Water Science and Technology最新文献

Trenchless pipe renewal can be a more cost-, time- and environmentally effective alternative to traditional open-cut replacement. It reduces service disruptions for surrounding infrastructures and is often cheaper, especially when extensive excavation works are necessary, particularly in cold climates, like Norway, where trenches are traditionally deep due to frost security requirements. Still, the uptake of trenchless technologies is still limited in the Norwegian market. In this study, interviews were conducted with representative actors in the Norwegian water industry (water utilities, contractors, and consultants), with the aim of revealing how the technology for renewal of pipes is selected in the planning phase and identifying hindering and enabling factors for trenchless technology uptake in the market. Factors identified include market conservativism, lack of trust between stakeholders, missing guidelines about the distribution of risk, lack of knowledge/specialization in utilities and consultant offices, and issues pertaining to the project delivery method and tendering process. These factors indicate which measures could be implemented to increase the uptake of trenchless technologies in the Norwegian and similar markets. Suggested measures include strengthening the position of stakeholder independent trade organization, facilitating cooperation between smaller utilities and adapting the tendering process to better reflect the requirements of the projects.

Coal power plants adversely impact air pollution, but they also pose a risk to our water sources. Discharge wastewater from power plants may degrade the quality of nearby water bodies. This study evaluates the potential water-related environmental impacts of electricity generation at an ultra-supercritical coal power plant in Malaysia using the life cycle assessment method. The inventory data were gathered from a Malaysian power plant, and supporting data were taken from the relevant literature. Utilizing the ReCiPe 2016 impact assessment method, this study analyses the mid-point impact categories of freshwater eutrophication (FEP), marine eutrophication (MEP), freshwater ecotoxicity (FETP), and marine ecotoxicity (METP). The results indicate that METP is the leading risk, with an average impact of 1.94 × 10^-2 kg 1,4-DCB per kWh electricity generated, followed by FETP (1.40 × 10^-2 kg 1,4-DCB), FEP (4.66 × 10^-4 kg P eq), and MEP (2.95 × 10^-5 kg N eq). About 95% of the mid-point impact is due to the extraction and processing of hard coal. These findings underscore a critical aspect of environmental management at the supply chain level. Furthermore, mitigating direct emissions from power generation could reduce the mid-point impact, as demonstrated by comparisons with previous research.

The advanced anaerobic technology (AAT), developed based on an immobilized high-rate anaerobic reactor, was applied as a pretreatment of municipal wastewater (WW) at Karmiel's treatment plant in Israel. The demonstration-scale AAT (21 m³) system was operated at a flow rate of 100 m³day^-1 municipal WW mixed with olive mill wastewater (OMW) (0.5 m³day^-1) to simulate the scenario of illegal discharge of agro-industrial WW. The AAT provided a stable performance. Specifically, AAT enabled treating high organic loads (9.3 kg m^-3day^-1) resulting from OMW discharge by shaving the high peaks of organic content and protecting the subsequent activated sludge process. This system enabled the recovery of a significant part of the organic load by anaerobic biodegradation to produce biogas, shown to be highly dependent on temperature and partly on the organic loading rate. The outcomes indicate that the AAT could tolerate an addition of up to 0.5% OMW to municipal WW by removing more than 50% of the total chemical oxygen demand and 18-47% of polyphenols. This work shows that the AAT system has the potential of pretreating municipal WW, increasing the energy efficiency of the plant, and protecting small-medium WWTPs from sudden agro-industrial discharges.

Road runoff underwent treatment using a filter filled with sludge from drinking water treatment plants to assess its capacity for removing dissolved organic matter (DOM). This evaluation utilized resin fractionation, gel permeation chromatography, three-dimensional excitation-emission matrix fluorescence spectroscopy, and UV-Visible spectroscopy. The filter demonstrated enhanced efficiency in removing dissolved organic carbon, achieving removal rates between 70 and 80%. It effectively targeted macromolecular DOM components present in road runoff, with hydrophobic organic compounds showing higher removal rates than hydrophilic ones. Additionally, acidic and neutral organic substances were preferentially removed over basic organic compounds. Fluorescent substances identified in road runoff DOM included fulvic acid-like, humic acids, and protein-like substances, all of which exhibited significantly reduced intensities in fluorescence peaks after filtration. Furthermore, filtration led to a decrease in the aromatization and humification of runoff DOM due to the effective removal of aromatic compounds and macromolecular structural components.

Anaerobic treatment of sulfur-rich wastewater is challenging because sulfide greatly inhibits the activity of anaerobic microorganisms, especially methanogenic archaea. We developed an internal phase-separated reactor (IPSR) that removed sulfide prior to methanogenesis by gas stripping using biogas produced in the reactor. The IPSR was fed with synthetic wastewater containing a very high sulfide concentration of up to 6,000 mg S L^-1 with a chemical oxygen demand (COD) of 30,000 mg L^-1. The IPSR was operated at an organic loading rate of 5-12 kg COD m^-3 day^-1 at 35 °C. The results show that the sulfide concentration was reduced from 6,000 mg S L^-1 in the influent to <700 mg S L^-1 in the first-stage effluent. The second-stage effluent contained <400 mg S L^-1. As a result of effective sulfide removal by its gas stripping function, the IPSR had a COD removal efficiency of >90% over the entire experimental period. High-throughput 16S rRNA gene sequencing revealed that the major anaerobic archaea were Methanobacterium and Methanosaeta, which are frequently found in high-rate anaerobic reactors. Thus, the IPSR maintains these microorganisms and achieves high-process performance even when fed wastewater with very high sulfide concentrations.

