ROCHA ET AL. (2010)

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abstract

New alternative routes for the treatment and disposal of stillage should be proposed, as fertigation could become unfeasible, due to the increasing transport costs and environmental concerns. The aim of this paper is to show the results of the application of the Life Cycle Assessment methodology for the analysis and comparison of four alternatives for stillage treatment and disposal: conventional ‘in natura’ fertigation, anaerobic digestion, concentration until 40% for fertigation and concentration until 65% for combustion in boilers using fuel oil as supplementary fuel. For the LCA study, a hypothetic Standard Sugar and Alcohol Mill was assumed with a milling capacity of 1.99 million tonnes of sugarcane per crop, producing 154,000 tonnes of sugar and 81,000 m³ of ethanol. The mill is located near the city of Sertãozinho, Brazil and local soil characteristics were also considered. The environmental evaluation results comparing the 4 alternatives of disposal are shown. The Simapro® software and the CML 2 baseline 2000 are used as support tools. Conventional and concentrated stillage fertigation alternatives have the best environmental performance. In the combustion of stillage, we considered the installation of pollution control devices for SOx and NOx with 95% efficiency. From the point of view of climate change, based on the life cycle greenhouse gases balance, the best alternative was anaerobic digestion.

Keywords: anaerobic digestion, combustion, concentration, fertigation, life cycle assessment, stillage

Empleo de la Evaluación del Ciclo de Vida (LCA) para la comparación del Comportamiento ambiental de cuatro alternativas para el tratamiento y disposición de las vinazas residuales del etanol

Es conveniente proponer nuevas rutas para el tratamiento y disposición de las vinazas residuales de la producción de etanol en cuanto la

fertirrigación puede resultar inviable debido a los incrementos de los costos de transporte y preocupaciones ambientales. El objetivo de este trabajo

es mostrar los resultados de la aplicación de la metodología de Evaluación del Ciclo de Vida (LCA, en inglés) para el análisis y la comparación de

cuatro (4) alternativas para el tratamiento y la disposición de las vinazas residuales: convencional con fertirrigación ‘al natural’, digestión anaeróbica,

concentración hasta el 40% (de sólidos) para fertirrigación y concentración a 65% para combustión en calderas empleando fuel oil como

combustible complementario. Para el estudio del LCA, se asumió un hipotético Central Productor de Azúcar y Alcohol (SSAM), con una capacidad

de molida de 1.99 millones de toneladas de caña por zafra, produciendo 154 mil toneladas de azúcar y 81 mil m³ de etanol. El central está localizado

cerca de la ciudad de Sertaozinho y se consideraron las condiciones de los suelos locales. Se presentan los resultados de la evaluación ambiental

al comparar las cuatro alternativas de disposición. Se emplearon como herramientas de soporte digital el software Simapro® y la baseline CML 2,

2000. Las alternativas de fertirrigación convencional y la de concentración tuvieron en general el mejor desempeño ambiental. En la combustión de

las vinazas consideramos la instalación de componentes de control de la contaminación, con 95% de eficiencia para SOx y NOx. Desde el punto

de vista del Cambio Climático, basado en el balance del Ciclo de Vida de Gases de Efecto Invernadero, la mejor alternativa resultó la biodigestión.

Nutzung der Lebenszyklusbewertung (LCA) zum Vergleich der Umweltleistung von vier Alternativen für die Behandlung und Entsorgung von Bioethanolschlempe

Neue alternative Methoden zur Behandlung und Entsorgung von Schlempe müssen gefunden werden, da die Fertigation aufgrund der zunehmenden

Transportkosten und Umweltbedenken undurchführbar werden könnte. Das Ziel dieses Papers besteht darin, die Resultate der Anwendung der

Lebenszyklusbewertungs-Methodik zur Analyse und zum Vergleich von vier Schlempebehandlungs- und Entsorgungsalternativen aufzuzeigen:

konventionelle in Natura Düngung, anaerobe Gärung, Konzentration auf 40% zur Fertigation und Konzentration auf 65% zur Verbrennung

in Heizkesseln unter Nutzung von Heizöl als zusätzlichem Brennstoff. Für die LCA-Studie wurde eine hypothetische Standard-Zucker- und

Alkoholmühle mit einer Mahlkapazität von 1,99 Millionen Tonnen Zuckerrohr pro Ernte unterstellt, die 154.000 Tonnen Zucker und 81.000 m³ Ethanol

produziert. Die Mühle befindet sich in der Nähe der Stadt Sertãozinho, und lokale Bodeneigenschaften wurden ebenfalls mit in Betracht gezogen.

