Methods of research to assess biodegradability of biomass materials

Methods of research to assess biodegradability of biomass materials

Agnieszka GUTOWSKA, Małgorzata MICHNIEWICZ, Danuta CIECHAŃSKA, Magdalena SZALCZYŃSKA
- Institute of Biopolymers and Chemical Fibers, Łódź, Poland
Please cite as: CHEMIK 2013, 67, 10, 945–954
Introduction
In many member states of the European Union, sustainable power
engineering has been developing dynamically in the recent period as
a result of implementation of ratiied ProEco documents and legislative
solutions. The small amounts of energy obtained from sustainable
sources produced in Poland to date originate in approximately 98%
from processes based on burning biomass, which, as the third most
abundant renewable energy source (RES) in the world can become an
important substitute of fossil fuels, especially coal [1, 2].
The search for, and utilization of, renewable energy sources (RES)
is an important aspect of the sustainable development idea, addressed
in the European Union policy. It is associated with the fact that mining of
conventional mineral resources and their use generates environmental
pollution. The increasing popularity of RES results, irst of all, from
environmental considerations [3, 4].
In view of slow development of wind, geothermal and solar power
engineering, water and biomass are the most important renewable
energy sources in Poland (98% of energy obtained from RES in the
year 2000). The renewable power sector in Poland has high hopes
associated with increased use of that energy source. The advent of
new technologies associated with biomass utilization, supplementing
the power management systems used to date, necessitates complex
assessment of the environmental impacts and determination of ecologic
effects obtainable by their modernization [5, 6].
Biomass in terms of legal regulations
Biomass, in the generally accepted notion, is the organic matter
contained in animals and/or plants or derived from these organisms.
Biomass usually occurs in the form of wood, straw, sludge from
wastewater treatment, or in processed forms such as biogas, production
waste and postconsumer waste from agriculture, forestry and related
industries. The most important sources of biomass include:
• forestry
• agriculture: waste and semi-inished agricultural products, energy crops
• industry, mainly wood, pulp and paper and food processing.
The fundamental legal document regulating this issue in the
European Union is the Directive 2009/28/EC of the European
Parliament and of the Council of 23 April 2009 on the promotion of
the use of energy from renewable sources. The directive contains the
following deinition of biomass: „biomass” the biodegradable fraction
of products, waste and residues from biological origin from agriculture
(including vegetal and animal substances), forestry and related industries
including isheries and aquaculture, as well as the biodegradable fraction
of industrial and municipal waste” [7].
The legislation introducing the aforementioned obligations
to produce energy from renewable sources within the national
power system in Poland is the Polish Energy Law Act [8]. The law
does not include the deinition of biomass; however, biomass is
mentioned in the deinition of a renewable energy source, whereas it
is deined in the implementing Regulation accompanying this Act [9]:
„biomass” – solid or liquid substances of vegetal and animal origin that
undergo biodegradation, originating from products, wastes and residues
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of agriculture and forestry, of industries processing products of the above
sectors, as well as biodegradable fractions of other waste and cereals
non-compliant with quality requirements for crops bought-in under public
intervention speciied in Art. 7 of the Commission Regulation (EU) No
1272/2009 of 11 December 2009 delineating the detailed rules for
implementation of the Council Regulation (EC) No 1234/2007 with
respect to purchases and sales of agricultural products within the public
intervention framework (Oficial Journal of the European Union L 349
of 29.12.2009, p. 1, as amended) and cereals not subject to buying-in
under public intervention [8].
It is notable that in the Regulation of the Minister of Economy cited
above [9] the notion of biomass, deined as: „solid or liquid substances
of vegetal and animal origin that undergo biodegradation, originating from
products, wastes and residues of agriculture and forestry, of industries
processing products of the above sectors, as well as biodegradable fractions
of other waste”, includes both wastes and products obtained on purpose.
From the point of view of energy production from biomass, it does not
matter whether waste or products are processed. Their properties,
and biodegradability in particular, are important [10].
