(563e) Evaluation of Food Waste and Paper-Cardboard Waste Blend for Biohydrogen and Methane Production Using Mixed Microbial Consortia

Evaluation
of food waste and paper-cardboard waste blend for biohydrogen and methane
production using mixed microbial consortia

Brahmaiah
Pendyala¹, Subba Rao Chaganti², Jerald A. Lalman^3*
Daniel D Heath⁴

¹Department of
Civil and Environmental Engineering, Essex Hall, University of Windsor, 401
Sunset Ave., Windsor, ON, Canada, N9B 3P4. Email: pendyala@uwindsor.ca

²Great Lakes
Institute for Environmental Research, University of Windsor, 401 Sunset Ave.,
Windsor, ON, N9B 3P4   Email: chaganti@uwindsor.ca

³*Department of
Civil and Environmental Engineering, Essex Hall, University of Windsor, 401
Sunset Ave., Windsor, ON, Canada, N9B 3P4. (Corresponding Author): +1 519 253
3000 (ext.2519), +1 519 971 3686 (fax), Email: lalman@uwindsor.ca

⁴Great Lakes
Institute for Environmental Research, University of Windsor, 401 Sunset Ave.,
Windsor, ON, N9B 3P4   Email: dheath@uwindsor.ca

Abstract

         A food waste and
paper-cardboard waste blend was used to evaluate the H₂ production
using a mixed microbial community.  At a feed concentration of 10 g COD/L, the
maximum H₂ production (34±1 mL/g COD) was observed for linoleic acid
(LA) treated cultures.  The microbial diversity data showed that Methanosarcina
sp. was dominant in the 5 g/L COD untreated culture.   In comparison,
methanogens were inhibited and the dominant populations were Lactobacillus sp.
and Clostridium sp in the LA treated cultures fed with 10 g/L COD of the
blended filtrate (food plus paper cardboard waste).  For the LA treated
cultures fed with 5 g/L COD and 10 g/L COD, the H₂ yield were
statistically the same.

Introduction

    
Urban
waste management is a key global concern because of environmental concerns such
as local pollution issues and green house gas emissions.  According to 2010
data from the United States Environmental Protection Agency (USEPA), the
estimated annual production of municipal solid waste (MSW) in the United States
(U.S.) was 250 million tonnes with approximately 136 million tonnes (54.2 %) sent
to landfills.  Conventional
landfilling practices are unsustainable because it leads to the production of
leachate and uncontrolled greenhouse gas emissions.  The organic fraction of
MSW (OFMSW) in landfills is a large renewable energy asset.  OMSW can be converted
into renewable fuels such as hydrogen and ethanol using bioprocessing technologies. 
Developing bioprocesses to produce fuels and chemicals from OMSW will reduce
the environmental pollution impact and add-value to a waste product.   Optimizing
conditions to extract free sugars and minimize the formation of microbial
inhibitory byproducts from treating OMSW using different technologies is
challenging.  In the proposed work, steam explosion is used to extract free
sugars from a synthetic OMSW and paper cardboard waste.

Materials and Experimental Methods

     Degrading a food waste plus a paper-cardboard
blend by mixed anaerobic communities into H₂ and methane was
assessed at 37ºC, at a pH set at 5.5 and different organic concentrations.  The
characteristics of municipal food waste from collection facilities are
variable; hence, a synthetic food waste was prepared to minimize compositional
variation. The waste was prepared based on unused portions of food pieces which
consisted of protein, carbohydrates, vegetables and fats. The diet composition
was in accordance with the Canada Food Guide (CFG, 2007) and thus, it was
representative of Canadian kitchen waste.  The paper and cardboard slurry samples
were prepared using 50 g paper and 50 g corrugated cardboard in 1.5 L water.  The
solid waste samples were liquefied using a domestic food blender and water was
added to prepare a slurry. The slurries were divided into three portions of
which two were heated in a steam explosion reactor in batch mode with a working
volume of 1 L. The two portions were heated separately for 1 h at 160ºC, 180ºC
and the third portion not heat treated.

Results and Discussion

     The
filtrate from heat treated and untreated samples were analysed for COD, free
reducing sugars and furfurals (Table 1).  When compared to untreated samples, the
COD concentration, the free reducing sugars and furfurals levels increased in the
steam exploded samples. With increasing temperature conditions, the COD
decreased and the free reducing sugar concentration reduced; however, the furfural
(furfural and hydroxyl methyl furfural) quantities increased in the food waste steam
exploded filtrate samples.  In contrast, the paper-cardboard waste filtrate samples
showed an increase in the COD and furfural concentration and a slight decrease
in the free reducing sugar concentration.

