Methods of research to assess biodegradability of biomass materials
Transkrypt
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 nr 10/2013 • tom 67 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 • 951 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: nr 10/2013 • tom 67 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 nr 10/2013 • tom 67 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 • 953 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. nr 10/2013 • tom 67