Search Results (1,267)

Constructed wetlands (CWs) are acknowledged as an effective and sustainable ecological technology for the treatment of wastewater, especially in the removal of nitrate and phosphate. This study investigated the application of natural siderite as a substrate in laboratory-scale tidal flow CWs to enhance simultaneous nitrate and phosphate removal. A systematic study was conducted to evaluate the impact of critical operational parameters, including siderite dosage, influent COD/N ratio, and hydraulic retention time (HRT) on system performance. Moreover, the corresponding changes in microbial community structure were explored. The results indicated that siderite significantly improved the elimination of nitrate and phosphate. Denitrification efficiency exhibited a strong dependence on both siderite dosage and organic carbon availability. The nitrate removal increased by 19.01 ± 6.37% compared to the non-siderite control under an optimal condition. Phosphorus removal demonstrated a primary reliance on the proportion of siderite, reaching a maximum removal improvement of 77.68 ± 26.27%. Analysis of microbial diversity revealed that siderite enhanced both richness and evenness of the microbial community and facilitated the proliferation of essential denitrifying genera, specifically Dechloromonas and Thiobacillus. Full article

In this study, we investigated the impact of varying iron (Fe) and aluminum (Al) contents on the adsorption of phosphonates to activated sludge. Phosphonates originating from household applications account for up to 40% of the non-reactive dissolved phosphorus in domestic sewage treatment plants and thus can contribute to the eutrophication of water bodies. Although these substances are not readily degradable, substantial quantities, ranging from 40% to more than 90%, are removed by sludge adsorption. The results demonstrate a strong correlation between the adsorption of aminophosphonates and the Fe³⁺ content of the sludge. The maximum phosphonate loadings were 5.94 mmol g⁻¹ Fe³⁺ for ATMP, 4.94 mmol g⁻¹ Fe³⁺ for EDTMP, 4.74 mmol g⁻¹ Fe³⁺ for DTPMP, and 2.25 mmol g⁻¹ Fe³⁺ for glyphosate. In contrast to pure ferric hydride flocs, the adsorption of phosphonates was approximately threefold higher when the hydroxides were located within activated sludge flocs. It is concluded that native sludge flocs provide larger iron surfaces than ferric hydroxide alone. Based on the weight of the adsorbents, aluminum salts were four times less efficient than ferric salts. In sludge without ferric or aluminum hydroxides, phosphonate adsorption was negligible. Full article

The study evaluated the feasibility of using the activated sludge process to treat real wastewater from used oil installations containing petroleum hydrocarbons, boron (B), and adsorbable organic halides (AOX). The aim was to determine the maximum ratio of this wastewater that could be added to the influent without impairing treatment efficiency. Tested shares ranged from 0.50% to 1.90%. An initial 1.30% of the tested share caused process instability, reflected in the elevated total nitrogen (TN) levels in treated wastewater. After reducing the share to 0.50%, an adaptation of the activated sludge was observed, manifested by a decrease in TN concentration to below 15.0 mg N/L. For the most favorable share of 1.60% (0.38 ± 0.10 kg_BOD5/kg_MLSS d, 0.51 ± 0.14 kg_COD/kg_MLSS d), the removal efficiencies of chemical oxygen demand (COD), biochemical oxygen demand (BOD₅), TN, and total phosphorus (TP) were 95.0% ± 1.5, 99.1% ± 0.2, 89.3% ± 2.7, and 94.0% ± 5.0, respectively. Increasing the share to 1.90% decreased treatment efficiency and exceedances of COD, BOD₅, TN, and TP occurred. At this ratio, an increase in ammonium nitrogen (NH4⁺-N) and TN concentrations was observed, indicating the inhibition of nitrification. However, the average concentrations of mineral oil index, AOX and B in the treated wastewater remained within permissible levels throughout the study. Full article

