Search Results (4,187)

Dairy wastewater is highly polluting and requires treatment before being discharged into receiving surface waters or destined for reuse. This study aimed to evaluate the performance of a wastewater treatment plant (WWTP) at a dairy facility, which includes the following treatment stages: screening, grease trap, and an upflow anaerobic filter (UAF). Monitoring data from a WWTP at a dairy situated in the southern region of Minas Gerais, Brazil, were assessed based on pollutant removal efficiency in accordance with Brazilian environmental regulations. The results showed that the WWTP achieved average removal efficiencies of 96.2% for COD and 97.1% for BOD₅. The BOD₅/COD ratio of raw and treated wastewater averaged 0.46 and 0.30, respectively, indicating preferential removal of the biodegradable organic fraction. The treated wastewater complied with legal standards for pH, settleable solids, and total suspended solids. However, at least one sample did not meet regulatory limits for discharge into water bodies regarding surfactants and oils & greases. Strong linear correlations (R² ~ 0.8) between COD and BOD₅ data were observed for both raw and treated wastewater. While the treated wastewater was not suitable for use in the facility’s wood-fired boiler, it may be reused for agricultural irrigation. Full article

The dual benefit of wastewater and microalgal biomass is a major advantage of high-rate algal ponds, enabling the environmental valorization of these byproducts. This research explored the effect of treated wastewater on the agri-food species Hordeum vulgare (L.) and its associated weed, Emex spinosa (L.) Campd., along with the effects of algal biomass (primarily composed of Closterium, Chlorella, and Scenedesmus spp.) and Diplotaxis harra leaf powder. Initial pot trials applied microalgae and D. harra at 2, 4, and 6 g·kg⁻¹ soil, also confirming that the treated wastewater met reuse standards and did not affect plant growth. The combined treatment at 4 g·kg⁻¹ led to the highest H. vulgare increases in fresh weight (162.71%), root length (73.75%), and shoot length (72.87%), while reducing E. spinosa shoot and root lengths by 30.79% and 52.18%, and fresh weight by 68.24%. Subsequent field experiments using 1.26 t ha⁻¹ of 0.5-cm-applied D. harra and microalgae powders enhanced H. vulgare growth, while reducing the growth of E. spinosa. The reduction in E. spinosa growth was associated with increased electrolyte leakage and malondialdehyde content. These results support the integration of high-rate algal ponds into agriculture, promoting water reuse and reducing reliance on synthetic fertilizers and herbicides in barley production. Full article

Ampicillin (AMP) and amoxicillin (AMX) are widely used penicillin antibiotics. After administration to humans and animals, they are largely excreted in unchanged or metabolized forms, leading to their release into wastewater. In surface waters, their concentrations usually reach the ng∙L⁻¹ range and rarely exceed µg∙L⁻¹, although in India AMX levels above mg∙L⁻¹ were detected in hospital effluents. The limited efficiency of wastewater treatment plants allows these compounds to enter aquatic and terrestrial environments, where they affect various organisms. The aim of this study was to assess the effects of AMP, AMX, and their mixture on wheat, one of the most extensively cultivated cereals. Determinations were carried out using standardized methodologies. The results showed that antibiotics induce oxidative stress in plants, with symptoms observed only at concentrations of 1000 mg∙kg⁻¹ of soil DW. At this level, changes included altered antioxidant enzyme activity (APX, SOD, POD, and CAT), increased proline and H₂O₂ content, and reduced MDA levels. By contrast, antibiotics had minimal influence on glutathione and ascorbate and caused only slight changes in photosynthetic pigments and chlorophyll fluorescence. Full article