Hexafluoropropylene oxide trimer acid (HFPO-TA) is an emerging alternative to traditional perfluoroalkyl substances (PFASs), which is characterized by its biotoxicity and persistence. The UV/sulfite/iodide photo-induced hydrated electrons system can effectively degrade HFPO-TA under mild conditions. However, the effects of water quality on this system need to be urgently investigated. This study explored the impact of common aqueous constituents, such as Cl-, HCO3-, PO43- and humic acid (HA) on the defluorination efficiency of HFPO-TA by the UV/sulfite/iodide system. Results indicated that low concentrations of Cl- (<1.0 mM), PO43- (<0.01 mM), and HA (<1.0 mg/L) have little effect on defluorination efficiency. However, as concentrations increase, these constituents can interact with photosensitizers or reactive species within the system, leading to a decrease in defluorination efficiency. HCO3-, in their various solution states, can compete with HFPO-TA for the hydrated electron (eaq-) or engage directly with the photosensitizer, resulting in a hindrance to the defluorination capabilities of the system. Furthermore, it was identified that the components in Xiaoqing River, especially Cl- and HCO3-, could greatly inhibit the defluorination and degradation efficiency of HFPO-TA by the system. Pretreatment such as nanofiltration would effectively mitigate this problem.

The increasing use of intermittent aeration controllers in wastewater treatment plants (WWTPs) aims to reduce aeration costs via continuous ammonia and oxygen measurements but faces challenges in detecting sensor and process anomalies. Applying machine learning to this unbalanced, multivariate, multiclass classification challenge requires much data, difficult to obtain from a new plant. This study develops a machine learning algorithm to identify anomalies in intermittent aeration WWTPs, adaptable to new plants with limited data. Utilizing active learning, the method iteratively selects samples from the target domain to fine-tune a gradient-boosting model initially trained on data from 17 plants. Three sampling strategies were tested, with low probability and high entropy sampling proving effective in early adaptation, achieving an F2-score close to the optimal with minimal sample use. The objective is to deploy these models as decision support systems for WWTP management, providing a strategy for efficient model adaptation to new plants, and optimizing labeling efforts.

In this study, three different materials were investigated for their ability to degrade benzene, toluene, and xylene (BTX) using light energy. The materials studied were activated charcoal (AC), zeolitic imidazolate framework (ZIF-8), and zirconium metal-organic framework (Zr-MOF). Initially, AC, ZIF-8, and Zr-MOF were characterized using X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET) surface area analysis, and spectroscopic analysis techniques. Based on their excellent features, that is, band gap (5.5, 5.45, and 4.75 eV), surface area (711.5, 1,122.1, and 535.4 m²/g), and pore volume (0.291, 0.369, and 0.628 cm³/g), a comparative photodegradation analysis of BTX was performed in acetonitrile. We found that Zr-MOF is the best photocatalyst to degrade BTX, with degradation percentages of 97, 95, and 94% (B > T > X), respectively, followed by ZIF-8 and AC. Our study suggests that these photocatalysts can be used to degrade BTX using light energy, which could reduce the health and environmental impacts of BTX. Our results illustrate that advanced porous materials may be established as photocatalyst materials with the potential to address the long-standing challenges associated with pollutant degradation.

Despite water being a significant output of water and resource recovery facilities (WRRFs), tertiary wastewater treatment processes are often underrepresented in integrated WRRF models. This study critically reviews the approaches used in comprehensive models for ozone (O₃) and biological activated carbon (BAC) operation units for wastewater tertiary treatment systems. The current models are characterised by limitations in the mechanisms that describe O₃ disinfection and disinfection by-product formation, and BAC adsorption in multi-component solutes. Drawing from the insights from the current O₃, BAC, and WRRF modelling approaches, we propose an integrated O₃-BAC model suitable for simulating dissolved organic carbon (DOC) and micropollutants removal in the O₃-BAC systems. We recommend a hybrid modelling approach in which data-driven models can be integrated to compensate for structural limitations in mechanistic models. The model is developed within the activated sludge model (ASM) framework for flexibility in coupling with other WRRF models and hence facilitates developing system-wide WRRF models for wastewater reclamation and reuse systems.

While several studies have investigated the effect of varying carbon-to-nitrogen (C/N) ratios on the ANAMMOX performance, there is still a research gap in illustrating the shift in 16S rRNA gene copy number and functional microbial population during operation. Hence, this study focuses on utilizing a reference gene and target functional genes to demonstrate the synergetic interaction between ANAMMOX, ammonia-oxidizing bacteria (AOB), and nitrite-oxidizing bacteria (NOB), using an up-flow anaerobic sludge blanket (UASB) under different C/N conditions. It was demonstrated that elevating the C/N ratio from 1.0 to 2.0 reduced the COD and NH4⁺-N removal efficiencies from 80.12 to 48.62% and from 88.99 to 72.59%, respectively. Based on the qPCR evaluation, at the C/N ratio of 1.5, the abundance of ANAMMOX, AOB, Nitrobacter, and Nitrospira was 2.52 × 10⁶, 82, 5.39 × 10³, and 12.98 × 10³ copies/μL, respectively. However, with the further increase of C/N ratio to 2.0, their abundance was reduced to 1.09 × 10⁶, 46, 0.98 × 10³, and 3.47 × 10³ copies/μL, respectively. The expression of hzo gene encoding for hydrazine dehydrogenase was 169-folds at C/N = 1 and almost inhibited at C/N = 2. The results of microbial population structure using 16S rRNA reverse transcriptase (RT)-qPCR technique depicted a competition between ANAMMOX and heterotrophic bacteria for the available substrate at higher C/N ratios.