Organic Matter Pollution Research Articles

Algal organic matter triggers re-assembly of bacterial community in plumbing system

Algal bloom outbreaks in upstream drinking water reservoirs inevitably lead to algal organic matter (AOM) pollution in downstream drinking water plants and distribution systems. However, the responses of indoor piped drinking water quality and microbial community to AOM remain to be well studied. In this study, we investigated the effects of low and high concentrations of Chlorella organic matters on pipe-based drinking water. We found that AOM introduced nitrogen and phosphorus contamination into drinking water and promoted massive regeneration of bacteria during stagnation, along with increased bacterial metabolic activity. Compared to the Control group, the utilization capacity of alcohols, acids, esters, and amino acids increased under the influence of AOM. In addition, AOM intrusion reduced the bacterial community diversity in drinking water. The bacterial communities became more saturated, interspecific relationships became more complex, and interspecific competition increased. Bacteria with the ability to denitrification, such as Pseudomonas putida, Sphingobium amiense, Delftia tsuruhatensis, and Acidovorax temperans, were the most abundant. Residual chlorine, ammonium, nitrite, and iron had notable effects on the bacterial community under the influence of AOM. The results help elucidate the response mechanism of microbial community to AOM contamination in indoor drinking water pipes and provide a scientific basis for drinking water safety risk management.

Trace metals and Mo isotopic fractionation in Skagerrak sediments–effects of different oxygen conditions

The Skagerrak is the main depot center for organic matter and anthropogenic pollutants from the entire North Sea. Changes in ocean circulation or suspended matter supply might impact the sediment redox conditions. Indeed, little is known about the response of Skagerrak sediment and associated pollutants to different oxygen levels. We investigated sediments from three stations within the Skagerrak and incubated them for up to twelve months under aerobic and anaerobic conditions. Furthermore, we present the first δ98/95Mo data for Skagerrak sediment profiles and the incubations to be utilized as a redox tracer. The sediment profiles of metals reflected anthropogenic pollution (Cu, Ni, Pb) but differed regionally with redox conditions. We differentiated redox conditions mainly by sediment and porewater Fe, Mn, Mo and δ98/95Mo. In aerobic incubations, no Mn or Fe reduction was detected, while under anaerobic conditions, initial Mn and Fe reduction decreased after approximately three months. Under anaerobic conditions, a strong isotopic fractionation of Mo in the dissolved phase was found, reaching up to 5.03 ± 0.10‰, probably caused by incomplete thiolation of molybdate under low hydrogen sulfide levels. During the incubations, Cd, Cu, Ni, Pb were mobilized. While Cu and Cd were mobilized under aerobic conditions, Ni and Pb mobilization depended mainly on remineralization and redox conditions. Our results show that changes in oxygen conditions in the Skagerrak can have significant effects on the (legacy) metals stored in the sediment over the past decades.Graphical

Online monitoring of water quality in industrial wastewater treatment process based on near-infrared spectroscopy.

Water quality monitoring is one of the critical aspects of industrial wastewater treatment, which is important for checking the treatment effect, optimizing the treatment technology and ensuring that the water quality meets the standard. Chemical oxygen demand (COD) is a key indicator for monitoring water quality, which reflects the degree of organic matter pollution in water bodies. However, the current methods for determining COD values have drawbacks such as slow speed and complicated operation, which hardly meet the demand of online monitoring. This article firstly proposed a novel quantitative analysis method based on NIR spectroscopy and multi-preprocessing stacking, successfully enabling real-time online monitoring of COD values during industrial wastewater treatment. First, the existing swarm intelligence algorithm was enhanced to optimize the hyperparameters of various base models. Next, multiple spectral preprocessing techniques were innovatively combined with a stacking strategy to construct multi-preprocessing stacking models, enabling comprehensive extraction of effective spectral information. Finally, various combinations of base models were evaluated, leading to the selection of the multi-preprocessing stacking model with optimal performance. The results indicate that the model achieves excellent predictive performance and strong generalization ability. For equalization tank samples, the R2 and RMSE values were 0.8640 and 326.6845 mg/L, respectively. For secondary settling tank samples, the R2 and RMSE values were 0.8798 and 15.1917 mg/L, respectively. Compared to traditional single and stacking models, the RMSE was reduced by at least 12.75 % and 5.11 %, respectively. In addition, the method has a relatively low modeling cost and offers interpretability. This study presents an efficient and straightforward solution for the online monitoring of COD values in industrial wastewater treatment, laying a solid technical foundation for the efficient management of industrial wastewater and the protection of water resources and the ecological environment.

