and pectin substances is reduced, fertilizer becomes more friable that makes it easier for soil injection.

Cutter

Cutter – in sausage production is used for blending and mixing with other components of sausage meat. Cutting mechanism and bowl are fixed at cutter plate. Cutting mechanism equipped with sickle -

shaped and straight knifes.

Chicken dung

Chicken dung - by chemical composition fermented chicken dung refers to the best kinds of organic

fertilizer. Most valuable are chicken and dove dung less valuable duck and goose dung.

Distillery slop (after alcohol production)

Distillery slop – is the waste product of alcohol production. Distillery Slop is a liquid with pale brown

color and grain smell. Dry matter content is 5-15%. Alcohol produced from grain, molasses, fruits, berries, many kinds of potato distillery..

Distillery slop pipeline

Distillery slop pipeline – is piping system for distillery slop transportation to the place of its recycling or filtration fields.

Decanter

Decanter – is a horizontal precipitating screw centrifuge of continuous operation. This is device used

for bio-fertilizer liquid and solid fraction detachment.

Digester

Digester (bioreactor, fermenter) – facility for biological wastes decomposition.

Digester

Digester – is a concrete reservoir with big volume for biological recycling (fermentation) of biomass

with the help of bacteria and other microorganisms in anaerobic environment (oxygen-free).

Distillery plant treatment facilities

Distillery plant treatment facilities – facility complex main function of which cleaning and filtration of

technical water.

Dung extraction

Dung extraction – the analog of manure extraction with the same extraction systems.

Dung storage

Dung storage – special storage for poultry dung storage.

Distillery slop separation

Distillery slop separation – the process of distillery slop liquid and solid fraction division. Liquid fraction

99% of water, solid fraction 70% of water. Separation is used for reduction active organics disposure to filtration fields. In biogas plants separation is also used but for fermented biomass.

Distillery slop dry fodder

Distillery slop dry fodder – solid fraction after distillery slop separation is used as feed for animals. Dry

feed is packed in granules or in bulk. This kind of fodder is suitable for cattle, pigs and poultry.

However this kind of distillery slop utilization is not optimal one.

Distillery slop drying

Distillery slop drying technology comprises 3 stages

1) Solid and liquid fraction division;

2) Evaporation up to 40% of dry matter content; 3) Products 1 and 2 drying (distillery slop drying system).

Dry distillery slop (protein and carbohydrate feed additive included into food of cattle and poultry) is

cooled and sold in bulky state. Distillery slop drying line consumes up to 50% of distillery plant overall

energy consumption.

Excrements

Excrements – organism vital functions waste products that are subject to disposal. Sweat, urine,

faeces, exhalted air are all excrements.

Entrails

Entrails – internals of animal (ingluvies, intestine etc.).

Energy crops

Energy crops – special crops that are used for biogas production. Corn, pilotweed, goat's rue are energy crops.

Energy conservation

Energy conservation – set of measures aimed for efficient electricity and heat usage.

Ethanol

Ethanol – alcohol or spirit. Is a highly inflammable, colorless liquid with characteristic odor. There are two ways of ethanol production, distillery fermentation and ethylene hydration.

Excrements

Excrements – the product of human and animal vital functions and undigested food remnants that are deposited to external environment from distal bowel.

Fodder yeast

Fodder yeast – On basis of undiluted grain distillery slop. Is a natural product obtained from natural raw material by means of alcohol production secondary product synthesis (dry distillery slop). This

kind of distillery slop application is not optimal one.

Feeding meal (tankage)

Feeding meal (tankage) – is compound of animal origin with high protein, fats and amino acids

content. Usage of feeding meal as fodder is prohibited in Europe. Feeding meal production is mostly used for slaughterhouse wastes recycling rather then for valuable fodder production. For feeding meal

production inedible materials like blood, entrails, bones, ruminant content, feather are used. Feeding meal production is highly energy consumptive and economically unfeasible.

Feeding mixture from distillery slop

Protein feeding mixture is based on distillery slop. As fodder yeast feeding mixture is protein source

for animals and poultry. Usage of this nutrients leads to large liver mass of animals and as a result there is no weight increase. Hence it is more feasible to produce energy and bio-fertilizer from those

substrates.