Table
1. Analysis of treated and untreated food and paper-cardboard waste samples

Notes:
FW180ºC = food waste treated at 180ºC; FW160ºC = food waste treated at 160ºC; PW180ºC
= paper-cardboard waste treated at180ºC; PW160ºC = paper-cardboard waste
treated at160ºC; UTFW = untreated food waste; UTPW = untreated paper-cardboard
waste  

  Because of inhibited microbial growth,
decreasing H₂ production was detected in cultures not treated with
LA but fed with the steam explosion samples treated at 180 ^oC and containing
higher furfural concentrations.  According to Modig et al. (2002), furan
derivatives are known to inhibit many metabolic pathways. The higher
concentration of furan derivatives in the samples treated at 180ºC can behave as
inhibitors and decrease the H₂ yield.  The lower COD content of 4.46
g COD/L for the paper-cardboard waste treated at 160ºC was unable to produce a
maximum H₂ yield (Ginkel et al., 2001). To eliminate the inhibitory
problem, a compromise option was developed by blending the food and
paper-cardboard waste treated at 160ºC to enhance the H₂ production
potential.  This blend was used as a feedstock for the anaerobic cultures.

      Mixed microbial anaerobic cultures
at an initial pH value of 5.5 and at 37 ^oC were treated with
linoleic acid (LA) and without LA and fed with the filtrate blend to assess
their H₂ producing capacity.  For the untreated cultures fed with 5
and 10 g COD/L of the blend, the H₂ yield reached 8.9±1 and 17±2
mL/g COD, respectively. In comparison, when the cultures were treated with LA and
5 and 10 g COD/L of the steam exploded samples, the H₂ production
was

Fig
1. Biohydogen and methane production potential of both treated and untreated cultures

Notes:
5UT = 5 g COD untreated culture; 5T = 5 g COD treated culture (LA); 10UT = 10 g
COD    untreated culture; 10T = 10 g COD treated culture (LA).

32±2 and 34±1 mL/g COD, respectively. 
The data clearly revealed that compared to higher methane producing untreated
cultures, the LA treated cultures significantly inhibited methane production by
suppressing methanogenic growth and subsequently, increasing H₂
production (Ray et al., 2008; Chaganti et al., 2011; Saady et al., 2012). 

Conclusions

     The optimum COD concentration for
higher H₂ production (34±1 mL/g COD) was observed at a feed
concentration of 10 g COD/L.  Microbial diversity data showed that Methanosarcina
sp., a methanogen, was the dominant microbial population in the 5 g/L COD untreated
culture.   In comparison, in cultures fed with 10 g/L COD of the blended
filtrate (food plus paper cardboard waste) and treated with LA, methanogens
were inhibited and the dominant populations were Lactobacillus sp.
and Clostridium sp.  The H₂ yield were statistically the
same for the LA treated cultures fed with the two different COD concentrations
(Figure 1).

REFERENCES

USEPA, 2010.
Municipal Solid Waste Generation, Recycling and Disposal in the United States:
Facts and Figs. for 2010. <http://www.epa.gov/msw/facts.htm>.

CFG, 2007. <www.hc-sc.gc.ca/fn-an/alt_formats/hpfb-dgpsa/pdf/food-guidealiment/
view_eatwell_vue_bienmang_e.pdf>.

Modig
T., Liden G., Taherzadeh M.J. (2002). Inhibition effects of furfural on alcohol
dehydrogenase, aldehyde dehydrogenase and pyruvate dehydrogenase. Biochem J,
363, 769?776.

Ginkel
S.V., Sung S., Lay J.J. (2001). Biohydrogen Production as a Function of pH and
Substrate Concentration. Environ. Sci. Technol., 35 (24), 4726?4730.

Ray
S., Chowdhury N., Lalman J.A., Seth R., Biswas N. (2008). Impact of initial pH
and linoleic acid (C18:2) on hydrogen production by a mesophilic anaerobic
mixed culture. J Environ Eng134, 110?117.

Chaganti
S.R., Kim D.H., Lalman J.A. (2011). Flux balance analysis of mixed anaerobic
microbial communities: Effects of linoleic acid (LA) and pH on biohydrogen
production. Inter J Hydrogen Energy, 36(21), 14141-14152.

Saady
N.M.C., Chaganti S.R., Lalman J.A., Heath D. (2012). Impact of culture source
and linoleic acid (C18:2) on biohydrogen production from glucose under
mesophilic conditions. Int J Hydrogen Energy. 37, 4036-4045.