Water Quality Safety Research Articles

Algorithm for monitoring water quality parameters in optical systems based on artificial intelligence data mining.

Due to the increasingly serious water environment pollution, the difficulty of Water Quality Monitoring (abbreviated as WQM for convenience) is also constantly increasing, which puts forward more requirements for the capabilities of various aspects of WQM systems. However, the current WQM method has drawbacks such as slow speed, long monitoring time, complex operation, poor stability, and the inability to obtain accurate information on water pollution in the first time, as well as the generation of toxic and harmful secondary pollutants after some measurement parameters are tested. To address these issues and ensure water quality safety, this paper investigated the algorithm for monitoring water quality parameters using artificial intelligence data mining optical systems. This article applied an artificial intelligence data mining system to detect water quality and designed various system through this method to improve system performance. To verify the actual effectiveness of artificial intelligence data mining systems, this article selected 10 water plants as experimental research subjects and compared the differences between traditional WQM methods and WQM methods based on artificial intelligence data mining systems in terms of WQM time, accuracy, sensitivity, and protective performance. The experimental results showed that the optical system based on artificial intelligence data mining took an average of 2.7 days in WQM and the average accuracy was 85.95%. The average sensitivity value was 84.19% and the average protective score was 8.46 points. This indicated that artificial intelligence data mining optical technology had vital significance and value for WQM.

Nano-Fe3O4/FeCO3 modified red soil-based biofilter for simultaneous removal of nitrate, phosphate and heavy metals: Optimization, microbial community and possible mechanism

The pollution of nitrogen, phosphorus and heavy metals in surface water is becoming more and more serious, affecting the safety of water quality. In this study, three biofilters were constructed using iron-modified red soil-based filler carriers (RSC, nano-Fe3O4@RSC, and FeCO3@RSC) combined with strain Zoogloea sp. ZP7 to simultaneously remove nitrate (NO3--N), phosphate (PO43--P), copper (Cu2+), and zinc (Zn2+). The long-term operation results showed that the three groups of biofilters could remove 85.0, 90.0, and 89.8% of NO3--N, respectively. Furthermore, the addition of iron compounds enhanced the removal of PO43--P and the resistance to the stress of Cu2+ and Zn2+ in the biofilter. The analysis illustrated that iron modification improved the redox activity and zeta potential of RSC surface. The secondary structure analysis of the protein showed that the microbial secreted proteins were more compact on the surface of the iron-modified RSC, which facilitated the formation of biofilm on the carrier surface. In addition, the iron-modified RSC-based biofilter also showed excellent NO3--N and PO43--P removal efficiency in the treatment of actual surface water. The microbial community analysis results showed that Zoogloea became the dominant species in the biofilter. On the other hand, the presence of iron-reducing bacteria and the expression iron cycle-related genes may contribute to denitrification under low nutrient conditions.

Novel Ternary System for Electrochemiluminescence Biosensor and Application toward Pb2+ Assay.

This study constructed an electrochemiluminescence (ECL) biosensor for ultrasensitive detection of Pb2+ in a ternary system by employing DNAzyme. The ternary system is composed of a potassium-neutralized perylene derivative (K4PTC) as the ECL emitter, K2S2O8 as the coreactant, and neodymium metal-organic frameworks (Nd-MOFs) as the coreaction accelerators. Nd-MOFs immobilize DNAzymes and enhance the luminescence intensity of the K4PTC/K2S2O8 system. As part of this system, K4PTC enhances the ECL signal in solution and supports Pb2+ detection. The sequence of ferrocene (Fc)-linked DNA (DNA-Fc) is catalytically cleaved by DNAzymes in the presence of Pb2+. This causes the removal of DNA1-Fc from the electrode surface to recover the ECL signal. As a result, the as-prepared ECL biosensor can quantify Pb2+ with a detection limit (LOD) of 4.1 fM in the range of 1 μM to 10 fM. The ECL biosensor displays high specificity, good stability, excellent reproducibility, and desirable practicality for Pb2+ detection in tap water. Moreover, by simply changing the sequence of the DNAzyme, new biosensors can be designed for ultrasensitive detection of different heavy metal ions, offering an excellent approach for monitoring water quality safety.

