1. Characteristics of inoculum and feedstock
References
Somashekar, R. K. et. al Potential of biogas production from food waste in a uniquely designed reactor under lab conditions. The 1st IWWG-ARB Symposium, March 2013, Hkkaido Univeristy, Japan.
Kalra, M. S. and J. S. Panwar Anaerobic digestion of rice crpe residues. Agicultural Waste 17:
Maria et. al Co-treatment of fruit and vegetable waste in sludge digesters. An analysis of the relationship among bio-methane generation, process stability and digestate phytotoxicity. Waste management,
Okeh et. al Biogas production from rice husks generated from various rice mills Ebonyi State, Nigeria. Renewable Energy, 62:
Continuous High Solids Co-Digestion of Food Waste and Rice Husk under Mesophilic Conditions at Pilot Scale
Maliha Jabeen a, Zeshan a*, Sohail Yousaf a
a Department of Environmental Sciences, Quaid-i-Azam University, Islamabad 45320, Pakistan ( *Project Supervisor, Corresponding Author,
Introduction
Materials and Methods
Food and agriculture waste management is one of the biggest challenges faced by many countries.
Anaerobic digestion is a good option to produce biogas (energy) and reduce food and agriculture waste
But mono digestion of food waste leads to abundant VFA production due to high biodegradability (low C/N ratio) & inhibits methanogenesis
Rice husk having low biodegradability (high C/N ratio) is an abundantly produced agricultural waste, and could be used as co substrate for smooth digestion of food waste
Substrate Used
Food waste (56 %)
Rice husk (44 %) +
Experimental Conditions
C/N ratio = 28
Temperature = 37 ℃
Organic loading rates (OLRs) 5, 6, 9 gVS/L/d
Research Objectives
To investigate effectiveness of co-digestion of food waste and rice husk for management of waste at large scale under high solids conditions
To determine the effect of different organic loading rates of feedstock mixture on digester stability and performance
Experimental Setup
Results
Characteristics of inoculum and feedstock
Parameters
Inoculum
Food waste
Rice husk
Mixture
TS (%)
13.79
27.45
90.00
52.97
VS (% TS)
87.70
91.99
81.09
84.80
TC (% TS)
37.60
51.10
45.03
48.72
TN (%TS)
2.80
3.04
1.17
1.74
Optimum range for VFA/Alkalinity
0.1 – 0.25
(Maria et. al., 2014)
Optimum pH range for anaerobic single phase digestion
(Jiunn-Jyi et. al., 1997)
VFA, alkalinity and VFA/ALK ratio at different OLRs
pH of the digestate at different phases
Reported GPR from anaerobic mono digestion
Rice husk = 1.2
(Karla and Panwar, 1986)
Rice husk dilution at 1:6 w/v = 0.4
(Okeh et. al., 2014)
Food waste = 3.4
(Somashekar et. al., 2013)
VS removal by anaerobic mono- digestion
Food waste= 50.6%
SBY by anaerobic mono-digestion
Rice husk = 47.8
(Karla and Panwar, 1986)
Food waste=780.1
(Somashekar et. al., 2013)
82.41%; %; %;
Specific biogas yield and VS removal at different OLR
Gas production rate at different OLRs
Conclusion
Stable functioning of the digester as VFA/ALK ratio and pH were within the optimum range.
High volatile solid removal (71-86 %)
Co-digestion of food waste and rice husk maintained satisfactory performance of the reactor under high OLR (9 gVS/L/d)