Fate of heavy metals during fixed bed downdraft gasification of willow wood harvested from contaminated sites

Vervaeke, Pieter; Tack, Filip; Navez, F; Martin, Johnson; Verloo, Marc; Lust, Noël

doi:10.1016/j.biombioe.2005.07.001

Cited by 71 publications

(59 citation statements)

References 30 publications

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“…Some Cd has also been removed to the cathode side, probably as Cd 2+ . Following the pH decrease in the fly ash suspensions and reduction of chloride content by removal by electromigration, Cd will be removed firstly towards the anode as CdCl 4 2− and as pH decreases is removed towards the cathode as Cd 2+ [23]. Removal of Cd towards the anode was especially seen in the experiments with straw ash and Cd has previously been found to be present in untreated ash as CdCl 2 [26].…”

Section: Electrodialytic Remediation Experimentsmentioning

confidence: 93%

“…The only bi-products produced from biomass combustion are, besides flue gas condensate, ash residues rich in plant nutrients such as K, P and Mg, which ideally should be recycled as soil fertilisers and/or liming agents. However, elevated concentrations of Cd in bio ash possess potential environmental risk and restrictions in reuse as fertilizer exists [2][3][4]. In Denmark recycling of bio ashes is regulated on the basis of the content of Cd [5].…”

Section: Introductionmentioning

confidence: 99%

“…When the flue gas temperature decreases downstream of the boiler, the volatilised compounds may condense on residual fly ash particles or aerosols, which are subsequently trapped in the dust removal filters. Hence, an enrichment of Cd in the fly ashes compared to the bottom ashes during combustion of biomass has been reported [4,8]. The ash fractions that most often fail to meet the Danish regulatory demands are the fly ashes, whereas the bottom ashes often meet even the most restrictive limits [9].…”

Section: Introductionmentioning

confidence: 99%

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Electrodialytic removal of Cd from biomass combustion fly ash suspensions

Kirkelund

Damoe

Ottosen

2013

Journal of Hazardous Materials

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h i g h l i g h t sElectrodialytic remediation could be used to remove Cd from biomass fly ash suspensions. Cd limiting concentrations in the fly ash were met for reuse as fertilizer. pH below 2 in the fly ash suspension was determining the effectiveness for Cd removal. a r t i c l e i n f o a b s t r a c tDue to relatively high concentrations of Cd, biomass combustion fly ashes often fail to meet Danish legislative requirements for recycling as fertilizer. In this study, the potential of using electrodialytic remediation for removal of Cd from four different biomass combustion fly ashes was investigated with the aim of enabling reuse of the ashes. The ashes originated from combustion of straw (two ashes), wood chips, and co-firing of wood pellets and fuel oil, respectively. A series of laboratory scale electrodialytic remediation experiments were conducted with each ash. The initial Cd concentration in the ashes varied between 8.8 mg Cd/kg (co-firing ash) and 64 mg Cd/kg (pre-washed straw ash), and pH varied from 3.7 (co-firing ash) to 13.3 (wood ash). In spite of such large variations between the ashes, the electrodialytic method showed to be sufficiently robust to treat the ashes so the final Cd concentration was below 2.0 mg Cd/kg DM in at least one experiment done with each ash. This was obtained within 2 weeks of remediation and at liquid to solid (L/S) ratios of L/S 16 for the pre-washed straw ash and L/S 8 for the straw, co-firing and wood ash.

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Section: Electrodialytic Remediation Experimentsmentioning

confidence: 93%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Electrodialytic removal of Cd from biomass combustion fly ash suspensions

Kirkelund

Damoe

Ottosen

2013

Journal of Hazardous Materials

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“…Vervaeke et al [32] illustrated the design of a small-scale pilot plant downdraft gasifier equivalent to 100 kW of electricity generation. The downdraft unit used in this study is a pilot scale of the Xylowatt gasifier.…”

Section: Biomassmentioning

confidence: 99%

Review of Biomass Thermal Gasification

Hamad¹,

Radwan²,

AshrafAmin³

2017

Biomass Volume Estimation and Valorization for Energy

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Gasification of biomass is one of the most attractive methods for producing hydrogen rich gas. Syngas production from biomass is an attractive solution for energy crisis. The production of energy from biomass reduces the dependence of developing countries on fossil fuels, as ample biomass is available in the developing countries and is renewable. Downdraft gasifiers are fixed bed gasifiers where the gasifying agent and biomass are flowing downwards, developed for high-volatile fuels such as wood or biomass gasification. Cocurrent flow regime throughout the oxidation and reduction zones reduces the tars and particulates in syngas, which will reduce the necessity of complicated cleaning methods compared to updraft gasifiers especially if the gas is used as a burnable gas in a small community. It is important to ensure homogenous distribution of gasifying agent at the downdraft gasifier throat. This chapter presents latest trends in gasification of biomass using downdraft gasification.