Gezeigt werden die Umweltbewertungsergebnisse, die die 4 Entsorgungsalternativen vergleichen. Als Support-Tools werden die Software Simapro®

und die CML 2 Baseline 2000 verwendet. Konventionelle und konzentrierte Schlempe-Fertigationsalternativen haben die beste Umweltleistung. Bei

der Verbrennung von Schlempe wurde die Installation von Vorrichtungen zur Kontrolle der Verschmutzung durch SOx und NOx mit einer Effizienz von

95% erwogen. Hinsichtlich des Klimawandels ist – wenn man die Treibhausgas-Lebenszyklusbilanz zugrunde legt – Biovergärung die beste Alternative.

Use of the life cycle assessment (LCA) for comparison of the environmental performance of four alternatives for the treatment and disposal of bioethanol stillage †

By M.H. Rocha 1*, E.E.S. Lora 1, O.J. VenturinI 1, J.C.P. Escobar 1, J.J.C.S. Santos 1 and A.G. Moura 2

1 Excellence Group in Thermal Power and Distributed Generation (NEST), Federal University of Itajubá (UNIFEI) Av. BPS, 1303, Itajubá, Minas Gerais, CEP 37500-903, Brazil.2 Dedini Indústria de Base S.A. Rod. Rio Claro/Piracicaba, km 26,3, Bairro Cruz Caiada, Piracicaba, São Paulo, CEP 13412-900, Brazil.

* Contact author: Email: [email protected]

INTERNATIONAL SUGAR JOURNAL 2010, VOL. 112, NO. 1343612 www.isjbuyersguide.com

Introduction

Stillage, the most important by-product of sugarcane bioethanol production, is the aqueous by-product from the distillation of bioethanol. On an average, 8-15 litres of stillage is generated for every litre of alcohol produced.

The stillage generated from distillation of fermented mash is in the temperature range 70-80ºC, deep brown in color, acidic in nature (low pH), and has high concentration of organic materials and solids. It is a very complex, caramelized and cumbersome agro industrial waste. The pollution load of the distillery effluent depends on different aspects related to the feedstock and process (Parnaudeau et al., 2008). Stillage might be handled several ways: discharge to an adjacent waterway or land area, return to agricultural fields (fertigation), anaerobic digestion and methane production, incineration, evaporation to an animal feed or use as an aquaculture feed (Willington and Marten, 1982; Wilkie et al., 2000; Pant and Adholeya, 2007; Mohana et al., 2009).

Different processes covering anaerobic, aerobic as well as physico-chemical methods have been employed to treat this effluent. Anaerobic treatment is the most attractive primary treatment due to over 80% BOD removal combined with energy recovery in the form of biogas. Thermophilic anaerobic digestion of ethanol stillage achieves similar treatment efficiencies and methane yields compared to mesophilic treatment, but at almost twice the organic loading rate. Therefore, application of thermophilic anaerobic digestion would improve process economics, since smaller digesters and less stillage cooling are required (Wilkie et al., 2000; Satyawali and Balakrishan, 2008).

Considering the incineration route, all the organic matter can

be treated, and the inorganic matter, amounting to 6–7% of the effluent, needs to be disposed. This material can be used as a fertiliser. The concentration-incineration of stillage is the only system that can provide a satisfactory solution to the pollution problem, its only draw-back being its expensiveness (Navarro et al., 2000; Patel, 2000).

Another route along incineration process is the gasification of concentrated effluent. This process can be described as substoichiometric combustion, in which oxidation reactions between the organic matter and oxygen in the oxidant (air), and reduction reactions between the products of combustion and unconverted carbon, lead to the generation of a combustible gas called producer syngas. This can be used as a fuel in an internal combustion engine or gas turbine in single fuel or dual-fuel mode to generate electricity (Patel, 2000).

Based on net energy analysis studies, which were first published in the 1970s and following the thrust for a more holistic approach to system analysis, there has recently been a substantial development of life-cycle methodologies to assess the energetic and environmental performance of product systems from cradle-to-grave, approach to evaluate environmental performance by considering the potential impacts from all stages of manufacture, product use (including maintenance and recycling), and end-of-life management, namely life cycle energy analysis and life cycle assessment (LCA). These methodologies have been receiving increasing attention, first by researchers and product manufacturers and more recently among policy-makers (Malça and Freire, 2006).

