Melamine, which has three free amino groups and three aromatic nitrogen atoms in its molecule, can be potentially used as an adsorbent for metal ions. Factors associated with adsorption efficiency of vanadium by melamine were systematically investigated, including initial pH value of solution, temperature, contact time, and dosage of melamine. The optimal operation conditions for adsorption performance of vanadium with melamine were obtained. The adsorption efficiency was over 99.97% at the initial pH value of 1.18, molar ratio of n (melamine)/n (vanadium) = 1.0 for 60 min. The kinetic data for the adsorption followed well the pseudo second-order kinetic model.

Sugarcane bagasse soot is an agro-industrial residue rich in carbon that can be transformed into value-added materials, such as activated carbons. Therefore, this work aimed at producing activated carbon from sugarcane bagasse soot, using CO₂ at 800, 850, and 900 °C, and investigating its efficiency to adsorb methylene blue as model contaminant. The results showed that the surface area and pore volume increased in the obtained carbons, with high specific areas (up to 829 m²/g), and the isotherms of the N₂ adsorption describe mesoporous materials. The morphology of the prepared activated carbons showed that sugarcane bagasse soot and the activated carbons kept the fibrous structure of sugarcane bagasse, but after activation, they have cavities that resemble a honeycomb. Adsorption studies with methylene blue dye showed that the activation process resulted in adsorption capacities up to 11 times higher than sugarcane bagasse soot, which is comparable with commercial activated carbon. Dye adsorption kinetics could be described by a pseudo-second-order dependency in the studied materials, and the adsorption isotherms were better fitted by the Langmuir model. It is emphasized that cost-effective materials that are similar to commercial activated carbon were obtained.

This paper discusses the possibility of including the culturing of microalgae within a conventional wastewater treatment sequence by growing them on the blackwater (BW) from biosolid dewatering to produce biomass to feed the anaerobic digester. Two photobioreactors were used: a 12 L plexiglas column for indoor, lab-scale tests and a 85 L plexiglas column for outdoor culturing. Microalgae (Chlorella sp. and Scenedesmus sp.) could easily grow on the tested blackwater. The average specific growth rate in indoor and outdoor batch tests was satisfactory, ranging between 0.14 and 0.16 day⁻¹. During a continuous test performed under outdoor conditions from May to November, in which the off-gas from the combined heat and power unit was used as the CO₂ source, an average biomass production of 50 mgTSS L⁻¹ day⁻¹ was obtained. However, statistical analyses confirmed that microalgal growth was affected by environmental conditions (temperature and season) and that it was negatively correlated with the occurrence of nitrification. Finally, the biochemical methane potential of the algal biomass was slightly higher than that from waste sludge (208 mLCH₄ gVS⁻¹ vs. 190 mLCH₄ gVS⁻¹).

Most bioremediation studies on volatile organic compounds (VOCs) have focused on a single contaminant or its derived compounds and degraders have been identified under single contaminant conditions. Bioremediation of multiple contaminants remains a challenging issue. To identify a bacterial consortium that degrades multiple VOCs (dichloromethane (DCM), benzene, and toluene), we applied DNA-stable isotope probing. For individual tests, we combined a ¹³C-labeled VOC with other two unlabeled VOCs, and prepared three unlabeled VOCs as a reference. Over 11 days, DNA was periodically extracted from the consortia, and the bacterial community was evaluated by next-generation sequencing of bacterial 16S rRNA gene amplicons. Density gradient fractions of the DNA extracts were amplified by universal bacterial primers for the 16S rRNA gene sequences, and the amplicons were analyzed by terminal restriction fragment length polymorphism (T-RFLP) using restriction enzymes: HhaI and MspI. The T-RFLP fragments were identified by 16S rRNA gene cloning and sequencing. Under all test conditions, the consortia were dominated by Rhodanobacter, Bradyrhizobium/Afipia, Rhizobium, and Hyphomicrobium. DNA derived from Hyphomicrobium and Propioniferax shifted toward heavier fractions under the condition added with ¹³C-DCM and ¹³C-benzene, respectively, compared with the reference, but no shifts were induced by ¹³C-toluene addition. This implies that Hyphomicrobium and Propioniferax were the main DCM and benzene degraders, respectively, under the coexisting condition. The known benzene degrader Pseudomonas sp. was present but not actively involved in the degradation.