Electrospun PMMA fiber biofilm for the removal of COD and NH3–N in wastewater

Organic matter and ammonia-nitrogen pollution are the research focuses of sewage purification. PMMA fiber biofilm carriers were prepared using the electrospinning technique and compared with nonwoven fiber biofilm carriers in purification experiments. The two biofilm carriers are bacteria-cultured for several days, and the chemical oxygen demand (COD) and ammonia nitrogen (NH3–N) of the sewage are tested and analyzed. The results showed that after four days of purification, the COD concentration removal rate of the non-woven fiber biofilm group reached 77.89%, and the COD removal rate of the PMMA fiber biofilm group reached 82.70%. After six days of purification, the NH3–N concentration in the non-woven fiber biofilm group did not decrease but increased, from the original 7.64 to 8.74 mg/l, with an increase rate of 13.87%. The NH3–N concentration in the PMMA fiber biofilm group decreased from the original 7.62 to 6.22 mg/l, with a removal rate of 13.87%. It can be seen that the PMMA fiber biofilm carrier has more advantages in the reduction of COD and NH3–N in organic wastewater.

Biological importance and environmental quality of the Laguna Santa Ana in Zacatecas, Mexico

Objective: To determine the environmental quality and diversity of the waterfowl species of the Laguna Santa Ana, located in the municipality of Fresnillo, Zacatecas. Design/Methodology/Approach: A physicochemical analysis of the water was carried out to determine its organic matter pollution. In addition, the Bradford method was applied to establish protein levels, and an optical emission spectrometry was conducted to detect heavy metals. The Shannon-Weiner diversity index (H’) was carried out to identify and count the populations of the lagoon. Results: The physicochemical analysis of water recorded 55 and 230.6 mg/L BOD5 and COD, respectively. High protein levels (0.27-2.95 mL/mL) indicated organic pollution and high arsenic levels. The Shannon-Weiner index (2.7) recorded a high waterfowl diversity. Study Limitations/Implications: Biological abundance was not determined, as a result of the sample size. The changes regarding waterfowl diversity may be the consequence of the seasonal conditions. Findings/Conclusions: The Laguna de Santa Ana has a high waterfowl diversity, including species of international interest; however, organic pollution has caused a a significant environmental deterioration.

Analysis of Water Quality of Le'an River in Poyang Lake Basin Based on CCME-WQI Method

As the largest freshwater lake in China, Poyang Lake plays a key role in supporting the balance of aquatic ecosystems, and the water quality of its inlet rivers affects the lake's water quality. Le'an River, a typical inlet river of Poyang Lake, was selected as the research object. Based on the water quality data of six monitoring points in the upper, middle, and lower reaches of the mainstream of Le'an River from 2012 to 2020, the CCME-WQI method was used to evaluate the water quality of the river after systematically analyzing the spatiotemporal variation of the concentration of pollutants in the mainstream of the river. Finally, the main influencing factors of the water quality of the river were extracted and analyzed according to the PCA method. The results showed that： ① The water volume upstream and downstream of the river was more seriously polluted in the pre-study time period, which was due to the presence of Dexing Copper Mine in the upstream and small and medium-sized mines and farmland downstream. ② Before 2017, the water volume downstream of Le'an River had the worst water quality, with TP and NH4+-N exceeding the standard rate of 43.3% and 85.0%, respectively, and the lowest WQI mean value of 86.2. After 2017, due to the effective management of pollutant discharges in the watershed, the water volume downstream of the river improved significantly and continued to be in an excellent state, and the mean value of the WQI reached 100.0. ③ The factors influencing the water quality of the mainstem of the Le'an River could be divided into four categories： human activities, seasonal factors, atmospheric deposition of pollutants, and the physical and chemical properties of the water volume itself, with human activities being the dominant factor for water quality changes at Dawuhekou and Shizhenjie, whereas the seasonal factors had the greatest influence at the remaining locations. ④ Organic matter pollution was obvious in the upper and lower Le'an River water volume, and the water volume at Dawuhekou was mainly affected by nearby mining activities, whereas the water volume at Shizhenjie was mainly affected by agriculture. Le'an River had serious organic matter pollution downstream before 2017, and mining and agricultural activities in the watershed had a high degree of impact on water quality. The treatment of mineral processing wastewater should be upgraded, and the discharge of pollutants from agriculture in the downstream of the watershed should be regulated.

