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The transition from the use of fossil fuels to renewable and green energy is a worldwide challenge that must be seriously considered in order to ensure sustainable development and the preservation of the environment. The conversion of wet biomasses (i.e., sewage sludge) into energy through thermochemical processes in general and hydrothermal carbonization (HTC) in particular has been pointed out as an interesting and attractive approach for the energetic and agricultural valorization of the produced solid residues, named hydrochars. The success of such valorization options is highly dependent on these hydrochars' physico-chemical and energetic properties that are influenced not only by the type of the sludge (urban or industrial) and its nature (primary, secondary, or digested) but also by the HTC parameters, especially temperature, pressure, and residence time. This editorial provides a summary of the latest studies regarding the impact of the cited above parameters on the properties of the produced hydrochars. The economic and environmental feasibility of this process for sewage sludge management is also presented. [ABSTRACT FROM AUTHOR]

This study investigates—for the first time—the synthesis of a novel Ca-rich biochar (N–Ca–B) and its potential use for phosphorus (P) recovery from both synthetic solutions (SS) and treated urban wastewater (TUW) in a continuous stirring tank reactor (CSTR) mode. The novel biochar was synthesized by pyrolysis at 900 °C of a mixture composed of three different materials: animal biomass (poultry manure; PM), lignocellulosic waste (date palm fronds; DPFs), and abundant mineral waste (waste marble powder; WMP). Characterization of N–Ca–B showed that it has good textural properties: well-developed porosity, and high specific surface area. Furthermore, high calcium hydroxide (Ca(OH) 2) and calcium oxides (CaO) nanoparticle loads were observed on the biochar surface. The dynamic CSTR assays indicated that the P recovery efficiency mainly depended on the biochar mass, P influent concentration, and, especially, the Ca content of the feeding solution. Owing to its richness in Ca cations, TUW exhibited the highest adsorbed P amount (109.2 mg g−1), i.e., about 14% larger than the SS. P recovery occurs through precipitation as hydroxyapatite, surface complexation, and electrostatic interactions with positively charged biochar particles. In real-world scenarios, CSTR systems can be applied as a tertiary treatment step in existing wastewater treatment plants (WWTPs). Decanted P-loaded biochar can be used in agriculture as a slow-release fertilizer instead of commercial products. [Display omitted] • Waste marble powder used for calcium-rich biochar synthesis. • Ca-rich biochar has interesting physico-chemical properties. • Ca-rich biochar efficiently recovers phosphorus in CSTR mode. • Ca-rich biochar recovers high phosphorus amounts from wastewater. • Proposed approach promotes sustainability and circular economy. [ABSTRACT FROM AUTHOR]

The sustainable management of loaded adsorbents with organic pollutants represents an important environmental challenge. The current research work investigates the regeneration process optimization of raw orange tree sawdust (ROS) loaded with methylene blue (MB) by using NaCl solutions as eluent. The MB desorption was assessed in static mode under different process variables, notably the desorbing NaCl solution’s pH and concentration and the MB-loaded biomass dose. A full factorial design composed of 24 experiments was employed to apprehend the statistical significance of each followed parameter. Experimental results showed that the maximum desorption yield was estimated to be about 82.4% for the following parameter’s values: aqueous pH = 3, [NaCl] = 0.2 M and MB-loaded-ROS dosage in the desorbing solution = 1 g·L −1 . The statistical study confirmed the good fit of the experimental data with the statistical model used as well as regression and adjusted regression coefficients of about 99.0% and 96.6%, respectively. Moreover, the ranking of the effect of each studied parameter in terms of standardized effect on the desorption efficiency of MB from ROS was assessed through ANOVA test. The desorption mechanisms involved were explored by using multiple analysis techniques. It appears that the MB molecules’ desorption from ROS’s particles is mainly driven by a counter chemisorption process based on cationic exchange with the sodium and hydronium ions present in the desorbing solutions [ABSTRACT FROM AUTHOR]

Lignite, as an abundant and low-cost material, was tested for lead (Pb(II)) removal from aqueous solutions under various experimental conditions for both static (batch) and dynamic (column) experiments. Static assays showed that Pb(II) removal efficiency increases with rising in its initial concentration, aqueous pH, and adsorbent dosage values. Adsorption kinetic and isothermal data were well fitted with the pseudo-second-order and Freundlich models, respectively, suggesting that lead removal by lignite is mainly governed by chemical processes and occurs heterogeneously on multilayer surfaces. The maximum Langmuir’s adsorption capacity was equal to 61.4 mg·g −1, which is high in comparison to various natural materials. The laboratory column experiments showed that Pb(II) breakthrough curves and subsequent lignite adsorption efficiency is highly dependent on the bed height. Due to the short time contact between Pb(II) and lignite particles inside the column, the highest adsorption capacity was about 21%, which is lower than the one found in the batch mode. Even under dynamic conditions, lignite exhibits a high adsorption capacity compared to other adsorbents, which promotes its use as a low-cost and efficient material for Pb(II) and the removal of other heavy metals from wastewaters. [ABSTRACT FROM AUTHOR]

Phosphorus (P) represents a major pollutant of water resources and at the same time a vital element for human and plants. P recovery from wastewaters and its reuse is a necessity in order to compensate the current important depletion of P natural reserves. The use of biochars for P recovery from wastewaters and their subsequent valorization in agriculture, instead of synthetic industrial fertilizers, promotes circular economy and sustainability concepts. However, P retention by pristine biochars is usually low and a modification step is always required to improve their P recovery efficiency. The pre- or post-treatment of biochars with metal salts seems to be one of the most efficient approaches. This review aims to summarize and discuss the most recent developments (from 2020- up to now) in: i) the role of the feedstock nature, the metal salt type, the pyrolysis conditions, and the experimental adsorption parameters on metallic-nanoparticles-loaded biochars properties and effectiveness in recovering P from aqueous solutions, as well as the dominant involved mechanisms, ii) the effect of the eluent solutions nature on the regeneration ability of P-loaded biochars, and iii) the practical challenges facing the upscaling of P-loaded biochars production and valorization in agriculture. This review shows that the synthesized biochars through slow pyrolysis at relatively high temperatures (up to 700–800 °C) of mixed biomasses with Ca– Mg-rich materials or impregnated biomasses with specific metals in order to from layered double hydroxides (LDHs) biochars composites exhibit interesting structural, textural and surface chemistry properties allowing high P recovery efficiency. Depending on the pyrolysis's and adsorption's experimental conditions, these modified biochars may recover P through combined mechanisms including mainly electrostatic attraction, ligand exchange, surface complexation, hydrogen bonding, and precipitation. Moreover, the P-loaded biochars can be used directly in agriculture or efficiently regenerated with alkaline solutions. Finally, this review emphasizes the challenges concerning the production and use of P-loaded biochars in a context of circular economy. They concern the optimization of P recovery process from wastewater in real-time scenarios, the reduction of energy-related biochars production costs and the intensification of communication/dissemination campaigns to all the concerned actors (i.e., farmers, consumers, stakeholders, and policymakers) on the benefits of P-loaded biochars reuse. We believe that this review is beneficial for new breakthroughs on the synthesis and green application of metallic-nanoparticles-loaded biochars. [Display omitted] • Biochars usually have low phosphorus contents limiting their use in agriculture. • Raw biochars exhibit low phosphorus adsorption yields. • Loading biochars with nanomaterials improve their P recovery capacities. • Mixing biomasses with Ca– Mg-rich materials is an interesting option. • Biochars decoration with LDHs permits high P recovery efficiency. [ABSTRACT FROM AUTHOR]