Pathways and enhancement strategies for magnesium hardness removal in modified induced crystallization softening

Elevated levels of total hardness in drinking water can readily result in scaling, which poses a threat to both the safety of water quality and the convenience of its use. While there is a wealth of research on the removal of calcium hardness, there is a dearth of studies focusing on the removal of magnesium hardness. In light of this, the present study employs modified induced crystallization softening (MICS) to delineate the removal pathways and mechanisms of magnesium hardness, and to investigate viable methods for its enhancement and application. Our research has determined that magnesium hardness can be effectively removed from water through the MICS, with the dosage of softening agents (NaOH) being a significant factor that influences this removal, whereas the fixed bed height within the fluidized bed exerts minimal impact on the process. In the low-dose stage (less than 250 mg/L), when the pH is below 10.0, up to 20% of magnesium hardness can be removed, predominantly through the crystallization of (Ca0.936Mg0.064)CO3. As the dosage increases to the moderate stage (250–400 mg/L), the conversion of excess bicarbonate (HCO3−) to carbonate (CO32−) in the water hinders further removal of magnesium hardness. In the high-dose stage (exceeding 400 mg/L), when the pH rises above 10.5, the removal rate of magnesium hardness can be enhanced to over 75%, with the crystallization of Mg(OH)2 being the primary removal mechanism. Density functional theory calculations, along with molecular dynamics simulations of cohesive energy and bond energy, substantiate the feasibility of the identified magnesium removal pathways. The addition of coagulants (FeCl3) and an decrease in the up-flow velocity can further augment the removal efficiency of magnesium hardness by promoting the crystallinity of Mg(OH)2 during the high-dose stage (exceeding 400 mg/L). In practical engineering applications, the strategic control of softening agent dosages enables the achievement of varying levels of magnesium hardness removal, tailored to specific water quality requirements.

Artificial Cultivation of Aquatic Plants Promotes Nitrogen Transformation and the Abundance of Key Functional Genes in Agricultural Drainage Ditch Sediments in the Yellow River Irrigation Area in China

Excess nitrogen in agricultural drainage poses a serious threat to the water quality safety of the Yellow River basin. Utilizing aquatic plants to modify the rhizosphere microbial community structure and facilitate nitrogen transformation is a crucial strategy for mitigating regional water eutrophication. We here compare key processes of nitrogen transformation occurring in the rhizosphere of sediments of a ditch artificially planted with a mix of species (Phragmites australis, Typha orientalis, Nymphaea tetragon) with the rhizosphere of a ditch occupied by naturally occurring aquatic vegetation, dominated either by P. australis or T. orientalis. Our results revealed a species effect, with an increased denitrification rate (DR) and dissimilatory nitrate reduction to ammonium rate (DNRAR) in the cultivated ditch for P. australis, compared to the naturally occurring T. orientalis vegetation. The nitrogen fixation rate (NFR) increased in the artificial setting with T. orientalis in comparison to natural P. australis vegetation. The richness of the bacterial community and the relative abundances of Bacteroidota, Firmicutes, and Geobacter were significantly greater in the rhizosphere of the artificially cultivated ditch due a greater availability in nitrogen and organic carbon. In the artificially cultivated ditch, the dominant functional genes affecting DRNARs in the rhizosphere sediments of P. australis were nrfC and nrfA, whereas DRs were driven mainly by norB and napA, which were influenced by the nitrogen and carbon levels. The dominant functional genes affecting NFRs in the rhizosphere sediments of T. orientalis were nifD, nifK, and nifH. Our results provide a scientific basis for the use of aquatic plants for mitigating excess nitrogen levels in agricultural drainage.

Recent progress in lanthanide-based fluorescent nanomaterials for tetracycline detection and removal.

