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

1. BIOMETHANATION
1
BIOGAS PLANTS
FOR
RURAL AND INDUSTRIAL
WASTE WATER TREATMENT

2. 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.

3. 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.

4. Biogas Technology: Topics
4
 Digesters for rural application.
 MNES Recognized Rural biogas-plant
models.
 High rate digesters for industrial waste water
treatment.

5. 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.

6. 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%

7. 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

8. 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.

9. 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.

10. Rural Applications of biogas plant
10

11. 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

12. 12

13. 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.

14. 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.

15. 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.

16. Biogas Purification
16

17. High Pressure Water Scrubbing
17

18. 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

19. 19

20. 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

21. 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.

22. 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

23. 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

24. 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

25. 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.

26. 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.

27. 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.

28. 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

29. 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.

30. 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

31. KINETICS OF DIGESTION
31
 Refer: Chen and Hashimoto, Biotechnology
Bio-engineering Symposium 8, (1978) p
269-282 and
 Biotechnology Bioengineering (1982) 24: 9-
23

32. 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

33. 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

34. 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

35. TYPES OF RURAL BIOGAS PLANTS
35
 FIXED DOME: JANATHA, DINABANDHU,
UTKAL / KONARK
 FLOATING DRUM: K.V.I.C
 COMBINED FEATURES: PRAGATI

36. 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

37. 37

38. 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

39. 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

40. Floating drum (rural)
40

41. K.V.I.C floating drum plant
41

42. Dinabandhu model
42

43. Dinabandhu model
43

44. Pragati rural biogas plant
44

45. 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

46. 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)

47. UTKAL / KONARK DIGESTER
47

48. 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

49. 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

50. 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

51. 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

52. 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

53. 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

54. TYPES OF HIGH RATE BIOGAS PLANTS
54
 ANAEROBIC CONTACT
 ANAEROBIC FILTER:UPFLOW, DOWNFLOW
 UPFLOW ANAEROBIC SLUG BLANKET
 ANAEROBIC FLUIDISED/ EXPANDED BED
 ANAEROBIC ROTATING CONTACTOR

55. Anaerobic contact digester
55

56. Anaerobic filter, downflow reactor
56

57. Upflow Anaerobic Sludge Blanket Digestor
57

58. Fluidized/expanded bed reactor
58

59. 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.

60. 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

61. 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.

62. 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.

63. 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.

64. 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

65. 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