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“…Furthermore, the residual lignin content (15-20%) (Ververis et al, 2004) could be of interest for compost production or other high-value materials such as lignin-based resin coatings and N o n -c o m m e r c i a l u s e o n l y composites (Piccolo et al, 1997;Park et al, 2008). If high levels of metals in the phytoextracting biomasses do not allow any other uses, the most environmentally-safe solution is the production of energy from combustion or pyro-gasification (Chen et al, 2004;Vervaeke et al, 2006;Lievens et al, 2008) followed by metal recovery from the molten fly ashes by using hydrometallurgical routes, such as the carried-inpulp method proposed by Alorro et al (2008).…”

Section: Introductionmentioning

confidence: 99%

Assisted phytoextraction of heavy metals: compost and Trichoderma effects on giant reed (Arundo donax L.) uptake and soil N-cycle microflora

et al. 2013

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Little information is available as to the real effectiveness of the phytoextraction remediation technique, since laboratory experiments are still the most common way in which this is measured. Given this, an experiment on a cadmium-polluted soil was carried out in open field conditions in Southern Italy with the aim of assessing the growth and the phytoextraction potential of giant reed (Arundo donax L). Compost fertilisation and Trichoderma harzianum A6 inoculations were used to verify the possibility of increasing the metal uptake of the crop. Biomass yield of giant reed in the first growth season (average 12.8 Mg ha -1 ) was not affected by the Cd concentration in the soil and this increased significantly with compost fertilisation (13.8 Mg ha -1 ). Both compost fertilisation and T. harzianum inoculation increased cadmium uptake and translocation in leaves. Nitrifying bacteria was shown to be a useful tool to biomonitor soil quality. These results proved the suitability of the giant reed for assisted-phytoremedation with the use of compost fertilisation and T. harzianum. IntroductionThe extent of soil pollution by potentially toxic elements (PTE) in industrialised areas is well documented (Glass, 1998;Black, 1999) and represents an important environmental concern due to their potential accumulation in the food chain. Human activities such as industrial plants, mining, road transport and the unwise application of sewage sludges, fertilisers and pesticides to agricultural soils are recognised to be the main sources of PTE pollution (do Nascimento et al., 2006;Lado et al., 2008). A large number of methods are available to remediate soils, such as soil washing with synthetic surfactants. However, these are extremely expensive, such that a large number of sites remain contaminated (Ensley, 2000). Moreover, ex situ soil reclamation techniques lead to a big reduction in soil fertility due to the soil disturbance and to the toxicity of synthetic surfactants. Soil washing with humic substances extracted from composted organic matter or from geochemical deposits represents a reliable alternative (Conte et al., 2005) and phytoextraction is a valuable complementary technique. It is low cost and environmentally safe (Wu et al., 2006) and is able to both remove heavy metal pollutants from the soil and to offer important economic and agronomic advantages (Mattina et al., 2003). It involves the utilisation of plants to remove heavy metals from soil and concentrate them in the biomass. For years now, metal hyperaccumulating plants such as Alyssum murale, Berkheya coddii, Brassica juncea and Thlaspi caerulescens have been considered the most suitable tool to decontaminate metal-polluted soils, but the low biomass growth and scarce ability to accumulate various different metals together (Krämer, 2005) have discouraged their inclusion in commercial phytoextraction protocols (do Nascimento et al., 2006). Consequently, the current trend is to use fast-growing high biomass crops that accumulate moderate levels of metals in ...

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Fate of heavy metals during fixed bed downdraft gasification of willow wood harvested from contaminated sites

Cited by 71 publications

References 30 publications

Electrodialytic removal of Cd from biomass combustion fly ash suspensions

Electrodialytic removal of Cd from biomass combustion fly ash suspensions

Review of Biomass Thermal Gasification

Assisted phytoextraction of heavy metals: compost and Trichoderma effects on giant reed (Arundo donax L.) uptake and soil N-cycle microflora

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