Abstract One of the main challenges of dyes adsorption technology application wide-spreading is the fate of the generated dyes-loaded-biomasses, which in certain cases could represent a serious threat to the environment. In this research work, an innovative and eco-friendly approach was established for the management of a lignocellulosic material (alkaline treated orange tree sawdust: ATOS) loaded with methylene blue (MB) at a concentration of 107 mg g−1. This approach consists first of all to a rapid and important MB desorption (more than 91%) from fixed bed depth columns by low cost saline solutions (NaCl: 0.5 M). The issued solutions contained high MB concentrations (>3400 mg L−1) permitting a partial recovery of the dye as a solid phase with a purity of 93% that could be reused again in the industrial process. The second step concerns the treatment of the remaining dissolved MB in the desorbed solutions through anodic oxidation process by using bipolar Si/BDD (Boron Doped Diamond) electrodes. The presence of chlorides anions in the desorbed solutions enhances considerably their discoloration and organic carbon removal efficiencies and kinetics and significantly reduces the related consumed energy. The quality of the resulting treated wastewaters allows its possible reuse in the industrial process. Finally, five consecutive adsorption/desorption cycles experiments showed that ATOS could be reused several times for the MB adsorption without significant efficiencies decrease. All these results confirm the validity of our strategy aiming to turn dyes-loaded-lignocellulosic-biomasses from pollution source to values. Graphical abstract Image 1 Highlights • Methylene blue desorption was studied in fixed bed column mode. • Methylene blue desorption was governed by an ion exchange mechanism. • Dye recovery was achieved with a high purity level of more than 92%. • Biomass ability for reuse was confirmed after five successive regeneration cycles. • High efficiency and low energy consumption when degrading MB by anodic oxidation. [ABSTRACT FROM AUTHOR]

Lead removal from aqueous solutions by raw cypress ( Cupressus sempervirens L.) sawdust (RCS) and its derivative magnesium pretreated biochar (Mg-B) was investigated under static and dynamic conditions through batch and column assays. The Hydrus-1D model was used to estimate the transport parameters of the lead measured breakthrough curves. The batch experiments results showed that Mg-B was very efficient in removing lead compared to RCS and several other previously tested natural and modified materials. The column experiments results indicated that for both RCS and Mg-B, lead breakthrough curves and the related removal efficiencies were mainly dependent on the used initial concentration and the adsorbents bed height. The use of Hydrus-1D showed that the two-site chemical non-equilibrium model describes better the experimental lead breakthrough curves for both RCS and Mg-B as the equilibrium model. [ABSTRACT FROM AUTHOR]

Studies on the removal of methylene blue (MB) from aqueous solutions by anodic oxidation (AO) using a boron-doped diamond (BDD) electrode, adsorption onto sawdust, and combined treatment have been undertaken. The results proved that AO presents a high efficiency in removing both color and COD in a wide pH interval. The total mineralization of the dye solution was performed in 6 h, which corresponds to relatively high-energy consumption. On the other hand, high sawdust dosage (12 g·L −1 ) was needed to ensure 98% of color and 81% of COD removal. Combining AO and adsorption onto sawdust constitute a very interesting technology. For instance, AO for 1 h followed by sorption permits a reduction in energy consumption by 80 W·h·g COD −1 , a reduction of more than 24 times the adsorbent dose and an enhancement of color and COD removal, indicating that sawdust is efficient in removing not only the MB initial molecules but also the electrogenerated by-products. [ABSTRACT FROM AUTHOR]

Phosphorus removal from synthetic solutions by raw and calcined powdered marble wastes (RPMW and CPMW) has been investigated in batch mode under different experimental conditions. The results showed that RPMW and CPMW have high removal efficiencies, especially in acidic media. The maximum phosphorus removal capacities were evaluated to 103.9 and 181.2 mg·g −1 at an initial pH and an aqueous concentration of 5 and 350 mg·L −1 , respectively. Phosphorus removal by RPMW occurred mainly through adsorption. However, for CPMW, phosphorus was removed not only by adsorption, but also by precipitation as calcium phosphate complexes. Specific analyses using scanning electron microscopy, energy dispersive spectroscopy, X-ray diffraction and Fourier transform infrared spectroscopy confirmed that this precipitate is most probably hydroxyapatite. On the other hand, CPMW have demonstrated an important ability in removing phosphorus from highly concentrated dairy wastewater ( C 0,P = 1000 mg·L −1 ) since only one dosage of 10 g·L −1 was enough to ensure more than 97% of phosphorus removal. [ABSTRACT FROM AUTHOR]

During the last decade, biochars have been considered as attractive and eco-friendly materials with various applications including wastewater treatment, energy production and soil amendments. However, the important nitrogen losses during biochars production using the pyrolysis process have limited their potential use in agriculture as biofertilizer. Therefore, it seems necessary to enrich these biochars with nitrogen sources before their use in agricultural soils. This paper is the first comprehensive review on the assessment of biomass type and the biochars' properties effects on N recovery efficiency from aqueous solutions as well as its release and availability for plants when applying the N-enriched chars in soils. In particular, the N recovery efficiency by raw biochars versus the type of the raw feedstock is summarized. Then, correlations between the adsorption performance and the main physico-chemical properties are established. The main mechanisms involved during ammonium (NH 4 –N) and nitrates (NO 3 –N) recovery process are thoroughly discussed. A special attention is given to the assessment of the biochars physico-chemical modification impact on their N recovery capacities improvement. After that, the application of these N-enriched biochars in agriculture and their impacts on plants growth as well as methane and nitrous oxide greenhouse gas emissions reduction are also discussed. Finally, the main future development and challenges of biochars enrichment with N from wastewaters and their valorization as biofertilizers for plants growth and greenhouse gas (GHG) emissions reduction are provided. This systematic review is intended to promote the real application of biochars for nutrients recovery from wastewaters and their reuse as eco-friendly fertilizers. [Display omitted] • Biochars have low nitrogen contents which limit their use in agriculture. • Biochars hybrid modifications allow high recovery yields of ammonium and nitrates. • N-laden biochars promote the seedling stage and the vegetative growth. • N-enriched biochars significantly reduce the N 2 O and CH 4 emissions. • N-enriched biochars promote sustainability and circular economy concepts. [ABSTRACT FROM AUTHOR]

Fenton-based treatments have received tremendous attention in recent decades as viable strategies for soil decontamination. Historically contaminated soils are characterized by particular contamination types, pollution composition patterns, soil constituents, and complex soil-pollutant interactions arising due to long-term pollutant aging. These major pitfalls dictate the remediation efficiency in a significantly different way in soils with a history of contamination than that in a spiked soil. It becomes, therefore, highly challenging to treat historically contaminated soils. Despite the immense amount of collected research data in these soils, to our knowledge, no comprehensive review of this topic has been published. This article is intended to provide a critical review of the applications, limitations, and implications of various Fenton-based processes exclusively in these soils. These processes are differentiated on the basis of experimental conditions, reaction chemistry, efficiency, and impacts on soil biota. These processes are critically evaluated to illustrate the promising techniques with a brief description of related challenges and their potential solutions. Moreover, coupling Fenton oxidation with other remediation techniques such as bioremediation, chemical reduction, and soil washing has also been discussed. The last part of this review describes the effects of these processes onto soil quality and native biota, and how they can be addressed. It is also highly demanding to identify the processes which are not likely to evolve in practice either due to their poor efficiency, treatment cost, or environmental impacts. Future critical research directions have been identified to promote research for the upscaling of this technique for real field application. [Display omitted] • 1st review evaluating the Fenton oxidation exclusively in real contaminated soils. • These soils with complex pollution pose particular challenges to oxidation. • Fenton-based techniques are critically reviewed along with the related challenges. • Their implications and potential solutions in soil-plant system are evaluated. • Future research needs are highlighted to facilitate upscaling at field scale. [ABSTRACT FROM AUTHOR]

Abstract: The present study aims to investigate the key parameters and mechanisms affecting the removal of phosphorus ions from aqueous solutions onto phosphate mine slimes (PMS) in batch mode. PMS is an abundant waste generated by phosphate mine industry. The results indicate that phosphorus removal increases with increasing initial aqueous phosphorus concentrations, adsorbent dosage and temperature, and decreased with increasing pH values. The adsorption data kinetic modeling, the energy dispersive spectroscopy (EDS) and the Fourier transform infra-red spectroscopy (FTIR) analysis before and after adsorption of phosphorus onto PMS show that the main involved mechanisms are both ion exchange with chlorides and sulphur anions and complexation with some functional groups such as hydroxyl, carboxylic and acid halides groups. Furthermore, the results of the elementary composition analysis of PMS before and after adsorption indicated that the phosphorus content in PMS has increased by about 43% which promote its potential to be used as a fertilizer. In comparison with other natural adsorbents, PMS could be considered as one of the most efficient natural materials for the removal and recovery of phosphorus with the possibility of agronomic reuse as fertilizer. [Copyright &y& Elsevier]

