Biomass Pre-Extraction as a Versatile Strategy to Improve Biorefinery Feedstock Flexibility, Sugar Yields, and Lignin Purity.

Feedstock flexibility is highly advantageous for the viability of (solvent-based) biorefineries but comes with the considerable challenge of having to cope with the varying nature and typically high abundance of nonlignocellulose compounds in the most readily available residual biomass streams. Here, we demonstrate that mild aqueous acetone organosolv fractionation of various complex lignocellulosic raw materials (roadside grass, wheat straw, birch branches, almond shells, and a mixed stream thereof) is indeed negatively affected by these compounds and present a versatile strategy to mitigate this bottleneck in biorefining. A biomass pre-extraction approach has been developed to remove the detrimental extractives with (aqueous) acetone prior to fractionation.

Isolation of Low Dispersity Fractions of Acetone Organosolv Lignins to Understand their Reactivity: Towards Aromatic Building Blocks for Polymers Synthesis.

Two organosolv lignins extracted during pilot runs of the Fabiola process were analyzed, fractionated and chemically modified with ethylene carbonate (EC) to produce building blocks suitable for polymer synthesis. Isolation of low dispersity fractions relied on the partial solubility of the lignins in organic solvents. Lignins solubility was first evaluated and analyzed with Hansen and Kamlet-Taft solubility parameters, showing a good correlation with the solvents dipolarity/polarizability parameter π*.

Legal situation and current practice of waste incineration bottom ash utilisation in Europe.

Almost 500 municipal solid waste incineration plants in the EU, Norway and Switzerland generate about 17.6 Mt/a of incinerator bottom ash (IBA). IBA contains minerals and metals.

Assessment of biomass ash applications in soil and cement mortars.

The pH-dependent availability and leaching of major and trace elements was investigated for a wide range of biomass ash from different fuels and conversion technologies. A technical and environmental assessment of selected biomass ash for application in soil or cement mortars was performed, using both the total content and leaching of elements. A large variation in biomass ash composition, yet consistent pH dependent leaching patterns were observed for most elements and conversion technologies.

Leaching of monolithic and granular alkali activated slag-fly ash materials, as a function of the mixture design.

This study explores the leaching of oxyanionic metalloid species (As, Mo, Se, V and Cr) from alkali activated slag-fly ash materials (AAM), dependent on various mixture parameters i.e., activator molarity, slag-fly ash precursor/binder compositions, liquid to binder ratio, curing time and strength.

Site-specific aftercare completion criteria for sustainable landfilling in the Netherlands: Geochemical modelling and sensitivity analysis.

A novel, regulatory accepted approach is developed that enables competent authorities to decide whether landfill aftercare can be reduced or terminated. Our previous paper (Brand et al., Waste Management 2016, 56, 255-261, https://doi.

When soils become sediments: Large-scale storage of soils in sandpits and lakes and the impact of reduction kinetics on heavy metals and arsenic release to groundwater.

Simulating the storage of aerobic soils under water, the chemical speciation of heavy metals and arsenic was studied over a long-term reduction period. Time-dynamic and redox-discrete measurements in reactors were used to study geochemical changes. Large kinetic differences in the net-complexation quantities of heavy metals with sulfides was observed, and elevated pore water concentrations remained for a prolonged period (>1 year) specifically for As, B, Ba, Co, Mo, and Ni.

Evaluation of the Single Dilute (0.43 M) Nitric Acid Extraction to Determine Geochemically Reactive Elements in Soil.

Recently a dilute nitric acid extraction (0.43 M) was adopted by ISO (ISO-17586:2016) as standard for extraction of geochemically reactive elements in soil and soil like materials. Here we evaluate the performance of this extraction for a wide range of elements by mechanistic geochemical modeling.

Leaching, geochemical modelling and field verification of a municipal solid waste and a predominantly non-degradable waste landfill.

