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Solid residues from thermal treatments of sewage sludge (SS) represent a valuable source of phosphorus (P) for the fertilizer production. This study aims at evaluating the P recovery potential from solid residues obtained from wet air oxidation of SS under subcritical water conditions (WAO residues). A series of P extraction experiments was performed by acidic and alkaline leaching at different liquid to solid ratios. Hot chemical extractions and P fractionations were also carried out to characterize the chemical composition of the WAO residues. The main objectives of this work were to determine the best operating conditions for P extraction, and to describe and understand the kinetics and the main mechanisms leading to P release. The results obtained in this study indicate that 1 M citric acid and 1 M HCl at the liquid to solid ratio of 10 L/kg can extract 61% and 65% of the total P content after 2 h of contact time at room temperature, thus giving P extraction capacities of 81 and 86 g P/kg WAO residues, respectively. The analysis of kinetic data indicates that P extraction with 1 M HCl is faster, but 1 M citric acid can give higher P extraction efficiencies at the equilibrium. The molar ratios of Ca to P of the leachates suggest that P extraction from WAO residues was primarily due to the dissolution of a mixture of various Ca-P complexes., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Management options for digestate produced by anaerobic digestion plants influence the environmental and economic sustainability of the biogas sector. Further, digestate can be both used or disposed of according to its legal classification: that is, waste or by-product, or product (by using End of Waste procedure). Currently, legal digestate status is decided by EU member states on a case-by-case basis, according to specific positive lists of input feedstocks and quality requirements in terms of physical properties and chemical concentrations. Biased exclusion of input feedstock can force digestate to a specific waste classification and undergo post-treatment and disposal options that can negatively affect the profitability of biogas installations. This is the case of the Italian regulation, where the positive list of input feedstock excludes a priori separately collected organic fractions of municipal solid waste (OFMSW), while including agro-industrial residues (AGRO). This study determined the differences between the two digestate typologies (OFMSW versus AGRO) through statistical analysis, implemented on a dataset, designed to gather data about digestate's physical-chemical parameters from relevant scientific literature and unpublished private databases. The datasets consisted of 190 entries, derived from more than 2,000 samples. Further, the study provided a compliance assessment between the resulting parameter means and the current regulation limits. Upper confidence limits for the means (level of significance α = 0.05) calculated for both digestate typologies were found to be compliant with the legal requirements. Therefore, no statistical ratio seems to support the difference in the legislative approach as proposed by Italian law-makers. OFMSW resulted significantly different from AGRO for VS (650.1 g/kg TS vs. 843.8 g/kg TS, respectively), N-NH4 (81.9 g/kg TS vs. 46.19 g/kg TS), N-TOT (109.7 g/kg TS vs. 65.32 g/kg TS), P-TOT (7.22 g/kg TS vs. 21.9 g/kg TS), Pb (18.6 mg/kg TS vs. 4.66 mg/kg TS), Ni (11.03 mg/kg TS vs. 8.20 mg/kg TS), Cr-TOT (12.74 mg/kg TS vs. 8.74 mg/kg TS) and Hg (0.08 mg/kg TS vs. 0.05 mg/kg TS). However, the statistical analysis must be implemented on a wider set of parameters not covered by this study (e.g. ecotoxicological features)., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Significant knowledge and data gaps associated with the fate of product-embedded engineered nanomaterials (ENMs) in waste management processes exist that limit our current ability to develop appropriate end-of-life management strategies. This review paper was developed as part of the activities of the IWWG ENMs in Waste Task Group. The specific objectives of this review paper are to assess the current knowledge associated with the fate of ENMs in commonly used waste management processes, including key processes and mechanisms associated with ENM fate and transport in each waste management process, and to use that information to identify the data gaps and research needs in this area. Literature associated with the fate of ENMs in wastes was reviewed and summarized. Overall, results from this literature review indicate a need for continued research in this area. No work has been conducted to quantify ENMs present in discarded materials and an understanding of ENM release from consumer products under conditions representative of those found in relevant waste management process is needed. Results also indicate that significant knowledge gaps associated with ENM behaviour exist for each waste management process investigated. There is a need for additional research investigating the fate of different types of ENMs at larger concentration ranges with different surface chemistries. Understanding how changes in treatment process operation may influence ENM