EFFECT OF AMMONIA PRETREATMENT ON PADDY STRAW DIGESTIBILITY AND BIOGAS PRODUCTION

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EFFECT OF AMMONIA PRETREATMENT ON PADDY STRAW
DIGESTIBILITY AND BIOGAS PRODUCTION

•  
• Presented by
• Urmila Gupta Phutela
• Scientist (Biogas)
• School of Energy Studies for Agriculture
• College of Agricultural Engineering and
  Technology
• Punjab Agricultural University, Ludhiana-141004,
  India.
• Email phutelau_at_gmail.com

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CONTENTS

• Introduction
• Biomass Characteristics
• Principal biomass conversion pathways
• Present use of paddy straw
• Paddy straw and Biogas production
• Pretreatment of Paddy straw
• AmmoniaMicrowave Pretreatment and its effect on
  paddy straw digestibility and biogas production
• Conclusions
• Future perspectives

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INTRODUCTION

• Main problems faced by the developing countries
  Food, fuel and fertilizers
• Rural population heavily dependent on the
  traditional fuels such as firewood, animal wastes
  and agricultural residues
• World energy demand is expected to increase by
  50 by 2030
• NON-RENEWABLE ENERGY SOURCES
• very costly
• limited in nature
• e.g. OIL, COAL, ELECTRICITY
• RENEWABLE ENERGY SOURCES
• cheap
• unlimited in nature
• e.g. BIOMASS, SOLAR, WIND, ANIMAL AND HUMAN WASTE

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Contd.

• Energy potential of the biomass is still
  unutilized
• Plant residues have high content of cellulose
  which has combustion energy of 15 kJ/g and if
  converted to methane, a preferred fuel, has a
  combustible energy of 50 kJ/g (Khan et al., 1983)

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BIOMASS

• Biomass is a contemporary plant matter which is
  continually being replenished by the
  photosynthetic reduction of CO2 by the solar
  energy
• (Ragauskas et al., 2006).

Plant converts Solar Energy into Chemical
Energy in the Biomass via Photosynthesis by CO2
Fixation
SUN
BIOMASS
PLANT RESIDUES
FOOD GRAINS, VEG., FRUITS
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Principle biomass conversion pathways
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Biomass Statistics
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Present use of Paddy Straw

• Composting
• As animal feed
• Surface Mulching
• In Situ Incorporation
• Mushroom production
• Card board/Paper making
• Thatched roofs for animals

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Burning
A common scene during harvesting season
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Current Science (2004)

• Burning leads to pollutant emission of trace
  gases like CH4, CO, N2O, NOX, SO2, hydrocarbons
  and particles of organic and inorganic sp.
• 1 tonne of straw burning releases 3 kg
  particulate matter, 60 kg CO, 1460 kg CO2, 199 kg
  Ash, 2 kg SO2 (Jenkins and Bhatnagar, 2003)
• Adverse impact on health of human beings (asthma,
  respiratory diseases, cough and cold)

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Composition of Paddy Straw

Source Pathak et al, 1986
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Cellulose

• Cellulose consists of D-glucose subunits, linked
  by ß-1,4 glycosidic bonds.
• Composed of crystalline (organized) and amorphous
  (non-organized)) regions.

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Hemi-cellulose

• Complex carbohydrate that consists of pentoses
  (like xylose and arabinose), hexoses (like
  mannose, glucose and galactose), and sugar acids.
• connection between lignin and cellulose fibres,
  providing more rigidity to the whole
  cellulose-hemicellulose-lignin network

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Lignin

• Amorphous heteropolymer consisting of three
  different phenylpropane units (p-coumaryl,
  coniferyl and sinapyl alcohol) that are held
  together by different kind of linkages.
• Provides structural support, impermeability and
  resistance against microbial attack to the plant.

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Silica

• Silicon is typically present in living plants in
  three basic forms insoluble silica (90),
  silicate ions (0.5-0.8) and colloidal silicic
  acid (0-3.3)
• Silicon present in paddy straw is involved in
  various roles i.e carbohydrate synthesis, grain
  yield, phenolics synthesis and plant cell wall
  protection.

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Factors influencing yields of lignocellulose to
monomeric sugars

• Particle size
• Liquid/ solid ratio
• Temperature
• Reaction time
• Length of macromolecules
• Degree of polymerization of cellulose
• Configuration of cellulose chain
• Association of cellulose with other protective
  polymeric structures within the plant cell wall
  such as lignin, pectin, hemi-cellulose, proteins
  and mineral elements

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PAU trial (1)

• Chopped paddy straw cattle dung
• conventional biogas plants
• Problem
• Being light weight, floats on the surface
• Scum formation

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PAU trial (2)
Chopped paddy straw cattle dung(515 w/w dry
wt basis)
Filled in PVC sacs of 20-30 kg capacity
Loaded manually in 1m3 3m3 digester
Gas could not be recovered
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PAU trial (3)
Powdered PS cattle dung (11.5w/w)
Fed in biogas plant(0.37m3/m3 digester)
Problem with flow of slurry
Choking after 3 months
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Biphasic technology

• Paddy straw

Gas outlet
drum
Acidogenic bacteria
Methane reactor
Acid reactor
outlet
Acid tank
Methanogenic bacteria
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Lab methane reactor
Acid reactor
Leachate collection tank
Methane reactor
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Pretreatment of paddy straw

• Lignin and silica are the main deterrents in
  efficient utilization of Paddy straw
• Pretreatment Methods
• Physical (mechanical and thermal),
• Chemical (acid, alkali, oxidising agents),
• Physico-chemical (AFEX, CO2 and steam explosion)
• Biological (lignocellulosic microbes, enzymes)
• Pretreatments technologies either change or
  remove structural and compositional constraints
  to improve hydrolysis rate of Paddy straw.

