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Sewage sludge (SS) formed in wastewater treatment plants can contain organic matter and nutrients in concentrations that are valuable for amending poor soil. This work aims to compare the performance of six residues not only as drying adjuvants of SS but also as improvers agents in agronomic properties of the final product. According to criteria in line with circular economy and industrial ecology, the selected adjuvants were weathered coal fly ash (CFA), bottom biomass ash (BBA), green liquor dregs (GLD), lime mud (LM), eggshell (ES), and rice husk (RH). The main physicochemical properties of these materials were determined. Then, small cylinders with and without 0.15 g adjuvant/g SSwet basis were shaped at room temperature and dried at 130 oC in a moisture analyzer to evaluate the drying kinetics. The profiles were modeled, and the main parameters determined. Furthermore, several relevant parameters for agronomic applications of the final products were determined, such as pathogen contamination, acid neutralization capacity (ANC), and oxygen uptake rate (OUR). Adding BBA to SS (named as SS_BBA product) promoted the highest diffusion coefficient (2.55·10−7 m2/s) and drying rate (41.6 g H2O/kg min). On the other hand, SS_ES showed a positive impact in almost all agronomic parameters, with an ANC of 0.166 g CaCO3/g, OUR of 10.18 mmol O2/kg organic matter h, and germination index of 29.1%. In general, the results indicate that several residues can be used to improve not only sludge drying but also the final properties of the product for soil applications.

Air pollution control residues (APCr) from municipal solid waste (MSW) incineration are hazardous waste, and their management requires holistic approaches within technical, economical, legislative, and environmental constraints. This work deals with the recycling of APCr for producing lightweight aggregates (LWA) commonly manufactured by firing natural clay. The main objectives are to evaluate the environmental impacts of LWA with and without incorporating APCr and assess whether APCr recycling in LWA is beneficial, based on the life-cycle assessment (LCA) methodology. The system boundary included raw material extraction, grinding, mixture, firing, cooling, and packing (cradle-to-gate). Results were analysed following the impact assessment methods recommended by the International Reference Life Cycle Data System. Results pointed out a reduction of impacts in all categories when 3% of natural clay are replaced by APCr. The highest gains occurred for toxicity categories (HTc, HTnc) and resulted mainly from avoiding landfill of APCr. For non-toxicity categories, impacts were dominated by the emissions from the kiln firing process, which were similar for both LWA; therefore, impact reductions from APCr use in LWA in these categories were modest. LCA results show that the valorisation of APCr in LWA may be an environmentally sound solution to avoid landfill disposal practices.

The feasibility of recycling red mud waste by its direct transformation into highly-porous cellular ceramics was successfully demonstrated. Ceramic materials with designed cellular porosity were processed by emulsification of red mud suspensions with liquid paraffin. Taguchi method was used to study the effects provided by varying the red mud load in the suspension, gelatine content and emulsion stirring time on the micro structural features of the cellular ceramics. Additional experiments analysed the effects of the organic to suspension ratio and firing temperature. Emulsification of paraffin followed by gelatine consolidation, drying, elimination of the droplets of the discontinuous organic phase and firing, allowed one to design cellular ceramic pieces with open porosity up to 75%, consisting in interconnected cells with adjustable cell size and low resistance to percolation. These results allow one to consider prospective applications of red mud-based cellular ceramics with designed microstructures as highly-porous membranes for the capture of pollutants.

This work presents an updated overview of waste lubricant oil (WLO) management practices in Europe to promote a circular economy. The characteristics of virgin and waste oil, their hazardous proper...