Tetracycline (TC) has been widely used in clinical medicine and animal growth promotion due to its broad-spectrum antibacterial properties and affordable prices. Unfortunately, the high toxicity and difficult degradation rate of TC molecules make them easy to accumulate in the environment, which breaks the ecological balance and seriously threatens human health. Rapid and accurate detection of TC residue levels is important for ensuring water quality and food safety. Recently, fluorescence detection technology of TC residues has developed rapidly. Lanthanide nanomaterials, based on the high luminescence properties of lanthanide ions and the high matching with TC energy levels, are favored in the real-time trace detection of TC due to their advantages of high sensitivity, rapidity, and high selectivity. Therefore, they are considered potential substitutes for traditional detection methods. This review summarizes the synthesis strategy, TC response mechanism, removal mechanism, and applications in intelligent sensing. Finally, the development of lanthanide nanomaterials for TC fluorescence detection and removal is reasonably summarized and prospected. This review provides a reference for the establishment of a method for the accurate determination of TC content in complex food matrices.

Effects of storm events on nutrient characteristics in a stratified drinking water reservoir: Behavior, transmission pathways and management strategy

Storm events result in nutrient fluctuations and deterioration of reservoir water supply quality. Understanding of nutrient dynamics (e.g., concentration, composition, loads and transport pathways) and adoption of effective management strategies are critical for safeguarding water quality. A comprehensive monitoring was conducted for three storm events during the rainy season in 2023. Results showed nitrogen (N) and phosphorus (P) dynamics demonstrate a significant response to hydrological process. Rainfall resulted in the highest event mean concentrations (EMCs) of total nitrogen (TN), nitrate nitrogen (NO3−-N), ammonia nitrogen (NH4+-N), total phosphorus (TP), and particulate phosphorus (PP) in the runoff being 1.97, 2.15, 2.30, 44.17, and 62.38 times higher than those observed in baseflow. On average, NO3−-N/PP accounted for 82 %/96 % of N/P exports. Hysteresis analyses reveal that NH4+-N and PP were mainly transported by surface runoff from over-land sources, whereas TN and NO3−-N were primarily delivered by subsurface runoff. Additionally, nutrient concentrations were significantly higher in the intrusive layer in reservoir compared to the pre-storm period, which gradually decreased from the tail to the head as particulate sedimentation and water column mixing occurred. Water-lifting-aerators (WLAs) were employed to alter the reservoir thermal stratification regime via artificial mixing to affect the intrusive layer of storm runoff. Comparison of the intrusive layer for three storms reveals that WLAs triggers the storm runoff to form an underflow via increasing the reservoir bottom water temperature above that the runoff, ensuring that water quality at the intake position remains unaffected by inflows. These findings serve as a reference for the response of reservoir eutrophication levels to storm events and present practical engineering experience for enhancing water quality safety during the rainy season.

Physicochemical behavior and impact of CO2 and CH4 plumes during gas-rich water leakage in a shallow carbonate freshwater aquifer

Carbon capture and storage (CCS) is a promising technology for reducing CO2 emissions. Significant concerns have emerged about the potential leakage of CO2 into shallow aquifers, highlighting the risk to water quality and environmental safety. This underscores the importance of finding monitoring tools suitable for different geological scenarios. If leakage occurs in the context of depleted reservoirs being used for CO2 storage, residual CH4 from the storage complex will likely be entrained together with CO2. However, few studies have addressed the implications of CH4 presence and its potential as a monitoring parameter during CO2 leakage.To address this gap, we simulated a leakage event by injecting water enriched with CO2 and CH4 into a shallow limestone aquifer. The impact of the injection was monitored using a combination of laboratory measurements on water samples and in-situ sensors located downstream from the injection well.All parameters were affected by the simulated leakage. Some monitoring tools allowed us to differentiate the leakage event from natural variations. A key finding of this study was that at 7 m from the injection well, the CH4 breakthrough occurred roughly one day before the CO2 breakthrough, highlighting the potential of CH4 as an early indicator of CO2 leakage and suggesting interesting prospectives for industrial-scale sites. However, further research is needed to confirm the potential of CH4 as a CO2 leakage indicator at industrial scales, due to potential methane oxidation and loss of the signal with longer times and distances.This study contributes to a better understanding of the potential risks and effective monitoring strategies associated with CO2-CH4 leakage in carbonate aquifers.