Uranium-contaminated environments pose a risk to human health by means of its transfer to the food chain. Overcoming this issue requires using effective methods to minimize the availability of uranium and other metals in soils. Jordan has a promising project for electricity generation from nuclear power. To move forward with this nuclear project, the Jordan Central Area has been mined for uranium. The expansion of the mining activities in this area led to elevated contents of heavy metal in the surface soil. Phytoremediation efficiency in reducing uranium content from uranium-rich carbonate soil was tested using sunflower plants. Forty-eight sunflower plants were planted in three soil samples containing three different uranium concentrations. The plants were harvested after different planting periods in order to investigate the phytoremediation efficiency over time. The ability of sunflowers to translocate uranium was investigated and the results showed that the translocated amount of uranium to plant increased as the initial concentration of uranium in the soil increased. However, most of the uranium taken up by the sunflower was accumulated in the roots, and only 3% of the uranium concentration in the roots passed to the harvestable shoots. Moreover, the biomass of the plants was not affected by increasing uranium concentration in the plants indicating that sunflower is resistant to radiation and toxicity of uranium at these levels found in the soil.

Petroleum products which are used in a wide variety of industries as energy sources and raw materials have become a major concern in pollution of terrestrial and marine environments. The purpose of this study was to assess the potential of indigenous microbial isolates for degradation of diesel fuel. Two most proficient bacterial strains among five isolated strains from polluted soil of an industrial refinery were studied. The isolates then were identified as Pseudomonas aeruginosa and Bacillus subtilis using biochemical tests and 16S rRNA gene sequence analyses. P. aeruginosa showed higher biodegradation efficiency than B. subtilis in shaking flask containing diesel-contaminated water. P. aeruginosa and B. subtilis degraded about 87 and 75% of total hydrocarbons, respectively, in flasks containing 2% diesel and 98% water. The biodegradation efficiency of the isolates decreased as diesel contamination increased from 2 to 5%. The isolates showed significantly higher efficiency on degradation of short-chain hydrocarbons in 20 days, i.e., by using P. aeruginosa, removal efficiency of C₁₀ hydrocarbons was near 90%, while about 69% of C₂₀₊ hydrocarbons and 47% of aromatic hydrocarbons were removed. Therefore, the isolates showed high capability in biodegradation of diesel contamination of the refinery.

A vermifilter (with earthworms, VF), with a conventional biofilter (no earthworms, BF) as a control, was established to examine the survival state and adaptability of earthworms in protein perspective. The VF behaved with a significantly higher organic matter decomposition and lower sludge yield due to the presence of earthworms. However, during the steady stage (12 months), the earthworm biomass decreased slightly from 32.0 to 24.2 g/L, while the earthworm average weight increased, indicating that the earthworm suffered some adverse effects from the VF. Notably, from the perspective of the earthworm protein, the earthworms showed a higher Shannon-Weaver index (from H = 2.76 to 3.06) than the BF and up-regulated some proteins to cope with the negative effects from the VF. These up-regulated differential proteins played a variety of crucial roles in many cellular processes. The results suggested that a more specialized and stable protein expression of earthworms was developed in the VF, reflecting the adaptabilities of the earthworms in the VF.

