Marine Protected Areas (MPAs) aim to protect habitats, biodiversity, and ecological processes as a conservation tool. These areas have been affected by contamination, which threats the biodiversity and ecological functioning. In this study, we evaluated the sediment quality of Xixová-Japuí State Park (XJSP), an MPA located in an urbanized Bay (Santos, Southeast Brazil) by integrating multiple lines-of-evidence. Six sites were selected within the XJSP and analyzed for sediment chemistry, toxicity, and benthic community descriptors using Sediment Quality Triad approach (SQT). Whole-sediment Toxicity Identification Evaluation (TIE) was employed as a complementary line of evidence to confirm the presence of domestic effluent discharges as a potential stressor. The SQT showed that sediments collected within XJSP are impacted by contaminants, exhibiting chronic toxicity and changes in benthic community. TIE results indicated that trace metals, organic contaminants, and ammonia contributed to the observed effects. Our results also indicate a lack of effectiveness of MPA in protecting the biodiversity due to the contamination sources, which requires efforts to pollution control in order to ensure the environmental conservation and management plan goals.

The novel waste alkaline battery-sawdust-based adsorbents (WABAs) are prepared by a two-stage activation method with the negative electrode materials as activator and different doping ratio of the positive electrode materials and pine sawdust as raw materials. The characteristics of the WABAs are analyzed by SEM, XRD, FT-IR, and specific surface determination (SBET). The Pb²⁺ adsorption properties of the WABAs are studied by changing the pH of solution, contact time, initial concentration, and temperature. It turns out that when the doping mass ratio is 1:4, the optimum performance of the WABAs is obtained, and comparing with the samples prepared by pure biomass, the iodine adsorption value, total acid groups, and cation exchange capacity (CEC) separately increased by 13, 106, and 22%, respectively. Kinetic studies show that the pseudo-second-order model is more suitable for describing the Pb²⁺ adsorption process and the Langmuir isotherm provides better fitting to the equilibrium data. The thermodynamic parameters indicate the adsorption process would be spontaneous and endothermic. Besides, the prepared WABAs could be reused for 5 cycles with high removal efficiency. This study provides an alternative route for waste alkaline battery treatment. Graphical abstract The schematic diagram of synthesis of waste batteries-sawdust-based adsorbent via a two-stage activation method for Pb²⁺ removal

The aim of the present experimental study was to perform a technical-economic evaluation of a combined treatment system, consisting of coagulation-flocculation or rapid sand filtration as pre-treatment followed by column adsorption, for reducing the arsenic concentration from approximately 1 mg/L to below the limit set for groundwater remediation and drinking water, i.e., 0.01 mg/L, according to the legislation in force. A wide number of operating conditions were experimentally evaluated in the different tests. In the coagulation-flocculation study, it was initially investigated if the iron contained in a mining drainage co-mixed with the groundwater would be able to achieve a better As content reduction by adsorption/precipitation, thus avoiding fresh coagulant addition. Then, different polyelectrolyte dosages were tested varying the mixing ratio. None of the tested conditions allowed to improve the arsenic removal so significantly to warrant the consequent incremental costs. Therefore, the optimal condition was considered any mixing with a different liquid stream and any polyelectrolyte dosage. The iron content naturally present in the groundwater and contact with air was capable alone of reducing As concentration of about 80%. Sand filtration reached approximately the same removal efficiency (about 80%) at the lower surface loading rate among the values tested. Between coagulation and sand filtration, in terms of costs, the latter showed to be more convenient than coagulation-flocculation, at the same removal efficiency: therefore, it was considered the optimal pre-treatment. The following adsorption column plant was capable of further reducing As concentration up to the required value of 0.01 mg/L. Among the two iron-based commercial adsorbents applied in the adsorption column tests, the hybrid media consisting of an exchange resin with iron oxides showed to be preferable under the selected operating conditions: it offered higher adsorption capacity at breakthrough and, after exhaustion, could be regenerated for a number of cycles. The influent pH showed to have a great influence on the duration of the adsorbent media, and values around neutrality were considered preferable. The estimated cost of the full treatment was computed to be about 0.50 €/m³ of purified water. Therefore, the capacity of achieving the required remediation goal, the limited cost, and simplicity of operation make the proposed combined treatment being potentially suitable for real application.