fate is also needed. A series of specific research questions associated with the fate of ENMs during the management of ENM-containing wastes have been identified and used to direct future research in this area., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Different ecotoxicological test batteries and concentration limits have been proposed to assess the hazard property (HP) HP 14 'Ecotoxic' for waste in the European Union and its member states. In test batteries, if the concentration of waste in the culture/dilution medium producing 50% of inhibitory biological effect in one or more test(s) is below the concentration limit of the test, the waste is classified as hazardous. A summarized review of the test batteries proposed since 1998 is presented. The last proposed test battery uses seven aquatic and terrestrial species with standardized methods, but with options and uniform concentration limits of 10% of waste eluate or solid waste in the culture/dilution medium. No attempt was made to match this hazard assessment with the classification made in the European List of Waste (LoW). The aim of this paper is to propose for the same test battery (reduced to 6 tests without options) concentration limits that match with the European List of Waste. This list was taken as reference (despite the fact that waste can be hazardous for other properties than the most frequent HP 14, and its partly political nature for some opinions). The concentration limits (CLs) for tests are the concentrations producing the highest ecotoxicological effects for each test observed in a non-hazardous waste set. Data from Germany, France and Belgium (from in total 5 different sources from 2009 to 2016) with the above-mentioned test battery (without options) were gathered for 81 samples, being the largest set ever published. In total, ten non-hazardous (NH) waste samples (as defined by the LoW and for most of them checked by chemical composition) were used to establish CLs. These CLs were then applied to 13 hazardous (H) waste by the LoW, and all were classified as hazardous. The matching of the resulting classification with the LoW is convincing. For the 58 'mirror entries' in the LoW (hazardous or not depending of the presence of hazardous substances), 37 were classified H (64%) and 21 were classified NH (36%). These concentration limits can be refined with the method proposed here, as soon as additional data of NH waste (by list and by composition) are available. The test battery (without options) and the concentration limits (in percent of waste in the culture/dilution medium) proposed are the following: A waste is hazardous for HP 14 'Ecotoxic' if the concentration of waste (eluate or solid) in the culture/dilution medium producing 50% of biological effect relative to the control EC 50 -30 min of Vibrio fischeri (EN ISO 11348-3) is lower than 15.8%, or if the EC 50 -72 h of Pseudokirchneriella subcapitata (EN ISO 8692) is lower than 7.03%, or if the EC 50 -48 h of Daphnia magna (EN ISO 6341) is lower than 7.95%, or if the EC 50 -6h of Arthrobacter globiformis (ISO 18187) is lower than 2.25%, or if the EC 50 -14d of Brassica rapa (EN ISO 11269-2) is lower than 13.7%, or if the EC 50 -48 h of Eisenia fetida avoidance test (ISO 17512-1) is lower than 3.75%. These CLs range between 2% and 16%, which is in line with the typically 10% concentration proposed without validation. To fix regulatory concentration limits, the regulators can use these CLs and the uncertainty of the ecotoxicological tests (standard deviation of inter-laboratory reproducibility typically of 25% of the mean, as published in the standards). Classification of waste for HP 14 with these tests and concentration limits will agree with the European List of Waste., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

The plastics of waste of electric and electronic equipment (WEEE) are improved for fire safety by flame retardants, and particularly brominated flame retardants (BFR). As waste, the management of these plastic fractions must comply with the update of the regulation of waste hazard classification (2014, 2017), the publication of a technical standard on management of WEEE (2015), and a restriction of use for decabromodiphenylether in the product regulation (2017). Data of bromine (n=4283) and BFR concentrations (n=98) in plastics from electric and electronic equipment (EEE), and from WEEE processing facilities before and after sorting for bromine in four sites in France have been studied for chemical composition and for regulatory classification. The WEEE was analysed by handheld X-ray fluorescence, and the waste was sorted after shredding, by on-line X-ray transmission for total bromine content (< or > 2000 mg/kg) in small household appliances (SHA), cathode ray tubes (CRT) and flat screens plastics. In equipment (n=347), 15% of the equipment items have no bromine, while 46% have at least one part with bromine, and 39% have all parts brominated. The bromine concentration in plastics is very heterogeneous, found in high concentrations in large household appliance (LHA) plastics, and also found in unexpected product categories, as observed by other authors. Clearly, an unwanted global loop of brominated substances occurs via the international recycling