Abstract: The present paper aims to study the effectiveness of an abundant marine waste named Posidonia oceanica (P. oceanica) on ammonium removal from aqueous solutions under different experimental conditions. The results of this study have shown that ammonium biosorption onto P. oceanica fibers increases with initial ammonium concentrations and pH increase. Biosorption isothermal data were well fitted by Langmuir model suggesting a monolayer and uniform adsorption process. The kinetic modeling of the experimental data indicated that they were well described by a pseudo-second-order model predicting a chemisorption process. The scanning electron microscopy (SEM), the energy dispersive spectroscopy (EDS) and the Fourier transform Infra-red spectroscopy (FTIR) analysis before and after biosorption of ammonium onto P. oceanica revealed that the main involved mechanisms are both surface ion exchange with magnesium and calcium cations and surface or intraparticle sharing between ammonium and functional groups, such as O–H, N–H, C=O and C–H stretching, and N–H bending. [Copyright &y& Elsevier]

Abstract: Phosphate mine slimes (PMS), an abundant waste generated from phosphate mines, was used in this study as a cost-effective adsorbent to investigate the phosphate anions removal from synthetic and urban secondary treated wastewater solutions. Dynamic experiments using laboratory reactors were carried out to study the effect of phosphate influent concentration, PMS dosage and feed flow rate on phosphate removal and a kinetic model was used to determine the phosphate mass transfer coefficients. The results show that the phosphate removal increases with influent phosphate concentration and PMS dosage. The feed flow rate has no significant effect. On the other hand, the phosphate removal from wastewater is less efficient than the synthetic solution due to anions competition process. The evaluation of phosphates mass transfer coefficients confirms the presence of anion competition phenomena and the necessity of increasing PMS dosage to provide more adsorption sites. The cost-effective and high adsorptive capability of PMS make them attractive materials for phosphate anions removal and recovery from secondary treated wastewaters with the possibility of agronomic reuse as fertilizer. [ABSTRACT FROM AUTHOR]

Abstract: In the present study, the effects of temperature and pH on ammonium biosorption onto Posidonia oceanica fibers were investigated. The results showed that the ammonium biosorption onto these fibers occurred for a wide pH range and the adsorption capacity of these fibers increased with increasing temperature. The modeling studies showed that the ammonium biosorption was well described by the pseudo-second-order model, predicting therefore chemisorption interactions-type at earlier stages and intraparticle diffusion at later stages. The ammonium biosorption was governed by film diffusion process at various temperatures. Besides, equilibrium data were very well represented by Langmuir isotherm, which confirmed the mono-layer coverage. The use of P. oceanica fibers presents an interesting option for both tertiary wastewater treatment (as a possible non-conventional biosorbent for the removal of ammonium), and waste recycling (as a fertilizer and compost). [ABSTRACT FROM AUTHOR]

Abstract: Sawdust, an available and renewable biomass, was investigated as a novel ammonium biosorbent. Biosorption occurred over a pH range of 6–10, reached an equilibrium state within only 20min, and can be described by a pseudo-second-order model predicting a chemisorption process. Equilibrium data were very well represented by Langmuir isotherm and confirm monolayer coverage. FTIR analysis before and after biosorption of ammonium onto sawdust suggested that the main mechanisms involved in the removal of ammonium might be the ionic exchange and complexation. The use of sawdust presents an interesting option for both tertiary wastewater treatment (as a possible non-conventional biosorbent for the removal of ammonium), and waste recycling (as a fertilizer and compost). [Copyright &y& Elsevier]

Abstract: The hydraulic residence time (HRT) is a key parameter affecting the soil aquifer treatment process (SAT) efficiency as tertiary treatment of wastewater through infiltration in vadose zone. In order to maximize the HRT, a pulsed feeding technique of a salt solution (used as conservative tracer) was adopted to allow the increase of HRT and soil aeration between pulses. For this reason, several laboratory column experiments combined with the use of a numerical model was conducted. The optimal number of pulsations that meet with the maximum of the HRT and the temporal variation of the water saturation into the column was determined for different applied hydraulic heads. It varies between 10 and 12. The maximum corresponding water stock in the porous media column was evaluated to about 84%, 79% and 73%, respectively, for an applied hydraulic head of 96, 75 and 50 cm. The applied hydraulic head had an important effect on the HRT. In fact, this parameter varies from almost 6.5 to 10.8 h for an applied hydraulic head of 96 and 50 cm. The change in the permeability of the soil had also a significant effect on the HRT. Hence, HRT is decreased of about 9% when the soil permeability at saturation is multiplied by 2, and increases of about 11% when the permeability is two times lower. [Copyright &y& Elsevier]

A large-scale experiment was conducted to investigate the transport of trichloroethylene (TCE) vapors in the unsaturated zone and to determine the mass transfer to the groundwater and the atmosphere. The experiment involved injection of 5 l of TCE in the unsaturated zone under controlled conditions, with multidepth sampling of gas and water through the unsaturated zone and across the capillary zone into underlying groundwater. The mass transfer of TCE vapors from the vadose zone to the atmosphere was quantified using a vertical flux chamber. A special soil water sampler was used to monitor transport across the capillary fringe. Experimental data indicated that TCE in the unsaturated zone was mainly transported to the atmosphere and this exchange reduced significantly the potential for groundwater pollution. The maximum measured TCE flux to the atmosphere was about 3 g/m2/day. Observed and calculated fluxes based on vertical TCE vapor concentration gradients and Fick''s law were in good agreement. This confirms that TCE vapor transport under the experimental conditions was governed essentially by molecular diffusion. TCE vapors also caused a lower, but significant contamination of the underlying groundwater by dispersion across the capillary fringe with a corresponding maximum flux of about 0.1 g/m2/day. This mass transfer to groundwater is partly uncertain due to an inadvertent entry of some nonaqueous phase liquid (NAPL) from the source area into the saturated zone. Application of an analytical solution to estimate the TCE flux from the unsaturated zone to the groundwater indicated that this phenomenon is not only influenced by molecular diffusion but also by vertical dispersion. The mass balance indicates that, under the given experimental conditions (e.g. proximity of the source emplacement relative to the soil surface, relatively high permeable porous medium), nearly 95% of the initial TCE mass was transferred to the atmosphere. [Copyright &y& Elsevier]

In the present study, methylene blue (MB) removal from aqueous solutions via the photocatalytic process using TiO2 as a catalyst in the presence of external ultra-violet light (UV) was investigated. The results of adsorption in the absence of UV radiation showed that adsorption reached an equilibrium state at 60 min. The experimental kinetic data were found to be well fitted by the pseudo-second-order model. Furthermore, the isotherm study suggested that dye uptake by TiO2 is a chemisorption process with a maximum retention capacity of 34.0 mg/g. The photodegradation of MB was then assessed under various experimental conditions. The related data showed that dye mineralization decreased when dye concentrations were increased and was favored at high pH values and low salt concentrations. The simultaneous presence of organic and inorganic pollution (Zinc) was also evaluated. The effect of the molar ratio Zn2+/MB+ in the solution at different pH values and NaCl concentrations was also monitored. The corresponding experimental results showed that at low values of Zn2+ in the solution (30 mg/L), the kinetic of the MB removal became faster until reaching an optimum at Zn2+/MB+ concentrations of 60/60 mg/L; it then slowed down for higher concentrations. The solutions' carbon contents were measured during the degradation process and showed total mineralization after about 5 h for the optimal Zn2+/MB+ condition. [ABSTRACT FROM AUTHOR]

