Corrigendum: Rare cell variability and drug-induced reprogramming as a mode of cancer drug resistance.

This corrects the article DOI: 10.1038/nature22794.

Insight into the wheat residues-derived adsorbents for the remediation of organic and inorganic aquatic contaminants: A review.

Wheat is a major grain crop of the world that provides a stable food for human consumption. Large amounts of by-products/waste materials are produced after the harvesting and processing of wheat crop. Such materials can cause an environmental issue if not disposed of properly. Several studies have shown that wheat residues can be efficient precursors for adsorbents because of their availability, renewability, lignocellulosic composition, and surface active groups enriched structure. In the literature, there are few review articles that address wheat residues-based adsorbents. However, these reviews were specific in terms of adsorbate or adsorbent and did not provide detailed information about the modification, properties, and regeneration of these adsorbents. This article extensively reviews the utilization of wheat biomass/waste including straw, bran, husk, and stalk as precursors for raw or untreated, chemically treated, carbonaceous, and composite adsorbents against various environmental pollutants. The influences of inlet pollutant amount, adsorbent dose, pH, temperature, and time on the performance of adsorbents against pollutants were considered. The maximum uptakes, equilibrium time, and adsorption nature were identified from isotherms, kinetic, and thermodynamic studies. The highest adsorbed amounts of most tested contaminants were 448.20, 322.58, and 578.13 mg/g for lead, chromium, and copper, 1374.6 and 1449.4 mg/g for methylene blue and malachite green, and 854.75, 179.21, and 107.77 mg/g for tetracycline, phosphate, and nitrate, respectively. For the studied adsorbate/adsorbent systems the adsorption mechanism and regeneration were also discussed. Significant results and future directions are finally presented.

Rare cell variability and drug-induced reprogramming as a mode of cancer drug resistance.

Therapies that target signalling molecules that are mutated in cancers can often have substantial short-term effects, but the emergence of resistant cancer cells is a major barrier to full cures. Resistance can result from secondary mutations, but in other cases there is no clear genetic cause, raising the possibility of non-genetic rare cell variability. Here we show that human melanoma cells can display profound transcriptional variability at the single-cell level that predicts which cells will ultimately resist drug treatment. This variability involves infrequent, semi-coordinated transcription of a number of resistance markers at high levels in a very small percentage of cells. The addition of drug then induces epigenetic reprogramming in these cells, converting the transient transcriptional state to a stably resistant state. This reprogramming begins with a loss of SOX10-mediated differentiation followed by activation of new signalling pathways, partially mediated by the activity of the transcription factors JUN and/or AP-1 and TEAD. Our work reveals the multistage nature of the acquisition of drug resistance and provides a framework for understanding resistance dynamics in single cells. We find that other cell types also exhibit sporadic expression of many of these same marker genes, suggesting the existence of a general program in which expression is displayed in rare subpopulations of cells.

Bamboo-derived adsorbents for environmental remediation: A review of recent progress.

The bamboo family of plants is one of the fastest-growing species in the world. As such, there is an abundance of bamboo residues available for exploitation, especially in southeast Asian, central African and south American regions. The preparation of efficient adsorbents from bamboo residues is an emerging exploitation pathway. Biochars, activated carbons or raw bamboo fibers embedded with nanoparticles, each class of materials has been shown to be highly efficient in adsorption processes. This review aims to summarize recent findings in the application of bamboo-based adsorbents in the removal of organic, inorganic, or gaseous pollutants. Therefore, this review first discusses the preparation methods and surface modification methodologies and their effects on the adsorbent elemental content and other basic properties. The following sections assess the recent progress in the adsorption of heavy metals, organics, and gaseous substances by bamboo-based adsorbents, focusing on the optimum adsorption capacities, adsorption mechanisms and the optimum-fitting kinetic models and isotherms. Finally, research gaps were identified and directions for future research are proposed.

Differential response of N2O emissions, N2O-producing and N2O-reducing bacteria to varying tetracycline doses in fertilized soil.