Mismanagement of rural wastewater can lead to environmental contamination with the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D). Fungi with bioremediating potential constitute a sustainable alternative to decontaminate such wastewater before its reuse. This study evaluated the ability of Aspergillus oryzae pellets to remove 2,4-D from natural and sterile rural wastewater (i.e., with/without native microbiota). The pellets were produced by incubating conidial solutions of A. oryzae strains RCA2, RCA4, RCA5, and RCA10 in synthetic wastewater for 21 days at 25 °C. The wastewater samples were characterized physicochemically and microbiologically upon arrival at the laboratory. Afterwards, they were supplemented with 1, 2.5, or 5 mmol L⁻¹ of 2,4-D and inoculated with the pellets. Physicochemical characterization was repeated throughout the experiment. Herbicide removal and the presence of 2,4-D degradation intermediate, 2,4-dichlorophenol (2,4-DCP), were assessed through high-pressure liquid chromatography with UV/Vis detection (HPLC-UV) and mass spectrometry. At the beginning of the assay, the macro- and micronutrient content in the samples were suitable to sustain fungal growth. By the end, pH had increased and sodium and nitrate levels decreased in comparison with the control. RCA2, RCA4, and RCA10 removed over 80% of 2,4-D after 7 days of incubation, at the three herbicide concentrations tested. Moreover, wet fungal biomass had increased by the end of the assay. These findings demonstrate that RCA2, RCA4, and RCA10 can grow, form pellets, and remove 2,4-D in natural rural wastewater, which makes them potential candidates for bioremediation strategies aimed at improving the quality of water set to be reused. Full article

Ciprofloxacin (CIP), a persistent fluoroquinolone antibiotic, poses serious environmental concerns due to its low biodegradability and widespread presence in aquatic ecosystems. This study investigates the synergistic application of low-frequency ultrasonic cavitation and biological treatment to enhance CIP removal efficiency. Experiments have shown that under the optimal biological treatment conditions (6 g/L sludge concentration, pH 8), single biological treatment for 48 h can only remove 41.9% CIP and 24.9% total organic carbon (TOC). Ultrasonic pretreatment was conducted under varying frequencies and pH conditions to determine optimal cavitation parameters, while biodegradation performance was evaluated at different sludge concentrations and pH levels. Results indicated that in 10 mg/L CIP wastewater under alkaline conditions (pH 9.0), CIP and TOC removal efficiencies reached 58.9% and 35.2%, respectively, within 30 min using 15 kHz ultrasound irradiation. When ultrasonic pretreatment was followed by biological treatment, overall removal rates increased to 96.3% for CIP and 90.4% for TOC, significantly outperforming either method alone. LC-MS analysis identified several degradation intermediates during ultrasonic pretreatment, revealing key transformation pathways such as piperazine ring cleavage, hydroxylation, and defluorination. Furthermore, toxicity evaluation using the T.E.S.T. model confirmed a substantial reduction in ecological risk after ultrasonic treatment. Overall, the combined ultrasonic–biological process offers a cost-effective and environmentally sustainable strategy for the efficient removal of fluoroquinolone antibiotics from wastewater. Full article

This study examined the effect of sulfur, ethylenediaminetetraacetic acid (EDTA), olive mill wastewater (OMW), and their mixtures in remediating metal-polluted soils by implementing both leaching trials and a greenhouse experiment with sunflower (Helianthus annuus). In the leaching study, soils were subjected to five discharge volumes (V1–V5). EDTA significantly improved metal mobility of Cd (221.4) mg·kg⁻¹ in V2, Pb (340.8) mg·kg⁻¹ in V3, and Zn (1.01) mg·kg⁻¹ in V3, while OMW moderately mobilized Cd and Mn. However, sulfur mitigated leaching by buffering soil pH and metal immobilization. Mixed treatments revealed moderate leaching behavior. EDTA lowered soil pH (5.3) and raised EC (1763) µS/cm, while sulfur maintained stable chemical environments. In the greenhouse experiment, amendments significantly influenced biomass and metal uptake. Sunflower roots accumulated the highest Cd under sulfur (733.5) mg·kg⁻¹ and Mn under EDTA (743.3) mg·kg⁻¹. EDTA restricted Cd translocation (TF = 0), while OMW enhanced Cr movement to shoots (TF = 17.6). EDTA also reduced Cd bioavailability, whereas OMW raised Pb and Mn availability. Overall, EDTA improved metal solubility for potential removal and sulfur in stabilized metals, while OMW acted as a moderate mobilizer. Sunflower demonstrated selective metal uptake, indicating its potential in phytoremediation strategies tailored to specific contaminants. Full article

