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Biogas technology

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Anaerobic digestion of wastewater has two benefits for energy and environment.

Anaerobic digestion of wastewater has two benefits for energy and environment.

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Biogas technology Biogas technology Presentation Transcript

  • BIOMETHANATION 1 BIOGAS PLANTS FOR RURAL AND INDUSTRIAL WASTE WATER TREATMENT
  • Biogas Technology: Topics 2  Biogas Basics - Global Carbon Cycle - Utility – Composition and Properties – Purify for use as engine fuel- Rural Applications of biogas - Feedstock for biogas: Aqueous wastes containing bio-degradable organic matter, animal residues.
  • Biogas Technology: Topics 3  Dry and wet fermentation.  Microbial and biochemical aspects.  Operating parameters for biogas production by anaerobic digestion.  Kinetics and mechanism of biomethanation.
  • Biogas Technology: Topics 4  Digesters for rural application.  MNES Recognized Rural biogas-plant models.  High rate digesters for industrial waste water treatment.
  • Biogas Basics 5 • What is biogas? • Biogas originates from bacteria by bio- degradation of organic material under anaerobic (without oxygen) conditions. • The generation of biogas is an important part of the biogeochemical carbon cycle.
  • Biogas Basics 6 • Methanogens (methane producing bacteria) are the last link in a chain of microorganisms that degrade organic material and return the decomposition products to the environment, producing biogas. Methane in atmosphere, from biogenic sources: 90 % Methane in atmosphere, from petrosources: 10%
  • UTILITY OF RURAL BIOGAS PLANTS 7  ENERGY RECOVERY: FOR COOKING, LIGHTING, PUMPING, OR POWER- - WITH BURNER, MANTLE LAMP, ENGINE-PUMP AND GENERATOR  HYGIENIC DISPOSAL OF ANIMAL WASTE AS MANURE  SUBSTITUTES FOR FUELWOOD & KEROSENE
  • Anaerobic digestion process contributes to: 8  Energy recovery and reduction of greenhouse gas [methane] emissions from open WWT ponds gives environmental benefit also.  Substitutes for fossil fuels by utilizing methane generated from the waste.  The energy generation from industrial wastewater, with recycling of recovered water has double benefit in India.
  • Biogas and the Global Carbon Cycle 9  Through microbial activity, 590-880 million tons of methane are released into atmosphere worldwide per annum.  In the northern hemisphere, the present tropospheric methane concentration amounts to about 1.65 ppm.
  • Rural Applications of biogas plant 10
  • Compositon of Biogas 11 Composition:  60 to 70 per cent Methane,  30 to 40 per cent Carbon Dioxide,  traces of Hydrogen Sulfide, Ammonia and Water Vapor
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  • Properties of Biogas 13  It is about 20% lighter than air (density is about 1.2 gm /liter).  Ignition temp is between 650 and 750 C.  Calorific value is 18.7 to 26 MJ/ m3 (500 to 700 Btu/ ft3.)  Calorific value without CO2: is between 33.5 to35.3 MJ/ m3  Explosion limit: 5 to 14 % in air.
  • Properties of Biogas continued 14  Air to Methane ratio for complete combustion is 10 to 1 by volume.  One cubic meter of biogas is equivalent to 1.613 liter kerosene or 2.309 kg of LPG or 0.213 kw electricity.
  • Biogas Purification 15  Removal of CO2: Scrubbing with limewater or ethanol amine solution.  Removal of H2S: Adsorption on a bed of iron sponge and wood shavings.  Pressure & Temperature needed to liquefy: Biogas needs 500 psi, at –83 C & LPG Needs 160 psi, at ambient temperature.