Comparing the environmental impacts of pollution from two types of industrial zones on the coast

IntroductionThe construction of coastal industrial zones has significantly impacted the marine environment, with the extent of these effects varying based on the type of industrial activity. This study compares the environmental impact of two prevalent types of industrial zones along South Korea’s coast: ironworks and shipyards.MethodsWe assessed heavy metal pollution near these industrial zones using the Pollution Load Index (PLI) and Nemerow Pollution Index (Pn). To evaluate the impact of heavy metals and organic matter on macrobenthic communities, we employed redundancy analysis (RDA) and Spearman correlation analysis. Additionally, we used the AZTI’s Marine Biotic Index (AMBI), Multivariate AMBI (M-AMBI), and Benthic Pollution Index (BPI) to gauge the ecological quality of the affected marine environments.Results and discussionOur findings indicated that the biodiversity and abundance of species near shipyards were significantly lower than those near ironworks. Results of PLI and Pn revealed that the ecological risk posed by heavy metals from shipyard activities was significantly higher than from ironworks. The AZTI’s Marine Biotic Index (AMBI), Multivariate AMBI (M-AMBI), and Benthic Pollution Index (BPI) demonstrated that the ecological quality of Asan Bay (ironworks) is better than that of Dangdong Bay (shipyard). RDA analysis identified Lumbrineris longifolia, Ancistrosyllis hanaokai, and Theora fragilis as biological indicators for assessing heavy metal and organic matter pollution. Spearman correlation analysis indicated that BPI and species richness index are effective indicators for evaluating such pollution. Overall, the negative impact of shipyards on the marine environment was significantly more significant than that of ironworks. Our study provides valuable insights for the South Korean government in managing coastal industrial zones and formulating relevant policies.

Analysis of dissolved organic matter characteristics in pharmaceutical wastewater via spectroscopy combined with Fourier-transform ion cyclotron resonance mass spectrometry

Studying the changes in organic matter and characteristic pollutants during the treatment of penicillin-containing pharmaceutical wastewater, which can be reflected by changes in dissolved organic matter (DOM), is crucial for improving the effectiveness of wastewater treatment units and systems. Herein, water quality indicators, spectroscopic methods, and Fourier-transform ion cyclotron resonance mass spectrometry were utilized to characterize the general molecular compositions and specific molecular changes in DOM during the treatment of typical penicillin-containing pharmaceutical wastewater, including in each of the influent, physicochemical treatment, biological treatment, oxidation treatment, and effluent stages. The influent exhibited a high organic matter content (concentration of dissolved organic carbon >10,000 mg·L−1), its DOM mainly contained protein- and lignin-like substances composed of CHON and CHONS molecules, and the relative intensity (RI) of penicillin was extremely high (RI = 0.220). Compared with the influent, the abundance of CHON and CHONS molecules detected after physicochemical treatment decreased by 70.3 % and 62.5 %, respectively, and the RI of penicillin decreased by 85.5 %. Biological treatment caused substantial changes in DOM components through oxidation, dealkylation, and denitrification reactions, accounting for 36.8 %, 28.9 %, and 14.8 % of the total identified reactions, respectively. Additionally, lignin-like substances were generated in large quantities, the overall humification level significantly increased, and the RI value increased for the penicillin intermediate, 6-aminopenicillanic acid (6-APA). Oxidation treatment effectively removed phosphorus-containing substances and some lignin-like substances produced by biological treatment; however, it was not effective in removing characteristic pollutants such as 6-APA. Such characteristic substances continued to be present in the effluent, and the DOM mainly contained protein- and humus-like substances, accounting for 30.8 % and 47.3 %, respectively. The study findings reveal the changes in organic matter and characteristic pollutants during the treatment of penicillin-containing wastewater from the perspective of the general molecular composition and specific molecular changes in DOM, providing support for further exploration of wastewater treatment mechanisms and improvements in treatment unit efficiency.

