Environmental Science: Water Research & Technology最新文献

Hydrogenotrophic denitrification (H₂Den) is an encouraging biological technology to remove nitrate (NO₃⁻) from supply water with a low carbon/nitrogen ratio or in the absence of organic carbon. This study provides important insights into the use of anaerobic granular sludge for NO₃⁻ removal from a synthetic water with an initial concentration of 200 mg NO₃⁻ L⁻¹ (i.e., 45.2 mg NO₃⁻-N L⁻¹). This study investigated the effect of the inoculum input, expressed as percentage of reactor filling, i.e., 10% vs. 20% vs. 40% (v/v) by the anaerobic granular sludge, as well as the hydrogen (H₂) supply, i.e., stoichiometric vs. 50% excess vs. 100% excess, on the H₂Den process. Coupling 10% (v/v) inoculum percentage with 100% excess of H₂ supply was the most favourable condition, ensuring a NO₃⁻ removal efficiency of up to 96%. Indeed, a 10% (v/v) inoculum percentage ensured the maximal denitrification rate, reaching 6.0 mg NO₃⁻ g⁻¹ VS d⁻¹, which was further enhanced when increasing the H₂ dosage. Despite the great potential, this study also highlighted possible drawbacks of the anaerobic granular sludge-driven H₂Den process, such as nitrite (NO₂⁻) accumulation as a denitrification intermediate. On the other hand, the release of gaseous denitrification intermediates such as N₂O and NO was negligible under most of the investigated experimental conditions.

Correction for ‘Kinetics and mechanism of hydrolysis of PF₆⁻ accelerated by H⁺ or Al³⁺ in aqueous solution’ by Takuto Miyashita et al., Environ. Sci.: Water Res. Technol., 2025, 11, 281–292, https://doi.org/10.1039/D4EW00758A.

Operations at uranium (U)-mining and nuclear facilities have left a global legacy of significant radionuclide contamination in groundwaters which must be managed to minimize environmental harm. Uranium groundwater contamination is present at several sites globally, including Oak Ridge National Laboratory and Hanford, USA and Sellafield nuclear site, UK. In situ phosphate biomineralisation offers a promising method for radionuclide (including ⁹⁰Sr and U) remediation at these sites. Typically, phosphate-generating amendments are injected into the subsurface to sequester select radionuclides in groundwaters by precipitation of poorly soluble Ca-phosphate phases and subsequent adsorption and/or incorporation of radionuclides to these poorly soluble phases, a remediation route being explored for both U and ⁹⁰Sr. In this study, we investigate the mechanisms of U-phosphate precipitation in two phosphate-generating amendments (Ca-citrate/Na-phosphate and glycerol phosphate) under conditions relevant to Sellafield, UK. Using aerobic batch sediment experiments, we show both Ca-citrate/Na-phosphate and glycerol phosphate amendments are effective at enhancing removal of U(VI) from representative groundwaters (from 94% to >97%). Aqueous geochemical data coupled to speciation modelling highlighted that precipitation of U(VI) phosphate phases was the likely mechanism of U(VI) removal from groundwaters. Further X-ray absorption spectroscopy (XAS) analysis of solids confirmed U was present as a highly insoluble uranyl orthophosphate-like phase after treatment with both Ca-citrate/Na-phosphate and glycerol phosphate amendments. These data provide underpinning information on U-phosphate remediation in Sellafield relevant conditions thus expanding the range of treatment options for radionuclide contaminated groundwaters and defining the transport and fate of U during phosphate biomineralisation.

In this study, clinoptilolite (Clp)-doped poly(vinylidene fluoride) (PVDF) membranes (1–4 wt%) were prepared using an electrospinning method. Further, filtration tests on the simulated gray water components were investigated. Methylene blue (MB), linear alkyl benzene sulfonate (LAS), oil (soybean oil), and microplastic (MP) filtration were performed. MB filtration with the PVDF membrane resulted in over 99% of MB rejection. Oil rejection with the PVDF membrane without Clp was observed to be 95%, while the addition of Clp increased the oil rejection to over 99%. It was observed that LAS rejection increased as the Clp content increased. MP rejection using PVDF-based membranes was 100%. Considering all the test results, the membrane containing 3 wt% Clp showed the best performance, and the process parameters and rejection efficiencies were determined through experimental optimization. Synthetic gray water analyses included the chemical oxygen demand (COD), pH, conductivity, and total dissolved solids (TDS). COD rejection was 63.1%, while turbidity rejection was 97.2%.