Pyrolysis is a thermochemical process that permits the conversion of biomasses into energy (bio-oil and biogas) and a solid residue called biochar. The generation of biochar from lignocellulosic materials has been, for longtime, the predominant research focus. Wastewater treatment plants produce huge amounts of sludge biomass and there exists an increasing evidence for their possible reuse as a promising pyrolysis feedstock in recent literature. Though the valorization of biochars generated from lignocellulosic biomasses has been the subject of many reviews, there exists a critical knowledge gap regarding the effect of synthesis conditions of the sludge-derived biochars (SDBs) on their efficiency in the treatment of wastewater. This review critically analyzes the available literature related to SDBs characteristics and application to adsorb inorganic and organic pollutants from effluents. The physico-chemical properties and adsorption efficiency of SDBs are mainly tuned by the nature of raw sludge, pyrolysis conditions, and pre/post-treatments. Indeed, biochars originating from digested sludge have better adsorption capacities towards nutrients and heavy metals compared to those obtained from the non-digested sludge. The nutrients recovery from urban wastewater could be significantly improved when the raw sludge is mixed with lignocellulosic biomass and Mg/Ca rich materials. On the other hand, the chemical activation of sludge at reagent/sludge ratios higher than 2:1 permits to generate SDBs with adsorption capacities comparable and even better than commercial activated carbons. Moreover, the embedment/coating of SDBs with specific nanomaterials and tailored functional groups could significantly improve the adsorption capacities of various organic toxic pollutants and at the same time enhance their chemical degradation. The effect of the nature of target pollutants (organic or inorganic) on the underlying adsorption mechanisms by SDBs was also deeply reviewed. Finally, this paper provides the main application challenges as well as insights regarding the promising future directions for SDBs research and development. • This review evaluates the use of sludge-derived biochars for wastewater treatment. • Synthesis conditions influence the adsorption properties of SDBs. • Higher removal capacities of pollutants are obtained with activated SDBs. • Significant increases of removal capacities with nanocomposite-embedded SDBs. • Adsorption mechanisms are different for organic and inorganic pollutants. [ABSTRACT FROM AUTHOR]

This work aimed to study petiole palm tree wastes (PTW) efficiency in removing two basic dyes: Rhodamine B (RB) and Victoria blue B (VBB) from aqueous solutions in single and binary systems under various experimental conditions including the effect of contact time, pH, initial concentration, and temperature. The PTW characterization shows that the PTW is a lingo-cellulosic material. The experimental results indicate that the removal of both dyes was relatively fast, spontaneous, exothermic and occurred on monolayers. Moreover, the adsorption competition between these two dyes on the adsorbent particles surface was important since the Langmuir's adsorption capacities were evaluated to 260.1; 440.1; 168.0; and 417.4 mg/g for RB and VBB in single and binary systems, respectively. These adsorption capacities, even in binary systems, are interesting compared to other raw materials and prove that this abundant agricultural waste can be considered as a promising material for an efficient dyes removal from aqueous effluents. [ABSTRACT FROM AUTHOR]

In the present research, the optimization of the photocatalytic degradation of simulated textile effluent containing two pollutants (Methylene blue (MB) and Zinc) consisted of studying the variation of four parameters, namely initial MB concentration ([MB] I , mg/L), zinc concentration ([Zn 2+ ] I , mg/L), sodium chloride concentration ([NaCl] I , M) and flow rate (Q, mL/min) through a design of experiment using the response surface methodology approach. Results showed that MB degradation depends by order of importance on NaCl concentration > MB concentration > ionic zinc concentration > flowrate. Modeling results presented a good concordance between predicted and experimental values with acceptable correlation coefficients (R 2  = 0.9879 and R 2 (adjusted) = 0.9773). Desirability function was applied on the second-order polynomial equation to determine the optimal experimental condition for fastest total photocatalytic degradation and it was identified as follows: For a maximal target of 85.91% and a desirability of d = 1.0, [MB] = 75 mg/L, [Zn 2+ ] = 45 mg/L, [NaCl] = 0.125 M and Q = 500 mL/min. Moreover, results showed that zinc had a good affinity to cellulose material and contributed on enhancing the photocatalytic activity in terms of degradation. Mineralization of the dye was assessed for the optimal conditions using the TOC method. Moreover, special attention was also paid to better understand the effect of inorganic pollutant, scavenging effects of different molecules such as EDTA, isopropyl alcohol and CCl 4 were examined and discussed. [ABSTRACT FROM AUTHOR]

The goal of the present research is to study the effect of the inorganic species on the pyrolysis mechanism of lignocellulosic biomass. Many contradictions as the catalytic role of inorganic salts characterize the research works published up to now. These ambiguities are reasonably due to the morphological and structural modifications of the reacting biomass by the various demineralization and impregnation methods, that impact on the pyrolysis mechanism. In order to clarify the effect of inorganics on the pyrolysis mechanism, alkali and alkaline earth (AAEM) containing salts were deposited by impregnation method on cypress sawdust. Nuclear magnetic resonance analyses showed that the biomass structure was preserved and that metal deposition passes through a cationic exchange mechanism. The thermogravimetric analyses show that AAEMs have different effects by influencing the degradation behavior and the mass balances. In particular, potassium and sodium elements accelerated the hemicellulose thermal degradation without modifying the reaction mechanism. In addition, they showed a catalytic effect in the cellulose degradation towards low weight molecules decomposition and condensation reactions leading to the increase of the char yield. Contrary, the presence of magnesium and calcium seems to inhibit the hemicellulose thermal degradation without a significant effect on the cellulose degradation mechanism. [ABSTRACT FROM AUTHOR]

The purpose of the present research is to investigate the effect of background electrolytes on the phosphorus (P) sorption by four different natural clay samples (NCS): Jebel Tejera-Esghira (JTE) in Medenine area, Douiret (DR) in Tataouine area, Jebel Aidoudi (JA) and Zemlet El Beida (ZB) in Gabes area. The mineralogical and chemical characterization of the NCS showed that they are essentially composed of illite, kaolinite, smectite, with small fractions of quartz and calcite. The P sorption was investigated in batch mode in the presence of three different background electrolytes (CaCl 2 , NaCl and KCl with 99% of purity) under different experimental conditions of contact times (3 h), initial concentrations (25–150 mg.L−1), ionic strength (0–1 M), temperature (295–325 K) and pH (3–11). Experimental results indicated that P sorption in the presence of electrolytes is a rapid process since about 95% of P was observed within a contact time of 180mn. The highest P adsorption capacity was determined to 7.39 ± 0.65, 7.96 ± 0.82, 8.07 ± 0.55 and 8.83 ± 1.05 mg g1 for JTE, JA, ZB and DR. At equilibrium, the P adsorbed amount by the raw NCS was assessed to 7.75 ± 0.55, 8.34 ± 0.75, 8.8 ± 0.3 and 8.85 ± 0.75 mg g−1 for JTE, JA, ZB and DR. This amount increased by about 0.11, 0.08, 0.05%; 0.14, 0.06, 0.04%; 0.17, 0.1, 0.09 and 0.13, 0.11, 0.01% when adding the CaCl 2 , NaCl and KCl respectively. Moreover, the NCS capacity in removing increased with the increase of the initial P concentrations and the decrease of the liquid medium pH values. Also, P adsorption decreases with the increase of temperature. The P kinetic and isothermal removal experimental data were well fitted with the Pseudo-second order and Langmuir models respectively indicating that P adsorption onto NCS particles is mainly governed by chemical processes and occurs heterogeneously on multi-layers surfaces. • Sorption study on natural clay relevant to Tunisia repository program. • Sorption follows ion exchange at low pH and inner sphere complexation at high pH. • Smectite dominates the sorption behavior of natural clay. • Modeling of sorption data for phosphorus-natural clay–ground water system. • Isotherm data are well reproduced by the model at lower phosphorus ion concentration. [ABSTRACT FROM AUTHOR]