Source apportionment of organic carbon and nitrogen in sediments from river and lake in the highly urbanized Changjiang Delta

While the impact of human activities on organic matter pollution is recognized, how these impacts vary seasonally in the Changjiang Delta needs further investigation. This study addresses this gap by investigating seasonal variations in organic matter sources and ecological responses to human activities in Changjiang Delta sediments. Total organic carbon (TOC), total nitrogen (TN), and carbon (δ13C) and nitrogen (δ15N) isotopic compositions of surface sediments collected from the Taipu River and Dalian Lake wetland were analyzed. Both water bodies exhibited similar seasonal trends for TOC and TN, with the Taipu River containing an average of 0.46% and 0.03% higher concentrations of TOC and TN, respectively, compared to Dalian Lake. Additionally, the organic index (OI) and organic nitrogen (ON) index were elevated in both water bodies during the wet season. Sediments from Dalian Lake remained uncontaminated to moderately contaminated, while those from the Taipu River were generally classified as moderately to heavily contaminated. Stable isotope analysis identified terrestrial C3 plants (averaging 25.5%), C4 plants (averaging 16.0%), and municipal wastewater (averaging 16.0%) as the main contributors to organic matter in the sediments. These findings suggest that terrestrial plant material and municipal wastewater are key targets for managing organic matter contamination in the Changjiang Delta. Implementing strategic land-use planning and targeted interventions to minimize these inputs can significantly improve water quality and ecosystem health.

Comprehensive analysis of classroom microclimate in context to health-related national and international indoor air quality standards.

Indoor air quality (IAQ) and indoor air pollution are critical issues impacting urban environments, significantly affecting the quality of life. Nowadays, poor IAQ is linked to respiratory and cardiovascular diseases, allergic reactions, and cognitive impairments, particularly in settings like classrooms. Thus, this study investigates the impact of indoor environmental quality on student health in a university classroom over a year, using various sensors to measure 19 environmental parameters, including temperature, relative humidity, CO2, CO, volatile organic compounds (VOCs), particulate matter (PM), and other pollutants. Thus, the aim of the study is to analyze the implications of the indoor microclimate for the health of individuals working in the classroom, as well as its implications for educational outcomes. The data revealed frequent exceedances of international standards for formaldehyde (HCHO), VOC, PM2.5, NO, and NO2. HCHO and VOCs levels, often originating from building materials and classroom activities, were notably high. PM2.5 levels exceeded both annual and daily standards, while NO and NO2 levels, possibly influenced by inadequate ventilation, also surpassed recommended limits. Even though there were numerous exceedances of current international standards, the indoor microclimate quality index (IMQI) score indicated a generally good indoor environment, remaining mostly between 0 and 50 for this indicator. Additionally, analyses indicate a high probability that some indicators will exceed the current standards, and their values are expected to trend upwards in the future. The study highlighted the need for better ventilation and pollutant control in classrooms to ensure a healthy learning environment. Frequent exceedances of pollutant standards can suggest a significant impact on student health and academic performance. Thus, the present study underscored the importance of continuous monitoring and proactive measures to maintain optimal indoor air quality.