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Objectives

• To analyze the digestibility of paddy straw after
  Ammonia and Microwave pretreatment
• To evaluate the biogas production from pretreated
  paddy straw

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Importance of NH3 for paddy straw pretreatment

• NH3 is utilized by methanogens as a nitrogen
  source
• Helps in maintaining CN ratio of paddy
  straw-digested cattle dung slurry mixture
• NH3 and urea simply crack the silicified
  cuticular layer of paddy straw but do not
  dissolve silica Van Soest, 2003
• Ammoniation of rice straw resulted in two-fold
  increase in gas production at 24 h of incubation
  Eun et al., 2006
• Although there have been many pretreatment
  methods, few can be used on an industrial scale
  based on economics and environmental
  consideration Sun and Chang, 2002

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Importance of Microwave irradiations for paddy
straw pretreatment

• Microwave irradiation has been widely used in
  many areas because of its high heating efficiency
  and easy operation
• Microwave irradiation could change the ultra
  structure of cellulose Xiong et al, 2000
• Microwave irradiation could degrade lignin and
  hemicellulose and increase enzyme susceptibility
  Azuma et al., 1984 Ooshima et al., 1984
  Kitchaiya et al., 2003
• Causes accelration of ions,collision with other
  molecules,rapid rotation of dipoles
• An increase of 30.6 cellulose and 43.3
  hemi-cellulose content of paddy straw by
  microwave pretreatment (680W 24 minutes) has
  been reported Ma et al., 2009

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Chemical-soaking pretreatment of paddy straw

• NH3 solution (2, 4, 6, 8 and 10)
• ?
• Prepared 200 ml solution of each concentration
• ?
• Soaked 20 gram of paddy straw (chopped, washed
  and dried) for 24 h and 48h
• ?
• Washed pretreated paddy straw
• ?
• Dried overnight at 1000C
• ?
• Proximate analysis i.e.
• total sugars
• cellulose
• hemi-cellulose
• lignin
• silica

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Chemical-microwave pretreatment of paddy straw

• Suspended 20 gram paddy straw in 200ml solution
  of different concentrations
• ?
• Exposed to microwave irradiations (720W 1800C)
  for 30 and 60 minutes
• ?
• Washed pretreated paddy straw
• ?
• Dried it overnight in oven at 1000C
•  ?
• Proximate analysis

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Biogas production from pretreated paddy straw

• Biogas production experiments were carried
  out in two litre capacity digesters following
  monophasic method and biogas produced was
  measured by water displacement method

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Conclusions

• Supplementation of microwave irradiation to
  ammonia solution enhanced digestibility of the
  paddy straw as compared to ammonia soaking
  pretreatment.
• Although, 10 NH3-30 min microwave pretreatment
  showed maximum reduction (34) in lignin content
  but 6 NH3-30 min microwave was best pretreatment
  with significant increase in paddy straw
  digestibility and biogas production.
• Biogas production enhanced in all pretreatments
  but an increase of 45.9 and 53.5 was seen in 6
  NH3-48h soaking and 6 NH3 30 min microwave
  respectively.
• The lesser increase in 10 NH3-48h soaking and
  10 NH3-60 min microwave could be result of
  inhibition/toxicity caused by higher
  concentration of ammonia-N2.

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Future perspectives

• Further research is required to get insight into
  the
• Optimization of the physico-chemical parameters
  for biogas production from the pretreated paddy
  straw like
• Inoculum size/type
• adjustment of the C/N ratio of the feedstock.
• pH adjustment
• Use of additives to mitigate the inhibitory/toxic
  effects of chemicals.
• Fast growing and more efficient
  lignolytic/lignocellulolytic microbes should be
  worked out.
• Anaerobic lignolytic fungi should be more
  stressed upon as that could work well in the
  anaerobic conditions prevailing in the biogas
  digesters.

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Hurdles in the way to biogas technology

• The main factors responsible for limiting the
  response for undertaking biomass power projects
  are
• collecting and transporting surplus biomass
  resources in the command area to the project site
  
• lack of trading surplus biomass
• funding these projects is also a major problem.
  Banks do not have experience in funding such
  projects so they are apprehensive

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Future with biogas technology

• More than 1000MW of energy could be generated
  from 'waste' biomass in Punjab only using
  highly-efficient, modern bio energy systems.
• Sufficient for the energy needs of some 8 to 16
  million people.
• It could prove to be a cost-effective option.
  Liquid and gaseous fuel production from renewable
  sources and usage in rural areas could be Rs.
  20-30,000-crore/year industry and can bring
  substantial wealth to these areas.
• Positively impact "energy conservation, social
  hygiene, employment generation and womens
  health.
• Biomass can beat oil and coal.
• Energy self-sufficiency to villages.
• For plants to be introduced on large scale in
  villages it is necessary to set up a National
  mission on electricity production for rural
  areas.

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Train and Car running on Biogas
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THANKS !!!