This work comprises results of the laboratory tests on formation and potential release of contaminants from underground gasification of lignites. Four large scale and multi-day trials were carried out using ex-situ gasification facilities. Two different kinds of lignite were tested, i.e. Velenje lignite (Slovenia) and Oltenia lignite (Romania). Gasification tests were conducted in the artificial coal seams under two distinct pressure regimes—atmospheric and high pressure regime (35 bar and 10 bar for the Velenje and Oltenia samples respectively). The UCG wastewater samples were periodically collected from the gas purification module to measure the rate of the wastewater and contaminants production at each phase of the experiment and to assess the effect of gasification pressure and lignite physicochemical properties. The group of target contaminants included: phenols, aromatic hydrocarbons, and some non-specific water parameters. The effect of gasification pressure was confirmed, especially for BTEX and phenols and significant drops in the contents of these compounds were observed at elevated pressures. The effect of pressure was more pronounced for the geologically older coal (Velenje), i.e. drop in the average concentrations from 1994 μg/l (atmospheric) to 804 μg/l (35 bar) and from 733 mg/l (atmospheric) to 17 mg/l (35 bar) for BTEX and total phenols, respectively. The differences in the macromolecular structure and ash content of the both coals were found to be the main reason behind the differences in the contents of organic and inorganic species respectively. The study also shown that composition of UCG wastewaters significantly varied over the time of the particular experiments, which reflected changes in the gasification thermodynamic conditions and development of oxidation and pyrolysis zones. During the atmospheric gasification experiments, the values of BTEX for the Velenje lignite dropped from 3434 μg/l to 1364 μg/l and for the Oltenia lignite from 1833 μg/l to 978 μg/l. A similar downward trend in the concentrations of BTEX was observed for the pressurized experiments. For the Velenje trial a drop from 1111.6 μg/l to 211.2 μg/l and for the Oltenia - from 1695 μg/l to 688 μg/l was observed. Concentrations of phenolic compounds during the atmospheric gasification experiments varied significantly during both atmospheric trials and no significant trends were noticed.

The brewing industry is an important sector in the world economy, and its production process generates a large amount of wastewater. It is essential the proper treatment of this wastewater and a significant amount of biomass may be recovered by coagulation/flocculation process. When using vegetable tannin as an organic flocculant, biomass can be used in the preparation of organic fertilizer, unlike what would occur if a metal base flocculant was used, some of which are considered to be toxic. This work presents a study on the use of vegetable tannin as flocculant agent (Tanfloc SL) for the treatment of brewery wastewater, which also contains microalgae originated from an aerated pond of a local brewery industry. Experiments of coagulation/flocculation and sedimentation were carried out using jar test equipment. A sequential 2² factorial design and two-factor Doehlert design were used to determine the optimum levels of pH and tannin concentration for turbidity and apparent color removals from the wastewater. The higher efficiency results in the biomass separation were obtained by employing 0.23 mL L⁻¹ of vegetable tannin at pH = 4.9, resulting in the substantial removal of approximately 99% of turbidity and apparent color. The removals of biomass and nutrient components were also evaluated: N-NH⁴⁺ (80.8%), N-NO₂- (83.6%), N-NO₃ (56.9%), total phosphorus (82.3%), orthophosphate (76.2%), COD (96.5%), BOD (69.4%), and total solids (40.8%). The Tanfloc SL showed to be efficient in flocculation of the brewery effluent, allowing the reuse of water in industry and the recovered biomass material containing nutrients in agriculture.

In this study, a novel Fe–Mn–Ce oxide-modified biochar composite (FMCBC) was synthesized via pyrolysis to enhance the adsorption capacity of biochar (BC). Scanning electron microscopy-energy-dispersive X-ray spectroscopy confirmed that Fe, Mn, and Ce were successfully loaded onto the surface of the BC. A series of adsorption experiments showed that the FMCBC exhibited improved adsorption of As(III) in an aqueous environment. The adsorption process was well expressed by the pseudo-second-order kinetic model. The adsorption capacity of FMCBC reached 8.74 mg L⁻¹, which was 3.27 times greater than that of BC. The pH of the solution significantly influenced the adsorption of As(III), where the amount of As(III) adsorbed by FMCBC was maximized at pH 3. A high phosphate concentration inhibited adsorption, whereas nitrate and sulfate ions promoted As(III) adsorption and increased the FMCBC adsorption capacity. Similarly, with increasing humic acid concentration, the adsorption capacity of FMCBC for As(III) decreased; however, a low concentration of humic acid promoted adsorption. X-ray photoelectron spectroscopy analysis revealed that the adsorption of As(III) by FMCBC occurred through redox and surface complexation reactions. Therefore, FMCBC has excellent potential for purifying arsenic-contaminated water.