Reactions between ferric oxyhydroxide mineral coatings and a dimethoxyhydroquinone: A source of hydroxyl radicals

Quinones are organic molecules that facilitate electron-transfer reactions in terrestrial environments. The reduced forms, hydroquinones, are powerful reductants that can trigger non-enzymatic radical-based decomposition of organic matter and contaminants by simultaneous reduction of iron and oxygen. Iron oxides often occur as coatings on other minerals, thus our study investigated the reactions between the ferric oxyhydroxide (FeO(OH)) surface coatings on gibbsite (Al(OH)3) and 2,6-dimethoxy-1,4-hydroquinone (2,6-DMHQ). The main aim was to investigate the oxidation of 2,6-DMHQ and the generation ∙OH in the presence of O2 at low Fe concentrations in a novel setup that allows local structural characterization. The heterogeneous redox reactions between 2,6-DMHQ and the FeO(OH) coatings were studied at pH 5.0 as a function of the amount of Fe present on the gibbsite surfaces, including the effect of aging of the FeO(OH) coatings. The results showed that reactions between 2,6-DMHQ and FeO(OH) coated gibbsite under ambient conditions can generate substantial amounts of ·OH, comparable with amounts generated on pure ferrihydrite surfaces. The ·OH is the product of two sequential reactions: hydroquinone oxidation by O2 and degradation of the formed H2O2. The calculated rate constant of the former reaction is the same regardless of amount of FeO(OH) coating suggesting a surface catalytic process where 2,6-DMHQ is oxidized by O2 resulting in formation of H2O2. Subsequently, the observed induction period, the low Fe2+ (aq) concentrations in solution and the dependency of FeO(OH) coating amount influencing ·OH formation suggest that the pathway for ∙OH is through H2O2 decomposition by the surface sites on the FeO(OH) coating. Overall, this study shows that co-existence of oxygen, FeO(OH) and organic reductants, possibly secreted by soil microorganisms, creates favorable conditions for generation of ·OH contributing to decomposition of organic matter and organic pollutants in soil environments.

Novel strategy for efficient energy recovery and pollutant control from sewage sludge and food waste treatment

Considering the high organic matter contents and pollutants in sewage sludge (SS) and food waste (FW), seeking green and effective technology for energy recovery and pollutant control is a big challenge. In this study, we proposed a integrated technology combing SS mass separation by hydrothermal pretreatment, methane production from co-digestion of hydrothermally treated sewage sludge (HSS) centrate and FW, and biochar production from co-pyrolysis of HSS cake and digestate with heavy metal immobilization for synergistic utilization of SS and FW. The results showed that the co-digestion of HSS centrate with FW reduced the NH4+-N concentration and promoted volatile fatty acids conversion, leading to a more robust anaerobic system for better methane generation. Among the co-pyrolysis of HSS cake and digestate, digestate addition improved biochar quality with heavy metals immobilization and toxicity reduction. Following the lab-scale investigation, the pilot-scale verification was successfully performed (except the co-digestion process). The mass and energy balance revealed that the produced methane could supply the whole energy consumption of the integrated system with 26.2 t biochar generation for treating 300 t SS and 120 t FW. This study presents a new strategy and technology validation for synergistic treatment of SS and FW with resource recovery and pollutants control.

Sustainability of global small-scale constructed wetlands for multiple pollutant control

The global wastewater surge demands constructed wetlands (CWs) to achieve the UN’s Sustainable Development Goals (SDG); yet the pollutant removal interactions and global sustainability of small CWs are unclear. This study synthesizes small CW data from 364 sites worldwide. The removal efficiency of organic matter and nutrient pollutants of small CWs had a 75th percentile of 68.8–84.0%. Bivariate analysis found consistent synergies between pollutant removals, lasting 3–12 years. The optimal thresholds for maintaining the synergistic effects were as follows: area size—17587 m2, hydraulic loading rate—0.45 m/d, hydraulic retention time—8.2 days, and temperature—20.2 °C. When considering the co-benefits and sustainability of small CWs for multi-pollutants control, promoting small-scale CWs could be an effective and sustainable solution for managing diverse wastewater pollutants while simultaneously minimizing land requirements. This solution holds the potential to address the challenges posed by global water scarcity resulting from wastewater discharge and water pollution.