  • Biogas Purification 16
  • High Pressure Water Scrubbing 17
  • The water scrubbing process contains two main waste streams. The first waste stream is the exhaust of air which was used to strip the regenerated water. This stream mainly consists of air and a high percentage of CO2 but also contains traces of H2S. Because H2S is rather poisonous this stream needs to be treated. Also the stream contains small amounts of CH4 Because CH4 is far more damaging to the environmental than CO2 the CH4 in this stream should be burned. 18
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  • Biogas as I.C. engine Fuel 20  Traces of H2S, NH3, water vapor to be removed by absorption/adsorption.  With modified fuel injection system, in stationary diesel or petrol engine biogas can be used.  In Diesel engine, dual fuel mode is needed.  After initial start up with petrol, engine can run on biogas
  • Substrate and Material Balance of Biogas Production 21  Homogenous and liquid biodegradable substrates are suitable for simple biogas plants.  The maximum of gas-production from a given amount of raw material depends on the type of substrate.
  • WET BIODEGRADABLE WASTES: 22 WASTE STARCH & SUGAR SOLUTIONS: Fruit processing, brewery, press_mudfrom sugar factory etc OTHER HIGH B O D EFFLUENTS: Leather industry waste. Pulp factory waste liquor
  • FEED FOR BIOGAS : WET BIODEGRADABLE WASTE 23 DOMESTIC ANIMAL WASTES: Excreta of cow, pig, chicken etc MANURE, SLUDGE: Canteen and food processing waste, sewage MUNICIPAL SOLID WASTE: separation of non-degradable After
  • WET FERMENTATION: 24 FEED SUBSTRATE TOTAL SOLID CONCENTRATION, (TSC) = 8 TO 9 % FOR COW DUNG, RATIO OF DUNG TO WATER = 1:1 BIOGAS PRODUCED IS: IN SUMMER AT 47 C, 0.06 M3 / KG DUNG ADDED / DAY IN WINTER AT 8 C, 0.03 M3 / KG DUNG ADDED / DAY
  • DRY FERMENTATION OR SOLID STATE FERMENTATION: 25 FEED SUBSTRATE TOTAL SOLID CONCENTRATION, ( TSC) OF 20 TO 30 %, A MIX OF COW DUNG AND A WIDE VARIETY OF AGRO - RESIDUES.
  • DRY FERMENTATION OR SOLID STATE FERMENTATION : 26  FOR CATTLE DUNG AND MANY AGRO- RESIDUES AT INITIAL CONCENTRATIONS OF TSC BETWEEN 16 TO 25 % , BIOGAS PRODUCTION HAS BEEN DEMONSTRATED SATISFACTORILY IN SMALL BATCH TYPE AND PLUG FLOW TYPE DIGESTERS.
  • Biology of Methanogenesis 27 • This knowledge is necessary for planning, building and operating biogas plants. • Microbial Decomposition Occurs in Three Stages: Hydrolysis, VFA Formation and Methane formation.
  • 1. Hydrolysis of Biopolymers like carbohydrates and proteins To Monomers 2. Convert sugars, amino acids, fatty acids to H2, CO2, NH3, Acetic, Propionic And Butyric Acids [VFA] 3. Convert [H2, Co2, Acetic Acid] To CH4 And CO2 Mixture 28
  • Biochemistry of Anaerobic Digestion 29 • Methanogenic bacteria take up acetic acid, methanol,H2, CO2 to produce methane • O2,nitrites,nitrates etc. inhibit activity • Acid formation and bicarbonate formation by two set of bacteria is balanced, the pH and biomethanation are stabilized.