Tetracyclines are the most widely used antibiotics worldwide. Their presence in soils could affect nutrient cycling, but our knowledge regarding how they affect soil microbial communities involved in greenhouse gas emissions is limited. The objective of the current study was to evaluate how tetracycline is affecting N2O emissions and the abundance of denitrifiers in fertilized soil. For this purpose, soil mesocosms were treated with only NH4NO3 (100 mg/kg) or NH4NO3 (100 mg/kg) plus three different doses of tetracycline (0.1, 0.5 and 2 mg/kg). Soils that did not receive tetracycline or NH4NO3 were used as controls. Nitrous oxide fluxes were monitored daily for 16 days. The total bacterial (16S rRNA), the abundance of N2O-reducing and -producing bacteria were quantified by qPCR at the end of the experiment. The application of NH4NO3 caused a significant increase of N2O emissions and AOB abundance but did not affect the abundance of denitrifiers and AOA compared to control soils. Different doses of tetracycline in fertilized soils did not mitigate these N2O emissions; instead, higher cumulative emissions were noticed in soils treated with the lowest dose. In these soils the total bacterial abundance was higher compared to soils received higher tetracycline concentration. The abundances of the N2O-producing and N2O-reducing communities were also differently affected by the addition of tetracycline, which was dose-dependent. Higher doses of tetracycline favored N2O-reducers within the total bacterial community, which could be important for mitigating N2O emissions in the long term.

Process Parameters Optimization, Characterization, and Application of KOH-Activated Norway Spruce Bark Graphitic Biochars for Efficient Azo Dye Adsorption.

In this work, Norway spruce bark was used as a precursor to prepare activated biochars (BCs) via chemical activation with potassium hydroxide (KOH) as a chemical activator. A Box-Behnken design (BBD) was conducted to evaluate and identify the optimal conditions to reach high specific surface area and high mass yield of BC samples. The studied BC preparation parameters and their levels were as follows: pyrolysis temperature (700, 800, and 900 °C), holding time (1, 2, and 3 h), and ratio of the biomass: chemical activator of 1: 1, 1.5, and 2. The planned BBD yielded BC with extremely high SSA values, up to 2209 m2·g-1. In addition, the BCs were physiochemically characterized, and the results indicated that the BCs exhibited disordered carbon structures and presented a high quantity of O-bearing functional groups on their surfaces, which might improve their adsorption performance towards organic pollutant removal. The BC with the highest SSA value was then employed as an adsorbent to remove Evans blue dye (EB) and colorful effluents. The kinetic study followed a general-order (GO) model, as the most suitable model to describe the experimental data, while the Redlich-Peterson model fitted the equilibrium data better. The EB adsorption capacity was 396.1 mg·g-1. The employment of the BC in the treatment of synthetic effluents, with several dyes and other organic and inorganic compounds, returned a high percentage of removal degree up to 87.7%. Desorption and cyclability tests showed that the biochar can be efficiently regenerated, maintaining an adsorption capacity of 75% after 4 adsorption-desorption cycles. The results of this work pointed out that Norway spruce bark indeed is a promising precursor for producing biochars with very promising properties.

Hydra: A mixture modeling framework for subtyping pediatric cancer cohorts using multimodal gene expression signatures.

Precision oncology has primarily relied on coding mutations as biomarkers of response to therapies. While transcriptome analysis can provide valuable information, incorporation into workflows has been difficult. For example, the relative rather than absolute gene expression level needs to be considered, requiring differential expression analysis across samples. However, expression programs related to the cell-of-origin and tumor microenvironment effects confound the search for cancer-specific expression changes. To address these challenges, we developed an unsupervised clustering approach for discovering differential pathway expression within cancer cohorts using gene expression measurements. The hydra approach uses a Dirichlet process mixture model to automatically detect multimodally distributed genes and expression signatures without the need for matched normal tissue. We demonstrate that the hydra approach is more sensitive than widely-used gene set enrichment approaches for detecting multimodal expression signatures. Application of the hydra analysis framework to small blue round cell tumors (including rhabdomyosarcoma, synovial sarcoma, neuroblastoma, Ewing sarcoma, and osteosarcoma) identified expression signatures associated with changes in the tumor microenvironment. The hydra approach also identified an association between ATRX deletions and elevated immune marker expression in high-risk neuroblastoma. Notably, hydra analysis of all small blue round cell tumors revealed similar subtypes, characterized by changes to infiltrating immune and stromal expression signatures.

Enhancing cadmium extraction potential of Brassica napus: Effect of rhizosphere interactions.