Sewage sludge production is increasing rapidly, yet current sludge treatment capacity and technology remain insufficient. The thermochemical process has been widely adopted for sewage sludge disposal; its solid product (bio/hydro-char) shows considerable potential to improve soil quality by enriching soil nutrient contents. However, limited heavy metals are volatilized during the thermochemical process, and the majority is concentrated in the derived bio/hydro-char. Therefore, it is essential to ensure the environmental safety of sewage sludge-derived bio/hydro-char and avoid heavy metal risk, and thus appropriate heavy metal removal technology is required prior to land application. This review provides an overview of the major sewage sludge treatment approaches focusing on the heavy metal removal and phosphorus recovery, along with emerging challenges and future perspectives for the sustainable utilization of sewage sludge. Notably, the combination of electrokinetic treatment with thermochemical treatments emerges as a promising strategy to simultaneously treat sewage sludge and achieve P reclamation. Full article

Constructed wetlands (CWs), which combine biological and physicochemical processes and adhere to circular economy principles, are increasingly recognized as nature-based wastewater treatment solutions. With an emphasis on resource valorization and pollutant removal efficiency, this review assessed the use of organic residues as substrates in CWs. In total, 44 peer-reviewed open-access case studies in English were obtained from 325 documents that were retrieved from Scopus using PRISMA-based eligibility criteria. Information about the wastewater source, substrate, CW type, and results was extracted. The results indicated that biochar (66.7%) predominated because of its high adsorption capacity and microbial support, while shell or forest residues and agricultural residues (20.5%) helped remove micropollutants and phosphorus. CWs with vertical subsurface flow were most prevalent (54%). According to studies, the removal efficiencies of biochar and agricultural or shell residues were 10–15% higher than those of inorganic substrates for phosphorus, TSS (total suspended solids), NH₄⁺ (ammonium), and BOD (biochemical oxygen demand) in wastewater. Through innovative designs and the application of circular economy strategies, including revalorize, reuse, reutilize, reintegrate, rethink and reconnect, organic substrates enhance pollutant removal and improve the overall sustainability of CWs. Overall, CWs with organic residues provide cost-effective and environmentally sustainable wastewater treatment; further research on local resources, hybrid systems, and supportive policies is recommended to promote broader implementation. Full article

Phosphorus recovery from wastewater as struvite via electrochemical magnesium dosing is a promising approach to address the growing demand for fertilizers. However, its large-scale implementation is often constrained by energy requirements. To overcome this limitation, this study investigates electroless struvite precipitation from cheese whey wastewater using sacrificial magnesium anodes. Under optimal conditions, up to 90% of the phosphorus was recovered within 4–6 h. In this process, spontaneous magnesium dissolution acts as the driving force for phosphorus precipitation and is strongly influenced by the wastewater’s ionic composition. To identify conditions that favor efficient recovery, the effects of ammonium, chloride, and sulfate ions were evaluated by monitoring phosphorus removal and magnesium corrosion behavior. Sulfate ions enhanced magnesium corrosion more strongly than chloride during the initial stages, likely due to stronger coulombic interactions with Mg²⁺ at the electrode–electrolyte interface, whereas chloride ions were more effective at disrupting the passivation layer that develops over time. Based on these observations, a mechanistic interpretation of ion-specific effects on anodic corrosion is proposed. Solid-phase analyses using multiple characterization techniques confirmed struvite formation, with ammonium sulfate and ammonium chloride systems yielding the highest product purity. Overall, these findings improve the understanding of electroless struvite precipitation and highlight its potential as an energy-efficient approach for nutrient recovery. Full article

Background: Post-thyroidectomy hypocalcemia is a common complication, yet the optimal perioperative markers for identifying high-risk patients and guiding supplementation remain debated. This study aimed to evaluate factors associated with hypocalcemia at 24 h after total thyroidectomy, identify independent predictors, and assess the reliability of early PTH measurement in determining supplementation needs. Methods: We conducted a single-center prospective cohort study including 200 patients undergoing total thyroidectomy at Genesis Hospital, Thessaloniki, between November 2022 and March 2025. PTH was measured preoperatively, 10 min post-resection, and at 24 and 72 h; calcium and phosphorus were measured preoperatively and postoperatively. Results: Independent predictors of hypocalcemia at 24 h were female sex, preoperative calcium, and PTH at 10 min. Age, pathology, incidental parathyroid excision, and extent of surgery were not significantly associated with hypocalcemia. ROC analysis showed that a preoperative calcium cutoff of 9.47 mg/dL yielded an AUC of 0.73, with 70.1% sensitivity and an NPV of 82%. PTH at 10 min with a cutoff of 24.6 pg/mL yielded an AUC of 0.66, with 70.1% sensitivity and an NPV of 79%. For supplementation needs, PTH at 10 min demonstrated excellent discrimination, with a cutoff of 16.3 pg/mL at 24 h and 14.1 pg/mL at 72 h. Conclusions: Preoperative calcium and PTH measured 10 min after thyroid removal are useful markers for predicting hypocalcemia after total thyroidectomy, with early PTH also accurately identifying supplementation needs. Full article