The classification of wastes regarding hazardous property HP 14 (ecotoxicity) is essential for proper waste management. In the EU, HP 14 has been estimated based on waste chemical composition rather than using biotests, and guidelines for experimental assessment are still lacking. This study aims at evaluating the potential ecotoxicological impacts of weathered coal fly ash (CFA) from a landfill, as a case study to assess the current EU methodology used to classify wastes regarding HP 14. A large amount of CFA is still landfilled, but its valorisation would be of interest. The analysis was based on the chemical composition of CFA (in ClassifyMyWaste software), and on a battery of five biotests applied to eluates, with Lepidium sativum, Aliivibrio fischeri, Raphidocelis subcapitata, Lemna minor and Daphnia magna. Through chemical analysis, most of the simulations with data from the literature indicated "Possible Hazard", including the sample of this work. Biotests revealed low impairment for most endpoints. D. magna was the most sensitive organism, but the inhibitory effect was significantly reduced after pH adjustment of the eluate. The test with A. fischeri does not seem to be adequate to assess CFA due to the high variability observed in results. The methodology involving a simple battery of bioassays was proven to be enlightening, providing relevant results for HP 14 assessment. The chosen battery of biotests (excluding the A. fischeri test) may be a good starting point to represent the aquatic environment in this context. In short, it seems that weathered CFA can be considered non-hazardous, and therefore the material under analysis could be valorised in practical applications without significant ecotoxic effect on the environment.

The ubiquitous presence of CBZ, SMX and LRZ in water is a subject of increasing concern. This study represents a new approach in terms of these contaminants’ removal through Fenton process in three different ways, employing a solid catalyst, RM, which, alone, is a source of Fe3＋ just as much is a source of environmental problems. Alongside RM, 100 mg/L of H2O2 were utilized as the initial solution’s pH remained unaltered. It was observed that, at these operating conditions, an appreciable degradation rate of contaminants was achieved. Solar photo-Fenton under visible light radiation led the way by attaining more than 50% removal for all three contaminants, reaching its peak when degrading around 62% of LRZ initially present. Therefore, RM, a residue from the alumina industry, seems to be a promising choice in terms of CECs degradation through Fenton process. Nevertheless, some parameters still need optimization, in order to achieve a better understanding and certainty of this oxidation process’ skilfulness for detoxifying CECs from the world’s water resources. Keywords: Decontamination, Fenton process, Pharmaceuticals, Red mud, Sunlight radiation, Waste management

This study aims to evaluate the effect of weathered coal fly ash (CFA) as a drying adjuvant of sewage sludge (SS) to produce a soil amendment. The high amount of SS and CFA creates a complex waste management problem in many countries, requiring more research efforts. Towards a circular economy, CFA can be viewed as an anthropogenic inorganic by-product with valuable nutrients (e.g. K), which can be recovered in combination with SS (rich in organic matter, N, and P). Different temperatures (70, 85, 100, 115, and 130 °C) are tested to dry small SS cylinders, without and with 0.15 g CFA g

In the European Union (EU), waste is classified according to the List of Waste (LoW) and relying on the assessment of 15 hazardous properties (HPs). Incineration bottom ash (IBA) from municipal solid waste is a mirror entry in the LoW, which leads to extremely different management options within the EU. IBA has shown potential for different applications under a circular economy perspective, contributing both to avoiding waste landfilling and the consumption of natural resources, such as sand and gravel. In this context, IBA evaluation and classification play a significant role in understanding which protection measures should be taken. This work aims to present an assessment of the 15 HPs and the consequent classification of IBA using data from the industry. Each HP is assessed based on knowledge of waste, chemical composition considering concentration limits for hazardous substances, and/or through tests (chemical, physical, or biological). According to the criteria followed, 5 out of 6 samples from a Portuguese Waste-to-Energy plant were considered non-hazardous. Only one sample was classified as hazardous due to the assignment of HP 10, which resulted from Pb content (0.36%) above the concentration limit established for this property (0.3%). Nonetheless, although most hazardous entries in the LoW have this classification based on HP 14, the results obtained for the samples of this work seem to indicate IBA from this study is non-ecotoxic. Moreover, it has been suggested that IBA could possibly achieve the End-of-Waste status according to the Waste Framework Directive. For such purpose, clear criteria should be laid down to safely use the material, and testing is a crucial step.