of plastic scrap. In waste (n=65), polybromobiphenyls, polybromodiphenylethers (PBDE), tetrabromobisphenol A (TBBPA) and hexabromocyclododecane were analysed. The most concentrated BFRs are decaBDE (3000 mg/kg) and TBBPA (8000 mg/kg). The bromine concentration of regulated brominated substances was identified in 2014 and 2015 to be up to 86% of total bromine in "old" waste (SHA, CRT), 30-50% in "younger" waste (Flat screens), and a mean of only 8% in recent products (2009-2013). Regulated substances are a minority of all the brominated substances and the only practical way to sort is to measure total bromine on-line. The sorting reduces the mean bromine concentration in the "Low Br" fraction in all sites, and reduces the decaBDE concentration to levels below the restricted use limit. After sorting, the concentration in the "High Br" fractions exceeds all present or future regulatory limits. In conclusion, sorting of small household appliances, cathode ray tubes and flat screen plastics is necessary to avoid uncontrolled dispersion of regulated substances in recycled raw material. Other categories (large household appliances, electric and electronic tools, lighting equipment) should also be considered, since their total bromine content (unweighted mean concentration) is high for some of these products. A European campaign consisting of 7 countries and 35 sites will begin in 2017, directed by WEEE Forum, the European association speaking for thirty-one not-for-profit e-waste producer responsibility organisations, to assess the mean bromine content of plastics from large household appliances after shredding., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

A stepwise method for assessment of the HP 12 is proposed and tested with 49 waste samples. The hazard property HP 12 is defined as "Release of an acute toxic gas": waste which releases acute toxic gases (Acute Tox. 1, 2 or 3) in contact with water or an acid. When a waste contains a substance assigned to one of the following supplemental hazards EUH029, EUH031 and EUH032, it shall be classified as hazardous by HP 12 according to test methods or guidelines (EC, 2014a, 2014b). When the substances with the cited hazard statement codes react with water or an acid, they can release HCl, Cl 2 , HF, HCN, PH 3 , H 2 S, SO 2 (and two other gases very unlikely to be emitted, hydrazoic acid HN 3 and selenium oxide SeO 2 - a solid with low vapor pressure). Hence, a method is proposed:For a set of 49 waste, water addition did not produce gas. Nearly all the solid waste produced a gas in contact with hydrochloric acid in 5 min in an automated calcimeter with a volume >0.1L of gas per kg of waste. Since a plateau of pressure is reached only for half of the samples in 5 min, 6 h trial with calorimetric bombs or glass flasks were done and confirmed the results. Identification of the gases by portable probes showed that most of the tested samples emit mainly CO 2 . Toxic gases are emitted by four waste: metallic dust from the aluminum industry (CO), two air pollution control residue of industrial waste incinerator (H 2 S) and a halogenated solvent (organic volatile(s) compound(s)). HF has not been measured in these trials started before the present definition of HP 12. According to the definition of HP 12, only the H 2 S emission of substances with hazard statement EUH031 is accounted for. In view of the calcium content of the two air pollution control residue, the presence of calcium sulphide (EUH031) can be assumed. These two waste are therefore classified potentially hazardous for HP 12, from a total of 49 waste. They are also classified as hazardous for other properties (HP 7, 10and14 for one of them, and HP 10and14 for the other one respectively). Given these results, it can be assumed that few common household and industrial waste will be classified hazardous only by HP 12., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Legislation published in December 2014 revised both the List of Waste (LoW) and amended Appendix III of the revised Waste Framework Directive 2008/98/EC; the latter redefined hazardous properties HP 1 to HP 13 and HP 15 but left the assessment of HP 14 unchanged to allow time for the Directorate General of the Environment of the European Commission to complete a study that is examining the impacts of four different calculation methods for the assessment of HP 14. This paper is a contribution to the assessment of the four calculation methods. It also includes the results of a fifth calculation method; referred to as "Method 2 with extended M-factors". Two sets of data were utilised in the assessment; the first (Data Set #1) comprised analytical data for 32 different waste streams (16 hazardous (H), 9 non-hazardous (NH) and 7 mirror entries, as classified by the LoW) while the second data set (Data Set #2), supplied by the eco industries, comprised analytical data for 88 waste streams, all classified as hazardous (H) by the LoW. Two approaches were used to assess the five calculation methods. The first approach assessed the relative ranking of the five calculation methods by the frequency of their classification of waste streams as H. The relative ranking of the five methods (from most severe to less severe) is: Method 3>Method 1>Method 2 