The ISO, a worldwide federation of national standards bodies, has standardised this framework within the ISO 14040 series on

Use of the life cycle assessment (LCA) for comparison of the environmental performance of four alternatives…

Uso da avaliação do ciclo de vida (ACV) para a comparação do desempenho ambiental das quatro alternativas para o tratamento e descarte da vinhaça do bioetanol

Novas rotas alternativas para o tratamento e disposição de vinhaça deverão ser propostas, já que a fertirrigação pode se tornar inviável, devido aos

custos de transporte e aumento das preocupações ambientais. O objetivo deste artigo é mostrar os resultados da aplicação da metodologia de

Avaliação do Ciclo de Vida para a análise e comparação das quatro alternativas para o tratamento e eliminação da vinhaça: fertirrigação ‘in natura’

convencional, a digestão anaeróbia, a concentração de até 40% para a fertirrigação e concentração de até 65% para a combustão em caldeiras

que utilizam óleo combustível como combustível suplementar. Para o estudo da ACV, um engenho padrão de açúcar e álcool hipotético com uma

capacidade de moagem de 1,99 milhões de toneladas de cana por safra, produzindo 154 mil toneladas de açúcar e 81 mil m³ de etanol. A fábrica

está situada perto da cidade de Sertãozinho e as características do solo local também foram consideradas. Os resultados da avaliação ambiental

comparando as quatro alternativas de escoamento são mostrados. O programa Simapro® e o CML 2 baseline 2000 são utilizados como ferramentas

de apoio. As alternativas de fertirrigação convencional e concentrada de vinhaça têm o melhor desempenho ambiental. Na combustão da vinhaça,

considerou-se a instalação de dispositivos de controle de poluição para SOx e NOx, com 95% de eficiência. Do ponto de vista das mudanças

climáticas, com base no ciclo de vida de gases de efeito estufa, a melhor alternativa é a biodigestão.

Nomenclature

1,4-DB eq. 1,4 Dichlorobenzene equivalents

ACP Acidification Potential

ADP Abiotic Depletion Potential

CIP Clean In Place

ER Relationship between renewable energy output and fossil fuel energy input

ETP Eutrophication Potential

FEP Fresh Water Aquatic Ecotoxicity Potential

FU Functional Unit

GHG Greenhouse Gases

GWP Global Warming Potential

HTP Human Toxicity Potential

ISO International Standard Organisation

LCA Life Cycle Assessment

LCI Life Cycle Inventory

LCIA Life Cycle Impact Assessment

MEP Marine Aquatic Ecotoxicity Potential

ODP Ozone Layer Depletion Potential

POP Photochemical Oxidation Potential

SB System Boundaries

SSAM Standard Sugar and Alcohol Mill

TEP Terrestrial Ecotoxicity Potential


LCA (ISO, 1997; 1998; 1999 and 2000).Preliminary attempts of LCA application for the evaluation

and comparison among alternatives of stillage treatment were accomplished by Rocha et al. (2007) and Rocha et al. (2008).

The objective of this work is to accomplish a comparative environmental analysis between the different scenarios corresponding to different stillage treatment and disposal alternatives.

LCA methodology for this study

Definition of the goal and scope

The function of the systems of products analysed in this work relative to different alternatives for stillage treatment:• FCDCC: conventional fertigation with ‘in natura’ stillage distribution through concrete channels and dispersal on farms through diesel-fuelled motor-pumps.• ABDCC: stillage anaerobic digestion, with the biogas used for

electric power generation and the subsequent disposition of the resulting effluent on farms.• SCDTT: stillage concentration by evaporation up to 40% of solids, distribution on farms through trucks.• SCCBA: stillage concentration by evaporation up to 65% of solids, to allow incineration in a boiler, together with an auxiliary fuel for steam and electric power generation. The ashes can be used for supplementary fertilisation.

Definition of the FU and SB

The FU is 1 m³ of stillage treated/disposal. In the agricultural system, the sum of the fertigated area with application of ashes and/or the area fertilised with mineral fertilisers will be the same for the four scenarios, but the magnitude changes (Table 1).

The operations of soil preparation, herbicide application, pesticide and limestone, harvest and transport will not be considered because they are the same for all scenarios.

The capital infrastructure contributes on average less than 5% of the global impact in all the impact categories (Rocha, 2009). So the build-up stage of the systems of stillage will not be considered in this study.

A SSAM in the municipal district of Sertãozinho, State of São Paulo, Brazil, was established, hypothetically (Figure 1). The total period of operation will be 20 years, with 210 days of crop a year (4440 useful hours of operation). The milling capacity is of 1.99 Mt of sugarcane per crop, producing 0.154 Mt of sugar and 81 000 m³ of ethanol.