The application of TiO2 as a slurry catalyst for the degradation of contaminants of emerging concern (CEC) in liquid effluents has some drawbacks due to the difficulties in the catalyst reutilization. Thus, sophisticated and expensive separation methods are required after the reaction step. Alternatively, several types of materials have been used to support powder catalysts, so that fixed or fluidized bed reactors may be used. In this context, the objective of this work is to systematize and analyze the results of research inherent to the application of ceramic materials as support of TiO2 in the photocatalytic CEC removal from liquid effluents. Firstly, an overview is given about the treatment processes able to degrade CEC. In particular, the photocatalysts supported in ceramic materials are analyzed, namely the immobilization techniques applied to support TiO2 in these materials. Finally, a critical review of the literature dedicated to photocatalysis with supported TiO2 is presented, where the performance of the catalyst is considered as well as the main drivers and barriers for implementing this process. A focal point in the future is to investigate the possibility of depurating effluents and promote water reuse in safe conditions, and the supported TiO2 in ceramic materials may play a role in this scope.

Green liquor dregs (GLD) are a major waste of the pulp and paper industry, and their correct classification is important to finding alternatives to landfill disposal. In the European Union, the met...

In this study, the performance of chemically modified pine bark for removal of Cr(III) from solutions was investigated. Initially, several chemicals were tested (NaOH, C5H9NO4, H3PO2 and CS2). The xanthate pine bark (XPB) obtained with CS2, was screened as the best adsorbent and thus, it was characterized in respect to morphological and textural properties. Sulfur groups after xanthation reaction were identified on XPB by FTIR and EDS spectroscopies. Equilibrium isotherm and kinetics were determined. The equilibrium data were well described by the Langmuir isotherm allowing to calculate the maximum adsorption capacity (56.5 mg/g). The kinetics is fast and follows a pseudo-second order model. Furthermore, an ion-exchange sorption mechanism between Cr(III) and Na+ was proposed. Among the desorbing agents tested, the best results were achieved with 2.0 M H2SO4. Moreover, in the column tests, a reduction on the breakthrough time and the stoichiometric time from 36.5 and 22.8%, respectively, was observed, when the feed concentration increased from 230 to 500 mg/L. The breakthrough curves were well modeled by Bohard-Adams, Thomas or Yoon-Nelson equations. Globally, XPB revealed to be a promising adsorbent for uptake Cr(III). The scale-up design and the economic assessment indicated potential applicability for the treatment of real effluents.

This work aims to contribute to the discussion of using a waste (sewage sludge) to obtain a valuable product (organic-rich fertilizer), based on a circular economy perspective. The compo- sition of sewage sludge (SS) was considered, highlighting important characteristics as raw ma- terial for fertilizer production (e.g., macronutrients, microbiological contamination, phytotoxicity). Particularly, the biological stability of SS was evaluated measuring the oxygen uptake rate (OUR) using the Oxitop® method, and the phytotoxicity using germination tests. The potential of thermal drying to stabilize the SS was evaluated at two temperatures (100 and 130◦C). The results showed that the organic matter (OM), N, and P levels are within the range of interest for agronomic valorization, while the content of some potentially toxic metals (e.g., Zn and Cu) may exceed the legal limits. The phytotoxicity assessment showed that raw SS samples negatively impacted the germination phase. Concerning the biological stability, results showed that raw anaerobic digested samples were characterized by OUR values above 50 mmol O2/kg OM.h (the limit for stable SS). Although thermal treatment of SS at 100 and 130◦C eliminated pathogens and significantly stabilized SS to OUR values below 50 mmol O2/kg OM.h, it was not enough to reach the limit established for a stable fertilizer (25 mmol O2/kg OM.h). Globally, SS has potential for soil application, within the scope of circular economy, but it is essential to control its microbiological contamination and stability. info:eu-repo/semantics/publishedVersion