It is of great interest and importance to explore low-cost, high-efficiency adsorbents for phosphate removal. Herein, we developed a microwave-assisted hydrothermal method to fabricate three-dimensional, flower-like pseudo-boehmite adsorbents using a separate nucleation and aging steps (SNAS) method. We carefully investigated their adsorption behavior toward phosphate in aqueous solution. The morphologies were controlled by adjusting the feeding ratios of the aluminium salt to the alkali in the reaction system, resulting in different pore structures and varying degrees of exposure of the (020) facet. The adsorption behavior followed the Elovich kinetic model and the Langmuir isotherm model based on the correlation coefficient. High doping of aluminium salt promoted the specific surface area by 32.7% and increased the (020) facet exposure by 59.6%. Among the three samples, notably, sample A-1/10, obtained with a molar ratio of Al³⁺ to NaOH of 1 : 10, demonstrated the largest specific surface area (430.67 m² g⁻¹) and the greatest proportion (19.25%) of the exposed (020) facet. Sample A-1/10 exhibited high phosphate removal performance in an acidic solution (pH 3), with the highest adsorption capacity of 158.58 mg g⁻¹. Furthermore, the fixed-bed adsorption column removed 95% of phosphate in a continuous operation system with alginate-assisted pseudo-boehmite beads, consisting of 75% pseudo-boehmite. These results indicate a promising avenue for practical applications in phosphate removal.

Excessive accumulation of particulate material and biofilms on the inner walls of drinking water pipes increases the risk of water discoloration events, known to be the major cause of customer complaints worldwide. As a result, water utilities use pipe flushing operations to mobilize material deposits from ‘dirty sections’ of their pipe networks. Nevertheless, the development of preventative strategies is still limited by the lack of knowledge about the material accumulation process and the behaviour of resuspended particles during flushing. The goal of this paper is to investigate the behaviour of insoluble iron oxide particles during controlled accumulation and flushing processes in PVC drinking water pipes. A set of four experiments was completed where water with a known concentration of iron oxide particles was introduced into a full-scale pipe loop laboratory system under steady flow conditions producing the accumulation of particles along half the pipe length. The system was then flushed using two sequential velocities (0.7 and 1.2 m s⁻¹) and the direction of flush was changed between each independent flushing stage. During the flushing operations, it was found that a small number of mobilized particles can reattach to downstream sections pipes, and resist mobilization to elevated wall shear stresses of 1.2 Pa. Furthermore, even after successive flushes in one direction, a subsequent flush of equal velocity in the opposite direction was able to mobilize new particles from the pipe wall surface. These findings revealed a new mechanism of particle resistance to mobilization that is independent of the WSS. These results may assist water utilities in improving flushing strategies for DWDSs and managing accumulated material in their networks.

Biofilm growth in drinking water distribution systems (DWDS) has become a concern due to the various water quality issues it causes, and thus suitable disinfection methods are required to ensure drinking water safety. Micro-nano bubbles (MNBs) technology provides a possible breakthrough in dealing with the above issues. This paper simulates the hydraulic conditions of the terminal pipeline in a DWDS to explore biofilm formation under the influence of MNBs from different gas sources. To further understand the changes in water quality, this study evaluated the biofilm morphology, composition, microbial communities, and water quality at different experiment stages. Therefore, we divide the biofilm formation into three phases: the slow growth phase (0–27 days) (SP), rapid growth phase (27–42 days) (RP), and dynamic stability phase (42–66 days) (DP). Biofilm formation was significantly inhibited in the slow growth and rapid growth phases, especially after combining the MNBs with oxygen, causing a reduction in biofilm dry weight of 77.87%. The mechanism by which the MNBs regulate biofilm growth is different at each stage. During the SP stage, physical obstruction and chemical oxidation occurs, at the RP stage oxidative inactivation takes place, whilst at the DP stage adsorption and scour predominate. Notably, the MNBs first attach to the tank's inner surface, forming a hydrophobic layer to increase the difficulty of microbe adherence. Then, an extensive amount of hydroxyl radicals (˙OH) were generated by the MNBs collapsing, reducing the number of bacteria present while increasing the competitive advantage of oxidation-resistant bacteria. This disinfection method narrows the differences in number between the dominant bacterial populations in the biofilm, which changes the key strains and reduces microbial community diversity. As a result, the inactivation rate of Planctomycetes reached 54.22–61.66%, and a significant reduction of the organic matter in water was achieved (87.9% removal of TOC). These results proved that the MNBs have great potential in treating biofilms in DWDS and improving drinking water quality.