In spite of the known heterogeneity, wastes destined for landfilling can be characterised for their leaching behaviour by the same protocols as soil, contaminated soil, sediments, sludge, compost, wood, waste and construction products. Characterisation leaching tests used in conjunction with chemical speciation modelling results in much more detailed insights into release controlling processes and factors than single step batch leaching tests like TCLP (USEPA) and EN12457 (EU Landfill Directive). Characterisation testing also can provide the potential for mechanistic impact assessments by making use of a chemical speciation fingerprint (CSF) derived from pH dependence leaching test results.

High performance of treated and washed MSWI bottom ash granulates as natural aggregate replacement within earth-moist concrete.

Municipal solid waste incineration bottom ash was treated with specially designed dry and wet treatment processes, obtaining high quality bottom ash granulate fractions (BGF) suitable for up to 100% replacement of natural gravel in concrete. The wet treatment (using only water for separating and washing) significantly lowers the leaching of e.g.

Life cycle assessment and residue leaching: the importance of parameter, scenario and leaching data selection.

Residues from industrial processes and waste management systems (WMSs) have been increasingly reutilised, leading to landfilling rate reductions and the optimisation of mineral resource utilisation in society. Life cycle assessment (LCA) is a holistic methodology allowing for the analysis of systems and products and can be applied to waste management systems to identify environmental benefits and critical aspects thereof. From an LCA perspective, residue utilisation provides benefits such as avoiding the production and depletion of primary materials, but it can lead to environmental burdens, due to the potential leaching of toxic substances.

Enhanced biodegradation at the Landgraaf bioreactor test-cell.

From 2001 to 2011, a bioreactor demonstration was performed in a 25,000m(3) (8m deep, 3500m(2) surface) test-cell. In this bioreactor, biodegradation was enhanced by premixing and homogenizing of waste, recirculation of leachate and aeration. Anaerobic biodegradation was completed within four years and was followed by two years of aeration.

Leaching of major and trace elements from paper-plastic gasification chars: an experimental and modelling study.

The control of soluble metal species in the sub-product leachate generated in electricity production processes is of great concern from an environmental and health point of view. Unlike fly ash, the leaching behaviour of char materials has received little attention. Yet, these solids are captured together with fly ashes in the particle control devices of power plants and are emitted in the same way as by-products.

Mechanisms contributing to the thermal analysis of waste incineration bottom ash and quantification of different carbon species.

The focus of this study was to identify the main compounds affecting the weight changes of bottom ash (BA) in conventional loss on ignition (LOI) tests and to obtain a better understanding of the individual processes in heterogeneous (waste) materials such as BA. Evaluations were performed on BA samples from a refuse derived fuel incineration (RDF-I) plant and a hospital waste incineration (HW-I) plant using thermogravimetric analysis and subsequent mass spectrometry (TG-MS) analysis of the gaseous thermal decomposition products. Results of TG-MS analysis on RDF-I BA indicated that the LOI measured at 550°C was due to moisture evaporation and dehydration of Ca(OH)(2) and hydrocalumite.

Characterisation of major component leaching and buffering capacity of RDF incineration and gasification bottom ash in relation to reuse or disposal scenarios.

Thermal treatment of refuse derived fuel (RDF) in waste-to-energy (WtE) plants is considered a promising solution to reduce waste volumes for disposal, while improving material and energy recovery from waste. Incineration is commonly applied for the energetic valorisation of RDF, although RDF gasification has also gained acceptance in recent years. In this study we focused on the environmental properties of bottom ash (BA) from an RDF incineration (RDF-I, operating temperature 850-1000°C) and a RDF gasification plant (RDF-G, operating temperature 1200-1400°C), by evaluating the total composition, mineralogy, buffering capacity, leaching behaviour (both at the material's own pH and as a function of pH) of both types of slag.

Changes in mineralogical and leaching properties of converter steel slag resulting from accelerated carbonation at low CO2 pressure.

Steel slag can be applied as substitute for natural aggregates in construction applications. The material imposes a high pH (typically 12.5) and low redox potential (Eh), which may lead to environmental problems in specific application scenarios.

Landfill sustainability and aftercare completion criteria.