There are large amounts of carbohydrates and proteins in rban perishable organic waste (UPOW), which can be converted to short chain fatty acids (SCFAs) through microbial methods. In this study, the mass balance and properties of organic slurry generated from UPOW pretreatment were investigated first. Then, the optimal conditions for SCFAs production from organic slurry of UPOW was studied. It was found that under the conditions of pH 8 ± 0.5 and reaction time of 3 d, the yield of SCFAs, mainly composed of acetic and propionic acids, in the full-scale reactor was 0.68 gCOD/gTCOD of organic slurry. Under the conditions of influent NH₄⁺-N, total nitrogen, soluble ortho-phosphorus, and soluble COD of 27–39, 33–45, 2–9, and 220–300 mg/L, respectively, the use of SCFAs-enriched fermentation liquid (100 mg COD/L) as the additional carbon source for full-scale biological municipal wastewater treatment showed a higher total nitrogen and phosphorus removal efficiency than that of sodium acetate (88.1 ± 5.2% against 81.4 ± 4.5% and 96.9 ± 3.1% versus 91.5 ± 2.8%) due to greater key enzyme activity and short-cut nitrification and denitrification capacity. Finally, based on the actual operation process, an economic benefit analysis on the production of SCFAs-enriched fermentation liquid from UPOW was conducted, and the issues that need to be addressed for the promotion and application of this technology were discussed. This study contributes to achieving sustainable synergistic treatment of organic waste and wastewater. Full article

China possesses abundant stover resources, and promoting the recycling of stover instead of open burning is a crucial measure for reducing carbon emissions and protecting the atmospheric environment. This study systematically investigated the effects of four stover management strategies—stover removal (CK), direct stover return (SD), stover biochar return (BC), and a combined half-stover half-biochar return (SB)—on soil physicochemical properties, enzyme activities, and microbial communities in the meadow brown soil of Northeast China. The results demonstrated that BC treatment significantly increased the soil total carbon (TC), total nitrogen (TN), total phosphorus (TP), available phosphorus (AP), and available potassium (AK) contents. SB treatment showed the most pronounced enhancement in TP. Regarding enzyme activities, Compared with CK, SD significantly increased the activity of N-acetyl -β -D-glucosaminase (NAG). Furthermore, all stover return practices significantly enhanced bacterial community diversity but suppressed fungal diversity. SB treatment resulted in the greatest improvement in bacterial richness and diversity. Beta diversity analysis revealed that SD and SB significantly altered the soil microbial community structure, whereas BC had a minimal impact. In conclusion, the combined application of stover and biochar (SB) exhibited the most consistent and beneficial outcomes across multiple soil health indicators, highlighting its potential as an effective integrated strategy for enhancing soil fertility, promoting carbon sequestration, and sustaining the health of the meadow brown soil ecosystem in Northeast China. Full article

This paper examines the tensions between existing infrastructure and the need for transitional change in Dutch municipal wastewater collection and treatment. In the Netherlands, sanitation is primarily managed by public actors, with local government playing a major role. The paper demonstrates how local governments navigate these tensions and are both restricted and enabled by the current infrastructure and governance arrangements. Based on interviews, literature reviews, and analyses of statistical trends, it describes five attempts at reform in Dutch sanitation from 1980 to 2020: phosphorus removal; separating stormwater from combined sewers; water cycle companies; energy factories; and decentralized sanitation. The multi-level governance system, with decentralized infrastructure and financing, allows local governments to experiment with alternative practices, develop knowledge, and employ various interactions to mainstream innovations. However, the division of tasks in Dutch sanitation governance tends to optimize sub-systems rather than the entire system. For nationwide implementation, legislation and strong central coordination are essential. Additionally, New Public Management reinforces existing infrastructure lock-in. The paper enhances our understanding of the local government’s role in transitional change and offers insights into how the challenges of existing infrastructure can be mitigated in pursuit of sustainable wastewater solutions. Full article