The predominant soil in the region is of the type Rhodic Hapludox and Typic Hapludox, with an average composition of 33.8% silt and 52.9% of clay (Alves, 2002).

Table 2 shows the main parameters adopted in process simulation. It is considered that 12.0 litres of stillage per litre of ethanol will be produced with the composition shown in Table 3 (Elia Neto and Nakahodo, 1995).

The main agricultural parameters considered for energy and emission analyses are presented in Table 4. The diesel consumption in the equipment used during conventional fertilisation, fertigation with ‘in natura’ and concentrated stillage and fertilisation with ashes was calculated starting from indicators presented by Macedo et al., 2004. It is considered that the cycle of the sugarcane consists of the plant cane and four ratoon crops with an average productivity of 87 tc/ha.

In this work, it is assumed that the stillage is applied in the plant and ratoon cane with nitrogen (48 kg/ha) and phosphorus (125 kg/ha) complementation in the plant cane (Penatti and Donzelli (2000)). The emissions originating from the mineral fertilisation were calculated by the indicators shown in Table 5.


Figure 1. Localisation of the SSAM in São Paulo State, Brazil

Parameter Considered items

FU 1 m³ of treated stillage

Reference flow 83.3 litres of ethanol

Sugarcane corresponding to the FU 1.67 tonnes of sugarcane

Fertigated and non-fertigated areas total 0.0192 ha

Allocation method Mass or energy

Impacts evaluation methodology CML 2 baseline version 2000

Data requirements Data obtained from literature

Table 1. Necessary information for inventory accomplishment

Parameter Value Units Reference

Specific sugar production 80.0 kgsugar/tc UNICA (2008)

Specific ethanol production 50.0 lethanol/tc UNICA (2008)

Bagasse production 260.0 kgbagasse/tc Ometto (2005)

Mechanical power demand of cane preparation and juice extraction 16.0 kWh/tc Hassuani et al. (2005)

Electric power demand of sugar and ethanol process 12.0 kWh/tc Hassuani et al. (2005)

Specific steam consumption 540.0 kgsteam/tc Hassuani et al. (2005)

Table 2. Parameters adopted for the process simulation


Description of evaluated scenarios

Scenario I: FCDCC - conventional fertirrigation

The stillage application rate during fertirrigation is 183 m³/ha, calculated according to CETESB (2005). The scenario I scheme is shown in Figure 2.

The mass and energy balances were calculated using the software GateCycle® (Figure 3). The steam parameters considered were 6.5 MPa and 480°C.

Information about environmental impacts to atmosphere from stillage application to soil is practically nonexistent; only CO2

emissions were considered according to Almeida (1983).

Scenario II: ABDCC - stillage digestion

The anaerobic digestion plant is composed of four internal circulation anaerobic reactors.

The generated biogas will be used in internal combustion engines for electricity generation, the resulting effluent of the

anaerobic digestion process will be applied on farms through waterproof concrete channels and the dispersal will be accomplished by diesel motor-pumps (Figure 4).

The rate of application of the digested stillage in the agricultural soil is 266 m³/ha.

It is considered that the biogas has the following composition: 60% CH4, 39% CO2 and 1% H2S. The LHV and HHV of the biogas are 18.20 MJ/kg and 20.19 MJ/kg respectively, the specific mass is 1.10 kg/m³ and the mass flow 0.593 kg/s.

The total electric power consumed by the anaerobic digestion plant is 539.0 kW and, for FU, the consumption will be 2.46 kWh.

The sizing of the power generation system was accomplished using the software Thermoflex®, and consisted of 2 motor-generators Jenbacher®, each one with a nominal power of 2.56 MW and global efficiency of 40.0% and 1 group motor-generator Wartsila® with a nominal power of 1.35 MW and efficiency of 31.0%; in that way, the groups will generate 16.82 kWh/m³ of stillage.

Scenario III: SCDTT - stillage concentration and fertirrigation

In this scenario, the stillage is concentrated by evaporation up to 40.0% solids. The design of the plant was accomplished using the software Aspen Plus® (Moura, 2008, Pers. Comm.).

In the scheme, 5 evaporation effects were considered also a condenser and a CIP system.

Figure 5 displays the outline of the cogeneration plant for this case. The efficiency of the cycle was 19.0%, therefore 173.29 kWh/m³ of stillage are generated. In the whole plant, 2430 kW are consumed; therefore, to the FU, it corresponds to 11.11 kWh.