The term „biomass” is also deined by the regulation on emission
standards of installations [11], according to which the biomass materials,
including biomass waste, are classiied as fuels: Any reference in this
Regulation to: biomass – means products consisting of vegetable matter
from agriculture or forestry incinerated to recover the energy content and
the following waste:
• vegetal from agriculture and forestry
• vegetal from the food processing industry, when the generated
heat energy is recovered
• ibrous vegetal from primary pulp production and paper production processes, if the wastes are incinerated at the place
where it arises and the generated heat energy is recovered
• cork
• wood, except for wood waste which might contain organohalogen compounds or heavy metals as a result of treatment with
wood preservatives or coating, including in particular wood waste
originating from construction and demolition waste.
The third and the most detailed deinition of biomass can be found
in the provisions of the regulation on the monitoring of emissions of
substances covered by the European Community emissions trading
scheme (EU ETS):
All and any references to biomass in this Regulation mean
a non-fossil organic material undergoing biodegradation, originating
from plants, animals, or microorganisms, as well as products, byproducts, residues and waste from agriculture, forestry and related
industrial sectors, non-mineral and biodegradable organic fractions
of industrial and communal waste, including gases and liquids
recovered in the processes of decomposition of non-fossil and
biodegradable organic material.
As it follows from the quoted deinitions, biodegradability, i.e.
capability of undergoing aerobic or anaerobic decomposition in which
microorganisms are involved is the key characteristics of biomass, which
arouses most doubts because of the lack of any regulations either in
the fundamental document – The Energy Law Act (Journal of Law of
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XIV Conference Environmental
Methods of research to assess biodegradability
of biomass materials
Classiication of biomass materials
Table 1 presents the list of materials regarded as biomass neutral
as far as CO2 emissions are concerned [12], i.e. such energetic material
that can be incinerated without contributing to the greenhouse effect
and climatic changes. Therefore, the types of biomass speciied in
the table should be covered by a support scheme in the case of their
utilization as renewable energy sources.
Table 1
Groups and types of materials regarded as biomass according to [12]
(1)
Group
speciication
(2)
Main biomass types in the group
(3)
Group 1
straw, hay, grass and leaves
Plants and their
parts
wood, roots, tree trunks, bark
crops, including maize and triticale
industrial wood waste, including post- machining and post-processing waste, waste generated by production of wooden objects and constructions, as well as of wood-derived materials
drewno poużytkowe, w tym produkty i materiały drewniane
oraz poużytkowe produkty inalne i półprodukty przetwórstwa drzewnego
wood and wood-derived waste from pulp and paper industry,
e.g. black liquor, crude tall oil, tall oil
forestry waste
Group 2
XIV Conference Environmental
2006, No. 89 item 625, as amended) [8] or in the regulations referred
to above. At the same time, all and any support for biomass energy
production in the form of origin certiicates must undoubtedly address
the actual utilization of energy contained in the biomass and not in the
contaminants which are not biodegradable. Therefore, the solution
according to which the biomass must not contain non-biodegradable
substances in the amount deviating from the known natural properties
of the particular biomass type has been adopted in the regulatory
practice concerning qualiication of biomass for energy purposes [11].
Biomass waste,
products and
by-products
lignin from processing of plants containing ligno-cellulose
animal, ish and food meal, fats, oils and animal tallow
biomass waste from production of food and drinks
edible oils and fats
animal manure
crop residues
sewage sludge
biogas produced during putrefaction, fermentation or gasiication of biomass
harbor sludge and other water pool sludge
landill gas
charcoal
Peat and fossil fractions of the aforementioned materials are not
regarded as biomass. According to the Regulation [12], no analytic
procedures to demonstrate the purity of materials classiied as
belonging to groups 1 and 2 are required unless the admixture of
other materials/fuels is clearly discernible by visual inspection or
olfactory assessment.