In this study, lead removal from aqueous solutions using biochar derived from olive mill solid and liquid wastes has been investigated by applying batch experiments and geochemical modelling. The batch adsorption experiments included the assessment of several key parameters such as the contact time (kinetic), initial concentration (isotherm), pH, adsorbent dose, and the presence of competitive cations, whilst the geochemical modelling focused on the involved adsorption mechanisms using the PHREEQC code. The kinetic studies showed that lead adsorption is a relatively fast process, where intraparticle diffusion is the rate-limiting step. Biochar dose, solution pH and the presence of competitive ions significantly affected the Pb adsorption effectiveness by the biochar. Especially the higher Pb removal percentages were observed in mono-elemental solutions with high biochar dose at mildly acidic solution pH values. The maximum Pb adsorption capacity of biochar was estimated as 40.8 mg g−1 which is higher than various biochars derived from sludge, lignocellulosic and animal biomasses. On the other hand, the geochemical modelling employing the PHREEQC code showed that ion exchange and Pb precipitation are the main reactions controlling its removal from aqueous solutions, whilst surface complexation is insignificant, mainly due to the low surface functional groups on the used biochar. • Utilise olive mill solid waste (OMSW) biochar to remove Pb from aqueous solutions. • Batch sorption experiments described by Elovich kinetic equation and Sips isotherm model. • Modelling sorption process using the PHREEQC code. • Ion-exchange and precipitation were found as the key retention mechanisms of Pb. • OMSW biochar can be applied as a cost-effective and environmentally friendly sorbent. [ABSTRACT FROM AUTHOR]

In this work, six Tunisian local biomasses, namely ziziphus wood (ZW), almond shells (AS), olive stones (OS), vine stems (VS) and date palmleaflets (DPL) and trunks (DPT)were slowly pyrolyzed under inert atmosphere at a heating rate of 5 °C/min through thermogravimetric (TG) analyses. The thermal degradation of samples involves the interaction in a porous media of heat, mass and momentum transfer with chemical reactions. Heat is transported by conduction, convection and radiation and, mass transfer is driven by pressure and concentration gradients. Thermal degradation curves have been studied with minute details for each degradation step. The Coats-Redfern model was used to extract the kinetic parameters from the TG data, then the kinetic parameters such as the activation energy, the pre-exponential factor and the order of the reaction were calculated. Results showed that the total mass losses amounts and kinetics are dependent on the type of the used biomass. Moreover, the devolatilization could be described by the first order model, while the char formation stage was better described by the second and third order reactions model. The physicochemical characteristics of these samples were also determined. The volatile matter (VM) content varies considerably, with values ranging from 67.19% for AS to 77.4% for ZW. The maximum values were obtained for ZW and VS with values of 77.4% and 71.9%, respectively. The lowest value (67.19%) was determined for AS. In addition, the ash contents vary between 0.8% for OS and 5.66% for DPT. The ashes vary significantly from one sample to another, with the values being even lower than 1% for OS, whereas the higher values in the DPT is 5.66%. Further, activation energies corresponding to main devolatilization regions were 59.5, 47.0, 55.8, 41.1, 89.1, 45.2 kJ/mol for ZW, AS, OS, VS, DPL, and DPT respectively. Among all the tested biomasses, the ZW and VS appear to have an important potential to be used for energy production. [ABSTRACT FROM AUTHOR]

The clear absence of a policy for the waste management and treatment of PV panels may also arise due to the crisis in leadership with an emphasis on global waste management, as mentioned by Zorpas et al. [[10]]. The expansion process, which corresponds to the crosslinked and non-crosslinked parts of the films, widens the gap between the tempered glass and the silicon panel, while the dissolution process dissolves the ethylene-vinyl acetate film into liquid. For that reason, Rubino et al. [[11]] proposed " I The PhotoLife process i " for the treatment of end-of-life PV panels in order to recover high value glass, Al, and Cu scraps, as well as an upgrade process enabling polymer separation and Ag and Si recycling. Furthermore, Zieminska-Stolarska et al. [[12]] analysed the possible waste management scenarios of PV panels through LCA and they have used several key performance indicators such as the energy payback time, CO SB 2 sb footprint, and GHG emissions. [Extracted from the article]

The present study aimed to assess the efficiency of two wastewater treatment plants (WWTPs) operating with different biological processes and to investigate the electrocoagulation process as alternative to improve their operation. Results revealed the consistent efficiency of urban WWTP that uses activated sludge process, the station operated with removal efficiencies higher than 91% for biological oxygen demand (BOD), chemical oxygen demand (COD) and total suspended solids (TSS) and produced high quality effluent whereas the efficiency of WWTP of an industrial complex using trickling filter process was in the monitored period very small and did not meet the minimum acceptable treatment efficiency of discharged wastewater. The treatment assays with electrocoagulation process using aluminium electrodes exhibited high COD removal particularly for plant of industrial site, the optimal operating conditions for the maximum COD removal are found to be the initial pH of 3, current density of 29.79 mA/cm², electrolysis time of 5 min and charge loading of 26.11 F/m³. Under these conditions, the removal efficiency of COD is found to be 79% . Consequently, electrocoagulation process can be recommended to improve the performance of WWTPs. Nonetheless, the implementation of EC into industrial or municipal systems should be investigated more. [ABSTRACT FROM AUTHOR]

Abstract: In order to reduce the impact of nitrogen pollution and to increase the agronomic value of plant wastes to be reused as organic fertilizer, we have investigated the removal of ammonium from aqueous solutions onto cactus leave fibers (CLF), and the mechanisms involved in the retention of ammonium at CLF surface. The results showed that ammonium retention onto these fibers occurred for a wide pH (6–10) and temperature ranges (20–60°C) and the biosorption potential of CLF increased with temperature from 1.4 to 2.3mgg−1 for initial concentration of 50mgL−1. The modeling studies showed that the ammonium biosorption was well described by the pseudo-second-order model, predicting therefore, chemisorption interactions-type at earlier stages and by intraparticle diffusion at later stages. Biosorption is governed by film diffusion process at higher concentrations and by particle diffusion process at higher temperatures. The surface of CLF determined by SEM revealed the presence of cracks and cavities which may allow the intraparticle diffusion and the ion exchange processes. Moreover, FTIR and EDX analysis before and after ammonium retention showed that the main mechanisms involved in the removal of ammonium were the ionic exchange by calcium ions as well as H+ and the complexation with carboxylic, alcoholic and phenolic groups. [Copyright &y& Elsevier]

Abstract: Adsorption efficiency of orthophosphate from aqueous solution onto Posidonia oceanica fibers (POF) as a raw, natural and abundant material was investigated and compared with other common natural materials. A series of batch tests were undertaken to assess the effect of the system variables, i.e. initial aqueous orthophosphate concentration, contact time, adsorbent dosage, pH and temperature. Results indicate that orthophosphate uptake increased with increasing initial orthophosphate concentration, temperature and adsorbent dosage and decreased with increasing pH values. The maximum adsorption capacity (Q m) determined from the Langmuir isotherm was calculated to be 7.45mgg−1 for the studied orthophosphates concentration range of 15–100mgL−1, pH 7; adsorbent dosage of 2gL−1 and temperature of 20±2°C. The adsorption data were very well described by the pseudo-second order model predicting a chemisorption process. The energy dispersive spectroscopy (EDS) and FTIR analysis before and after adsorption of orthophosphate onto POF showed that the main involved mechanisms are ligand exchange between orthophosphate and Cl−, SO4 2− and OH− and precipitation with calcium. In comparison with other natural adsorbents, raw POF could be considered as one of the most efficient natural materials for the removal of orthophosphate with the possibility of agronomic reuse. [Copyright &y& Elsevier]

Abstract: The present study aims to develop a new potentially low-cost, sustainable treatment approach to soluble inorganic phosphorus removal from synthetic solutions and secondary wastewater effluents in which a plant waste (Posidonia oceanica fiber: POF) is used for further agronomic benefit. Dynamic flow tests using a continuous stirred tank reactor (CSTR) were carried out to study the effect of initial concentration of phosphorus, amount of adsorbent, feeding flow rate and anions competition. The experimental results showed that the removal efficiency of phosphorus from synthetic solutions is about 80% for 10gL−1 of POF. In addition, the variation of the initial concentration of phosphorus from 8 to 50mgL−1 increased the adsorption capacity from 0.99 to 3.03mgg−1. The use of secondary treated wastewater showed the presence of competition phenomenon between phosphorus and sulphate which could be overcoming with increasing the sorptive surface area and providing more adsorption sites when increasing the adsorbent dosage of POF. Compared with columns studies, this novel CSTR system showed more advantages for the removal of soluble phosphorus as a tertiary treatment of urban secondary effluents with more adsorption efficiency and capacity, in addition to the prospect use of saturated POF with nutriment as fertilizer and compost. [Copyright &y& Elsevier]