The electrochemical elimination of the herbicide diquat dibromide (DQ) in an undivided electrochemical cell (Condiacell®-type cell) and an H-type cell (a divided electrochemical cell) using boron-doped diamond (BDD) electrodes is reported for the first time. The degradation of essentially 100% of the DQ present was achieved in the undivided electrochemical cell and ca. 92% in the H-type cell. Nearly 80% of the total organic carbon (TOC) and of the chemical oxygen demand (COD) were removed after 5 h of treatment at different current densities (i.e., 0.5, 1.0, and 1.5 mA/cm² for the undivided cell, and 2.5, 5.0, and 7.5 mA/cm² for the H-type cell) with a maximum specific energy consumption of approximately 150 kWh kg⁻¹ of COD degraded in the undivided cell, and 300 kWh kg⁻¹ of COD in the H-type cell. Energy consumption of about 0.30 kWh g⁻¹ of TOC occurred in the undivided electrochemical cell and 2.0 in the H-type cell. In spite of obtaining similar percentages of DQ degradation and of COD and TOC removal, a smaller energy usage was required in the undivided cell since smaller current densities were employed. Best results were obtained with the undivided cell, since it required a smaller current density to obtain virtually the same percentage of DQ degradation and removal of COD and TOC. The results obtained herein show that the use of electrochemical advanced oxidation processes may be a good alternative for DQ degradation in polluted water.

The objective of the present study was to investigate the transport and removal of Escherichia coli, Bacillus subtilis, Staphylococcus aureus, bacteriophage MS2, and bacteriophage Phix174 in the soils and pyrophyllite-amended soils. Laboratory columns experiments were performed under saturated flow conditions. Our results showed that bacteriophages passed through the soils more easily than bacteria under the given experimental conditions (pulse injection = 15 min, flow rate = 0.5 mL/min, column length = 20 cm, inner diameter = 2.5 cm, pH = 7.6, electrical conductivity (EC) = 150.1 μS/cm); the log removals of bacteria were in the range of 0.44 to 1.72, whereas the log removals of bacteriophages were between 0.01 and 0.13. Our results also demonstrated that the transport of bacteria and bacteriophages in the soil columns could be reduced considerably in the presence of pyrophyllite. Under the same column experimental conditions above, the log removals for MS2 and Phix174 in 50% soil + 50% pyrophyllite were 2.64 and 3.05, respectively, whereas the log removals in 100% pyrophyllite were 5.70 for MS2 and 5.10 for Phix174; those values were far greater than the log removals in 100% soil (MS2 = 0.063, Phix174 = 0.128). Additional column experiments (step injection, flow rate = 0.3 mL/min, column length = 30 cm, inner diameter = 2.5 cm, solution pH = 8.4, EC = 39.8 mS/cm) showed that the log removals for B. subtilis (1.72) and Phix174 (1.48) in the pyrophyllite were greater than those in the soil (B. subtilis = 1.41; Phix174 = 0.39). This study demonstrated that the pyrophyllite amendment method could be used for protecting groundwater from microbial contamination by animal carcass burial soils.

Heavy metals, chemical elements considered toxic at certain concentrations, can be considered potential threats to plants, animals, and biological resources of a particular ecosystem. Among them, mercury and aluminum, when involved in bioaccumulation processes, can cause damage to various organ systems of both animals and plants. In vegetables, heavy metals produce reactive oxygen species (ROS), which are involved in the occurrence of malformations and deficits in the growth of roodets and plumule of several species of plants, which justifies the study of natural antioxidant agents that may come to reverse or ameliorate the deleterious effects caused by these compounds. In this sense, this study aims to evaluate the cytoprotective effect of hydroethanolic extract of Stryphnodendron rotundifolium Mart., species popularly known as “barbatimão” against the heavy metals mercury and aluminum in vegetable model, because of its known antioxidant potential. To this end, there was the cytoprotection test in microbial and lettuce seeds (germination) in order to ascertain the potential of the said extract on the protection of roots and stem this. It was observed that the extract showed no allelopathic effect on lettuce seeds at a concentration of 32 μg/mL and in combination with HgCl₂ and AlCl₃, it enabled a higher growth in the roodets and stem Lactuta sativa L. These results demonstrated that the extract of Stryphnodendron rotundifolium can be an alternative to solve the problem with soil contamination by heavy metals, showing thus its promising potential cytoprotective in plant species.