This work aims to study the removal of contaminants from waste lubricating oil (WLO) with distinct properties by solvent extraction to recover the base oil. 1-Butanol and methyl ethyl ketone (MEK) were selected as green solvents. Three WLO samples (class A, B, and C) with substantially different properties were considered. Class A is the most common type of WLO; Class B corresponds to mineral oil with low level of contaminants (e.g. oxidation products and additives); Class C is mainly constituted by synthetic ester base oils. The analysis involved the response surface methodology and the desirability function to model two response variables (Yield and percent sludge removal - PSR) and to find the best operating conditions for the most influential factors (solvent/oil ratio and KOH dosage). The rates of contaminant removal were very dependent on the type of WLO. The maximum PSR achieved were 8.5 and 6.5% using 1-Butanol for class A and C oils, respectively, while 6.3 and 4.7% were observed for MEK. Thus, 1-Butanol is the most efficient extracting agent than MEK for both classes A and C. The extraction process was not effective for class B (PSR ≈ 0%), and this oil can bypass the deasphalting stage, saving materials and energy. The addition of KOH as flocculation agent in class C was less effective than to other classes due to the saponifiable matter content in the oil. However, the solvent extraction is a suitable treatment route for the regeneration of synthetic ester-based oils (class C). Reasonably accurate models regarding the response variables were obtained for both solvents and class A and C oils. Considering desirability functions, a solvent/oil ratio of 5 w/w and KOH dosage of 1.5 or 2 g/L were found as optimal conditions.

Iron oxides are attractive for a variety of applications, since they offer unique physical and chemical properties, while being abundant and environmentally friendly. Some of those potential applications, including electrochemical and catalytic systems, require ceramics with designed porosity and well-developed percolation networks. In the present work, representative Al- and Mg-substituted hematite and magnetite- based cellular ceramics were processed by emulsification of mixed oxide suspensions. Reactive firing conditions were adjusted to attain a reasonable compromise between designed porosity, percolation and phase composition. The impact of firing conditions on the cellular ceramics microstructure, porosity, phase content and interconnectivity of the cells was studied and discussed. Thus, the applicability of the proposed emulsification of ceramic suspensions method was demonstrated for iron oxide-based ceramics.

The biorefinery approach must be boosted in the management of agro-residues in the future. The present study aims to investigate the valorization of tomato production residues, namely rotten tomato (unfit for consumption - RT), green tomato (GT), and tomato branches (TB). The assessment involves the recovery of value-added compounds through the extraction process followed by biogas production through anaerobic digestion. A thorough characterization of the three residues (RT, GT, and TB) was carried out, including the identification of volatile compounds by solid-phase microextraction (SPME) and gas chromatography/mass spectrometry (GC/MS). The volatiles analysis revealed the presence of flavor enhancer compounds and molecules with insecticidal properties. A solid-liquid extraction with ethanol allowed the recovery of value-added compounds in the extracts, in particular phenolic compounds, β-carotene, and lycopene, which contributed to the antioxidant activity. RT and TB extracts were found to be richer in total phenolic compounds (~27 mg GAE/gdb dry basis) and exhibited higher antioxidant activity (IC50 = 0.911 and 0.745 mg/mL). The tomato branches extract had the highest concentration of carotenoids with 37.23 and 3.08 mg/kgdb of β-carotene and lycopene, respectively. The biochemical methane potential (BMP) was assessed in sealed reactors operating in anaerobic conditions for all the raw (RT, GT, and TB) and extracted substrates waste (RTe, GTe, and TBe). While the BMP of RT and GT was in the range of 232–285 mL CH4/g VS, a lower value of 141 mL CH4/g VS was obtained for TB. The methane production for each pair of raw and extracted substrates (RT/RTe, GT/GTe, and TB/TBe) was considered statistically similar at a 95 % confidence level. Overall, the value-added compounds recovery through ethanolic extraction did not compromise the methane production of the materials.

Sewage sludge (SS) is a global environmental, social, and economic problem that requires a sustainable management approach. Still, the production of other industrial wastes, such as lime mud (LM), has recently gained considerable attention to avoid landfilling. This work aims to present a new approach for converting SS and LM into value-added products within the circular economy perspective. In particular, the effect of LM and calcined lime mud (CLM) as drying adjuvants and SS sanitation agents are investigated. Two out of three SS samples show Escherichia coli contamination above the Portuguese limit established for soil application, while no Salmonella spp. was detected in the searched samples. The addition of CLM to SS in a ratio between 0.05 and 0.15 g CLM/gwb, lead to complete elimination of the microbiological contamination in almost all cases. Contrarily, the use of LM does not seem efficient to act as a sanitation agent. Both LM and CLM show a positive impact on the drying process when compared to the raw SS, increasing the drying rate, and reducing the drying time. The most favourable drying conditions to maximize the drying rate and minimize the drying time (until 30% of moisture) are 130 °C, 0.15 g adj/gwb, and 2.5 mm of plate thickness. The thermal treatment (100 and 130 °C) without adjuvants reduces the microbiological contamination below the legal limit. Overall, a beneficial effect is observed by adding CLM to SS, open the possibility of producing a safer organic soil improver.