Municipal wastewater (MWW) was treated using a microalgal–bacterial consortium without mechanical aeration. An inoculum for the reactor was prepared by acclimatizing Chlorella vulgaris to MWW and supplementing with a small amount of activated sludge. The hydraulic retention time (HRT) and solids retention time (SRT) were progressively reduced from 6.67 to 1.17 d and from 10 to 6.67 d, respectively, to test the process robustness under realistic MWW operation. The COD removal efficiency was 88% at 0.23 kg-COD/m³/d. Mass balance suggested the major nitrogen and phosphorus removal mechanism as assimilation. A high percentage (80%) of oxidized nitrogen indicated an efficient nitrification at all HRTs. Inorganic carbon (IC) balance calculation explained the observed IC dynamics. The chlorophyll a-to-mixed liquor volatile suspended solids (MLVSS) ratio and percentage of nitrite responded to IC limitation and supplementation. The mixed liquor exhibited excellent settleability (sludge volume index: 42 mL/g) with dense algal–bacterial flocs. An increased organic loading rate, however, reduced daytime dissolved oxygen, suggesting limitation under non-aerated conditions. These findings demonstrate the potential of microalgal–bacterial systems to achieve efficient COD removal and nitrification at realistic HRTs without aeration while emphasizing the importance of IC management. Full article

Black-odorous water pollution presents a serious threat to aquatic ecosystems and severely hinders the sustainable development of the ecological environment, as conventional remediation technologies often fall short in achieving the simultaneous removal of multiple pollutants. In this study, a novel composite remediation agent was developed by integrating microbial active components with modified clay minerals—sodium-modified zeolite (Na-Z) and magnesium–aluminum–lanthanum layered ternary hydroxides loaded onto sulfuric acid-modified bentonite (Mg-Al-La-LTHs@SBt)—through gel-embedding immobilization. This integrated system enabled the synergistic remediation of both overlying water and sediment pollutants. The modified clay minerals exhibited strong adsorption capacity for nitrogen and phosphorus compounds in the overlying water. Under 25 °C conditions, the composite agent achieved removal efficiencies of 58.14% for ammonium nitrogen (NH₄⁺-N) and 88.89% for total phosphorus (TP) while significantly reducing sedimentary organic matter and acid volatile sulfide (AVS). Notably, the agent retained substantial remediation efficacy even under low-temperature conditions (5 °C). High-throughput microbial community analysis revealed that the treatment enriched beneficial phyla (e.g., Proteobacteria) and beneficial genera (e.g., Thiobacillus) and suppressed sulfate-reducing groups (e.g., Desulfobacterota), promoting favorable nitrogen and sulfur transformations. These results provide a robust material and methodological basis for efficient, synergistic restoration of black-odorous water and the sustainable development of water resources. Full article