Susceptibility to biodegradation research and assessment
methods
No mentions concerning assessment of biomass biodegradability
can be found in the relevant world literature. The issue of biodegradation
of biomass products has been addressed in the Communication
(No 30/2011) of the President of Energy Regulatory Ofice concerning
qualiication of biomass for the energy purposes [13] as well as on many
websites devoted to climatic changes and biomass-based renewable
energy sources [14÷17].
952 •
The aforementioned Communication speciies the criteria,
according to which the fuel/waste can be regarded as biomass (solid or
liquid) suitable for energy purposes. The fuel/waste can be considered
biomass only when it undergoes biodegradation in the meaning that
it does not contain the substances that are not biodegradable to an
extent deviating from known, natural characteristics of the biomass
of the given kind, i.e. does not contain in itself non-biodegradable
“additives” not occurring naturally (for instance paints or varnish),
or to an extent exceeding the known, natural quantities of these
contaminants, for instance heavy metals or other non-biodegradable
impurities that inluence ion the combustion processes, and, therefore,
on the quantity of the certiicates of origin acquired [13].
Biodegradation is biochemical decomposition of organic compounds
to simple compounds, mediated by living organisms such as bacteria,
protozoa, actinomycetes, fungi and algae. The mechanism of that
process is very complex and involves numerous chemical and biological
reactions. In the natural environment, biodegradability is the common
characteristics of the matter of vegetal and animal origin, enabling the
matter and energy turnover in the nature. However, no material, even
a natural one, can undergo biodegradation unless the environmental
conditions are accessible for active microorganisms. The course and
rate of biodegradation processes depend on many factors, including
environmental ones (temperature, humidity, pH), availability and type
of the microorganisms involved, as well as the properties and chemical
structure of the material undergoing decomposition.
Many natural organic substances of biological origin,
deinitely classiiable as biomass, demonstrate limited susceptibility
to biodegradation, which, however, does not mean that they are not
biodegradable at all. Such substances include e.g.: lignin, long-chain
fatty acids, as well as the skeletal systems of animal organisms.
The biodegradability test methods have been developed
in connection with the growing problem of a huge amount of
postconsumer waste with high persistency in the environment, the
limited resources of fossil fuels and the global trend resultant from
these two aspects of replacing fossil fuels with renewable resources.
The organic matter of plants and animals – biomass – is the most
obvious example of renewable raw materials. All types of biomass,
by their nature, have the features of biodegradability, however,
there may be signiicant differences in the rate of biodegradation
processes depending on the environmental conditions and the
structure of the material.
Biodegradability tests are widely used in the following areas:
• development of new technologies for manufacturing environmentally
friendly products, such as: packaging and textiles
• development of new and improvement of existing techniques of
wastewater treatment and disposal of waste
• life cycle analysis and evaluation of innovative materials and
products, particularly in order to compare alternative products,
manufacturing technologies and ways of disposing of waste, and
to identify the environmental impacts
A number of methods of testing biodegradability depending on
the type of the test substance have been developed. For example, the
rules, requirements and test methods for environmentally friendly (i.e.
vegetable) oils and lubricants are relatively comprehensive. However,
there are no standardized methods for testing biodegradation of solid
biomass materials.
The accredited Biodegradation Laboratory (PCA Certiicate
No AB 388) of the Institute of Biopolymers and Chemical Fibers
developed the research procedure enabling assessment of
biodegradability of biomass materials: “Determination of the ultimate
aerobic biodegradation of biomass materials in an aqueous medium.
Determination of released carbon dioxide with an analytical method”.
The development of the procedure was based on the following
harmonized PN-EN ISO Standards:
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Determination of released CO2 by titration using barium
hydroxide Ba(OH)2 solution.