Fodder additives from pulp

Fodder additives from pulp – are fodder additives that are all based on different pulp kinds.

Filtration field

Filtration field - used as mechanical, chemical and biological treatment system. In biological layers

organic matter is decomposed by microorganisms. Filtration field are used for household and food

industry wastes utilization. Many factors should be taken into consideration in the process of filtration field project engineering like soil composition, sanitation zones, municipal requirements and other.

Flotation station

Flotation station – technological units for efficient treatment of sewage water containing so called insoluble substances like fats and cellulose.

Fermenter

Fermenter (bioreactor, digester) – tank in which the process of biogas formation takes place. This process flows with the help of microorganisms.

Filtrate

Filtrate – is a liquid fraction of distillery slop.

Flotation

Flotation – the method of solid particles division. As a rule particles are different substances. Flotation

is possible only for particles surface of which is not completely moisten. It can be achieved by adding small quantities of special substances - flotation agent.

Fruit marc

Fruit marc – fruit press cake.

Filtrate water

Filtrate water – sometimes distillery slop. Filtrate water can jam the pipes, riverbeds etc. Filtrate water has long decomposition period and disposes poison to environment. In past time the problem of

filtrate utilization was very important in the process of distillery or brewery plant waste facility project

engineering. Mostly evaporation technology was used for that. Actually filtrate water contains the whole range of pollutants. Biogas plant equipped with biomass destruction units (cavitators) can solve

the filtrate water problem. In addition enzymes application makes organics content after treatment in biogas plant equal to zero.

Gasholder

Gasholder – big reservoir for storage of natural gas or biogas. Gasholders can be of variable or constant volume; made of steel, rubber or film.

Gas-hydrate

Gas-hydrate – is supramolecular methane and water compound. Gas-hydrate is stable to low temperatures and widespread in nature.

Gas-engine power station

Gas-engine power station – co-generation system based on gas driven engine, which allows

conversion of fuel energy into electricity and heat power.

Gas turbine station

Gas turbine station – is unit based on gas turbine engine. In gas turbine engine gas compressed and

heated then energy of compressed and heated gas converted into mechanic energy of gas turbine

shaft. As opposed to reciprocating motor in gas turbine all processes take place in a gas flow.

Grease trap

Grease trap – used for fat detachment from water.

Hydrogen engine

Hydrogen engine – as an option, engine that use hydrogen as fuel.

Hydropower plant

Hydropower plant - is a complex of hydro technical facilities and equipment for potential water stream

energy conversion into electricity using hydro turbine.

Humus

Humus – is a set of organic compounds in soil but not being a part of life organisms or their remnants

preserving anatomic features. Humus comprises 85-90% of soil organic matter and is crucial for soil productivity evaluation.

Killing department

Killing department – is a facility for cattle slaughter and butchery.

Lagoons

Lagoons – special lakes for waste or manure storage.

Litter (straw or sawdust)

Litter – is a sawdust or straw floor layer in cattle or poultry house.

Landfill gas

Landfill gas – Macrocomponents of landfill gas are methane (CH4) and carbon dioxide (CO2) their correlation can be different accordingly from 40-70% to 30-60%. As microcomponents landfill gas can

contain many other organic compounds.

Manure granulation

Manure granulation – the process of manure drying and and its shaping in a form of small granules.

Mesophilous fermentation

Mesophilous fermentation – is an optimum temperature for methane bacteria germination 30- 40 °С.

This mode of fermentation is most cost effective to be compared to thermophile in terms of heat

power usage.

Methane

Methane – is elementary hydrocarbon, colorless gas without smell, chemical formula CH4. Slightly soluble in water, lighter then air. In industrial and household applications special odorants are added

to give “natural gas” smell.

Methane bacteria

Methane bacteria – bacteria that can obtain energy form the process of CO2 reduction to methane.

Some methane forming bacteria can ferment methyl alcohol and acetic acid at that methane produced

from methyl group carbon.

Methane filling station

Methane filling station – is a filling station equipped with gas filling equipment.

Methane formation

Methane formation – is the process of methane production.

Mortuary

Mortuary – is the place for meat processing industry waste disposal.

Meat processing factory

Meat processing factory – meat processing industry plant.