Molecular biological mechanism of fillers with surface micro-electric field to enhance biodegradation of kitchen-oil wastewater

The kitchen-oil wastewater is characterized by a high concentration of organic matter, complex composition and refractory pollutants, which make wastewater treatment more difficult. Based on the study of using micro-electric field characteristic catalyst HCLL-S8-M to enhance the electron transfer between microorganisms in kitchen-oil wastewater which further improved the COD removal rate, we focus on the microbial community, intracellular metabolism and extracellular respiration, and make an in-depth analysis of the molecular biological mechanisms to microbial treatment in wastewater. It is found that electroactive microorganisms are enriched on the material surface, and the expression levels of cytochrome c and riboflavin genes related to electron transfer are up-regulated, confirming that the surface micro-electric field structure could enhance the electron transfer between microbial species and improve the efficiency of wastewater degradation. This study provides a new idea for the treatment of refractory organic wastewater.

Macroinvertebrate Diversity as Bioindicator of Water Quality in Anggoeya River, Kendari City

Anthropogenic activities will affect the quality of river water and the living things in it, including macroinvertebrates. Anggoeya River is one of the rivers that water source is used as raw water for PDAM Kendari, so its quality needs to be considered. The purpose of this study was to analyze the water quality of Anggoeya River using macroinvertebrate bioindicators and the relationship between macroinvertebrates and physicochemical parameters of water and substrate of Anggoeya River. Physico-chemical parameters consist of temperature, current velocity, TSS, turbidity, pH, COD, BOD, DO, substrate pH, and substrate type. The sampling technique used purposive sampling, where macroinvertebrate sampling was carried out at three points at each station three times repetitions, namely on the left, middle, and right sides of the river, based on the type of river habitat, namely pool, riffle, and rapid. Top of Form The results obtained for the highest diversity value is at Station I with a value of 1.99 and the highest dominance value is at Station III with a value of 0.98. As for the best FBI value of the three stations, namely at Station II with a value of 5.43 with a moderate organic matter pollution category. For the results of physicochemical parameters, some of which do not meet or exceed the Quality Standards based on Government Regulation Number 22 of 2021, namely TSS at Station III, BOD at Station I and Station II, and DO at Station III. The results of the macroinvertebrate diversity index relationship with physicochemical parameters has a strong to very strong relationship.

Response surface methodology for process optimization in livestock wastewater treatment: A review

With increasing demand for meat and dairy products, the volume of wastewater generated from the livestock industry has become a significant environmental concern. The treatment of livestock wastewater (LWW) is a challenging process that involves removing nutrients, organic matter, pathogens, and other pollutants from livestock manure and urine. In response to this challenge, researchers have developed and investigated different biological, physical, and chemical treatment technologies that perform better upon optimization. Optimization of LWW handling processes can help improve the efficacy and sustainability of treatment systems as well as minimize environmental impacts and associated costs. Response surface methodology (RSM) as an optimization approach can effectively optimize operational parameters that affect process performance. This review article summarizes the main steps of RSM, recent applications of RSM in LWW treatment, highlights the advantages and limitations of this technique, and provides recommendations for future research and practice, including its cost-effectiveness, accuracy, and ability to improve treatment efficiency.

EFFICIENT PRODUCTION OF SMALL-SIZED SiO2 NANOPARTICLES AND THEIR APPLICATION IN A WATERBORNE ACRYLIC-AMINO VARNISH

In this study, we optimized the preparation of 100–160 nm monodispersed SiO2 nanoparticles and, through doping, investigated their effects on the physical properties of a water-based acrylic-amino varnish. First, using a non-fixed point feeding technique based on the half-batch sol-gel method, we enhanced the yield of small-sized monodispersed SiO2 nanoparticles. To reduce the cost of production and organic-matter pollution, we assessed certain solution parameters including tetraethyl orthosilicate (TEOS), ethanol (ETOH) and ammonia in a single-reaction system. We found that the gloss, clarity, hardness, adhesion, and other physical properties of the acrylic-amino varnish were successfully enhanced through an addition of 1.2 % SiO2 nanoparticles.