with extended M-factors>Method 2>Method 4. This reflects the arithmetic ranking of the concentration limits of each method when assuming M=10, and is independent of the waste streams, or the H/NH/Mirror status of the waste streams. A second approach is the absolute matching or concordance with the LoW. The LoW is taken as a reference method and the H wastes are all supposed to be HP 14. This point is discussed in the paper. The concordance for one calculation method is established by the number of wastes with identical classification by the considered calculation method and the LoW (i.e. H to H, NH to NH). The discordance is established as well, that is when the waste is classified "H" in the LoW and "NH" by calculation (i.e. an under-estimation of the hazard). For Data Set #1, Method 2 with extended M-factors matches best with the LoW (80% concordant H and non-H by LoW, and 13% discordant for H waste by LoW). This method more correctly classifies wastes containing substances with high ecotoxicity. Methods 1 and 3 have nearly as good matches (76% and 72% concordant H and non-H by LoW, and 13% and 6% respectively discordant for H waste by LoW). Method 2 with extended M-factors, but limited to the M-factors published in the CLP has insufficient concordance (64% concordant H and non-H by LoW, and 50% discordant for H waste by LoW). As the same method with extended M-factors gives the best performance, the lower performance is due to the limited set of M-factors in the CLP. Method 4 is divergent (60% concordant H and non-H by LoW, and 56% discordant for H waste by LoW). For Data Set #2, Methods 2 and 4 do not correctly classify 24 air pollution control residues from incineration 19 01 07(∗) (3/24 and 2/24 respectively), and should not be used, while Methods 3, 1 and 2 with extended M-factors successfully classify 100% of them as hazardous. From the two sets of data, Method 2 with extended M-factors (corresponding more closely to the CLP methods used for products) matches best with the LoW when the LoW code is safely known, and Method 3 and 1 will deviate from the LoW if the samples contain substances with high ecotoxicity (in particular PAHs). Methods 2 and 4 are not recommended. Formally, this conclusion depends on the waste streams that are used for the comparison of methods and the relevancy of the classification as hazardous for ecotoxicity in the LoW. Since the set is large (120 waste streams) and no selection has been made here in the available data, the conclusion should be robust., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Hazard classification of waste is a necessity, but the hazard properties (named "H" and soon "HP") are still not all defined in a practical and operational manner at EU level. Following discussion of subsequent draft proposals from the Commission there is still no final decision. Methods to implement the proposals have recently been proposed: tests methods for physical risks, test batteries for aquatic and terrestrial ecotoxicity, an analytical package for exhaustive determination of organic substances and mineral elements, surrogate methods for the speciation of mineral elements in mineral substances in waste, and calculation methods for human toxicity and ecotoxicity with M factors. In this paper the different proposed methods have been applied to a large assortment of solid and liquid wastes (>100). Data for 45 wastes - documented with extensive chemical analysis and flammability test - were assessed in terms of the different HP criteria and results were compared to LoW for lack of an independent classification. For most waste streams the classification matches with the designation provided in the LoW. This indicates that the criteria used by LoW are similar to the HP limit values. This data set showed HP 14 'Ecotoxic chronic' is the most discriminating HP. All wastes classified as acute ecotoxic are also chronic ecotoxic and the assessment of acute ecotoxicity separately is therefore not needed. The high number of HP 14 classified wastes is due to the very low limit values when stringent M factors are applied to total concentrations (worst case method). With M factor set to 1 the classification method is not sufficiently discriminating between hazardous and non-hazardous materials. The second most frequent hazard is HP 7 'Carcinogenic'. The third most frequent hazard is HP 10 'Toxic for reproduction' and the fourth most frequent hazard is HP 4 "Irritant - skin irritation and eye damage". In a stepwise approach, it seems relevant to assess HP 14 first, then, if the waste is not classified as hazardous, to assess subsequently HP 7, HP 10 and HP 4, and then if still not classified as hazardous, to assess the remaining properties. The elements triggering the HP 14 classification in order of importance are Zn, Cu, Pb, Cr, Cd and Hg. Progress in the speciation of Zn and Cu is essential for HP 14. Organics were quantified by the proposed method (AFNOR XP X30-489) and need no speciation. Organics can contribute significantly to intrinsic toxicity in many waste materials, but they are only of minor importance for the assessment of HP 14 as the metal concentrations are the main HP 14 classifiers. Organic compounds are however responsible for other toxicological characteristics (hormone disturbance, genotoxicity, reprotoxicity…) and shall be taken into account when the waste is not HP 14 classified., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