Surplus electricity is 142.14 kWh. The allocation of the atmospheric emissions will be based on the share of generated/consumed electricity in the following way: 11.6% for the process, 6.4% for the stillage concentration plant and 82.0% for surplus electricity.

The rate of application of concentrated stillage will be 9.25 m³/ha. The fertirrigated and non-fertirrigated areas for the FU will be 0.0081 e and 0.0111 hectares, respectively (Figure 6).

Scenario IV: SCCBA - stillage concentration and incineration

The stillage is concentrated up to 65% to enable the combustion of the stillage in boilers. The design of the plant was accomplished using the software Aspen Plus® (Moura, 2008, Pers. Commun.). The ashes that result from the combustion can be used in partial substitution of the mineral fertilisers. The concentration plant will have a scheme equivalent to the one in the previous scenario; however, it should have an additional evaporation effect, having in total 6 effects (Figure 7).


Parameter BOD COD N P2O5 K2O CaO MgO MnO Fe2O3

Units mg/l

Value 16 949 28 450 356 60 2034 515 225 5 25

Table 3. Physic-chemical parameters of stillage (Elia Neto and Nakahodo, 1995)

Table 4. Basic data for sugarcane production, harvesting and transportation (Macedo et al., 2008)

Item Units Value

Sucrose % cane stalks 14.22

Fiber % cane stalks 12.73

Trash (dry basis) % cane stalks 14.00

Cane productivity tc/ha 87.0

Fertiliser utilisation

P2O5 Plant cane kg/ha 125

Ratoon cane without stillage kg/ha 25

K2O Plant cane kg/ha 117


Plant cane kg/ha 48

Nitrogen Ratoon cane with stillage kg/ha 75


Table 5. Emission factors resulting from mineral fertilisation

Released substances Quantity Reference

Emission to the air resulting from nitrogen fertilisation

CO2 3.64 kg CO2/kg N IPCC (2006)

N2O 0.05 kg N2O/kg N Crutzen et al. (2008)

NOx 0.053 kg NOx/kg N Renouf et al. (2008)

NH3 0.026 kg NH3/kg N Renouf et al. (2008)

Emissions to underground water (lixiviation)

NO3- 0.065 kg NO3

- /kg N Renouf et al. (2008

PO4-3 0.128 kg P/kg P2O5 Bloesch et al. (1997)

K+ 0.01 kg K+/kg K2O Paul et al. (1998)


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Figure 3. Steam and energy scenario of the FCDCC scenario

Figure 4. Scheme of ABDCC scenario



Figure 5. Cogeneration plant modeling results for SCDTT scenario

Figure 6. Stillage concentration plant modeling results for SCDTT scenario


Use of the life cycle assessment (LCA) for comparison of the environmental performance of four alternatives…Fi

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Results

Inventory of the consolidated life cycle

The methodology and indicators used in the LCI in this work are described in detail in Rocha (2009). Three evaluation categories were used for the evaluation of the environmental loads in LCI: energy evaluation (output/input energy relationship), GHG emissions balance

in relation to the surplus electricity exported for the public grid, and characterisation/normalisation of the environmental impacts in agreement with a specific Eco-Indicator (CML 2 baseline 2000 version 2.03).

Electricity exported as a function of the emission of CO2 equivalent

For the four appraised alternatives, the value of the electricity exported to the net was determined, and the emissions of GHG released during the system operation (emissions of the mineral fertiliser, cogeneration, use of diesel oil, decomposition of the stillage, etc.), based on the characterisation model developed by IPCC (2006).

The characterisation factors are expressed using the global warming for a horizon of 100 years (GWP100), in kg of CO2 equivalent/kg of emitted substance.

The substances considered in this study were CO2 (1.0 kg CO2 eq./kg), CH4 (23.0 kg CO2 eq./kg), CO (1.53 kg CO2 eq./kg) and N2O (296 kg CO2 eq./kg). The results are shown in Figure 8.

The smallest emissions of GHG per kWh of generated electricity correspond to the scenario ABDCC (1.92 kg CO2 eq./kWh), followed by FCDCC (2.13 kg CO2 eq./kWh), SCCBA (2.16 kg CO2 eq./kWh) and SCDTT (2.28 kg CO2 eq./kWh).

Evaluation of the energy flows (output/input relationship) of the scenarios of disposition of the stillage

In the specific case of this study, the ER relation will indicate which scenario contributes to the largest global energy recovery from stillage before the final disposition in the soil.