The emitted carbon dioxide (CO2) reacts with barium hydroxide
(Ba(OH)2) with precipitation of barium carbonate (BaCO3):
CO2 + Ba(OH)2 → BaCO3 + H2O
(1)
The amount of released CO2 is determined by titration of non-reacted
Ba(OH)2 with hydrochloric acid (HCl):
Ba(OH)2 + 2HCl → BaCl2 + 2H2O
(2)
The amount of released (ThCO2), expressed in milligrams, is calculated
from the following equation:
44 mg CO2
ThCO2 [mg] = X • 12mg
a • XHCl • 44
2
44 – molar weight of carbon dioxide, mol/g
a – molarity of HCl
XHCl – quantity of HCl used for titration, cm3
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Bt =
mg produced of CO2
× 100 %
mg Th CO2
(5)
where:
mgCO2 produced – the quantity of carbon dioxide released from the
investigated material, mg
mgThCO2 – the theoretical quantity of carbon dioxide released from
the investigated material, mg
The sample courses of biodegradation processes for the selected
biomass materials are presented below. The preliminary biodegradation
studies were carried out in aqueous medium using the method of carbon
dioxide release determination on waste biomass material samples such
as rape straw (sample No. 1), rye straw (sample No. 2) and hemp
straw (sample No. 3). The tested samples were obtained from the
experimental ields of the University of Agriculture in Krakow.
Prior to biodegradability assessment, the count of microorganisms
(biological activity) in the used test medium, which amounted
to 1.5x107 cfu/ml, was determined.
The course of the biodegradation processes for the selected
biomass material samples is presented in Figures 1÷3. The functions
of carbon dioxide release in time and the determined degree of
biodegradation are presented.
Fig. 1. Correlation of the released CO2 quantity and degree
of biodegradation with biodegradation time for rape straw
(3)
where:
X – quantity of carbon in the investigated material introduced into
the reactor, mg
12 – atomic weight of carbon
m – weight of the investigated material introduced into the test system, mg
mgCO2 =
Degree of biodegradation determination on the basis
of released CO2
The degree of biodegradation Bt expressed as per cent is calculated
on the basis of carbon dioxide released in each measurement interval
from the following equation:
(4)
Fig. 2. Correlation of the released CO2 quantity and degree
of biodegradation with biodegradation time for rye straw
On the basis of the obtained results of biodegradation tests
conducted for selected wood material samples, the determined degree
of biodegradation amounted to 100%. The investigated materials
were observed to be susceptible to biodegradation in the test medium
used. The preliminary biodegradation studies conducted using the
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XIV Conference Environmental
1. PN-EN ISO 14852: 2007: „Determination of the ultimate aerobic
biodegradability of polymeric materials in an aqueous medium
– Method by analysis of evolved carbon dioxide”.
2. PN-EN ISO 8192: 2007: „Water quality – Test for inhibition of
oxygen consumption by activated sludge for carbonaceous and
ammonium oxidation”.
The procedure is designed to determine the potential
biodegradability of biomass materials or to obtain information on
their biodegradability under the inluence of aerobic microorganisms
present in the natural environment. It describes the method
for determination of the emitted carbon dioxide by continuous
measurement of its quantity in time, to be used for calculating
the extent of aerobic biodegradation of biomass materials. The
test material is treated with inoculums consisting of activated
sludge, compost and soil. The extent of biodegradation studies are
conducted in simulated laboratory conditions, in an aqueous medium
using aerobic microorganisms at 20–25°C.
The test mixture contains inorganic substrate, the organic
material tested (the sole source of carbon and energy) and the
activated sludge or slurry of activated sludge, as well as soil and/or
compost as inoculums. The mixture is stirred, with simultaneous
supply of CO2 – free air for a time dependent on the kinetics of
biodegradation, not exceeding 180 days. The carbon dioxide isolated
during the microbial degradation is determined by titration using
standard solutions of barium hydroxide (Ba (OH)2) and hydrochloric
acid (HCl). The biodegradation test is considered to be correct and
complete in the case when it reaches the constant rate of carbon
dioxide release (plateau) and it can be expected that there will be no
further progress of biodegradation within the time not exceeding 180
days (6 months) of the process duration.