Detection to water quality for Yangtze River using a machine learning method

<p>The Yangtze River, the longest river in China and one of the most important water resources in the world, has been facing significant challenges regarding water pollution in recent years. The issue of water quality safety is related to the national economy and people's livelihood. Water pollution incidents not only damage the local water environment, but also seriously affect the drinking water safety of residents. Traditional chemical methods and other water quality anomaly detection methods are often time-consuming and may cause secondary pollution. This paper proposed a machine learning method used for detecting abnormalities of water quality in the Yangtze River, to provide technical support for ensuring water quality safety. The principle is that using the designed support vector machine separates anomalies and normal values, by doing so, anomalies can be mined. Since there are certain differences between the density of normal data and that of anomalous data, estimating the data density of both can assist promote the ability of the support vector machine to mine anomalies. Then, the probability of water quality anomalies is determined by analyzing the characteristics such as the density of outliers in the sequence. Finally, using the collected the data of water quality from forty different regions of the Yangtze River since 2018 to 2023 as the experimental dataset, and experimental results show that the proposed method can effectively detect the anomaly of water quality of Yangtze River.</p>

Full-length 16S rRNA gene sequencing reveals the operating mode and chlorination-aggravated SWRO biofouling at a nuclear power plant.

Reverse osmosis (RO) membrane fouling and biological contamination problems faced by seawater desalination systems are microbiologically related. We used full-length 16S rRNA gene sequencing to assess the bacterial community structure and chlorine-resistant bacteria (CRB) associated with biofilm growth in different treatment processes under the winter mode of a chlorinated seawater desalination system in China. At the outset of the winter mode, certain CRB, such as Acinetobacter, Pseudomonas, and Bacillus held sway over the bacterial community structure, playing a pivotal role in biofouling. At the mode's end, Deinococcus and Paracoccus predominated, with Pseudomonas and Roseovarius following suit, while certain CRB genera still maintained their dominance. RO and chlorination are pivotal factors in shaping the bacterial community structure and diversity, and increases in total heterotrophic bacterial counts and community diversity in safety filters may adversely affect the effectiveness of subsequent RO systems. Besides, the bacterial diversity and culturable biomass in the water produced by the RO system remain high, and some conditionally pathogenic CRBs pose a certain microbial risk as a source of drinking water. Targeted removal of these CRBs will be an important area of research for advancing control over membrane clogging and ensuring water quality safety in the future.

Ratiometric fluorescence detection of tetracycline in milk and tap water with smartphone assistance for visual pH sensing using innovative dual-emissive phosphorus-doped carbon dots

Tetracycline (TC) is a common antibiotic that poses risks to human and animal health when present in samples. pH is a crucial parameter for assessing water quality and food safety. The innovative ratiometric probe, designed based on dual-emissive phosphorus-doped carbon dots (DE-P-CDs), was synthesized through a green hydrothermal process. The sensor exhibited high analytical performance toward TC detection with a LOD of 5.78 μM and 6.18 μM, respectively, and visual pH detection. Furthermore, the DE-P-CDs were employed for visual pH sensing, with the solution color smoothly changing with variations in pH. The color transitioned from red to orange, green to dark green, and blue to dark blue, facilitating easy visual observation. This probe proves to be a versatile tool for detecting TC in milk and tap water samples, with visual capabilities for pH. Two metric tools which were AGREE and BAGI were also used to evaluate the method's greenness. The evaluation affirmed its outstanding environmental friendliness. It represents a valuable contribution to the fields of analytical chemistry, food, and environmental monitoring.

