Prerequisite – An electrohydrolysis pretreatment for anaerobic digestion of lignocellulose waste material

doi:10.1016/j.biortech.2017.03.137

Bioresource Technology

Volume 235, July 2017, Pages 274-280

https://doi.org/10.1016/j.biortech.2017.03.137 Get rights and content

Highlights

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Electrohydrolysis pretreatment was studied to fasten the hydrolysis step.
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Pretreatment at 15 V for 45 min shows highest impact on sludge solubilization.
•
XRD, FT-IR, FESEM revealed alteration in morphological structure.
•
CH₄ production was increased from 274 ± 5 to 301 ± 4 mL CH₄/g VS after pretreatment.

Abstract

This novel work is focused on evaluating the electrohydrolysis pretreatment conditions (applied voltage and time) and anaerobic digestion process for the biological bioconversion of pulp and paper mill sludge into biogas in batch assay. The pretreatment at 15 V for 45 min shows highest impact on sludge solubilization. The XRD and FT-IR spectroscopic characterization shows the development of aliphatic, unsaturated and carbonyl carbon functionalities in the pretreated samples. FESEM picture also qualities the change in alteration of structure after pretreatment. Batch anaerobic bioreactor was carried out to determine the efficacy of electrohydrolysis pretreated and untreated pulp and paper mill sludge. The methane production potential was increased from 274 ± 5 to 301 ± 4 mL CH₄/g VS after electrohydrolysis pretreatment.

Graphical abstract

Schematic diagram of electrohydrolysis pretreatment of anaerobic digestion of lignocellulose waste material.

Introduction

An anaerobic digestion is a mature technology widely applied for bioenergy production from the sewage sludge, animal manure, agricultural residue, industrial sludge and energy crops in developing and developed countries (Li and Khanal, 2016). These substrate has high levels of biodegradable organics make it an ideal feedstock for anaerobic digestion. Due to the continuous production in the industrial level, there is a huge accumulation of waste especially in pulp and paper mill industry, the gargantuan quantity of sludge was produced. Handling and management of this produced sludge from effluent treatment plant of pulp and paper mill has account more than 60% of the total wastewater treatment plant operating cost (Monte et al., 2009, Xu and Lancaster, 2009). Jackson et al. (2000) reported the produced sludge contains 45–50% of organic fraction with high moisture content that can be treated efficiently by biological treatment than thermal treatment.

The lignocellulose material consists mainly of cellulose, hemicellulose, and lignin. Due to the inherent recalcitrant structure of lignocellulose material towards enzymatic deconstruction (Himmel et al., 2007) pretreatment is necessary to make the holocelluloses amenable to enzymatic hydrolysis and fermentation (Yang and Wyman, 2008, Sharma et al., 2015). In recent years there has been renewed interest in pretreatment of lignocellulose biomass and waste for anaerobic digestion. The several structural and compositional properties of lignocellulosic content render it resistant to biodegradation. Even though there has been an extensive research on the effect of pretreatment, the correlation between the degradability of lignocellulose material, the structural and compositional properties remains unclear and contradictory (Zheng et al., 2014). Different kinds of physical, chemical, and biological pretreatments have been proposed for the conversion of organic matter to valuable energy source as biogas (Elliott and Mahmood, 2007).

As hydrolysis is a rate-limiting step in anaerobic digestion of pulp and paper mill sludge (PPMS) (Elliott and Mahmood, 2012, Wood et al., 2009) and also in previous study by Veluchamy and Kalamdhad (2017) reported that pretreatment is necessary to fasten the hydrolysis stage because of the longer digestion time. To accelerate the hydrolysis step, a novel electrohydrolysis pretreatment was investigated. Based on literature known so for, an electrohydrolysis pretreatment has been studied first to improve the hydrolysis stage in anaerobic digestion of lignocellulose waste material. The principle of electrohydrolysis pretreatment relies on electrophoresis, ohmic heating and electroosmosis resulting in the disintegration of particles and microbial cell lysis (Zhen et al., 2014). The electrophoresis is the process in which shifting of ions relative to a static phase depending on its electrical charge and molecular size (Mahmoud et al., 2010). The process in which thermal energy is generated by passing electric current through organic materials is known as ohmic heating (Varghese et al., 2014). The motion of solid particles suspended in a liquid, under the influence of an electrical field is known as electro-osmosis (Mahmoud et al., 2010). Electrohydrolysis is the process of passing direct current (DC) through an ionic substance to solubilize the organic matter by breaking the bonds between polymers induced by application of current through electrodes. Electrodes when connected to DC one becomes positively charged electrode and another becomes negatively charged electrode. This initiates the movement of electrolyte towards electrodes i.e., positive ions move to cathode and negative ions move to anode.

To delineate the effect of electrohydrolysis pretreatment, an applied voltage (DC) and time study were performed to fasten the hydrolysis step in anaerobic digestion. Therefore, in the light of literature studies the objective of this study is to the investigate the effect of electrohydrolysis pretreatment conditions (applied voltage and time), also to elucidate the changes produced in the structure and composition of the PPMS before and after pretreatment, followed by the batch anaerobic digestion process for the biological conversion of PPMS into biogas.