Abstract: GIS and expert knowledge are used as a decision support system to determine adequate potential soil aquifer treatment (SAT) sites for groundwater recharge of Hammamet–Nabeul aquifer located in ‘Cap Bon’ peninsula in North East of Tunisia. These sites are identified using a single-objective multi-criteria analysis. All criteria selected are assumed to be constraints. The acceptable range of each criterion is determined by a critical threshold value, corresponding to standards or normative statements. Based on these acceptable ranges, all criteria are expressed in a Boolean map: excluded areas are coded 0 and those open for consideration are coded 1. Multi-criteria evaluation were performed combining all Boolean maps by means of intersect operator in order to select sites meeting all the criteria. The selection of criteria and acceptable ranges is based on national expert consulting and international published guidelines and technical documents. The resulting map of this GIS-based multi-criteria analysis shows extended potential sites for SAT, exceeding 1000 ha, which indicates a possible use of treated wastewater for groundwater recharge; 8 ha could be supplied by Hammamet Sud plant, 764 ha by SE3 and 347 ha by SE4. 109 ha of these areas could be supplied by both SE3 and SE4. These potential sites are mostly located at rivers banks, around Grand-Nabeul urban area and in some agricultural domains and coastal dunes. [Copyright &y& Elsevier]

The olive oil industry is an important economic sector in Mediterranean countries. However, oil production is unfortunately accompanied by the generation of huge amounts of olive mill solid wastes (OMSW) and olive mill wastewater (OMWW). In the present study, a strategy is proposed for converting these olive mill wastes into biochar through pyrolysis, for their later use as an organic amendment in agriculture. Specifically, two biochars were prepared from the pyrolysis of OMSW at 500 °C, either alone or impregnated with OMWW (OMSW-B and I-OMSW-B). The characterization of the OMSW and I-OMSW samples and their derived biochars showed that the fixed carbon and ash contents in the feedstocks increased by 38% and 11% respectively for OMSW-B, and by 37% and 12% respectively for I-OMSW-B. Interestingly, the impregnation process significantly increased Na, P, K, Ca and Fe contents in the produced biochars. The effect of OMSW-B and I-OMSW-B amendments at different application dose (1%, 2.5% and 5% wt/wt) on the enzymatic activity of an agricultural soil was performed at laboratory scale with a pot test. The experimental results showed that phosphatase and urease activity increased with biochar application rate; amendment with I-OMSW-B at 1%, 2.5% and 5% enhanced the phosphatase activity by 63%, 142% and 285% and urease activity by 50%, 116% and 149%, respectively. On the other hand, dehydrogenase and protease activities were higher for the application rate of 2.5% biochar. Biochar amendment promoted tomatoes seedling growth after 10 weeks, which was highest in the application rates of 2.5% and 5% for both OMSW-B and I-OSMW-B. Thus, the produced biochars had great potential to be used as biofertilizers in agriculture. Unlabelled Image • Slow pyrolysis performed to convert OMSW and its impregnated form onto biochars • Biochars characterized using proximate, mineral analysis and crystalline structure • I-OMSW-B exhibited high contents of C, P and K comparing to initial feedstocks. • I-OMSW-B amendment promoted tomatoes seedling growth and enzymatic activities. • Studied biochars didn't have phytotoxic effect under tested doses. [ABSTRACT FROM AUTHOR]

Olive mill wastewater (OMW) is nowadays considered as a serious source pollution. At the same time, it contains high amounts of nutrients, especially potassium and phosphorus that could be recovered for agricultural purposes. The aim of the current experimental research work is to investigate the agronomic potential use of OMW based biochar produced from the slow pyrolysis at 500 °C of raw cypress sawdust (CS) impregnated with OMW (ICS-OMW-B). In order to understand the contribution of OMW, two additional biochars were produced from raw cypress sawdust (RCS-B) and cypress sawdust pretreated with potassium chloride (ICS-K-B). Results indicated that RCS impregnation by OMW significantly improved the produced biochar's chemical properties, especially its nutrients contents. Furthermore, in comparison with the other biochars, ICS-OMW-B application as an organic fertilizer showed promising results in terms of produced fresh and dry masses, as well as potassium bioavailability as assessed in test experiments with ryegrass. For instance, the dry matter masses of the rye-grass treated with ICS-OMW-B were about 23, 34 and 50 wt% higher than the ones measured for the tests using RCS-B, ICS-K-B and synthetic K-fertilizer as amendments, respectively. Besides, this biochar has a potential effect on the suppression of various pathogens existing in the tested agricultural soil. All these results demonstrated that the biochar generated from the slow pyrolysis of impregnated sawdust with OMW could be considered as attractive and promising organic fertilizer for acidic agricultural soils. Unlabelled Image • Cypress sawdust impregnated with olive mill wastewater was used to elaborate biochars. • The fertilizing potential of the biochars was evaluated through ryegrass growth tests. • Biochar enriched with olive mill wastewater is an efficient organic fertilizer. • The effect of biochar on soil aggregate stability and pathogen growth was assessed. • K and P bioavailabilities were estimated through the analyses of rye grass leaves. [ABSTRACT FROM AUTHOR]

In this work, four activated carbons were synthetized from natural olive stone (NOS) wastes using ZnCl2 as an activating agent. These activated carbons (OSAC) were synthetized for a constant mass ratio of ZnCl2: NOS of 2:1, a contact time of 2 h and four different heating temperatures (300, 400, 450 and 500 °C). The physicochemical characterization of these activated carbons by various analyses including N2 adsorption–desorption measurements, surface charge evolution versus pH, Boehm titration, Fourier transform(FTIR) and scanning electron microscopy (SEM) showed that the activated carbon produced at a temperature of 400 °C (OSAC 400 °C) exhibited the best properties. Indeed, it has the highest BET surface area, total pore and micropore volumes with values of 740 m2·g-1, 0.57 cm³·g-1 and 0.25 cm³·g-1, respectively. Moreover, it is rich in various acidic and basic functional groups that could react with various common adsorbents. The test of these activated carbons, for the adsorption of a cationic (methylene blue (MB)) and anionic (methyl orange (MO)) dye under various experimental conditions, showed that OSAC 400 °C could be considered as an effective, attractive and promising adsorbent for both the tested dyes. The Langmuir’s adsorption capacities of this adsorbent were assessed to 303.0 and 277.8 mg·g-1 for MB and MO, respectively, which are significantly high compared to other various activated carbons. The retention of the pollutants is mainly chemical including hydrogen bond and electrostatic attraction between the dyes and the activated carbon surface. [ABSTRACT FROM AUTHOR]

In this study, we assessed the transformation of raw olive pomace into carbon-richmaterial using olive mill wastewater (OMWW) as the liquid medium for the hydrothermal carbonization (HTC) process. The findings were compared accordingly with the use of distilled water (DW), which is the conventional practice. The use ofOMWWas a liquidmatrix enhanced the hydrochar yield, but volatile matter, fixed carbon content, and O/C and H/C ratios followed a decreasing trend. Furthermore, for an HTC temperature of 220 °C, the use ofOMWWconsiderably increased the high heating value of the hydrochars from approximately 24.2 MJ/kg to 31.6 MJ/kg. According to the van Krevelen diagram of feedstock and derived hydrochars, dehydration was the predominant carbonization reaction for both liquid sources. Morphological characterization of both sets of hydrochars indicated the generation of specific carbon nuclei when using DW while OMWW led to the creation of hydrochar with a less homogeneous surface. Structural analysis revealed the heterogeneous aspect of the hydrochar surface with an abundance of crystallized metal-based inorganic salts. [ABSTRACT FROM AUTHOR]