Study on water quality safety and microbial diversity of water source reservoirs in Daqing City

Water source reservoirs play a vital role in ensuring the drinking water safety. To explore the safety of water quality as the source of water supply projects in Daqing City, the chemical indexes of water quality in Daqing reservoir, Dongcheng reservoir and Hongqi reservoir were analyzed. The microbial diversity, community structure characteristics and Nitrogen metabolism functional bacteria were analyzed by high-throughput sequencing technology. Monitor the disinfection effect of three water source reservoirs after using sodium hypochlor disinfection. The results showed that, in 2021, the reservoirs water body was in a moderately eutrophic state, the main exceeding standard index was total nitrogen (TN) (1.25–1.57 mg/L). The microbial communities in water body and sediments were composed of 1048 genera. The microbial diversity in sediment was higher than that in water. Potential pathogenic microorganisms were detected in water and sediment samples. Although no coliform bacteria were detected, as a water source disinfection was also necessary. Redundancy analysis (RDA) showed that, the main water quality factors affecting microbial community structure in water samples were pH, in sediment samples were water temperature (WT), dissolved oxygen (DO), TN and total phosphorus (TP). Sodium hypochlorite has a good disinfection effect and can ensure the safety of drinking water.

Adsorption of Cr(VI) and Cr(III) on layered pipe scales and the effects of disinfectants in drinking water distribution systems

Pipe scales in drinking water distribution systems (DWDS) potentially adsorb chromium (Cr). Meanwhile, the fate of Cr in pipe scales and water could be influenced by the disinfectants used in DWDS since they might influence the valence state of Cr. Therefore, the adsorption of Cr (Cr(VI) and Cr(III)) on pipe scales, the transformation between different valence states, and the effects of disinfectants present in DWDS are important research topics for improving tap water quality but have not yet been sufficiently investigated. This study investigated the properties of layered pipe scales and conducted adsorption kinetic experiments in single and binary Cr(VI) and Cr(III) systems, as well as experiments related to the oxidation and adsorption of Cr(III) under the influence of decaying disinfectants. According to the results, pipe scales exhibited distinct layered structures with varying mechanisms for the adsorption of Cr(VI) and Cr(III). Cr(VI) was adsorbed through surface complexation on the surface and porous core layers, while redox reactions predominantly occurred on the shell-like layer. Furthermore, Cr(III) was adsorbed via surface precipitation on the three-layer pipe scales. Importantly, disinfectants promoted the transformation of Cr(III) to the less readily released Cr(VI) in pipe scales, reducing the Cr exposure risk from the pipe scale phase. Pipe scales also decreased the Cr(VI) concentration in water (almost 0 mg/L), enhancing the safety of DWDS. This study provides theoretical guidance on the safe operation of DWDS.

Spatial characteristics of surface-deposited diatoms in Weishan Lake and their relationship with the water environment (Shandong Province, China)

The Weishan Lake serves as a crucial reservoir and regulating lake in the Eastern Route of the South-to-North Water Diversion Project and the ecological health of its lake ecosystem directly impacts the water quality for water diversion. Diatoms are particularly sensitive to changes in water environments, and the composition of diatom communities serves as a significant indicator of the health of aquatic ecosystems. To understand the composition of diatom communities in Weishan Lake and their relationship with environmental factors, thereby providing scientific grounds for the protection of the lake’s ecological environment, surface sediment diatoms, water samples, and sediments were collected and analyzed. The study revealed that there are 64 species from 19 genera of diatoms in Weishan Lake, predominantly comprising epiphytic and planktonic species. Dominant species include Fragilaria brevistriata, Achnanthes minutissima, and Stephanodiscus parvus, indicating an overall meso-eutrophic status. According to the diatom composition and biodiversity index, the diatom community was divided into three combination zones. Redundancy analysis (RDA) results indicated that the water environmental factors influencing the composition and distribution of diatom communities in Weishan Lake are TP, TOC, DO, NO2 −–N, and Ca2+, collectively explaining 35.60% of the variation in diatom community composition. Due to the influence of agricultural and industrial wastewater runoff, domestic sewage discharge, and cage aquaculture, Weishan Lake is in a mesotrophic eutrophication state. Therefore, it is recommended that strict control over inappropriate human activities in the lake area be implemented in the future to ensure the safety of water quality for water diversion.