Although many countries are increasing their efforts to recycle and to re-use waste materials, landfilling will still be needed in order to dispose of wastes which cannot be recycled or treated in other ways. Since landfills will most probably be present for a long time, measures will have to be taken to reduce their (long-term) emissions. The European Commission has delegated the competent authorities to decide to end aftercare and several member states have provided regulations for this purpose.

Proton binding properties of humic substances originating from natural and contaminated materials.

Humic substances (HS) are ubiquitous organic constituents in soil and water and can strongly adsorb metal contaminants in natural and waste environments. Therefore, understanding and modeling contaminant-HS interactions is a key issue in environmental risk assessment. Current binding models for HS, such asthe nonideal competitive adsorption (NICA)-Donnan model, are developed and calibrated against natural organic matter from soils and surface waters.

Carbon speciation in municipal solid waste incinerator (MSWI) bottom ash in relation to facilitated metal leaching.

The release of inorganic and organic contaminants from municipal solid waste incinerator (MSWI) bottom ash is controlled to a large extent by the release of dissolved organic carbon (DOC), and in particular by the reactive humic (HA) and fulvic acids (FA) subfractions of DOC. The properties of organic matter contributing to the release of DOC, HA and FA are, therefore, important for environmental risk assessment. In this study we have quantitatively measured the carbon speciation, and its relation with the leaching of Cu, in three fresh and carbonated MSWI bottom ash samples.

Development of an automated system for isolation and purification of humic substances.

Characterization of humic substances (HS) in environmental samples generally involves labor-intensive and time-consuming isolation and purification procedures. In this paper, the development of an automated system for HS isolation and purification is described. The novelty of the developed system lies in the way the multiple liquids and columns used in the isolation/purification procedure are handled in both forward and back-elution mode by solenoid valves.

Measurement of humic and fulvic acid concentrations and dissolution properties by a rapid batch procedure.

Although humic substances (HS) strongly facilitate the transport of metals and hydrophobic organic contaminants in environmental systems, their measurement is hampered by the time-consuming nature of currently available methods for their isolation and purification. We present and apply a new rapid batch method to measure humic (HA) and fulvic (FA) acid concentrations and dissolution properties in both solid and aqueous samples. The method is compared with the conventional procedures and is shown to substantially facilitate HS concentration measurements, particularly for applications such as geochemical modeling where HS purification is not required.

Effect of accelerated aging of MSWI bottom ash on the leaching mechanisms of copper and molybdenum.

The effect of accelerated aging of Municipal Solid Waste Incinerator (MSWI) bottom ash on the leaching of Cu and Mo was studied using a "multisurface" modeling approach, based on surface complexation to iron/aluminum (hydr)oxides, mineral dissolution/precipitation, and metal complexation by humic substances. A novel experimental method allowed us to identify that the solid/liquid partitioning of fulvic acids (FA) quantitatively explains the observed beneficial effect of accelerated aging on the leaching of Cu. Our results suggestthat iron/aluminum (hydr)oxides are the major reactive surfaces that retain fulvic acid in the bottom ash matrix, of which the aluminum (hydr)oxides were found to increase after aging.

Test method selection, validation against field data, and predictive modelling for impact evaluation of stabilised waste disposal.

In setting criteria for landfill classes in Annex II of the EU Landfill Directive, it proved to be impossible to derive criteria for stabilised monolithic waste due to the lack of information on release and release controlling factors in stabilised waste monofills. In this study, we present a scientific basis, which enables a realistic description of the environmental impact of stabilised waste landfills. The work in progress involves laboratory testing of different stabilisation recipes, pilot scale studies on site and evaluation of field leachate from a full-scale stabilisation landfill.

Indices of slowness of information processing in head injury patients: tests for selective attention related to ERP latencies.

We explored the relation between neuropsychological (attention tests involving time constraints) and neurophysiological (N2 and P3 event-related potential (ERP) latencies) indices of slowness of information processing after closed head injury (CHI). A group of 44 CHI patients performed worse than healthy controls on most neuropsychological indices, and had significantly longer ERP latencies. Significant correlations between neuropsychological measures and ERP latencies were found only for the 3 subtasks of the Stroop test.