The amount of necessary ethanol to assist the functional unit (83.3 litres) and the electricity exported to the net were considered as exits of the system.

The outlet will be formed by the sum of the input amounts multiplied by the respective energy coefficient (Figures 9-12 and Table 6).

The alternative with the best energy performance was FCDCC (20.9), followed by ABDCC (19.1) and SCDTT (15.6). The SCCBA alternative presented an energy balance of 4.7 which is lower than that reported in the

literature for the whole production cycle of ethanol (Macedo et al., 2004). That is due to the use of fuel oil (9.66 kg fuel oil/m³ stillage) as auxiliary fuel for stillage combustion.

Characterisation and normalisation of the environmental impacts

In this stage, the potential effects caused by the environmental loads emitted in the product system are described in terms of

Figure 8. Rate of emission of CO2 in function of the electricity exported for the public net

Figure 9. Energy inputs and outputs considered for the evaluated scenarios for FCDCC

Figure 10. Energy inputs and outputs considered for the evaluated scenarios for ABDCC


consumption of natural resources, or in impacts caused to the ecosystem and human health, depending on the type of model used (midpoint or endpoint indicator).

The LCIA of the four treatment alternatives and disposition of the analysed stillage were accomplished through the use of the method CML 2 baseline 2000, with the help of the computational tool Simapro 7.0®.

Figure 13 displays a summary of the values of these categories for the disposition alternatives and treatment of the analysed stillage in percentile. Figure 14 presents a percentile comparison of the contribution of each evaluated scenario in each impact category.

In relation to the characterisation of the impacts (Figure 13), the SCDTT scenario obtained the best environmental behaviour in 5 categories, FCDCC scenario was better in 2 categories, ABDCC

scenario was better in 1 category and SCCBA was better in 1 category (Table 7).

In relation to the normalisation of the impacts (Figure 14), the CML 2 baseline 2000 considers the emissions of the equivalent substances for the year of 1995. The normalisation factors are: ADP (6.32*10-12 kg Sb eq./year), GWP (2.27*10-14 kg CO2 eq./year), HTP (1.67*10-14 kg 1,4-DB eq./year), FEP (4.83*10-13 1,4-DB eq./year), MEP (1.32*10-15 kg 1,4-DB eq./year), TEP (3.79*10-12 kg 1,4-DB eq./year), POP (9.59*10-12 kg C2H4 eq./year), ACP (3.09*10-12 kg SO2 eq./year) and ETP (7.53*10-12 PO-3

4 eq./

year). Therefore, in the global sum of all the categories, dimensionless the option of SCDTT obtained the best environmental performance (–1.14*10-11), followed by FCDCC (–1.01*10-11), ABDCC (–9.47*10-12) and SCCBA (–7.58*10-12).

Conclusions

Sustainability evaluation of biofuels is a multicriterial problem. Many issues must be further investigated, such as the ones related to fertiliser volatilisation, co-product allocation and land use impacts. The LCA methodology must be improved and normalised to ensure the same approach to difficult and different issues, and to compensate the lack of scientific understanding.

The recovery of the energy value of the stillage could be accomplished before its final disposition. In this scenario, the anaerobic digestion was shown to be quite favourable in three indicators: use of the soil, emission of GHG as a function of the generated kWh, and also in the use of abiotic resources. The energy recovery through combustion was shown to be environmentally unfavourable due to the intensive use of auxiliary fuel (fuel oil), which turned it into an unfavourable scenario from the energy point of view.

The application of LCA for evaluation of the environmental impacts caused by the stillage does not allow a complete analysis, because associated uncertainties exist about the lixiviation and volatilisation of the stillage applied to the soil. Besides, ions in the stillage, mainly potassium, phosphorus (phosphate) and the nitrogen compounds can be lixiviated for the

water table. The great obstacle in relation to the quantification of these impacts is the nonexistence of reliable information on what really happens with the stillage when it is applied to the soil.

Acknowledgement

We wish to thank the Brazilian National Research and Development Council (CNPq), the Research Support Foundation of the State of Minas Gerais (FAPEMIG) and the Coordinating Body for the Improvement of Postgraduate Studies in Higher Education (CAPES) for the funding of Research and Development projects, the support of graduate students and the production grants that allowed the accomplishment of the research projects whose results are included in this paper.