Phosphate is a crucial non-renewable mineral resource, mainly utilized in producing fertilizers that support global agriculture. As phosphorus is an indispensable nutrient for plant growth, phosphate holds a key position in ensuring food security. While deposits are distributed worldwide, the largest reserves are concentrated in Morocco. The Benguerir phosphate mining in Morocco generates heterogeneous waste (i.e., including overburden, tailings, and phosphogypsum) that complicates management and valorization, which is the beneficial reuse or value recovery from waste materials (e.g., use in cover systems, buffering, or other engineered applications). Therefore, it is essential to characterize their mineralogical properties to evaluate their environmental impact and possibilities for reuse or site revegetation. To do so, we integrate VNIR–SWIR reflectance spectroscopy with HandHeld X-ray fluorescence (HHXRF) to characterize phosphate waste rock and assess its reuse potential. For this purpose, field samples (n = 104) were collected, and their spectral reflectance was measured using an ASD FieldSpec 4 spectroradiometer (350–2500 nm) under standardized laboratory conditions. Spectra were processed (Savitzky–Golay smoothing, convex-hull continuum removal) and matched to ECOSTRESS library references; across the dataset, library matching achieved mean RMSE = 0.15 ± 0.053 (median 0.145; 0.085–0.350), median SAM = 0.134 rad, median SID = 0.029, and mean R² = 0.748 ± 0.170, with 84% of spectra yielding R² > 0.70. In parallel, HHXRF major and trace elements were measured on all samples to corroborate spectral interpretations. Together, these analyses resolve carbonate–clay–phosphate assemblages (dolomite commonly dominant, with illite/smectite–kaolinite, quartz, and residual carbonate-fluorapatite varying across samples). Elemental ratios (e.g., Mg/Ca distinguishing dolomite from calcite; K/Al indicating illite) reinforce spectral trends, and phosphate indicators delineate localized enrichment (P₂O₅ up to 23.86 wt % in apatite-rich samples). Overall, the combined workflow is rapid, low-impact, and reproducible, yielding coherent mineralogical patterns that align across spectroscopic and geochemical lines of evidence and providing actionable inputs for selective screening, targeted material reuse, and more sustainable mine reclamation planning. Full article

Ricotta cheese whey (RCW) is a by-product with nutritional potential, but its use in the human diet is limited due to its high salinity. Chlorella vulgaris can use RCW as a substrate to enhance biomass productivity. The aim of this work was to evaluate different conditions for C. vulgaris growth in RCW, during scaling-up analysis. After preliminary assays to select growth conditions, two systems were prepared as follows: 500 mL Erlenmeyer flasks (control-system) and a 3 L Bioreactor. Microfiltrated RCW was used as a substrate for C. vulgaris LPMA39 production. Biomass was measured and productivity at 96 h, cell growth kinetics behaviour, biomass biochemical characterisation, and the efficiency of nutrient removal were determined. Both systems presented the same biomass concentration at 96 h (2.2–2.8 g·L⁻¹) and productivity (0.021–0.027 g·L⁻¹·h⁻¹). Nevertheless, 11 h lag-period for cell adaptation to the 3 L Bioreactor was required; thereafter, cells grew faster (µ_max: 0.32 ± 0.08 h⁻¹) than control-system. Finally, slight but significantly lower C_max: 2.14 ± 0.08 was obtained when comparing it to control-system. Lipids, proteins, and pigment contents decreased by the scaling-up; meanwhile, higher reduction in chemical oxygen demand (COD), total phosphorus, and total nitrogen were recorded in the 3 L Bioreactor. Identifying the operating conditions that improve C. vulgaris performance in non-diluted RCW remains a challenge from a sustainability standpoint. Full article

Urban stormwater runoff, particularly during first-flush events, carries high loads of fine suspended solids and phosphorus that are difficult to remove with conventional best management practices (BMPs). This study developed and evaluated a laboratory-scale high-efficiency up-flow filtration system with Internet of Things (IoT)-based autonomous control. The system employed 20 mm fiber-ball media in a modular dual-stage up-flow configuration with optimized coagulant dosing to target fine particles (<3 μm) and total phosphorus (TP). Real-time turbidity and pressure monitoring via sensor networks connected to a microcontroller enabled wireless data logging and automated backwash initiation when thresholds were exceeded. Under manual operation, the two-stage filter achieved removals of 96.6% turbidity, 98.8% suspended solids (SS), and 85.6% TP while maintaining head loss below 10 cm. In IoT-controlled single-stage runs with highly polluted influent (turbidity ~400 NTU, SS > 1000 mg/L, TP ~1.6 mg/L), the system maintained >90% SS and ~58% TP removal with stable head loss (~8 cm) and no manual intervention. Turbidity correlated strongly with SS (R² ≈ 0.94) and TP (R² ≈ 0.87), validating its use as a surrogate control parameter. Compared with conventional BMPs, the developed filter demonstrated superior solids capture, competitive phosphorus removal, and the novel capability of real-time autonomous operation, providing proof-of-concept for next-generation smart BMPs capable of meeting regulatory standards while reducing maintenance. Full article