Ultraviolet technology application in urban water supply and wastewater treatment in China: Issues, challenges and future directions

This study thoroughly explores the application of Ultraviolet (UV) water treatment technology in urban wastewater treatment and water supply in China, highlighting its crucial role in enhancing water quality safety. UV technology, with its environmentally friendly and low-carbon characteristics, is deemed more in line with the demands of sustainable development compared to traditional chemical disinfection methods. The widespread application of UV technology in urban wastewater treatment in China, particularly in the context of urban sewage treatment, is examined. However, to better promote and apply UV technology, there is a need to deepen the understanding of this technology and its application among a broad base of users and design units. The importance of gaining in-depth knowledge about the performance of UV water treatment equipment, the design calculation basis, and operational considerations, as well as the ongoing development of relevant standards, is underscored to ensure that the equipment used in projects complies with engineering design and production requirements. Furthermore, the positive trend of UV technology in the field of advanced oxidation, indicating a promising trajectory for engineering applications, is pointed out. Regarding the prospects of industrial development, a thorough analysis is conducted in the article, emphasizing the necessity for all stakeholders to collaborate and adopt a multi-level approach to promote the sustainable development and application of UV water treatment technology. This collaborative effort is crucial for providing effective safeguards for China's environment, ecology, and human health.

Study on the Impact of Land Use Change on Ecosystem Services in the Water Source Area of the Middle Route Project of S-N Water Diversion

The South-to-North Water Diversion Project, a major project in China, is of great significance to alleviate the shortage of water resources in the north, and the ecological environment in the middle water source area has the most critical impact on water quality safety. As a natural resource and asset, ecosystem services in the water source area of the Middle Route of the South-to-North Water Diversion Project not only provide important resources and services for human beings but also are the necessary basis for the survival and development of other organisms on the earth.As an integral part of the earth’s economy, the value of ecosystem services in the water source area of the Middle Route of the South-to-North Water Diversion Project directly or indirectly contributes to human welfare. Scientific use of land resources can promote the upgrading and transformation of ecosystem services in the water source area of the Middle Route of the South-to-North Water Diversion Project. Based on this, this paper focuses on the impact of land use change on ecosystem services in the water source area of the middle route of South-to-North Water Diversion and its prevention strategies.

Sediment microbial fuel cell monitoring repeated Cr(VI) shocks in different wetlands for a year: Performance and mechanism

Cr(VI) is a major heavy metal contaminant that poses great threats to aquatic ecosystems and human health. To guarantee the safety of water quality, the development of in-situ and online sensors for monitoring Cr(VI) contamination events is crucial. In this work, sediment microbial fuel cell (SMFC) based sensors using floating cathode as sensing element were operated in outdoor environment for one year to monitor repeated Cr(VI) shocks in wetlands constructed with coastal alkaline soil (YC), paddy of acidic soil (YT), and paddy of neutral soil (NJ). K2CrO4 solutions were added to the cathode four times in January, March, June, and September, respectively. Results showed that each Cr(VI) addition triggered a voltage peak and the voltage increments were linearly correlated with Cr(VI) concentrations within the range of 5–120 mg L−1 Cr(VI). The highest sensitivity was observed for YC (1.2 mV L mg−1) and YT (1.4 mV L mg−1) in June and for NJ (1.2 mV L mg−1) in September. XPS analysis demonstrated the reduction reaction of Cr(VI) to Cr(III) on the cathode might contribute to the generation of voltage peaks. Despite repeated shocks, Cr(VI) was immobilized in the soil and completely reduced to low-toxic Cr(III) with the consumption of soil organic matter, and the diversity and abundance of exoelectrogenic bacteria-associated genera were not inhibited. As a result, stable operation of the SMFC sensors was ensured. The SMFC sensors exhibited great potential for in-situ and online monitoring of Cr(VI) contamination events across various wetlands.