  • Operating parameters affecting gas production: 30 • Temperature: Optimum =35 C • pH range: 6.8 to 7.8 • Favorable C/N ratio is 30:1 • Proportion of solids to water: 10 % for optimum operation • Retention time: ratio of volume of slurry in digester to volume fed into/ removed from it per day=30 days for Temp. of 25-35 C
  • KINETICS OF DIGESTION 31  Refer: Chen and Hashimoto, Biotechnology Bio-engineering Symposium 8, (1978) p 269-282 and  Biotechnology Bioengineering (1982) 24: 9- 23
  • KINETICS OF DIGESTION continued 32  For a given loading rate, [So/HRT], daily volume of methane per volume of digester depends on  biodegradability of influent(Bo) and  kinetic parameters k & m
  • KINETICS OF DIGESTION continued 33 • Volumetric methane rate in cubic meter gas per cubic meter of digester volume/day • V = (Bo So / HRT)[1- K / (HRT*m-1+K)] • Bo = Ultimate methane yield in cubic meters methane / kgVS (Varies from 0.2 to 0.5) • So = Influent volatile solids concentration in kg VS /cubic m
  • KINETICS OF DIGESTION, CONTINUED 34  (Loading rate range = 0.7 to 25 kg VS/m3 d)  HRT = Hydraulic retention time in days  K = Dimensionless kinetic parameter, for cattle dung, K= 0.8+ 0.0016e0.06 So  m = Maximum specific growth rate of the microorganism in day-1
  • TYPES OF RURAL BIOGAS PLANTS 35  FIXED DOME: JANATHA, DINABANDHU, UTKAL / KONARK  FLOATING DRUM: K.V.I.C  COMBINED FEATURES: PRAGATI
  • FIXED DOME: JANATHA 36  DIGESTER WELL BELOW GROUND LEVEL  FIXED DOME GAS HOLDER BUILT WITH BRICK & CEMENT  BIOGAS FORMED RISES PUSHES SLURRY DOWN  DISPLACED SLURRY LEVEL PROVIDES PRESSURE-UPTO THE POINT OF ITS DISCHARGE/ USE
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  • K.V.I.C floating drum plant 38  MASONRY CYLINDRICAL TANK  ON ONE SIDE INLET FOR SLURRY  OTHER SIDE OUTLET FOR SPENT SLURRY  GAS COLLECTS IN INVERTED ‘DRUM’ GAS HOLDER OVER SLURRY  GAS HOLDER MOVES UP & DOWN DEPENDING ON ACCUMULATION OF GAS /DISCHARGE OF GAS, GUIDED BY CENTRAL GUIDE PIPE
  • K.V.I.C floating drum plant continued 39  GAS HOLDER (MILD STEEL): PAINTED ONCE A YEAR.  K V I C Mumbai  MEDIUM FAMILY SIZE BIOGAS PLANT HAVING GAS DELIVERY OF 3 M3 /DAY REQUIRES 12 HEAD OF CATTLE AND CAN SERVE A FAMILY OF 12 PERSONS
  • Floating drum (rural) 40
  • K.V.I.C floating drum plant 41
  • Dinabandhu model 42
  • Dinabandhu model 43
  • Pragati rural biogas plant 44
  • Pragati rural biogas plant 45 •COMBINES FEATURES OF KVIC & DEENABANDU,DEVELOPED IN MAHARASHSTRA •LOWER PART: SEMI-SPHERICAL IN SHAPE WITH A CONICAL BOTTOM •UPPER PART: FLOATING GAS HOLDER •POPULARIZED IN MAHARASHTRA, UNDARP, PUNE
  • UTKAL / KONARK DIGESTER 46  SPHERICAL IN SHAPE WITH GAS STORAGE CAPACITY OF 50%  CONSTRUCTION COST IS REDUCED AS IT MINIMIZES SURFACE AREA  BRICK MASONRY OR FERROCEMENT TECHNOLOGY  A PERFORATED BAFFLE WALL AT THE INLET PREVENTS SHORT CIRCUITING PATH OF SLURRY (OPTIONAL)
  • UTKAL / KONARK DIGESTER 47
  • FERROCEMENT, FRP DIGESTER: 48  CAST SECTIONS, MADE FROM A REINFORCED (MORTAR+WIRE MESH)COATED WITH WATER PROOFING TAR S E R I, ROORKEE FIBER REINFORCED PLASTIC MADE BY CONTACT MOULDING PROCESS
  • FLEXIBLE PORTABLE NEOPRENE RUBBER MODEL 49  FOR HILLY AREAS, MINIMIZES TRANSPORT COST OF MATERIALS  BALLOON TYPE, INSTALLED ABOVE GL, MADE OF NEOPRENE RUBBER  FOR FLOOD PRONE AREAS, UNDERGROUND MODELS NOT SUITABLE  SWASTHIK COMPANY OF PUNE DESIGN