Hydrothermal carbonization (HTC) of wet solid wastes has been pointed out as an eco-friendly, flexible and highly efficient technology for the sustainable valorization of multiple sourced wastes. In this review paper, most recent studies on hydrochars (solid residue of the HTC process) production, characterization and application for wastewaters treatment was summarized and deeply discussed. The role of initial feedstock source nature and characteristics as well as the HTC experimental conditions including the temperature, the residence time and the pH media was assessed. Physical and chemical activation methods including the use of oxygen, steam, microwave, acids, alkaline, organics and salty solutions for the improvement of the physicochemical properties of the produced hydrochars are compared. The efficiency of these raw/modified hydrochars along with the involved mechanisms during organic (dyes) and mineral pollutants (heavy metals and nutrients) removal from aqueous solutions is also reviewed. Finally, this paper addresses the main challenges and also demonstrates insights on new directions for hydrochars research and development in the future. • Hydrochars showed a decrease in esters and hydroxyl groups compared to raw biomass. • Carbon content, minerals and polymeric structure influence hydrochars' adsorption capacity. • Solution temperature, pH and residence time impact hydrochar's efficiency. • Hydrochar's oxygen functional groups are reactive to heavy metals and organic molecules. • Post-activation improves significantly hydrochars' specific surface area. [ABSTRACT FROM AUTHOR]

Olive mill wastewater (OMWW) management is recognized as the major defy that olive oil industry is facing. Recently, we have established an eco-friendly strategy for the OMWW conversion into irrigation water sources, green biofuels and biofertilizers. This work is a part of a series of papers detailing the different steps established in this environmental friendly strategy for OMWW management. It deals with the bio-oil production and characterization during the pyrolysis of OMWW impregnated on olive pomace (OP) in a pyrolyzer pilot. Results show a bio-oil production yield of 36 wt% during the pyrolysis test. This yield could be attributed to the recovery of organic compounds from OMWW through OP impregnation and their conversion to bio-oil. The bio-oil properties show that viscosity and flash point values could reach the European standards. However, the lower heating values (26 MJ/kg) and the acidic character limit its direct use. These values are attributed to the higher water and oxygen contents. The GC/MS analysis confirms these properties showing the presence of phenolic molecules and long chain organic acids. Therefore, OMWW impregnation on OP and pyrolysis could be considered as a promising issue for bio-oil production. However, this bio-oil requires an upgrading step for a better valorization. • A strategy for olive mill wastes recovery is established using pyrolysis technique. • A bio-oil production yield of 36% confirms the OMWW organic matter valorization. • Bio-oil viscosity and flash point properties could reach biofuels Standards. • Bio-oil contains many components as phenolic molecules and long chain organic acids. • Oxygen and water contents, acidic pH require improvement before bio-oil direct use. [ABSTRACT FROM AUTHOR]

New polyoxometalate (POM)/polymer hybrid composites were prepared by photopolymerization under mild conditions for suitable photocatalytic processes. Polyoxometalates were incorporated in special photosensitive resins, which were photopolymerized under visible light to obtain new materials with photocatalytic activity for dye removal. The synthesized composites were characterized by real‐time FT‐IR, and the photocatalytic ability was investigated on Eosin‐Y removal using photolysis under near UV irradiation. Interestingly, the polyoxometalates keep their photocatalytic properties, while incorporated into the polymeric matrix since very high conversion rates of Eosin‐Y were achieved. Indeed, degradation efficiencies of about 98% and 93% were registered when using H3PMo12O40/polymer and 94% for SiMo12O40(IPh2)4/polymer composites, respectively. These first results reported in this article show that the new synthesized POM/polymer composites could be considered as promising materials for green and more suitable organic dye removal from aqueous solutions. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 1538–1549 [ABSTRACT FROM AUTHOR]

Electrochemical denitrification of highly concentrated synthetic wastewaters was investigated using bipolar Boron-Doped Diamond on silicone substrate (Si/BDD) electrodes under various experimental conditions. The effects of the key operational parameters on the removal efficiency of nitrates were assessed using the Response Surface Methodology. Results showed that the efficiency of removal of nitrates was mostly sensitive to the applied current density and the duration of treatment, which are optimized, respectively, at 35.7 mA cm − 2 and 120 min. Under these experimental conditions, the removal yield of nitrates was evaluated at 91% with formation of by-products of 0.4% and 3.6% of nitrites and ammonia, respectively. Furthermore, average current efficiency is optimized at 59% with an energy consumption estimated at 0.35 × 10 − 3 kWh(g-N) − 1 . To better understand the role of BDD anode/cathode, by-products electrogeneration and disappearance, as well as the effect of chloride ions on pathway electrochemical denitrification, series of experiments were carried out at three concentrations of NaCl. The kinetic constants were calculated using a pseudo first-order kinetic model based on the fitting of the experimental data to established numerical approximations using Matlab software. At first, we noted that the direct reduction to N 2 in the absence of NaCl was very low ( k = 1.7 × 10 − 9 s − 1 ) compared to NH 3 and NO 2 − electrogeneration ( k = 1.7 × 10 − 5 and 5.4 × 10 − 4 s − 1 , respectively), where N 2 seemed to be the result of a reduction in by-products. The presence of hypochlorous species had a negligible effect on the kinetic rates of NO 3 − reduction. [ABSTRACT FROM AUTHOR]

In order to set up a cost-efficient biorefinery in a Tunisian dairy industry, the production unit effluents are recovered. The main objective is to develop an optimum method for the production of bioethanol from whey. An energy analysis as well as environmental and economic analyses are performed for a bioethanol production plant. Four production scenarios are examined in order to determine the most provident as well as the less polluting ones. The process and cost models were developed using SuperPro Designer software which a simulation program that is able to estimate both process and economic parameters. This software uses energy and mass balances. The model can be used to assess the efficiency, the resources consumption, the profitability and the environmental impact of each scenario. The results demonstrate that the third scenario, in which a reverse osmosis procedure is added to concentrate the whey, a continuous stoichiometric reaction procedure is integrated to model the biotransformation in the fermenter and where streams are added in order to recycle the biomass, produces the highest amount of bioethanol with 1.65 MT/year but the second one (where no streams were added) is the most profitable one with revenues as high as 570 000 $/year. The corresponding cost of ethanol production is 0.271 US $ ethanol per liter. The net present value (NPV) and the return on investment (ROI) of each scenario are positive. Such result indicates that all these investments could be undertaken in order to find an eco-friendly issue for the dairy industry effluents. Cheese whey could serve as an alternative raw material for producing ethanol. [Display omitted] • A model of a cost-efficient biorefinery is built for Tunisian cheese whey recovery. • Lactose affects clearly the ethanol production. • Adding streams to recycle the biomass is efficient economically and ecologically. • Produce bioethanol from important amount of effluent without treatment. [ABSTRACT FROM AUTHOR]

This work examines in silico the dominant geochemical processes that control inorganic nutrients (Ca, Mg, Na, K) availability in irrigated agricultural soil amended with potassium-enriched biochar (from olive mill wastes) at mass doses of 0.5%, 1%, 2% and 10%. The geochemical modelling step was supported by analytical measurements regarding the physicochemical characteristics of the irrigation water, the agricultural soil and the biochar. Two geochemical approaches, namely equilibrium exchange (E.E.) and kinetic exchange (K.E.) models were applied and compared to assess nutrient release with an emphasis on potassium availability. Equilibrium exchange perspective assumed that nutrient release is controlled by ion-exchange reactions onto the biochar surface, whilst kinetic exchange perspective assumed the contribution of both ion-exchange and dissolution of salts. Results indicated that for the E.E. model, the soluble amount of potassium is readily available for transport within the pores of the porous media, and therefore is leached from the column within only 10 days. For the K.E. model that assumes a kinetically controlled release of potassium due to interactions occurring at the solid-solution interface, the assessed retention times were more realistic and significantly higher (up to 100 days). Concerning the applied doses of biochar, for a 2% biochar fraction mixed with soil, for example, the available K for plants doubled compared with the available K in the soil without biochar. In any case, the use of numerical modeling was proven helpful for a quick assessment of biochar performance in soil, by avoiding time-consuming and laborious experimental set-ups. Validation of the models by experimental data will further establish the proposed mechanisms. [ABSTRACT FROM AUTHOR]