Municipal solid waste (MSW) incineration in waste-to-energy plants plays an important role in waste management systems of developed countries, since the increasing amounts of waste cannot be all recycled, and diverting waste from landfilling is a priority. On the other hand, proper MSW management is a fundamental part of sustainable development, which requires the balance of the economic, social, and environmental dimensions. Thus, this chapter explores sustainability issues about MSW incineration with energy recovery. For this purpose, an overview of the MSW management systems is presented and incineration technology is highlighted. Subsequently, the three dimensions of sustainable development are explored regarding MSW incineration with energy recovery. Environmental considerations related to air emissions and solid residues from MSW incineration are discussed. Concerning economic issues, the costs and revenues of incineration treatment are reviewed. Finally, the social context of this management option is provided, pointing out public concerns and studies addressing these aspects.

The agro-industry of tomato generates three types of residues: ripe rotten tomato (unfit for consumption) (RT), green (unripe) tomato (GT), and tomato branches including leaves and stems (TB). These materials are commonly wasted or used as feed for livestock. Energy production through anaerobic digestion is an alternative way to manage and simultaneously valorise these materials. Initially, the operating conditions of mono anaerobic digestion were investigated using RT. Thus, a design of experiments based on a two-level fractional factorial design with resolution V was performed to determine the factors that affect biochemical methane potential (BMP). The substrate to inoculum ratio (SIR), total volatile solids concentration (VSt), working volume (WV), presence of nutrients (Nu), and the pre-incubation of the inoculum (Inc) were investigated. The results showed that SIR is the most important factor. The maximum BMP for RT was 297 NmLCH4/gVS with SIR = 0.5, tVS = 20 g/L, WV = 20%, no pre-incubation and the presence of nutrients. Using these optimum operating conditions, co-digestion was investigated through a mixture design approach. The substrates RT and GT presented similar BMP values, whereas TB led to a significantly lower BMP. Indeed, when high concentrations of TB were used, a significant decrease in methane production was observed. Nonetheless, the highest BMP was achieved with a mixture of 63% RT + 20% GT + 17% TB, with a production of 324 NmLCH4/gVS, corresponding to a synergetic co-digestion performance index of about 1.20. In general, although the substrate RT generates the highest BMP, the mixture with GT did not impair the methane yield. Overall, the co-digestion of tomato residues must be conducted with SIR close to 0.5 and the content of tomato branches in the reaction mixture should be kept low (up to 20%).

Phosphorus (P) is a non-renewable resource, irreplaceable for life and food production, and currently considered a Critical Raw Material to the European Union (EU). Due to concerns about the rate of consumption and limited reserves in countries with sensitive geopolitical contexts, it is urgent to recover P from urban and industrial flows. Indeed, the municipal wastewater treatment plants (WWTP) are considered relevant sources with several hot spots, especially sewage sludge with estimated recovery efficiencies of >80%. The most promising recovery strategies are based on thermal treatments (e.g., incineration of sludge) following by wet-chemical or thermochemical leaching, precipitation, and adsorption. The direct application of sludge on soil is no longer a primary route for P reintegration in the value-chain for countries as Switzerland, Germany, and The Netherlands. In fact, Switzerland and Austria paved the way for implementing P recovery legislation, focusing on recovery from raw sewage sludge or ashes. Indeed, industrial technologies with sludge ash as input show high recovery efficiencies (Ashdec® and Leachphos® with 98 and 79%) and lower environmental impacts, whereas Pearl® technology has about 12% recovery efficiency with wastewater as input. After all, struvite emerges as the most recovered product with recent access to the internal market of EU fertilisers and similar growth performance compared to triple-super-phosphate. However, several studies leave open the possibility of introducing loaded adsorbents with P as soil amendments as a new alternative to conventional desorption. Briefly, P recovery should be a compromise between efficiency, environmental impacts, and economic revenues from the final products info:eu-repo/semantics/publishedVersion