The excessive emission of cadmium (Cd²⁺) poses a serious threat to the aquatic environment due to its high toxicity and bioaccumulation potential. This study constructed three types of vertical-subsurface-flow constructed wetlands configured with iron–carbon–zeolite composite substrates, including an iron–carbon–zeolite constructed wetland (TF-CW), a zeolite–iron–carbon constructed wetland (FT-CW), and an iron–carbon–zeolite mixed constructed wetland (H-CW), to investigate the purification performance and mechanisms of constructed wetlands for cadmium-containing wastewater (0~6 mg/L). The results demonstrated that iron–carbon–zeolite composite substrates significantly enhanced Cd²⁺ removal efficiency (>99%) through synergistic redox-adsorption mechanisms, where the iron–carbon substrate layer dominated Fe-Cd co-precipitation, while the zeolite layer achieved short-term cadmium retention through ion-exchange adsorption. FT-CW exhibited superior NH₄⁺-N removal efficiency (77.66%~92.23%) compared with TF-CW (71.45%~88.05%), while iron–carbon micro-electrolysis effectively inhibited NO₃⁻-N accumulation (<0.1 mg/L). Under cadmium stress, Typha primarily accumulated cadmium through its root systems (>85%) and alleviated oxidative damage by dynamically regulating antioxidative enzyme activity, with the superoxide dismutase (SOD) peak occurring at 3 mg/L Cd²⁺ treatment. Microbial community analysis revealed that iron–carbon substrates promoted the relative abundance of Bacteroidota and Patescibacteria as well as the enrichment of Saccharimonadales, Thauera, and Rhodocyclaceae (genera), enhancing system stability. This study confirms that iron–carbon–zeolite CWs provide an efficient and sustainable technological pathway for heavy metal-contaminated water remediation through multidimensional mechanisms of “chemical immobilization–plant enrichment–microbial metabolism”. Full article

The pharmaceutical contamination of water, especially by widely used drugs, presents important environmental and health concerns due to the inefficiency of conventional treatment methods. The present study proposes a sustainable solution using biochar (Bch) obtained from tomato waste, functionalized with Fe₃O₄ and MnO₂ nanoparticles, for the removal of paracetamol from aqueous solutions. The composite materials were synthesized, characterized, and evaluated under varying conditions, including pH, temperature, contact time, initial drug concentration, and adsorbent dose. The materials exhibited porous structures with wide pore size distributions. Optimal removal efficiency was achieved for 30 mg L⁻¹ paracetamol concentration, pH 2, 25 °C, 0.3 g L⁻¹ adsorbent dose, and 20 min contact time. The Freundlich isotherm provided the best fit for the adsorption data. Kinetic studies revealed that the pseudo-second-order model best described the adsorption process. Thermodynamic parameters indicated that the process was spontaneous, feasible, and exothermic. Compared with similar materials derived from agricultural waste, the tomato waste-based composites demonstrated competitive adsorption capacities. These findings suggest that Bch-HCl/MnO₂ and Bch-HCl/Fe₃O₄/MnO₂ are promising, cost-effective adsorbents for mitigating pharmaceutical pollutants in wastewater. Full article

The wastewater treatment (WWT) industry is currently facing challenges imposed by the revised urban WWT directive, particularly in terms of nitrogen (N) and phosphorus (P) removal. This implies the need for mandatory tertiary treatment, for which microalgae cultivation shows great sustainability promise. This study investigated the impact of hydraulic retention time (HRT) on nutrient removal in open-air microalgae cultivation for tertiary WWT under winter conditions. Two pilot-scale semi-continuous raceway systems were operated with indigenous microalgae, natural sunlight, and no pH control. HRT values of 4, 5.5, and 7 days were tested, and N, P, and carbon (C) removal and recovery were measured. All conditions allowed nitrogen removal, complying with the revised urban WWT directive. Regarding P, only the 7-day HRT condition consistently complied with the directive’s lowest limit (<0.5 mg P·L⁻¹) in the treated water, while 5.5 and 4 days left up to 0.7 and 1.0 mg P·L⁻¹, respectively, in up to 25% of the samples. A stable microalgae consortium was established under variable light, pH, and dissolved oxygen conditions, albeit with variable biomass productivity. Elemental mass balances revealed that nutrients were mostly recovered in the produced biomass, particularly at high HRT, including effective CO₂ capture from the atmosphere. Full article