An important step of biodegradation studies is to assess the biological
activity (determination of the total number of microorganisms) in
the test medium used. Therefore, before the beginning of the tests
the total number of microorganisms is determined. It is required
to use the biodegradability test inoculums of appropriate biological
activity of not less than 106 cfu/ml. Biological activity is assessed in the
accredited IBCF Microbiological Laboratory (AB 388) according to the
procedure: „Determination of total microbial count in biodegradation
bath and activated sludge”.
XIV Conference Environmental
analytic respirometry method indicates that the developed research
methodology can be applicable for assessment of biodegradability
of biomass materials. However, further research addressing other
types of biomass materials, including the speciic biomass classiication
groups, should be planned.
10.
11.
12.
13.
14.
15.
16.
17.
Fig. 3. Correlation of the released CO2 quantity and degree
of biodegradation with biodegradation time for hemp straw
Conclusion
The European and Polish legal documents referred to above
have introduced the principle of promoting the use of energy coming
from renewable sources. The implementation of their provisions is
the responsibility of the member states. The institution designed for
implementation of a system promoting and supporting production
and use of energy obtained from renewable sources is the Energy
Regulatory Ofice (ERO). The duties and responsibilities of the ERO
President include, among others, issuing the certiicates of origin
conirming that the energy has been obtained from a renewable energy
source. If biomass incineration, especially utilizing vegetal material post
processing waste, is the energy source, the energy supplier is obligated
to demonstrate that the fuel contains high (approximating 100%)
percentage of the biomass fraction.
Biomass is measured and assessed according to the selective
dissolution method described in the PN-EN 15440:2011 Standard.
The accredited Biodegradation Laboratory (Accreditation Certiicate
No AB 388) of the Institute of Biopolymers and Chemical Fibers developed
a research method enabling assessment of biodegradability of biomass
materials, which has been implemented in the conducted research work.
Biodegradation studies are carried out in the aqueous medium using the
respirometric analytical method involving determination of the quantity of
carbon dioxide release in time.
References
1. Winnicka G., Tramer A., Świeca G.: Badania właściwości biomasy stałej do celów energetycznych, Instytut Chemicznej Przeróbki Węgla, Zabrze.
2. Hycnar J. J. et al.: Uwarunkowania współspalania węgla i biomasy, Polityka Energetyczna, Special issue, Vol. 6., 309, 2003.
3. Lelek Ł.: Ocena korzyści ekologicznych wynikających z wykorzystania biomasy
na cele energetyczne z zastosowaniem metodyki LCA (Life Cycle Assessment), Instytut Gospodarki Surowcami Mineralnymi i Energią, Polska Akademia Nauk,
307–314.
4. Janowicz L.: Biomasa w Polsce, Energetyka i Ekologia, No 8, 601–604, 2006.
5. Kubica K.: Spalanie biomasy i jej współspalanie z węglem, Biuletyn Ekologiczny,
No 5, 3–5, 2003.
6. Soliński I., Jesionek J.: Efekty ekologiczne współspalania biomasy z węglem kamiennym, Workshop „Współspalanie biomasy i termiczna utylizacja odpadów
w energetyce”, Kraków, 2007.
7. Directive 2009/28/EC of the European Parliament and of the Council of
23 April 2009 on the promotion of the use of energy from renewable sources
L 140/16. EN. (Oficial Journal of the European Union. 5.6.2009).
8. The Energy Law Act of 10 April 1997, uniied text (Journal of Law 2012.1059
9. Regulation of the Minister of Economy of 14 August 2008 on the detailed scope
of duties to obtain and submit to the redemption of certiicates of origin, the
954 •
substitute fee, purchase of electricity and heat from renewable energy sources
and to conirm the data on the amount of electricity produced from renewable
energy sources.