Electrochemical reduction of iron oxides into zero-valent iron (ZVI, Fe0) is a promising alternative to the traditional methods used for iron production. The electrochemical deposition of Fe0 from hematite and hematite-based Fe2−xAlxO3 ceramic in alkaline suspensions (10 M of NaOH) was assessed at relatively low temperature (90 °C). Ceramic compositions aimed to mimic the main components of red mud waste from the alumina refining industry for iron valorisation purposes. The impact of aluminium content on the electroreduction and microstructure of the deposited Fe0 films was demonstrated and discussed. Trapping and following the leaching of the aluminium species during deposition causes drastic morphological changes and induces significant porosity. Faradaic efficiencies of the reduction to Fe0 were found to decrease from 70% to 32% for Fe2O3 and Fe1.4Al0.6O3, respectively. The results highlight possible effects imposed by aluminium presence during Fe0 electrodeposition for future iron recycling from, for example, red mud or other aluminium containing wastes by electrowinning in alkaline conditions.

Water treatment sludge is an industrial by-product which has recently been classified as a waste by the European Commission. The main goal of this work is to valorise this waste to produce lightweight aggregates. Formulations with sludge substituting expanded clay up to 50 wt% were produced. The physical properties of the lightweight aggregates such as bloating index, density and porosity were studied. The introduction of the sludge without expanding properties, reduced the expandability of the clay and the porosity of the aggregates. The density increased from 0.32 g/cm3 in aggregates without sludge to 1.46 g/cm3 in aggregates with 50 wt% of sludge. It is shown that lightweight aggregates can be produced using mixtures of expanded clay and water treatment sludge, with low substitution percentages (up to 15 wt% of sludge). Aggregates up to 15 wt% of sludge were further studied. The compressive strength increased with sludge wt.%, and the concentrations of heavy metals and metalloids, assessed through leaching tests, were well below the stablished limits. Two preliminary tests of lightweight aggregate concrete were produced: LWAC 1 was formulated with commercial lightweight aggregates and LWAC 2 with aggregates containing 7 wt% of the sludge and commercial lightweight aggregates. The physical, mechanical and thermal properties of LWAC 1 and LWAC 2 were found to be very similar. Our work demonstrates the feasibility in using water treatment sludge as a by-product to produce lightweight aggregates suitable for thermal insulation and lightweight applications.

This work aims to evaluate the microbiological contamination of sewage sludge (SS) collected in urban wastewater treatment plants (WWTP) from Portugal. Two types of SS were considered: urban mixed (UM) and from anaerobic digestion (AD). The two types of samples were characterized in relation to the main physical and chemical parameters, as well as the microbiological contamination (Escherichia coli and Salmonella spp). Then, sanitation tests were conducted through thermal drying and chemical treatments. Towards a circular economy, industrial alkaline wastes (green liquor dregs - GLD, lime mud, coal fly ash, eggshell) were tested as alternatives to lime. Only six out of nineteen samples complied with the legal limits for both microorganisms. However, drying at 130 &deg, C sanitized selected samples below the E. coli limit, regardless of the initial moisture or contamination. Additionally, CaO (obtained from eggshell) led to the complete elimination of E. coli at any dosage studied (0.05&ndash, 0.15 g/g SSwet basis). GLD evidenced the ability to reduce E. coli contamination at room temperature, but not enough to comply with the legal limit. In general, this work highlights the need to sanitize the SS before its application to the soil, and the positive role of some wastes on this goal.