  • HIGH RATE BIOGAS PLANTS FOR INDUSTRIAL WASTE WATER TREATMENT 50  Brings down high BOD content to make it suitable for aerobic biological treatment  Faster disposal of waste water with partial recovery of energy as fuel [biogas]  Suitable for food processing waste water of high BOD content
  • INDUSTRIAL -WWT-BIOGAS PLANTS Present status in India 51 . • Industries • Distilleries • Paper & Pulp • Starch Existing plants 254 347 13 Bio- gas units 145 5 1
  • Indian Technology supplier – Foreign collaborator 52  Degremont India Limited  Hindustan Dorr-Oliver  Sakthi Sugars Limited  UEM India (Private) Limited  Degremont, France  Dorr-Oliver, USA  SGN, France  ADI International, Canada
  • Indian Technology supplier -Foreign collaborator … 53  Kaveri Engineering. Industries Limited  Western Paques India Limited  Western Bio Systems Limited  Vam Organic Chemicals Limited  Dewplane, UK  Paques, Netherlands  Sulzer Brothers, Switzerland  Biotim N V, Belgium
  • TYPES OF HIGH RATE BIOGAS PLANTS 54  ANAEROBIC CONTACT  ANAEROBIC FILTER:UPFLOW, DOWNFLOW  UPFLOW ANAEROBIC SLUG BLANKET  ANAEROBIC FLUIDISED/ EXPANDED BED  ANAEROBIC ROTATING CONTACTOR
  • Anaerobic contact digester 55
  • Anaerobic filter, downflow reactor 56
  • Upflow Anaerobic Sludge Blanket Digestor 57
  • Fluidized/expanded bed reactor 58
  • Applications of Biogas and Appliances needed: 59 1. Cooking fuel- Stove / Burner. 2. Lighting Fuel- Mantle lamp. 3. Dual fuel stationary I. C. Engine –To run a pump for drawing water 4. Dual fuel stationary I. C. Engine –To run a generator for electricity.
  • Biogas burner & lamp 60  Both biogas burner and mantle lamp have some structural similarity: each have inlet gas nozzle, air inlet, & a mixing chamber.  Burner has fire-stove plate  Lamp has mantle that glows to emit light
  • Features of Biogas Stove 61  Operate at pressure:75-90 mm [3-3.5 inch] water column; Air/Gas ratio is 10:1; Nozzle adjustment necessary.  Temperature: About 800 C  For cooking, 0.28 to 0.42 m3 of biogas per person per day is consumed.  Design different from those of LPG/Natural Gas stoves.
  • Features of biogas lamp: 62  Brightness depends on gas pressure, air to gas ratio, extent of mixing etc. Proper nozzle adjustment is necessary to achieve required light intensity.  Lamps designed for 100 candle-power consume 0.11 to 0.15 m3 biogas per hour.
  • Biogas for electricity Generation 63  One kwh can be generated from 0.7m3 of biogas to light 15 bulbs [60watts] for one hour.  For lighting, power route is better than direct burning  Economical for large sized plants, requires high initial capital investment.
  • TEXT BOOKS AND REFERENCES 1. Biotechnology Volume 8, H. J. Rehm and G. Reed, 1986, Chapter 5, “ Biomethanation Processes.‟ Pp 207-267 2. K. M. Mital, Non-conventional Energy Systems, (1997), A P H Wheeler Publishing, N. Delhi. 3. K. M. Mital, Biogas Systems: Principles and Applications, (1996) New Age International Publishers (p) Ltd, N. Delhi. 64
  • References : 1. Effluent Treatment & Disposal: I Ch. E, U.K., Symposium Series No 96, 1986, P 137-147, Application of anaerobic biotechnology to waste treatment and energy production, Anderson & Saw. 2. “Anaerobic Rotating Biological Drum Contactor for the Treatment of Dairy Wastes‟, S. Satyanarayana, K. Thackar, S.N.Kaul, S.D.Badrinath and N.G. Swarnkar, Indian Chemical Engineer, vol 29, No 3, July-Sept, 1987 65