Natural zeolites have gained attention as low-cost adsorbents for the removal of heavy metals (HMs) from wastewater. However, their performance can be compromised by the presence of competing cations such as ammonium (NH₄⁺). This study investigated the competitive adsorption and desorption dynamics of NH₄⁺ and six HMs (Cd, Cr, Cu, Ni, Pb, and Zn) on two natural zeolites. Batch and column experiments using synthetic wastewater were conducted to evaluate the effects of different NH₄⁺ concentrations, pH, and particle size on HM removal efficiency and desorption effects. Results showed that increasing NH₄⁺ concentrations significantly reduce HM adsorption, with total capacity decreasing by ~45% at 100 mg/L NH₄-N in kinetic tests. Adsorption isotherms of the HM mixture for both zeolite types followed a clear sigmoidal trend, which was captured well by the Hill model (R² = 0.99), with loading rates up to 56.14 mg/g. Pb consistently exhibited the highest affinity for zeolites, while Cd, Cr, Ni, and Zn were most affected by NH₄⁺ competition in the column tests. Desorption tests confirmed that NH₄⁺ rapidly re-mobilises adsorbed metals, in particular Cd, Cu, and Zn. Slightly acidic to neutral pH conditions were optimal for minimising HM remobilisation. These findings underscore the need to consider competitive interactions and operational conditions when applying natural zeolites for HM removal, especially in ammonium-rich environments such constructed wetlands, soil filters, or other decentralised applications. Full article

Trimethylamine (TMA) is a common malodorous pollutant known for its detrimental effects on both the natural environment and human health. In this study, strain PM-1 was successfully isolated from activated sludge in a sewage treatment plant and identified as the first Microbacterium lacticum capable of degrading TMA. Strain PM-1 is characterized as a mesophilic and mild halotolerant bacterium, thriving within a temperature range of 20–40 °C and a salinity range of 10–80 g/L NaCl. The optimal initial TMA concentrations for strain PM-1 were determined to be 0.1 wt% under aerobic conditions and 0.05 wt% under anaerobic conditions. The strain demonstrated efficient TMA degradation rates of 98.02 mg/L/h aerobically and 4.44 mg/L/h anaerobically. Additionally, beef extract and peptone significantly enhanced TMA degradation and bacterial growth by 293% and 688%, respectively, under aerobic conditions. Microbacterium lacticum strain PM-1 is the first isolated Microbacterium lacticum with the ability to convert TMA. Further research will focus on its TMA degradation pathway through the identification of key enzymes and application in TMA-containing wastewater and exhaust gas. Full article

This article presents an innovative method for phosphate(V) removal from industrial wastewater using cerium(III) chloride as a coagulant, integrated with reagent recovery. The process combines coagulation, acid extraction, and multistage recovery of cerium and phosphorus, enabling partial reagent loop closure. Based on our previously published studies, at an optimised dose (81.9 mg Ce³⁺/L), phosphate(V) removal reached 99.86% and total phosphorus (sum of all phosphorus forms as elemental P), 99.56%, and 99.94% of the added cerium was retained in sludge. Reductions were also observed for TSS (96.67%), turbidity (98.18%), and COD (81.86%). The sludge (101.5 g Ce/kg, 22.2 g P/kg) was extracted with HCl, transferring 99.6% of cerium and 97.5% of phosphorus to the solution. Cerium was recovered as cerium(III) oxalate and thermally decomposed to cerium(IV) oxide. Redissolution in HCl and H₂O₂ yielded cerium(III) chloride (97.0% recovery and 98.6% purity). The HCl used for extraction can be regenerated on-site from chlorine and hydrogen obtained from gas streams, improving material efficiency. Life cycle assessment (LCA) showed environmental benefits related to eutrophication reduction but burdens from reagent use (notably HCl and oxalic acid). Although costlier than conventional precipitation, this method may suit large-scale applications requiring high phosphorus removal, low sludge, and alignment with circular economy goals. Full article