Mining is an essential human activity, but results in several environmental impacts, notably the contamination of ground and surface water through the presence of toxic substances such as metals and sulfates in mine drainage. Permeable reactive barriers (PRB) have been applied to remediate this environmental impact, but the high costs associated with the maintenance of this system are still a challenge. The main objective of this study was to evaluate the use of kraft pulp mill alkaline residues, known as dregs and grits, as material for PRB, and to determine their capacity for retaining copper and sulfate. The work was carried out in laboratory adsorption kinetics assays, batch assays and column tests. Tests for elemental characterization, point of zero charge, acid neutralization capacity, total porosity, bulk density and moisture of the dregs and grits were conducted. The results showed high retention of Cu due to a chemical precipitation mechanism, notably for dregs (99%) at 5 min in adsorption kinetics. The grits presented similar results after 180 min for the same assay. Sulfate retention was effective at pH below 5, with an efficiency of 79% and 89% for dregs and grits, respectively. Dregs presented the best results for acid drainage remediation, notably with a solid:liquid (S:L) ratio of 1:10.

Olive mill wastewater (OMW) is a complex effluent, with a high organic load and toxic compounds. Its seasonal production is an added difficulty for treatment systems. In this work, the heterogeneous Fenton process is used with low-cost catalysts, that are wastes rich in iron and other materials naturally present in nature, namely Red Mud (RM), the volcanic rocks of the Azores (VRA) and the volcanic rocks of the Canaries (VRC), to treat a mixture of five phenolic compounds usually present in OMW (3,4 - Dihydroxybenzoic, 4 - Hydroxybenzoic, 3,4 - Dimethoxybenzoic, 3,4,5 - Trimethoxybenzoic and Trans-cinnamic acids). The effect of adding hydrogen peroxide stepwise was also investigated and it was found that adding the oxidant at once is more efficient than the staged addition, for removing phenols as well as leading to less residual hydrogen peroxide. With regard to the utilization of low-cost catalysts, it was concluded that at the end of 60 min and for a concentration of 1 g/L of catalyst, the removal of phenolic content reaches 100% for RM, while in the case of VRA and VRC this value is 72.0% and 74.6%, respectively.

Electrochemical reduction of iron oxides into zero-valent iron (ZVI, Fe0) is a promising alternative to the traditional methods used for iron production. The electrochemical deposition of Fe0 from hematite and hematite-based Fe2−xAlxO3 ceramic in alkaline suspensions (10 M of NaOH) was assessed at relatively low temperature (90 °C). Ceramic compositions aimed to mimic the main components of red mud waste from the alumina refining industry for iron valorisation purposes. The impact of aluminium content on the electroreduction and microstructure of the deposited Fe0 films was demonstrated and discussed. Trapping and following the leaching of the aluminium species during deposition causes drastic morphological changes and induces significant porosity. Faradaic efficiencies of the reduction to Fe0 were found to decrease from 70% to 32% for Fe2O3 and Fe1.4Al0.6O3, respectively. The results highlight possible effects imposed by aluminium presence during Fe0 electrodeposition for future iron recycling from, for example, red mud or other aluminium containing wastes by electrowinning in alkaline conditions.

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. Metals are mostly separated and sold to the scrap market and minerals are either disposed of in landfills or utilised in the construction sector. Since there is no uniform regulation for IBA utilisation at EU level, countries developed own rules with varying requirements for utilisation. As a result from a cooperation network between European experts an up-to-date overview of documents regulating IBA utilisation is presented. Furthermore, this work highlights the different requirements that have to be considered. Overall, 51 different parameters for the total content and 36 different parameters for the emission by leaching are defined. An analysis of the defined parameter reveals that leaching parameters are significantly more to be considered compared to total content parameters. In order to assess the leaching behaviour nine different leaching tests, including batch tests, up-flow percolation tests and one diffusion test (monolithic materials) are in place. A further discussion of leaching parameters showed that certain countries took over limit values initially defined for landfills for inert waste and adopted them for IBA utilisation. The overall utilisation rate of IBA in construction works is approximately 54 wt%. It is revealed that the rate of utilisation does not necessarily depend on how well regulated IBA utilisation is, but rather seems to be a result of political commitment for IBA recycling and economically interesting circumstances. Export Date: 20 December 2019 ispartof: Waste Management vol:102 pages:868-883 ispartof: location:United States status: published