Figure 11. Energy inputs and outputs considered for the evaluated scenarios for SCDTT

Figure 12. Energy inputs and outputs considered for the evaluated scenarios for SCCBA

Scenario Renewable Fossil fuel ER energy output energy input (MJ/m³ stillage) (MJ/m³ stillage)

FCDCC 118.45 2477.36 20.9

ABDCC 133.17 2538.56 19.1

SCDTT 152.56 2372.96 15.6

SCCBA 544.16 2564.36 4.7

Table 6. Energy balance for evaluated stillage disposal and treatment scenarios



References

Almeida, M.T. (1983) Decomposição

da vinhaça incorporação ao solo

(evolução de CO2 e formação de

biomassa microbiana) e destino

da complementação nitrogenada.

Dissertação (Mestrado em Agronomia),

Escola Superior de Agricultura Luiz de

Queiroz, Universidade de São Paulo,

Piracicaba, 1983, 75 p.

Alves, M.E. (2002) Atributos

mineralógicos e eletroquímicos,

adsorção e dessorção de sulfato em

solos paulistas. Tese de Doutorado.

Universidade de São Paulo. Escola

Superior de Agricultura Luiz de Queiroz,

2002, 169 p.

Bloesch, P.M, Rayment, G.E.

and Pulsford, J.S. (1997) Regional

total phosphorus budgets for sugar

production in Queensland. Proc. Aust.

Soc. Sugar Cane Technol. 19: 213-220.

CETESB. (2005) Companhia de

tecnologia de saneamento ambiental.

Norma Técnica CETESB - P4.231.

Vinhaça - Critérios e Procedimentos

para Aplicação no Solo Agrícola

jan./2005. 17 p.

Crutzen, P.J., Mosier, A.R., Smith,

K.A. and Winiwarter, W. (2008) N2O

release from agrobiofuel production

negates global warming reduction by

replacing fossil fuels. Atmos. Chem.

Phys. 8(2): 389-395.

Elia Neto, A. and Nakahodo, T.

(1995) Resíduos sólidos da agroindústria

sucroalcooleira - revisão - Projeto n°

9100873 RT 561-92/93 CTC - Centro de

Tecnologia Copersucar, Copersucar, Piracicaba, SP, p. 60.

Hassuani, S.J., Leal, M.R.L.V. and Macedo, I.C. (2005) Biomass power

generation: sugar cane bagasse and trash. Piracicaba: PNUD-CTC. Série

Caminhos para a Sustentabilidade.

IPCC (2006) Intergovernmental Panel on Climate Change Guidelines

† Paper presented at the XXVIIth Congress of the International Society of Sugar Cane Technologists, Veracruz, Mexico, March 2010 and published here with the agreement of the Society.

Figure 13. Characterisation of the environmental impacts of the considered scenarios using the Eco-Indicator CML 2 baseline 2000

Figure 14. Percentile comparison of the contribution of each evaluated scenario in each impact category

Impacts categories Unit FCDCC ABDCC SCDTT SCCBA

ADP kg Sb eq. –0.0455 –0.0551 –0.0171 0.1430

GWP kg CO2 eq. –698.0 –703.0 –749.0 –648.0

ODP kg CFC-11 eq. 0 0 0 0

HTP kg 1,4-DB eq. 66.9 66.9 61.3 66.7

FEP kg 1,4-DB eq. 0.0203 0.0204 0.0185 0.0234

MEP kg 1,4-DB eq. 36.0 38.1 33.1 43.2

TEP kg 1,4-DB eq. 0.00031 0.00523 0.00027 0.00373

POP kg C2H2 –0.00419 0.00337 –0.00264 0.00283

ACP kg SO2 eq. 0.0103 0.1950 0.0556 0.1670 ETP kg PO4

-3 eq. 0.6430 0.6700 0.5970 0.5940

Table 7. Characterisation of the environmental impacts of the considered scenarios



for National Greenhouse Gas Inventories. Volume 4: Agriculture, forestry

and other land use. Chapter 11: N2O Emissions from managed soils, and

CO2 emissions from lime and urea application. http://www.ipcc-nggip.iges.

or.jp/public/2006gl/pdf/4_Volume4/V4_11_Ch11_N2O&CO2.pdf

(Accessed: 14 August 2009).

ISO International Organisation for Standardisation. ISO series (1997;

1998; 1999 and 2000). Environmental management - life cycle assessment

- principles and framework, ISO 14040; Goal and scope definition and life

cycle inventory analysis, ISO 14041; Life cycle impact assessment, ISO

14042; and Life cycle interpretation, ISO 14043 (ISO, Geneva).