Spatiotemporal Variation Analyses of Water Quality, Fish Ecological Guilds, and the Longitudinal Connectivity in Musim Stream

The main objectives of this study were to analyze the spatiotemporal variations of water quality, fish ecological guilds and longitudinal connectivity in the weirs of Musim Stream. Fish were collected at 44 sites during spring and fall seasons for the analysis of trophic guilds, tolerance guilds, and the ecological stream health, based on FAI model. Total 33 species were observed in the stream and the dominant species were <i>Zacco platypus</i> and <i>Squalidus qracilis majimae</i>. Mean values of BOD and COD, as an indicator of organic matter pollution, showed high in the drought spring and low in fall (post-monsoon season). Also, TP showed same pattern with the BOD and COD pattern. The hierarchical clustering, based on the fish compositions, classified as three groups (up-stream, mid-stream and the down-stream). Based on the NMDS (Non-metric Multidimensional Scaling) analysis of fish abundance, high similarity was observed between S1-S5 sites, which were consistent with the results of hierarchical cluster analysis. Fish ecological guilds in the upper stream showed a high similarity between the insectivore and sensitive species, while in the middle and lower reaches, high similarity was found between the omnivore and intermediate species. Evaluations of longitudinal connectivity, based on the structural and hydrological characteristics of the weir, indicated all disconnections by the weirs, except for S15, in the spring. Stream ecological health, based on the FAI model, was significantly (<i>p</i> < 0.05, n=37) influenced by the height of overflow (<i>Hu1</i>). Overall, our study suggests that the longitudinal connectivity, based on the weir structures, flow regime and fish swimming capacity, were blocked off by the weirs in the stream. The results provide valuable insights for securing river management strategies and served as the fundamental data for stream restoration in the future.

Research progress of leachate treatment in waste transfer station

The garbage leachate generated by the waste transfer station has the characteristics of scattered water sources, relatively small water quantity, large fluctuations in water quality and quantity, and high concentrations of organic matter, ammonia nitrogen, suspended solids, and other pollutants. These characteristics make it prone to environmental hazards. This paper analyzes the characteristics and hazards of leachate from waste transfer stations and introduces the current research status of physico-chemical, biological, and combined treatment of leachate from waste transfer stations. Meanwhile, this paper introduces engineering practices for leachate treatment in waste transfer stations, offering a valuable reference for research and engineering practices in this field. Finally, this review discusses pretreatment, economic, low-carbon, and high-efficiency treatment methods and facilities, the recovery of valuable elements, energy recycling technologies, and the demand outlook for high-standard deep treatment processes.

Decomplexation of Pb-EDTA by electron beam irradiation technology: efficiency and mechanism.

As a common heavy metal complex in industrial wastewater, Pb-EDTA has garnered much attention due to its detrimental impact on both human health and the ecological environment. The degradation of heavy metal complexes by traditional methods requires subsequent treatment to recover heavy metals. This article attempts to find an effective method to simultaneously degrade both organic matter and heavy metal pollutants. Experimental results indicate that 1 mM Pb-EDTA can be effectively removed at 10 kGy with a degradation efficiency of 91.62%. Most lead ions were still in a stable complex state, with a removal rate of 24.42% (10 kGy). When the absorbed dose increased to 80 kGy, the degradation efficiency of Pb-EDTA was 95.24%. At this time, the removal rate of Pb2+ reached 68.82%. Through radical scavenging experiments and further mechanism analysis, it was demonstrated that electron beam irradiation primarily generates ·OH radicals, disrupting the structure of Pb-EDTA, gradually decarboxylating, and ultimately generating formic acid, acetic acid, and NO3 -. The released metal ions were reduced by eaq - and ·H to obtain lead monomers. Residual toxicity analysis indicates that the toxicity of degradation products generated by electron beam irradiation is significantly reduced. Experimental results showed that electron beam irradiation can effectively degrade Pb-EDTA and recover lead ions simultaneously.