The potential colloids release from a large panel of 25 solid industrial and municipal waste leachates, contaminated soil, contaminated sediments and landfill leachates was studied. Standardized leaching, cascade filtrations and measurement of element concentrations in the microfiltrate (MF) and ultrafiltrate (UF) fraction were used to easily detect colloids potentially released by waste. Precautions against CO(2) capture by alkaline leachates, or bacterial re-growth in leachates from wastes containing organic matter should be taken. Most of the colloidal particles were visible by transmission electron microscopy with energy dispersion spectrometry (TEM-EDS) if their elemental MF concentration is greater than 200 μgl(-1). If the samples are dried during the preparation for microscopy, neoformation of particles can occur from the soluble part of the element. Size distribution analysis measured by photon correlation spectroscopy (PCS) were frequently unvalid, particularly due to polydispersity and/or too low concentrations in the leachates. A low sensitivity device is required, and further improvement is desirable in that field. For some waste leachates, particles had a zeta potential strong enough to remain in suspension. Mn, As, Co, Pb, Sn, Zn had always a colloidal form (MF concentration/UF concentration>1.5) and total organic carbon (TOC), Fe, P, Ba, Cr, Cu, Ni are partly colloidal for more than half of the samples). Nearly all the micro-pollutants (As, Ba, Co, Cr, Cu, Mo, Ni, Pb, Sb, Sn, V and Zn) were found at least once in colloidal form greater than 100 μgl(-1). In particular, the colloidal forms of Zn were always by far more concentrated than its dissolved form. The TEM-EDS method showed various particles, including manufactured nanoparticles (organic polymer, TiO(2), particles with Sr, La, Ce, Nd). All the waste had at least one element detected as colloidal. The solid waste leachates contained significant amount of colloids different in elemental composition from natural ones. The majority of the elements were in colloidal form for wastes of packaging (3), a steel slag, a sludge from hydrometallurgy, composts (2), a dredged sediment (#18), an As contaminated soil and two active landfill leachates. These results showed that cascade filtration and ICP elemental analysis seems valid methods in this field, and that electronic microscopy with elemental detection allows to identify particles. Particles can be formed from dissolved elements during TEM sample preparation and cross-checking with MF and UF composition by ICP is useful. The colloidal fraction of leachate of waste seems to be a significant source term, and should be taken into account in studies of emission and transfer of contaminants in the environment. Standardized cross-filtration method could be amended for the presence of colloids in waste leachates., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

The classification of waste as hazardous could soon be assessed in Europe using largely the hazard properties of its constituents, according to the the Classification, Labelling and Packaging (CLP) regulation. Comprehensive knowledge of the component constituents of a given waste will therefore be necessary. An analytical protocol for determining waste composition is proposed, which includes using inductively coupled plasma (ICP) screening methods to identify major elements and gas chromatography/mass spectrometry (GC-MS) screening techniques to measure organic compounds. The method includes a gross or indicator measure of 'pools' of higher molecular weight organic substances that are taken to be less bioactive and less hazardous, and of unresolved 'mass' during the chromatography of volatile and semi-volatile compounds. The concentration of some elements and specific compounds that are linked to specific hazard properties and are subject to specific regulation (examples include: heavy metals, chromium(VI), cyanides, organo-halogens, and PCBs) are determined by classical quantitative analysis. To check the consistency of the analysis, the sum of the concentrations (including unresolved 'pools') should give a mass balance between 90% and 110%. Thirty-two laboratory samples comprising different industrial wastes (liquids and solids) were tested by two routine service laboratories, to give circa 7000 parameter results. Despite discrepancies in some parameters, a satisfactory sum of estimated or measured concentrations (analytical balance) of 90% was reached for 20 samples (63% of the overall total) during this first test exercise, with identified reasons for most of the unsatisfactory results. Regular use of this protocol (which is now included in the French legislation) has enabled service laboratories to reach a 90% mass balance for nearly all the solid samples tested, and most of liquid samples (difficulties were caused in some samples from polymers in solution and vegetable oil). The protocol is submitted to French and European normalization bodies (AFNOR and CEN) and further improvements are awaited., (Copyright © 2013 Elsevier Ltd. All rights reserved.)