Semi-arid agricultural soils have increasingly been subjected to urban sewage sludge (USS) applications due to accelerated soil depletion and shortages in manure supply. Research studies addressing USS reuse have mostly been conducted in cropping systems and focused on changes in topsoil properties of a given texture. Therefore, sludge-soil interactions could be largely influenced by the presence of plants, soil particle composition and depth. In this field study, two agricultural soils (sandy, S and sandy loam, SL) received simultaneously four annual USS applications of 40, 80, and 120 t ha−1 year−1 in absence of vegetation. Outcomes showed the increase of carbon and macronutrients in both soils proportionally to USS dose especially in the topsoil profile (0–20 cm). Subsoil (20–40 cm) was similarly influenced by sludge rates, showing comparable variations of fertility parameters though at significant lower levels. The depth-dependent improvement of soil fertility in both layers enhanced the microbiological properties accordingly, with significant variations in soil SL characterized by a higher clay content than soil S. Besides, positive correlations between increases in sludge dose, salinity, trace metals, and enzyme activities in both soils indicate that excessive sludge doses did not cause soil degradation or biotoxic effects under the described experimental conditions. In particular and despite high geoaccumulation indices of Ni in both soils and profiles, the global concentrations of Cu, Ni, Pb, and Zn were still below threshold levels for contaminated soils. In addition, the maintenance of pH values within neutral range and the increase of organic matter content with respect to control would have further reduced metal availability in amended soils. Therefore, we could closely investigate the effects of texture and depth on the intrinsic resilience of each soil to cope with repetitive USS applications. • Repetitive sludge applications changed soil properties in a dose-dependent manner. • Little variation in clay content influenced largely light-textured soil properties. • Topsoil samples had higher fertility and biological activities than subsoils. • Excessive sludge doses did not provoke soil contamination or degradation. • Absence of plants highlighted closely soil-sludge interactions on the long-term. [ABSTRACT FROM AUTHOR]

Three vulnerability index models were applied to assess the pollution potential of Nabeul-Hammamet shallow aquifer, Tunisia: DRASTIC, Pesticide DRASTIC and the Susceptibility Index (SI). An output map layer of each one was obtained using a geographic information system (GIS). The SI layer was overlain with DRASTIC and Pesticide DRASTIC and the percentage areas of agreement and divergence in vulnerability categories were extracted. DRASTIC results suggest the aquifer has mostly low vulnerability. Pesticide DRASTIC and SI identify three vulnerability categories (low, moderate, high) in the aquifer. Published data on current chemical groundwater composition indicate that parts of the aquifer are highly contaminated, revealing that DRASTIC underestimates the risk of pollution; Pesticide DRASTIC and SI reflect this risk better. Agreement in vulnerability categories between the two last models is found for 64 % of the aquifer area. To help manage land-use allocation and prevent Nabeul-Hammamet-aquifer contamination, DRASTIC is not recommended. Pesticide DRASTIC and SI are recommended but for slightly different applications. SI helps in the monitoring of current vulnerable areas and, thus, in contamination prevention. Pesticide DRASTIC could better intervene as a criterion in a multi-criteria analysis to select the best sites for specific on-the-ground practice or future land use. [ABSTRACT FROM AUTHOR]

Abstract: The current work tackles the problem of soil microbial growth and biofilm expansion assessment in infiltration percolation process in order to optimize the technique design and monitoring. Experiments were conducted on a sand filled PVC column fed at a pulsed rhythm of 8 sequences per day in order to maximize the soil aeration that generates a better oxygen renewal in the soil gas phase, enhances the oxidation of the oxidisable matters and improves sanitary performances. As we target the biofilm expansion study, we assessed the microbial biomass at different depths of the soil matrix (10, 25, 50 and 75 cm), by the chloroform fumigation–extraction and DNA extraction methods. Results showed that the microbial biomass increases with operating time especially between 10 and 25 cm depths until the 96th operating day (OPD) and decreases notably after this time. A highly significant positively correlation (r = 0.97) is registered between results of microbial biomass quantification by fumigation–extraction method (FEM) expressed as carbon material (biomass C) and those obtained by DNA extraction method (DNA-EM). In addition, we performed an enumeration of the biofilm total microbial flora using the solid medium cultivation method which corroborates the microbial biomass quantification results. In order to illustrate the biofilm shape generated by bacterial cells and extracellular polymeric substances (EPS)in the vicinity of the sand grains, we performed different scanning electron microscope (SEM) micrographs at different elapsed operation times. [Copyright &y& Elsevier]

Hydrothermal carbonization (HTC) is considered as a promising technique for wastes conversion into carbon rich materials for various energetic, environmental and agricultural applications. In this work, the HTC of olive mill wastewater (OMWW) was investigated at different temperatures (180–220 °C) and both, the solid (i.e., hydrochars) and the final process liquid derived from the thermal conversion process were deeply analyzed. Results showed that the solid yield was affected by the temperature, i.e., decrease from 57% to 25% for temperatures of 180 °C and 220 °C, respectively. Furthermore, the hydrochars presented an increasing fixed carbon percentage with the increase of the carbonization temperature, suggesting that decarboxylation is the main reaction driving the HTC process. The decrease in the O/C ratio promoted an increase of the high heating value (HHV) by 32% for hydrochar prepared at 220 °C. The process liquids were sampled and their organic contents were analyzed using GC–MS technique. Acids, alcohols, phenols and sugar derivatives were detected and their concentrations varied with carbonization temperatures. The assessment of the physico-chemical properties of the generated HTC by-products suggested the possible application of the hydrochars for energetic insights while the liquid fraction could be practical for in agricultural field. Unlabelled Image • Valorization of olive mill wastewater was studied using hydrothermal carbonization. • Characterization of the produced hydrochars was assessed by multiple techniques. • Carbonization process of the precursor was governed by decarboxylation mechanism. • Produced hydrochars presented a high calorific content (35.01 MJ/kg). • Final liquid fractions exhibited interesting organic compounds for agricultural use. [ABSTRACT FROM AUTHOR]

• Raw kenaf stems and its pyrolytic char are fully characterized. • Thermal properties of kenaf stems are more interesting than many other usual crops. • Kenaf stem derived char is very promising for pollutants removal or gas storage. • Kenaf derived char is suitable for soil amendments. • High SSA of the 500 °C-chars incite to activation process to get excellent AC. Kenaf stems are characterized in this present investigation in order to assess their suitability in energy recovery through a pyrolysis process and to identify sustainable applications of the generated biochar. In particular, the raw biomass properties are analyzed using numerous analytical techniques such as thermogravimetric analyses (TGA/DTG), X-Ray Fluorescence (XRF) and Scanning Electronic Microscopy (SEM). First, the thermogravimetric analyses monitor the pyrolysis parameters, control the proportion of its outputs and allow to extract the kinetic parameters. The latter is determined using Friedman, Flynn-Wall-Ozawa (FWO) and Kissinger-Akahira-Sunose (KAS) models. In a second step, Kenaf derived chars are produced at different pyrolysis temperatures and their physicochemical, morphological, textural and structural properties are determined using different techniques such as CO 2 adsorption, Raman Spectroscopy, and DRIFT Spectroscopy. The main results confirm the Kenaf potential for energy applications as its thermal properties are more interesting compared to other usual crops. The Kenaf stem derived char is also very promising for pollutants removal or gas storage as its surface area as well as its microporous structure are interestingly developed when increasing the pyrolysis temperature. Kenaf char could be also chemically or physically activated in order to be used for pollutants removal from gaseous and aqueous effluents. Finally, the XRF analysis indicated that contents in K and P elements are high. Ca and Mg are also major mineral species in the char. These contents indicate that Kenaf derived char could be also suitable for agricultural soil amendments. [ABSTRACT FROM AUTHOR]