Castro, P. M. L.

Marques, Ana P. G. C.

Paulo, Ana M. S.

English

Repositório Institucional da Universidade Católica Portuguesa

BIOMETHANE PRODUCTION FROM PHYTOREMEDIATION DERIVED MAIZE BIOMASS VIA ANAEROBIC DIGESTIONAna M. S. Paulo1, P.M.L. Castro1, Ana P.G.C. Marques11CBQF – CENTRO DE BIOTECNOLOGIA E QUÍMICA FINA, ESCOLA SUPERIOR DE BIOTECNOLOGIA, CENTRO REGIONAL DO PORTO DA UNIVERSIDADE CATÓLICA PORTUGUESA, RUA ARQUITETO LOBÃO VITAL, 4200-072 PORTO, PORTUGALAcknowledgementsThis work was supported by Programa Operacional Competitividade e Internacionalização (POCI), Fundo Europeu de Desenvolvimento Regional (FEDER), by POCI-01-0145-FEDER-006939 (Laboratory for Process Engineering, Environment, Biotechnology and Energy – UID/EQU/00511/2013) funded by the European Regional Development Fund (ERDF), throughCOMPETE2020 - Programa Operacional Competitividade e Internacionalização (POCI) and by national funds, through FCT - Fundac ̧ão para a Cie ̂ncia e a Tecnologia. The work alsohad the support of FCT through project PhytoEnergy PTDC/BTA-BTA/28761/2017. We would also like to thank the scientific collaboration under theFCT project UID/Multi/50016/2013.IntroductionSoils contaminated with heavy metals (HM) are widespread in Europe. Phytoremediation is a low cost biologically based technology attractive for soil requalification, whichestablishes a vegetation cover to stabilize the site, avoids the dispersion of contamination and simultaneously removes pollutants present in the brownfield [1]. However, the fate ofharvested biomass can be an obstacle for its implementation. The use of biomass grown in degraded and abandoned soils, not involving agricultural soils for energy crop cultivation,may increase the sustainability of utilizing biomass for bioenergy generation, while it may allow for increasing the available agricultural soil through the consequent gradualdecontamination of such brownfields. One possible solution is to use HM contaminated biomass for generating biogas. Although the information available in literature is still veryscarce, this strategy presents a considerable degree of success. Anaerobic digestion (AD), is a process in which organic matter can be decomposed by microbiota with the productionof biogas – methane rich renewable gas composed of 50 to 65% methane and 35 to 50% carbon dioxide. In this study, the main objective was to evaluate the potential of maize usedin contaminated soil bioremediation for biogas production. For this, mayze plants were grown in industrial soil, contaminated with HM (e.g., cadmium and zinc), and in agriculturalsoil, used as control soil. This work presents a novel integrated strategy comprising the utilization of maize phytoremediation derived biomass for the generation of biogas.Phytoenergy(PTDC/BTA-BTA/28761/2017)Parameter SoilRatio inoculum to substrate1:1 1:2 1:4Vmax (mL)Agricultural 21 40 67Industrial 20 40 68MPR (mL CH4 day-1)Agricultural 3 4 15Industrial 4 5 14MY(mL CH4 VS-1 day-1)Agricultural 173 192 170Industrial 146 164 174Table 1. Average values for maximum volume of methane (Vmax) producedduring the assays, initial methane production rate (MPR) and methane yield(MY), for ratios of 1:1, 1:2 and 1:4 (inoculum to substrate)MPR – average values obtained between days 1 and 2; All values determined after blanksubtractionFigure 1. Methane production (mL/assay) from anaerobic digestion of maize stalks grown inagricultural soil a) and industrial soil b) comparison between ratios inoculum to substrate (g VSS/ g VS)of 1:1, 1:2 and 1:4.Industrial soilAgricultural soila) b)Comparison between soil conditionsFigure 2. Methane production (mL/assay): comparison between ratios 1:1 a), 1:2 b) and 1:4 c) (inoculum to substrate (g VSS/ g VS)), for both soilconditions.1. Stable methane production was reached after ca. 8 days of incubation, for all assays2. More stalk, more methane → ratio 1:4 > ratio 1:2 > ratio 1:13. Initial methane production increased with increased substrate amount, independently from the soil condition, as well as final methanevolume4. This indicates that methane production is proportional to the amount of anaerobically degradable substrate5. Maximum volume of methane, initial methane production rate and methane production yield were similar between mayze grown onagricultural and industrial soil→ The anaerobic biodegradation of maize stalk was not significantly different after growth either onagricultural or industrial soil→ Maize stalk used for metals phytoremediation is a potential bioenergy source1. Maize plants were grown (5 months) in contaminated (industrial) and non contaminated soils (agricultural);2. Stalks were dried, grinded and used as substrate (carbon and energy source) for the biomethane assays (BMP);3. Inoculum → Anaerobic granular sludge from a full scale EGSB (Expanded Granular Sludge Bed) reactor, treating wastewater from a beverage company was used as inoculum;4. Different inoculum to substrate ratios (VS based) were tested → 1:1, 1:2 and 1:4;5. Biogas composition was measured using gas-chromatography.Agricultural soilIndustrial soilStalks Dried + grindedBiogas compositionRatio 1:1Agricultural soilRatio 1:2 Ratio 1:4Ratio 1:1Industrial soilRatio 1:2 Ratio 1:4Zn2+Cd2+b)a) c)MethodsResults and Conclusions[1] Marques A.P.G.C., Rangel AOSS, Castro PML (2009) Remediation of heavy metal contaminated soils: phytoremediation as a potentially promising clean-up technology. Critical Reviews Environmental Science Technology 39:622-654.References

Biomethane production from phytoremediation derived maize biomass via anaerobic digestion

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Biomethane production from phytoremediation derived maize biomass via anaerobic digestion

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