Disinfection is crucial to inactivate pathogenic bacteria and prevent the spread of epidemic diseases during drinking water/wastewater treatment. However, adverse disinfection by-products (DBPs) are inevitably produced during the disinfection process. Previous reviews primarily paid attention to the occurrence, formation, and control of some known DBPs, whereas few studies focused on the relatively large proportion of unknown DBPs. This study provided an overall review of unknown DBPs in different water bodies. Firstly, the analytical method of unknown DBPs based on Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) analysis was described in detail. Secondly, the molecular composition and characteristics of unknown DBPs in various water bodies during different disinfection processes were systemically summarized. Moreover, the possible transformation reactions involved in forming unknown DBPs were thoroughly proposed. Thirdly, the control strategies (e.g., pre-treatment, selection and optimization disinfection conditions, and post-treatment) of unknown DBPs were comprehensively listed. Finally, future studies should focus on identifying molecular structures, screening the highly toxic compounds, investigating the formation mechanisms, and developing more effective control strategies for unknown DBPs. Overall, this review will narrow the knowledge gap about the composition and control of unknown DBPs in different water bodies, thereby protecting human health and improving ecological safety.

Anaerobic ammonium oxidation requires the influent NO₂⁻–N/NH₄⁺–N ratio to be 1.32 : 1. At low temperatures, poor sludge settling performance, expansion, and loss are profound. The effluent water quality cannot meet the influent requirements of the anaerobic ammonium oxidation stage. In this study that was operated for more than 300 days, the SBR was used to inoculate flocculent sludge and cultivate it to form aerobic granular sludge (AGS), which was then domesticated into partially nitrosated granular sludge (PNGS), and gradually reduced to low-temperature for intensive cultivation. During the cooling process, the ratio of NO₂⁻–N/NH₄⁺–N in the effluent was maintained by controlling the aeration time and the operating cycle of the SBR to achieve the best partial nitrosation efficiency. PNGS cultured increased the volumetric load of NH₄⁺–N removal from 0.24 kg (m⁻³ d⁻¹) to 0.35 kg (m⁻³ d⁻¹) at 15 °C compared with 30 °C. Fly ash was used as the crystal nucleus and carrier to prevent the disintegration of AGS at low temperatures (15 °C). The effect of fly ash dosages 50, 100, 150, 200, 250, 300 mg L⁻¹ on partial nitrification efficiency was determined. It accelerates the formation of new AGS and improves partial nitrification performance. Compared with no fly ash addition at 15 °C, when fly ash dosage of 250 mg L⁻¹ was added, the NO₂⁻–N accumulation rate increased from 75% to 85%, and NH₄⁺–N volume removal load increased from 0.35 kg (m⁻³ d⁻¹) to 0.45 kg (m⁻³ d⁻¹). Effluent NO₂⁻–N/NH₄⁺–N increased from 0.55 : 1 to 1.20 : 1. Effluent NO₂⁻–N/NH₄⁺–N meets anammox influent requirements. This study can be used to build sustainable wastewater treatment in low-temperature regions worldwide.

Sensor availability and costs are nowadays no longer limiting data gathering at wastewater treatment plants (WWTPs). However, one should be aware that a higher amount of measured data gathered does not necessarily imply that also more information is obtained. In this light, this contribution assesses the general applicability and the added value of a structured experimental design approach for planning measurement campaigns at WWTPs, in view of mass-balance-based data reconciliation. To this end, the results from full-scale WWTP case studies available in the literature were compared to those obtained with the developed structured experimental design procedure. Planning measurement campaigns comprises the selection of (additional) measurements to meet a pre-set main goal. The need for a structured experimental design procedure replacing past expert judgment approaches became clear from the fact that three out of five case studies available in the literature failed to meet the main goal and/or performed unnecessary additional measurements. Translating the main goal into specific key variables was found essential in this respect. The general applicability of the procedure was proven with three outcomes. First, the procedure, involving well-defined steps, could be applied to different WWTP layouts. Second, it ensured the fulfilment of various main goals. Third, it provided useful outcomes, i.e., optimal measurement campaigns, which reduced the need for additional measurements (40–70% less) compared to expert knowledge approaches, hence more information could be obtained with less analytical data. Overall, the experimental design procedure proved a fast and useful tool ensuring the success of subsequent mass-balance-based data reconciliation.