Urbaniak W.: Paliwa alternatywne-paliwa z odpadów, W trosce o naturę,
Kwartalnik recyklingowy, No 3 (20), 4, 2008.
Regulation of the Minister of Environment dated April 22, 2011 on the installation emission standards (Journal of Law 2011.95.558).
Regulation of the Minister of Environment on the monitoring of emissions of
substances covered by the European Community emissions trading scheme
(EU ETS) (Journal of Law 2008.183.1142).
Communication (No 30/2011) of the President of Energy Regulatory Ofice concerning qualiication of biomass for the energy purposes, Warsaw,
04.10.2011.
http://www.biomasa.org/index.php?d=artykul&kat=49&art=1 (30.09.2013)
http://www.politrade.pl/biomasa.html (30.09.2013)
http://komunalny.pl/index.php?name=article&op=show&id=4622
(30.09.2013)
http://www.pigeo.org.pl/?menu=przegladaj&id=62 (30.09.2013)
Agnieszka GUTOWSKA – Ph.D., (Eng.), graduated from the Environment
Protection Secondary Technical School in Tomaszów Mazowiecki. In 1996
started the undergraduate study course at the Chemical Faculty of the
Technical University of Lodz (now Lodz University of Technology), major
– chemical technology, specialization – environment protection. In 2000
obtained the title of Engineer (B.Sc.) and in 2002 completed the Master
(M.Sc.) course. In 2007, she presented a doctoral dissertation entitled „The
application of ozone and hydrogen peroxide in processes of complementary
degradation of aqueous solutions of azo dyes”, obtaining the Ph.D. degree in
technical sciences.
Employed in the Institute of Biopolymers and Chemical Fibers in Łódź
since 2007. Since 2009, the manager of the Physico-chemical Laboratory and
the Biodegradation Laboratory.
Małgorzata MICHNIEWICZ – Ph.D., (Eng.) , In the years 1967÷1972
did the Chemical Engineering course at the at the Chemical Faculty of the
Technical University of Lodz (now Lodz University of Technology), which she
completed with M.Sc. degree. In 1991, conferred with the degree of Ph.D. in
chemical sciences after presenting a dissertation entitled „Chemical circuits
control in kraft pulp mills”.
Since 1972 a research worker, irst in the Institute of Pulp and Paper, then
in the Institute of Biopolymers and Chemical Fibers in Łódź.
The main areas of her scientiic and professional activity include
environment protection in industry, especially improvements of
manufacturing technologies aiming to reduce emissions/environmental
impacts, technologies of utilization/disposal of industrial waste and biomass
waste in particular, environment-related legislation and education in the
ield of environment protection.
Danuta CIECHAŃSKA - D.Sc. (Eng.) - Director of the Institute of
Biopolymers and Chemical Fibres (since 2005), graduated from the Łódź,
University of Technology (1990) and in 1996. She defended her doctoral
thesis at the Faculty of Food Chemistry and Biotechnology, and in 2013
the Doctor Habilitatus (D.Sc.) title. She specializes in: biotechnology,
processing of biopolymers and their application in medicine, agriculture and
technology. Her research focuses on the biosynthesis of bacterial cellulose,
enzymatic modiication of biopolymers, bio-catalysis and bio-treatment of
cellulose ibers, microbiological testing of polymers, ibers and textiles. She
is the author of 95 articles in scientiic journals, 28 patents and patents
applications, 106 conference presentation and she was awerded over 100
grands for research projects. She is the member of scientiic societies in
Poland and abroad Inter alia she is the expert of European Technology
Platform EURATEX, member of the Managment Committee and Executive
EPNOE, Vice-president of the Polish Chityn Society.
Magdalena SZALCZYŃSKA – Senior Technician , graduated from
the School of Science and Industry in Łódź, with the title of chemistry
technician (1995). In the same year employed in the Institute of Biopolymers
and Chemical Fibers in Łódź. Since 2009, a member of Laboratory of
Biodegradation personnel.
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