Brassica napus L. (oilseed rape) was grown with daikon and white lupin in a polyvinyl chloride split pot experiment (with no barrier between the compartments or by a nylon mesh barrier (37 µm) to license partial root interaction, or a solid barrier to stop any root interactions) to examine the effect of rhizosphere interaction on the cadmium uptake. The results showed that shoot and root biomasses of oilseed rape were 40.66% and 26.94% less than that of the monocropped treatment (solid barrier) when intercropping with daikon under the rhizosphere complete interaction. However, the intermingling of roots between oilseed rape and white lupin notably enhanced the dry biomass of oilseed rape by 40.23% and decreased with the reduction of root contact. Oilseed rape intercropping with daikon enhanced the shoot Cd concentration of oilseed rape. The shoot Cd concentration (44.8 mg/kg) of oilseed rape when intercropped white lupin under complete rhizosphere interaction were greater than those of other treatments. Additionally, the intermingling of roots played a positive role in the content of citric and malic acids when intercropping with white lupin. In all systems, the BCF values of oilseed rape >5. Therefore, intercropping with white lupin may contribute to higher biomass and increased uptake Cd by oilseed rape. We can toward sustainable positive effects on phytoremediation that based on a better understanding of rhizosphere processes.

Single-use surgical face masks, as a potential source of microplastics: Do they act as pollutant carriers?

Millions of people are using face coverings (including single-use surgical face masks) as a result of the COVID-19 pandemic and a large number of used masks, particularly single-use masks enter uncontrolled the environment since most of the users have little information on how to dispose of them safely. This new important waste is a potential source of microplastics, which is found nowadays in many parks, streets, and coastlines. Discarded masks will be finally drained to the ocean polluting the marine environment and threatening marine life. This short communication examines the role of face masks and subsequently mask-derived microplastics as pollutant carriers in environmental compartments (e.g. hydrosphere, biosphere, etc.) by investigating their sorption characteristics regarding dye molecules. In this context, batch-type equilibrium experiments were performed and the effect of different sorption parameters has been explored (i.e. contact time and temperature). The results show that single-use surgical face masks can act as dye carriers (Methylene Blue, Crystal Violet and Malachite Green) in the aquatic environment. In addition, preliminary experiments on the thermal treatment of face masks and the use of the resulting carbonaceous material as efficient adsorbent have been performed, pointing out a possibility for used mask disinfection and recycling.

The effect of chemical and organic N inputs on N2O emission from rain-fed crops in Eastern Mediterranean.

Nitrogen has a significant contribution to global warming and its reduction in agriculture is expected to reduce N2O emissions having however adverse effects on the productivity of agricultural ecosystems. Maintaining systems productivity with alternative N sources i.e manure and composts could be a strategy also to mitigate N2O emissions. In this paper, we present the effect of different N sources (organic and chemical) on field N2O emissions and how these emissions are associated with soil available N forms (NH4+ and NO3-) in three different rain-fed crops namely barley, pea and vetch grown in Cyprus for two growing seasons. The daily emissions ranged from -3.11 to 12.3 g N-N2O/ha/day, while cumulative emissions ranged from 119 g N-N2O/ha to 660 g N-N2O/ha depending on crop and nitrogen source type. The emissions showed a seasonal pattern and WFPS has been identified as a critical soil parameter controlling daily N2O emissions. The daily N2O fluxes in the current study derives mainly from nitrification irrespectively crop type or nitrogen source type. Specific emission factors for each crop cultivated under different N source type were calculated and ranged from 0.03% ± 0.02-0.34% ± 0.09. The application of manure and chemical fertilizers cause similar intensity of N2O emissions while compost exhibited the lower emission factors. These findings suggest that composts could be integrated in a nutrient management strategy of rain-fed crops with less N2O emissions. The high background emissions found suggest also that other factors than external inputs are associated with N2O emissions and further studies including the response of microbial community structure and their contribution and association with N2O emissions.

Editorial: New Research on Soil Degradation and Restoration.

The Virtual Special Issue (VSI) "New Research on Soil Degradation and Restoration" was proposed by the Guest-Editors (the authors of this editorial piece) to Journal of Environmental Management taking into account the following aspects: (a) Firstly, soil degradation is a main issue all over the world; (b) Secondly, physical, chemical and biological degradation of soil environments need detailed research, also going deeper in some new aspects poorly covered up to now; and (c) Similarly, new quality research on restoration of degraded soils, dumping sites, different areas affected by mining activities, and so on, would be clearly useful in order to prevent and/or solve critical environmental hazards. As a result, 110 manuscripts were submitted to the VSI by authors from around the world, and near 50 high quality works were finally published. The Guest-Editors of the VSI consider that the papers published will be of great interest for researchers working in this field, as well as for the overall community, as they include aspects clearly relevant at a global level.