Macedo, I.C., Leal, M.R.L.V. and da Silva, J.E.A.R. (2004) Balanço

das emissões de gases do efeito estufa na produção e no uso do etanol

no Brasil. Secretaria do Meio Ambiente, Governo de São Paulo. Abril de

2004. 19 pg. + anexos.

Macedo, I.C., Seabra, J.E.A and Silva, J.E.A.R. (2008) Greenhouse

gases emissions in the production and use of ethanol from sugarcane in

Brazil: The 2005/2006 averages and a prediction for 2020. Biomass and

Bioenergy 32(7): 582-595.

Malça, J. and Freire, F. (2006) Renewability and life-cycle energy

efficiency of bioethanol and bio-ethyl tertiary butyl ether (bioETBE):

Assessing the implications of allocation. Energy 31(15): 3362-3380.

Mohana, S., Acharya, B.K. and Madamwar, D. (2009) Distillery spent

wash: Treatment technologies and potential applications. Journal of

Hazardous Materials 163(1): 12-25.

Navarro, A.R., Sepúlveda, M. and Rubio, M.C. (2000) Bio-concentration

of vinasse from alcoholic fermentation of sugar cane molasses. Waste

Management, 20(7): 581-585.

Ometto, A.R. (2005) Avaliação do Ciclo de Vida do Álcool Etílico

Hidratado Combustível pelos Métodos EDIP, Exergia, e Emergia. Tese

(Doutorado em Engenharia Sanitária). Escola de Engenharia de São

Carlos, Universidade de São Paulo, São Carlos, 2005, 209 p.

Pant, D. and Adholeya, A. (2007) Biological approaches for treatment

of distillery wastewater: A review. Bioresource Technology 98(12): 2321-

2334.

Parnaudeau, V., Condom, N., Oliver, R., Cazevieille, P. and Recous,

S. (2008) Vinasse organic matter quality and mineralisation potential as

influenced by raw material, fermentation and concentration processes.

Bioresource Technology 99(6): 1553-1562.

Paul, J.P., Kwong, K.F.K. and Deville, J. (1998) Potassium leaching

in soils under rainfed sugar cane in Mauritius. Food and Agricultural

Research Council. AMAS 1998, Réduit, Mauritius, 71-74.

Patel, N. (2000) Studies on the Combustion and Gasification of

Concentrated Distillery Effluent. Thesis (Doctor of Philosophy). Faculty

of Engineering of Bagalore. Indian Institute of Science. Bangalore, 2000,

229 p.

Penatti, C.P. and Donzelli, J.L. (2000) Uso da Vinhaça na Lavoura de

Cana-de-açúcar. CTC - Centro de Tecnologia Copersucar, Copersucar,

Piracicaba, SP, 24 p.

Renouf, M.A., Wegener, M.K. and Nielsen, L.K. (2008) An environmental

life cycle assessment comparing Australian sugarcane with US corn and

UK sugar beet as producers of sugars for fermentation. Biomass and

Bioenergy 32(12): 1144-1155.

Rocha, M.H. (2009) Uso da Análise do Ciclo de Vida para a

Comparação do Desempenho Ambiental de Quatro Alternativas

para Tratamento da vinhaça. Dissertação (Mestrado em Engenharia

Mecânica), Instituto de Engenharia Mecânica, Universidade Federal de

Itajubá, 254 f., 2009.

Rocha, M.H., Lora, E.E.S. and Venturini, O.J. (2008). Life cycle analysis

of different alternatives for the treatment and disposal of ethanol vinasse.

Sugar Industry/Zuckerindustrie 133(2): 88-93.

Rocha, M.H., Lora, E.E.S. and Venturini, O.J. (2007) Life cycle analysis

of different alternatives for the treatment and disposal of ethanol vinasse.

Proc. Int. Soc. Sugar Cane Technol. 26: 1075-1081.

Satyawali, Y. and Balakrishnan, M. (2008)Wastewater treatment in

molasses-based alcohol distilleries for COD and color removal: A review.

Journal of Environmental Management 86(3): 481-497.

UNICA (2008) União da Indústria de Cana-de-açúcar. Dados e

Cotações - Estatísticas. See also: < http://www.unica.com.br/

dadosCotacao/estatistica/>.

Wilkie, A.C., Riedesel, K.J. and Owens, J.M. (2000) Stillage

characterisation and anaerobic treatment of ethanol stillage from

conventional and cellulosic feedstocks. Biomass and Bioenergy 19(2):

63-102.

Willington, I.P. and Marten, G.G. (1982) Options for handling stillage

waste from sugar-based fuel ethanol production. Resources and

Conservation 8(2): 111-129.

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