Controlled-release fertilizers (CRFs) are an effective approach in providing essential nutrients for plant growth while minimizing the loss of nutrients in water and air, reducing contamination risks. However, commercial CRFs often release nutrients either too quickly or slowly due to the properties of their coating materials (polymer or sulfur). In this work, a novel CRF technology was developed using chitosan (CS) and graphene oxide (GO) nanocomposites as coating materials. CS and GO solutions were applied at varying ratios in preparing different nanocomposites. CS and GO formed homogeneous nanocomposite films through their interactions with each other. Fertilizer beads were successfully encapsulated by the CS-GO films using the simple dipping method. Resulting CRFs showed controlled-release behaviors, with nutrient release lasting for about a week. Although additional investigations are required for further evaluation and optimization, this method presents a promising concept for an alternative fertilizer-coating technology.

The level of radioactivity in the soil has been increasing unpredictably due to the human uranium mining exploitation of uranium over the past 100 years. Remediation of metals in actual soil confronts many challenges, remaining poorly understood. This study intends to investigate the concentrations and distributions of U, Cd, Zn, Pb, and Cu in soils surrounded by a uranium mill tailing pond. Furthermore, a phosphorus-modified bio-char was prepared in order to determine its role in immobilizing uranium in soil samples. Results show that the contents of U and Pb are much higher than that of the background values, due to the influence of the uranium mill tailing pond. Phosphorus can enhance the immobilization efficiency of U, Cd, Pb, and Cu in soil samples. The concentration of uranium in the leaching supernatant of phosphorus-modified bio-char group is lower than that of control and unmodified bio-char groups due to the fact that the biosorption occurred in the exterior surface of the biomass, which imply that phosphorus-modified bio-char is a potential immobilization material to reduce the leaching rate of metals. These findings can provide references for remediation technology of metals in natural soil.

Biotemplating method is a promising way to obtain hierarchical materials with unique morphology and property. In the current work, a novel hierarchically porous ZnAl-CLDH (calcined layered double hydroxides)/FeWO₄ had been successfully synthesized by a facile biotemplated method. The obtained samples were characterized in detail via FESEM-EDX, TEM, XRD, IR, TGA, and BET techniques. The as-synthesized ZnAl-CLDH/FeWO₄ hierarchical microspheres were composed of ZnAl-CLDH nanosheets and FeWO₄ nanoparticles. The obtained sample exhibited both high adsorption and visible-light photocatalytic activity toward Congo Red (CR) in water. It was found that the adsorption process was well described by the pseudo-second-order kinetic model and the Langmuir isotherm model, while the photocatalytic degradation process was well fitted to the first-order kinetics model. The enhanced photocatalytic performance was mainly due to the hierarchically porous structure that could offer more exposed active sites, as well as the unique energy band structure of heterostructures, that facilitated the efficient separation and transfer of photoinduced carriers and enhanced light harvesting. In addition, the as-prepared sample had quickly magnetic response and could be easily separated from water under an external magnetic field after wastewater treatment.

Since decades, surface water bodies have been exposed to pesticides from agriculture. In many places, retention systems are regarded as an important mitigation strategy to lower pesticide pollution. Hence, the processes governing the transport of pesticides in and through a retention system have to be understood to achieve sufficient pesticide attenuation. In this study, the temporal dynamics of metazachlor and its transformation products metazachlor-oxalic acid (OA) and –sulphonic acid (ESA) were observed in an agricultural retention pond and hydrologic tracers helped to understand system-inherent processes. Pesticide measurements were carried out for 80 days after their application during transient flow conditions. During a short-term (3 days) experiment, the tracers bromide, uranine and sulphorhodamine B were used to determine hydraulic conditions, residence times and sorption potential. A long-term experiment with sodium naphthionate (2 months) and isotopes (12 months) provided information about inputs via interflow and surface-groundwater interactions. During transient conditions, high concentration pulses of up to 35 μg L⁻¹ metazachlor, 14.7 μg L⁻¹ OA and 22.5 μg L⁻¹ ESA were quantified that enduringly raised solute concentrations in the pond. Mean residence time in the system accounted for approximately 4 h showing first tracer breakthrough after 5 min and last tracer concentrations 72 h after injection. While input via interflow was confirmed, no evidence for surface-groundwater interaction was found. Different tracers illustrated potentials for sorption and photolytic degradation inside the system. This study shows that high-resolution sampling is essential to obtain robust results about retention efficiency and that hydrological tracers may be used to determine the governing processes.