Use of nano-/micro-magnetite for abatement of cadmium and lead contamination.

Structural variations of a mineral dictate its adsorption capacity which affects the mobility and toxicity of contaminants in natural and engineered systems. Present batch study evaluates the adsorption of lead (Pb) and cadmium (Cd) onto three magnetites having nanometric (M1-30 nm and M2-60 nm) and micrometric particle sizes (M3-1.5 µm). Obtained data revealed that particle size of tested magnetites strongly affected the extent and kinetics of metal adsorption and desorption. Observed order of adsorption efficiency was M1 > M2 > M3 with optimum monolayer adsorption of 408.14, 331.40, 178.47 mg/g (for Pb) and 228.05, 170.86, 83.49 mg/g (for Cd), respectively. Adsorption data were well fitted to the Freundlich (R2 = 0.99), Langmuir (R2 = 0.99) and pseudo-first order models (R2 = 0.98). Electrostatic attraction and surface precipitation interaction via external mass transfer between bulk liquid-solid interfaces were the potential adsorption pathways. Pb showed higher affinity than Cd in multi-metal system. Desorption efficiency was higher in acidic environment (92%) than in distilled water (44%). Moreover, regenerated magnetite samples retained good adsorption capacity for six cycles. As soils are characterized by large variability of iron minerals, these findings have important implications regarding the transport and immobilization of contaminants particularly in the management of contaminated soils.

Removal of caffeine, nicotine and amoxicillin from (waste)waters by various adsorbents. A review.

The fast growth in the anthropogenic activities, that involve a wide use of pharmaceuticals, has led to the appearance of new toxic and hazardous chemical compounds, called "emerging pollutants", which could cause unpredictable consequences to the ecosystems. The current review is focused on emerging pollutants occurring in food or air and include caffeine and nicotine, as well as on pharmaceuticals, in particular amoxicillin, and the concerns caused by its wide usage for medical purposes. This review, for the first time, analyzes and discusses the potential risks and implications of caffeine, nicotine and amoxicillin as emerging environmental pollutants, a field that remains underrepresented to date. Both caffeine and nicotine belong to life style compounds, while pharmaceutical amoxicillin is one of the very popular ß-lactam antibiotics used to take care of human and animal infections. The review covers the toxic effect caused by caffeine, nicotine and amoxicillin on humans and animals and describes some of the main adsorbents utilized for their removal (e.g., grape stalk, tea waste, wheat grains, bentonite, activated carbon, acid and base modified grape slurry wastes, graphene oxides, modified graphene oxides, zeolites, etc.). The isotherm and kinetic models for the analysis of caffeine, nicotine and amoxicillin adsorption by different adsorbents are presented. The impact of pH, temperature, adsorbent dosage and thermodynamic studies were deeply analyzed. The review also discusses the mechanism of adsorption for the above-mentioned emerging pollutants, which includes π-π interaction, cation-π bonding, electron-donor and electron-acceptor forces, van der Waals forces, electrostatic interactions, etc. The present review has a potential value for chemists, ecologists, toxicologists, environmental engineers, and other professionals that are involved in environmental protection.

The effects of different soil nutrient management schemes in nitrogen cycling.

It is imperative for sustainable agriculture to explore practices and inputs creating low N2O emission capacity without reducing the productivity of the agricultural system. To evaluate different nutrient management schemes, a microcosm study was conducted to assess the direct N2O emission from soil. Four different treatments were used to provide a preliminary assessment of N2O emissions, as well as the concentrations of nitrates (NO3-) and ammonium (NH4+) produced in soil: compost (derived from green plant residues), chickpea residues (green manure) in two different N concentrations (2.6% and 5.5%, respectively) and ammonium nitrate (fertilizer). The soil was thoroughly mixed with the organic amendments and ammonium nitrate and incubated for 31 days. The emissions of N2O were higher in green manure with high-N content, as a source of nitrogen in the soil, and were similar to the emissions measured from the chemically fertilized soil. In particular, chickpea residues, with high-N content, exhibited cumulative N2O emissions, equal to 266.17 µg N/m2, whereas in fertilized soil the emissions were 267.10 µg N/m2. On the contrary, the incorporation of chickpea plant residues with low-N content can be an efficient way to minimize the N2O emissions at 21.63 µg N/m2. The emissions of N2O when compost was applied, remained relatively low, equal to 5.47 µg N/m2, and in comparison to soil without any treatment. Overall, a positive association between NH4+, NO3- in soil and N2O emissions were observed. However, this response was treatment depended, and the significant positive correlation between NH4+ and N2O emissions were noticed in soils treated with ammonium nitrate, chickpea residues with low N content, as well as untreated controls. On the contrary, the positive correlation observed between NO3- and N2O emissions in soils receiving compost and high N chickpea residues, suggest that the different treatments are differentially affecting the processes that are contributing to N2O emissions in agricultural soils. These findings, emphasize that the different nutrient management schemes are differentially affecting the main process contributing to N2O emissions in agricultural soils.