Facing energy and environmental issues is recognized globally as one of the major challenges for sustainable development, to which sustainable chemistry can make significant contributions. Strontium ferrate-based materials belong to a little-known class of perovskite-type compounds in which iron is primarily stabilized in the unusual 4+ oxidation state, although some Fe³⁺ is often present, depending on the synthesis and processing conditions and the type and amount of dopant. When doped with cerium at the Sr site, the SrFeO_3−δ cubic structure is stabilized, more oxygen vacancies form and the Fe⁴⁺/Fe³⁺ redox couple plays a key role in its functional properties. Alone or combined with other materials, Ce-doped strontium ferrates can be successfully applied to wastewater treatment. Specific doping at the Fe site enhances their electronic conductivity for use as electrodes in solid oxide fuel cells and electrolyzers. Their oxygen storage capacity and oxygen mobility are also exploited in chemical looping reactions. The main limitations of these materials are SrCO₃ formation, especially at the surface; their low surface area and porosity; and cation leaching at acidic pH values. However, these limitations can be partially addressed through careful selection of synthesis, processing and testing conditions. This review highlights the high versatility and efficiency of cerium-doped strontium ferrates for energy and environmental applications, both at low and high temperatures. The main literature on these compounds is reviewed to highlight the impact of their key properties and synthesis and processing parameters on their applicability as sustainable thermocatalysts, electrocatalysts, oxygen carriers and sensors. Full article

Advanced oxidation processes (AOPs) utilizing peroxymonosulfate (PMS) have emerged as a promising technology for organic pollutant degradation due to their distinct environmental advantages. In this study, copper–iron bimetallic oxide catalysts with varying ratios were synthesized via a co-precipitation method to activate PMS for degrading simulated tetracycline hydrochloride wastewater. The catalysts were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). The effects of key parameters—including the PMS concentration, catalyst dosage, initial pH, and tetracycline hydrochloride concentration—on the degradation efficiency were systematically investigated. The results demonstrated that the CuFe(2)/PMS system exhibited the highest degradation efficiency. Under optimal conditions (20 mg/L tetracycline hydrochloride, 0.4 mM PMS, 0.5 g/L CuFe(2) catalyst, and pH 3), this system achieved a 94.12% degradation rate of tetracycline hydrochloride within 120 min. The electron paramagnetic resonance (EPR) tests and radical quenching experiments identified sulfate radicals (SO₄·⁻) as the predominant reactive species. Furthermore, the XPS analysis elucidated the persulfate activation mechanism, while the liquid chromatography–mass spectrometry (LC-MS) identified the potential degradation pathways and intermediate products of tetracycline hydrochloride. Full article

The increasing presence of tetracycline antibiotics (TCs) in water sources poses significant environmental and public health risks, necessitating effective treatment technologies. This study investigates the degradation of three types of TCs in water—Tetracycline (TC), Oxytetracycline (OTC), and Chlortetracycline (CTC)—using nonthermal plasma (NTP) coupled with the persulfate (PS) process. The combined NTP/PS system was optimized for various operational parameters, including PS concentration, pH, and reaction time, to achieve maximum degradation and mineralization efficiency. The results showed that the NTP/PS system achieved over 90% degradation of all TCs under optimal conditions, outperforming plasma alone treatment. The degradation kinetics followed a pseudo-first-order model, indicating a rapid initial breakdown of TCs. The degradation mechanism was elucidated through the identification of intermediate byproducts using liquid chromatography-mass spectrometry (LC-MS/MS). Free radicals, such as sulfate (SO₄^•−) and hydroxyl (^•OH) radicals, were identified as the primary reactive species responsible for TCs degradation. This study demonstrates the potential of the NTP/PS system as an efficient and sustainable solution for the removal of antibiotic contaminants from water. Further research on the scalability and application in real wastewater conditions is recommended. Full article