Manure extraction

Manure extraction – manure removal from cattle house – one of the most laborious processes. Adjusted and proficiently equipped manure extraction process is important for effective cattle

breeding. Manure extraction system efficiency influence to cattle house microclimate, animal health

and local ecological situation.

There are following manure extraction systems. 1. Water wash (humidity 99%) – manure extraction with big water quantity. This method is

characterized by maximum water pollution. Such extraction system implies further settling, aerobic treatment and flotation. Water treatment facilities for that systems consume about 20% of farm

overall energy need.

2. Self-flow (humidity 92-96%). System is made in a such way that manure falls through the slots and flows on inclined floor. Water wash is made periodically.

3. Mechanical (humidity 80-85%). Manure is extracted without water. It is pilled of with an scraper or falls to conveyor belt.

4. Semi-mechanical or manual(humidity 60-70%). In case straw or sawdust litter is used manure

removal is made 2-3 times per month. Litter is added periodically.

Modern farms mostly use self-flow system or it’s combination with mechanical system.

Manure storage

Manure storage – pit, special closed or open container can be used as manure storage.

Manure drying

Manure drying – the process of moisture extraction in drying chamber.

Marc storage

Marc storage – is a special place or building for marc or press cake storage.

Manure storage

Manure storage – is a farm facility for manure collection and storage. The manure storage volume is

defined by the number of cattle, duration of housing season, efficiency of mechanization means and time required for complete manure inactivation for soil injection. Generally the inactivation period

makes 3 years.

Plants tops

Plants tops – leaves of root crops (beet, swede, turnip, carrot, parsnip) and tuberous plants (potato,

topinambour). Used as a secondary product of such crops production.

Poultry factory waste

Poultry factory waste – chicken dung and slaughterhouse waste.

Pellets

Pellets (fuel briskets) – biofuel obtained from waste wood and agricultural wastes. Produced in a form

of granules of standard size.

Pyrolysis

Pyrolysis – is a thermal decomposition of organic matter (wood, oil, coal etc.) without oxygen access.

Pluck

Pluck – eatable internal part of animals (birds, fish, and other).

Press filter

Press filter – equipment that affects filtration with the help of filtration sieve.

Psychrophilic fermentation

Psychrophilic fermentation – the mode which uses temperatures between 8...20 °С.

Power efficiency

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Ruminant remnants

Ruminant remnants – content of ingluvies and entrails of butcher consisting of not completely digested fodder remnants. Ruminant content is utilized with other slaughterhouse content as fertilizer or pig

fodder.

Reactor

Reactor – system in active zone of which certain reaction takes place.

Slaughterhouse

Slaughterhouse – place for cattle slaughter

Sugar beet pulp

Sugar beet pulp – extracted chopper of sugar beet, waste product of sugar industry. Used as cattle fodder in dry (in bulk and briquettes) and ensilaged for biogas production.

Straw furnace

Straw furnace – are special furnace that are equipped for straw combustion.

Settling tank (vertical, conical)

Settling tank (vertical, conical) – special equipment for manure liquid and solid fraction division.

Separation

Separation – the process of detachment of heterogeneous compounds of mixtures, liquids with

different density, emulsions, liquid or solid suspended matters in gas or steam.

Solar cell (photovoltaics)

Solar cell – is the generator of renewable energy source that converts solar light to electricity.

Solar panel

Solar panel – sets of solar cells combined into groups.

Treatment facilities (cleaning system)

Treatment facilities (cleaning system) – used for complete or partial purification of industrial water

from pollutants that have negative environment impact.

Termophilic fermentation

Termophilic fermentation – 50 - 55оС the optimum temperature for methane bacteria germination.

Mesophilic fermentation is considered to be more economically attractive due to heating aspect.

Veterinary sanitation factory

Veterinary sanitation factory – other name meat-and-bone powder tankage factory. Such factory

recycles waste products of meat processing factories, slaughterhouses, animal dead bodies, murrain.

Wind power generation

Wind power generation – methods and means for wind energy conversion into mechanical, electrical of

heat energy

Waste utilization and recycling

Waste utilization and recycling – package of measures aimed for ecological safety and wastes

recycling and utilization.

Reference : http://www.zorg-biogas.com/library/biogas