Influences of Heavy Metals in Water Treatment Chemicals on Drinking Water Quality and Risk Management

Water treatment chemicals (WTCs) are important raw materials during the drinking water production process. Occasionally unqualified WTCs with heavy metals were provided to Water Treatment Plant（WTP） by supplier during emergency situation，such as earthquake, typhoon and city block for epidemic disease, just because it cannot obtain the qualified WTCs. The harmful heavy metals in WTCs may expose a certain health risk to the quality of drinking water. In this paper, the influence of heavy metals in WTCs on the quality of drinking water was explored and the feasible management measures are proposed, taking the ILha Verda Water Plant (IVP) in Macao as an example. The study was based on the testing results of heavy metals in WTCs and treated water from 2017 to 2022 in IVP. A series of mathematical models were established to evaluate the content of heavy metals in water brought by WTCs. The removal rates of the water treatment process to the heavy metals were calculated at same time. The maximum allowable concentrations of heavy metals in WTCs were calculated and accessed. The results show that the drinking water is safety if the heavy metals in unqualified WTCs are under the maximum allowable concentrations. Then it is proposed for the classification of WTCs and risk management. The study will provide theoretical and technical support for water quality safety supervision and water supply management.

The Water Hygiene of Street Food Vendors in Southeast Asia: A Review

The safety of street food vendors in Southeast Asian countries is of concern as many do not follow basic food safety principles. The water used to wash cutlery that is not hygienic may cause foodborne illnesses. Therefore, the general aim of this study was to summarize the water hygiene of street vendors in Southeast Asia. PRISMA guidelines were used to find suitable sources for this systematic review. Relevant studies are retrieved from several databases, such as Science Direct, PubMed, SAGE, EBSCOhost, Taylor and Francis, and Scopus. The keywords used to identify the relevant studies were water, water quality, hygiene, sanitation, street vendor, and food safety. The initial search in the databases yielded 80 articles. After the screening process based on the criteria of the article, only 9 articles were used in the final systematic review. The results showed that the water hygiene system in street vendors in Southeast Asia is still relatively unhygienic because most still use bucket water (non-tap water), which can contaminate food and lead to foodborne illness.

Preparation of PEI/La2O3/Polypropylene fiber filter for household water purifiers and investigation of its phosphate reduction and bacterial control

It has been accepted that limiting phosphate is a prerequisite for bacterial inactivation in tap water. La2O3 nanoparticles were loaded onto polypropylene (PP) fibers through the method of melt spinning. Hydrophilic modification of the adsorbent surface was performed using polyethyleneimine (PEI) to prepare PEI/La2O3/PP. The results indicated that the optimal loading amount of La2O3 was 1 %, and the optimal concentration of PEI was 1 %. The successful loading of La2O3 resulted in a roughened fiber surface and increased fiber diameters. After PEI modification the water contact angle was reduced from 98° to 50°. The pHzpc of PEI/La2O3/PP was determined to be 8.3. The co-existing ions have little effect on phosphate adsorption. Phosphate adsorption can be well described by Redlich-Peterson model with a maximum KR-P of 3.98 × 10−5 L/mg. Adsorption kinetics fit well with the pseudo-second-order reaction equation. The activation energy (Ea) is determined to be 57.9 kJ/mol, providing the evidence of chemical nature of the reaction involving phosphate ions on the surface of PEI/La2O3/PP. The PEI/La2O3/PP adsorbent can reduce the phosphate concentration in tap water to below 0.01 mg/L, leading to a reduction in Escherichia coli concentration from approximately 10,000 CFU/mL to around 10 CFU/mL. The survival rates of Escherichia coli in a multi-nutrient environment are higher than in a single phosphate source environment. Our research provides a new feasible approach for ensuring microbial water quality safety in household water purifiers.