Synthesis and characterization of a novel Fe3O4-loaded oxidized biochar from pine needles and its application for uranium removal. Kinetic, thermodynamic, and mechanistic analysis.

This work investigates the fabrication of magnetic biochar (pncm) and Fe3O4-loaded oxidized biochar (pncom) obtained from pine needles for uranium removal. Adsorbent properties were characterized by scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR) techniques. Using batch-type experiments the effect of the uranium concentration, solution pH, contact time, temperature and ionic strength on the uranium adsorption was investigated. The results showed better adsorptive properties for pncom, particularly in the acidic pH range. The experimental adsorption data were found to be well fitted with the Langmuir isotherm and the pseudo-second order kinetic model. For pncom, the maximum adsorption capacity obtained applying the Langmuir isotherm model was found to amount 2.6 mol/kg at pH 6 and 25 °C. Spectroscopic data indicated that the U(VI) adsorption was associated with the formation of inner-sphere complexes. Regeneration and reusability studies were performed with 0.1 M Na2CO3. After four cycles, the % relative adsorption and the desorption for pncom decreased from 99.5% to 87.2% and 99.6%-62.6%, respectively. The present results show that magnetization of oxidized pine needle biochar improves significantly the adsorption characteristics regarding the uranium removal from aqueous solutions.

Valorization of agricultural wastes could improve soil fertility and mitigate soil direct N2O emissions.

The emerging need for sustainable management of the increasing quantities of urban and industrial organic wastes creates opportunities for the development of alternative strategies for the improvement of degraded soils. The current study was performed to examine the effects of agricultural wastes application on soil bacterial community as well as CO2 and N2O direct gas emissions. Untreated soils were compared with soils, which received the same amount of N (100 µg/g soil) in the form of ammonium nitrate and organic agricultural waste. In particular, soils were incubated with three different organic agricultural wastes, orange (OP), mandarin (MP) and banana peels (BP) and ammonium nitrate (F) after adjusting soil water at 70% of its holding capacity. In the current study, soil chemical characteristics, quantitative PCR of denitrifiers (nirK, nirS, nosZI and nosZII) and16s rRNA amplicon sequencing were assessed to examine the links between the soil microbial communities and short-term soil direct N2O emissions when treated with agricultural wastes. The highest soil direct N2O emissions were recorded in soils received ammonium nitrate while soils received agricultural wastes exhibited substantially lower soil direct N2O emissions. On the contrary, agricultural wastes stimulated CO2 accumulation as well as the growth of copiotrophic bacterial groups like Proteobacteria and Firmicutes. Interestingly, direct soil N2O emissions were decoupled from the density of denitrifier community while agricultural wastes caused a substantial reduction of the relative abundance of bacterial taxa associated with N2O emissions in the soil. This study proves evidence that agricultural wastes could be integrated in a waste management strategy, which inter alia includes their direct use in agricultural ecosystems resulting in reduced N2O emissions.

Performance of aquatic weed - Waste Myriophyllum spicatum immobilized in alginate beads for the removal of Pb(II).

A new biosorbent - alginate encapsulated with Myriophyllum spicatum - MsA was investigated for lead ions removal. This biosorbent was characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), zeta potential, X ray Diffraction (XRD) and size distribution analysis. FT-IR analysis demonstrated that the lead ions sequestration mechanism included ion exchange and lead complexation with the carboxyl, carbonyl and hydroxyl groups in MsA. In order to better understand the mechanisms of the binding of Pb(II) on immobilized M. spicatum beads, 3 reaction and one diffusion based kinetic models were applied on kinetic data removal lead ions on three materials: M. spicatum, Ca-alginate and MsA. Myriophyllum spicatum encapsulated with alginate - MsA have higher adsorption capacity than M. spicatum. Among examined six isotherms Redlich-Peterson and the Langmuir isotherm model exhibited the best fit to the experimental data, with capacities ranging from 230 to 268.7 mg/g. Among the various tested desorption agents, nitric acid has proven to be the best. The obtained results suggest that the immobilized M. spicatum biosorbent holds great potential for lead wastewater treatment applications.