Section snippets

Materials

PPMS was obtained from the Nagaon paper mill located at Jagiroad, Assam, India. PPMS collected from the filter house of effluent treatment plant was used as a substrate. Collected PPMS was stored in refrigerator at 4 °C before further use. Cow dung collected from farm present in the vicinity of Indian Institute of Technology Guwahati, North Guwahati, India, was used as the inoculum for the batch study. Table 1 shows the initial chemical characterization of substrate and inoculum.

Experimental set up

Fig. 1 gives the

Effect of sCOD and VFA with applied voltage

The effect of applied voltage with constant time on PPMS treated by DC current in electrohydrolysis pretreatment was shown in Fig 2(a). It was observed from the Fig 2(a) that the increase in applied voltage has shown increase in solubilization rate which was measured in the form of sCOD and VFA. The sCOD and VFA increased up to 15 V and then it got reduced. Further increasing the applied voltage shows decrease in sCOD and VFA. At higher applied voltage, there is a release of higher quantity of

Conclusion

The novel study revealed that electrohydrolysis pretreatment has significant effect on lignocellulose content in speedup the hydrolysis step in anaerobic digestion process. It was perceived that the organic and inorganic compounds were efficiently solubilized at 15 V for 45 min in electrohydrolysis pretreatment. Compositional and instrumental analysis such as FESEM, XRD, and FT-IR spectra showed that the electrohydrolysis pretreatment has strongly affect the lignocellulose structures. Batch study

Acknowledgement

The authors would like to thank Dr. Praveen Kumar, Department of Electronics and Electrical Engineering, Indian Institute of Technology Guwahati, for providing the laboratory facility.

References (32)

K. Dhamodharan et al.
Effect of different livestock dungs as inoculum on food waste anaerobic digestion and its kinetics
Bioresour. Technol.
(2015)
A. Elliott et al.
Pretreatment technologies for advancing anaerobic digestion of pulp and paper biotreatment residues
Water Res.
(2007)
J. Gabhane et al.
Influence of heating source on the efficacy of lignocellulosic pretreatment – a cellulosic ethanol perspective
Biomass Bioenergy
(2011)
R. Gaur et al.
Bench scale dilute acid pretreatment optimization for producing fermentable sugars from cotton stalk and physicochemical characterization
Ind. Crop. Prod.
(2016)
Y. Hu et al.
Enhancing anaerobic digestion of lignocellulosic materials in excess sludge by bioaugmentation and pre-treatment
Waste Manage.
(2016)
J. Li et al.
Lignin depolymerization/repolymerization and its critical role for delignification of aspen wood by steam explosion
Bioresour. Technol.
(2007)
A. Mahmoud et al.
Electrical field: a historical review of its application and contributions in wastewater sludge dewatering
Water Res.
(2010)
C.E. Marcato et al.
Impact of anaerobic digestion on organic matter quality in pig slurry
Int. Biodeter. Biodegr.
(2009)
M.C. Monte et al.
Waste management from pulp and paper production in the European Union
Waste Manage.
(2009)
A.K. Patel et al.
Biohydrogen production from a novel alkalophilic isolate Clostridium sp. IODB-O3
Bioresour. Technol.
(2015)

S. Sharma et al.

Pilot scale study on steam explosion and mass balance for higher sugar recovery from rice straw

Bioresour. Technol.

(2015)

D.M. Updegraff

Semimicro determination of cellulose in biological materials

Anal. Biochem.

(1969)

C. Veluchamy et al.

Biochemical methane potential test for pulp and paper mill sludge with different food / microorganisms ratios and its kinetics

Int. Biodeter. Biodegr.

(2017)

N. Wood et al.

Pretreatment of pulp mill secondary sludge for high-rate anaerobic conversion to biogas

Bioresour. Technol.

(2009)

S. Yang et al.

Lignocellulosic structural changes of Spartina alterniflora after anaerobic mono-and co-digestion

Int. Biodeter. Biodegr.

(2009)

H.P. Yuan et al.

Enhancement of waste activated sludge dewaterability by electro-chemical pretreatment

J. Hazard. Mater.

(2011)

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Prerequisite – An electrohydrolysis pretreatment for anaerobic digestion of lignocellulose waste material

Highlights

Abstract

Graphical abstract

Introduction

Section snippets

Materials

Experimental set up

Effect of sCOD and VFA with applied voltage

Conclusion

Acknowledgement

Bioresour. Technol.

Water Res.

Biomass Bioenergy

Ind. Crop. Prod.

Waste Manage.

Bioresour. Technol.

Water Res.

Int. Biodeter. Biodegr.

Waste Manage.

Bioresour. Technol.

Bioresour. Technol.

Anal. Biochem.

Int. Biodeter. Biodegr.

Bioresour. Technol.

Int. Biodeter. Biodegr.

J. Hazard. Mater.