Sugarcane Bagasse: C/N Ratio Effects on Anaerobic Digestion

This presentation investigates the effect of varying carbon to nitrogen (C/N) ratios on the anaerobic digestion of sugarcane bagasse, both untreated and pre-treated, to optimize biogas production. The study aims to determine the ideal C/N ratio for maximizing methane yield using biomethane potential (BMP) tests. The methodology involves batch experiments at 37°C with C/N ratios ranging from 15:1 to 40:1, adjusting nitrogen levels with urea and using mesophilically digested sludge as inoculum. Results indicate that for untreated bagasse, a C/N ratio of 35:1 yields a 9.3% increase in methane production compared to the control, while pre-treated bagasse shows a 3.3% increase at a C/N ratio of 25:1. The presentation concludes with recommendations for co-digestion with nitrogen-rich sources and further research using lab-scale reactors to explore additional parameters and pre-treatment methods.

EFFECT OF CARBON TO
NITROGEN RATIO IN
ANAEROBIC DIGESTION OF
SUGRACANE INDUSRTY WASTE

CONTENTS
• Introduction
• Literature review
• Aim and Objective
• Material and Method
• Results
• Summary and Recommendation
• Acknowledgement

INTRODUCTION
• Bagasse production
• Global Production in 2013-14
• 179.68 Mt
• Australia production
• In that, how much is bagasse is produced
• Brazil is the leading producer
• India follows closely
• The higher the production of sugar by
a country the higher the quantity of
bagasse
• How this bagasse is treated
• Used as a fuel
• Manufacture of tableware and dinner
ware
• Manufacture of pulp, paper, board and
feed
• Need of Anaerobic digestion

LITERATURE REVIEW
• Anaerobic digestion
• A series of biological process where microorganism break down biodegradable material in
the absence of oxygen
• Biogas is one of the end products
• Biogas is used in producing electricity
• Advantages as a Renewable Energy Source
• Simple
• Cheap
• Production is 24/7

LITERATURE REVIEW
• Factors for AD
• pH
• Temperature
• Food to microorganism ratio (SIR)
• Type of substrate
• Retention time
• C/N ratio and trace nutrients: High C/N ratio increases digestion producing
more biogas
AD
Temperat
ure
pH
Substrate
s
OLR
HRT
C/N ratio

LITERATURE REVIEW
• Factors for AD
• C/N ratio and trace nutrients
• Importance of C/N ratio in AD process
• Influences the metabolic process of the
bacteria responsible for digestion
• If high C/N ratio: High production of biogas
• If low C/N ratio: Low production of biogas
• What is the optimum ratio from literature.
• Optimum ratio of C/N is 30:1
• Different agriculture residue C/N ratio
• 24:1 for desired composition of crop
residue
• How it can be maintained at optimum ratio
• By feeding the additional substrates into
the digester to make up for the missing
parts

Aim & Objective
 Aim
• Find out which C/N ratio is best for sugarcane bagasse (both
untreated and pre-treated) in Anaerobic digestion
 Objective
• Find out which C/N ratio is best for sugarcane bagasse (both
untreated and pre-treated) in Anaerobic digestion

MATERIALS AND METHOD
• Inoculum:
• Substrate used
• Bagasse (untreated)
• Pre-treatment: 2.5% dilute H2SO4 followed by steam pre-
treatment at 130°C for 5 minutes
• Experimental setup
• BMP test
• ISR
• Temperature
• pH
• C/N ratio (15,20,25,30,35,40)
• 3 Molar Urea
Materials TS (g/kg) VS (g/kg) C/N ratio
Untreated Bagasse 930.3 807.7 164.7
Pre-treated Bagasse 510.6 470.4 200.4
Inoculum 26.7 19.9 5.9

MATERIALS AND METHOD
• Sampling and Analysis
• Bottle
• Syringe
• Manometer
• GC
• Biogas composition
• Biogas production:
• Ideal gas equation
• Methane production
• Methane yield (methane produced by gVS added)
• Kinetics (1st order kinetic equitation)

RESULTS
• Methane yield potential of sugarcane bagasse
(untreated & pre-treated) in BMP test.
0
50
100
150
200
250
300
0 5 10 15 20 25 30 35 40
Days
Treated Bagasse
15:1 20:1 25:1 30:1 35:1 40:1 Control
0
50
100
150
200
250
300
0 5 10 15 20 25 30 35 40
Cumulative Yield (m3-CH4/ton-VSadded)

RESULTS
• Methane yield potential of sugarcane bagasse (untreated &
pre-treated) in BMP test.
Untr. Bagasse Trtd. Bagasse
15:1 178.61 211.06
20:1 183.77 216.66
25:1 180.06 216.70
30:1 180.36 209.16
35:1 192.59 213.15
40:1 182.02 214.95
Control 176.26 209.76
0
50
100
150
200
250
Cumulative Yield
(m3-CH4/ton-VSadded)

RESULTS • Effect of different C/N ratio in
methane yield.
0
50
100
150
200
250
15:1 20:1 25:1 30:1 35:1 40:1 Control
Cumulative Yield
(m3-CH4/ton-VSadded
Untreated Bagasse
1.34
4.26
2.16 2.33
9.27
3.27
% increase/decrease from the
control
Untr. Bagasse (Control = 176.26 L CH4/kg-VSfed)
0
50
100
150
200
250
15:1 20:1 25:1 30:1 35:1 40:1 Control