A novel route for preparation of chemically activated carbon from pistachio wood for highly efficient Pb(II) sorption.

Pistachio wood-derived activated carbon prepared by a two-stage process (PWAC-2), conducting two consecutive chemical activation processes with NH4NO3 and NaOH, respectively. The results showed that explosive characteristic of NH4NO3 can primarily be employed to produce a char, with a large surface area and a highly-ordered pore structure, which can be subjected to a second activation process with NaOH to prepare a more suitable activated carbon, with a highly porous structure and useful functional groups, for removal of lead ions from aqueous media. An L25 Taguchi experimental design was used by varying impregnation ratio, activation time and temperature in both pre- and post-activation stages, and the results showed that, in both stages, a small activating agent/precursor and a proportional low activation time suffice for preparation of an advantageous activated carbon for Pb(II) adsorption. A comprehensive study was performed on the equilibrium, kinetic and thermodynamic aspects of Pb(II) adsorption by the new activated carbon. The results exhibited that, having had a high lead adsorption capacity (190.2 mg g-1), a high adsorption rapidness, and thermodynamic favorability, PWAC-2 is a beneficial alternative for utilization in full-scale plants of lead removal from waters and wastewaters.

Adsorption property of Br-PADAP-impregnated multiwall carbon nanotubes towards uranium and its performance in the selective separation and determination of uranium in different environmental samples.

A newer efficient U(VI) ion adsorbent was synthesized by impregnating Br-PADAP [2-(5-Bromo-2-pyridylazo)-5-(diethylamino)phenol] onto multiwall carbon nanotubes (MWCNTs). The effects of various operation conditions on uranium adsorption (i.e., pH contact time, temperature, and initial uranium concentration) were systematically evaluated using batch experiments. The results indicated that the uranium adsorption on modified MWNCTs (5.571 × 10-3g/mg × min) reached faster equilibrium than that on pristine MWNCTs (4.832 × 10-3g/mg × min), reflecting the involvement of appropriate functional groups of Br-PADAP on the chelating ion-exchange mechanism of U(VI) adsorption. Modified MWNCTs (83.4mg/g) exhibited significantly higher maximum Langmuir adsorption capacity than pristine MWNCTs (15.1mg/g). Approximately 99% of uranium adsorbed onto modified MWNCTs can be desorbed by 2.5mL of 1M HNO3 solution. Therefore, Br-PADAP-modified MWNCTs can server as a promising adsorbent for efficient uranium adsorption applications in water treatment. Subsequently, the proposed solid-phase extraction (using a mini-column packed with Br-PADAP/MWCNT) was successfully utilized for analysing trace uranium levels by the ICP-AES method in different environmental samples with a pre-concentration factor of 300-fold. The coexistence of other ions demonstrated an insignificant interference on the separative pre-concentration of uranium. the detection limit was recognized as 0.14µg/L, and the relative standard deviation was approximately 3.3% (n = 7).

The use of olive tree pruning waste compost to sequestrate methylene blue dye from aqueous solution.

Considering that quality water supplies are diminishing and climate disorder affects water cycle, wastewaters should be decontaminated for reuse either by the same establishment or in agriculture for the growth of industrial plants. In that context, much research work has been focused on the development of low cost biosorbents. In this study, the effect of composting on the adsorption capacity of olive tree pruning waste (OTPW) biomass for methylene blue (MB) removal from aqueous solutions was examined. Composting procedure may improve the sorption properties of the raw organic materials, is economical and easy to apply. MB adsorption on both OTPW and composted olive tree pruning waste (COTPW) biomasses was found to be fast. The maximum monolayer adsorption capacity obtained from Langmuir isotherm was estimated to be 129.87 and 250.00 mg/g for OTPW and COTPW, respectively, indicating that composting procedure greatly improved the adsorptive properties of OTPW. The raise of temperature from 25°C to 60°C decreased the efficiency of OTPW for MB removal whereas the adsorption capacity of COTPW was not affected at high temperatures. Moreover, COTPW showed constant adsorption over the 2-8 solution pH range.