Black-odor Water Research Articles

Metal–organic framework-based SERS chips enable in situ and sensitive detection of dissolved hydrogen sulfide in natural water: Towards a bring-back-chip mode for field analysis

Hydrogen sulfide (H2S) in natural water plays an important role in carbon and sulfur cycles in biosphere. Current detection protocol is complicated, which need to “bring back water” to lab followed by gas chromatograph analysis. In situ, field detection is still challenging. Herein, a portable, sensitive surface enhanced Raman scattering (SERS) chip was proposed for in situ H2S sampling and SERS signal stabilizing, enabling a “bring back chip” manner for lab analysis. The SERS chip was composed of single core-shell gold nanorod-ZIF-8 framework (Au NR@ZIF-8) nanoparticle. Relying on headspace adsorption, evaporated H2S was enriched in the ZIF-8 shell and then reacted with Au NR, resulting in the weakening of the Au-Br bond Raman peak (175 cm−1) and the appearance of the Au-S bond Raman peak (273 cm−1). The SERS signal reached equilibrium in 10 min. The detection range of H2S was 0.1–2000 μg/L and limit of detection was 0.098 μg/L. SERS signal was not interfered by normal volatile gases. Moreover, SERS signal of a reacted chip was stable at an ambient condition, allowing for in situ sampling and bring-back detection. The applicability of the chip was verified by dynamic H2S monitoring during artificial black-odor water evolution, and in-field quantitative analysis of H2S content in river water and sediment. Finally, the chip was sealed in a waterproof breathable membrane device, which realized the detection of vertical profiles of H2S in the river. This work provided a promising tool for field analysis of H2S in natural environments.

Application of Immobilized Microorganism Gel Beads in Black-Odor Water with High Nitrogen and Phosphorus Removal Performance

Black-odor water, which is caused by the excessive accumulation of nitrogen and phosphorus in water, is a significant problem. Immobilized microorganisms are considered to be an effective technical solution, but there are still many key parameters to be determined, such as organic matter dissolution, insufficient stability, and insufficient phosphorus removal capacity, among other problems. In this study, the optimum raw material ratios of immobilized microorganism gel beads were determined by means of a response surface experiment. The optimal ratio of raw materials was 5% polyvinyl alcohol (PVA), 1% sodium alginate (SA), and 6% bacterial powder. In addition, the nitrogen and phosphorus removal performance of the materials was improved by loading inorganic compounds, such as 0.5 wt.% zeolite, 0.5 wt.% iron powder, and 0.2 wt.% activated carbon. Tolerance analysis determined that these gel beads could maintain a good performance in a series of harsh environments, such as during intense agitation, at high temperatures, and at low pH values, etc. The total nitrogen (TN), ammonia nitrogen (NH3-N), and phosphorus (TP) removal efficiencies were 88.9%, 90%, and 95%.

Novel drainage pipeline breakages detection based on MEMS inertial sensor: From mechanism to application

Urban water environment pollution is a global concern, in developing countries, sewage infiltration resulting from urban drainage pipelines breakage is an essential element in the urban groundwater pollution and the recurrence of black odor water bodies, it is crucial to accurately and efficiently detection and localisation of urban drainage pipelines breakage to protect the urban water resources. In this paper, a device for detecting defects in drainage pipelines was developed and assembled using microelectromechanical systems (MEMS) inertial sensors as the core components, and the improved cumulative sum (CUSUM) model was used for anomalous detection of the pitch angle of the device's movement along the course of the pipeline as a method of detecting pipeline breakage. In the laboratory simulation of drainage pipeline tests, the CUSUM peaks (0.709, 1.102, 3.038, 7.990) for the case of external water infiltration rates into the pipeline at the point of pipe breakage (2.9%, 4.6%, 5.8%, 9.2%), and for the cases of sewer exfiltration rates in the pipeline of 4.2% and 6.4% (0.760, 1.382). CFD simulations of the water flow in the laboratory pipeline show a high degree of overlap between the trend of the water surface near the point of breakage and the anomalous fluctuations in the pitch angle of the device motion in the laboratory tests. Finally, the authors tested the device on municipal drains in the city of A. The results demonstrated the reliability and high accuracy of the device. The device enables to improve the ecological quality of urban water environment by accelerating the rate of defect detection in urban drainage pipelines and reducing the detection expenses.

Occurrence and distribution of antibiotic resistance genes in urban rivers with black-odor water of Harbin, China

Antibiotic resistance gene contamination in polluted rivers remains a widely acknowledged environmental issue. This study focused on investigating the contamination conditions of antibiotic resistance genes (ARGs) in Harbin’s urban black-odor rivers, specifically Dongfeng Ditch and Hejia Ditch. The research employed a SmartChip Real-Time PCR System to explore the types, abundance, and distribution of ARGs in diverse habitats, such as surface water and sediment. Additionally, the study examined the correlation of ARGs with mobile genetic elements (MGEs) and various environmental factors. It was found that antibiotic resistance genes were prevalent in both water and sediment within the black-odor ditches. The dominant types of ARGs identified included aminoglycoside, sulfonamide, multidrug-resistant, and β-lactam ARGs. Notably, the top four ARGs, in terms of relative abundance, were sul1, fox5, qacEdelta1-01 and aadA1. Most categories of ARGs have significant positive connections with MGEs, indicating that the enrichment and spreading of ARGs in rivers are closely related to MGEs. Based on the correlation analysis, it is found that environmental factors such as dissolved oxygen (DO), ammonia nitrogen (NH4–N), and phosphate (PO4–P) played a substantial role in influencing the variations observed in ARGs. By employing a risk assessment framework based on the human association, host pathogenicity, and mobility of ARGs, the identification of seven high-risk ARGs was achieved. In addition, it is important to assess the environmental risk of ARGs from multiple perspectives (abundance,detection rateand mobility). This study provides a significant reference regarding the presence of ARGs contamination in urban inland black-odor rivers, essential for assessing the health risks associated with ARGs and devising strategies to mitigate the threat of antibiotic resistance.

Revealing microbial community assembly patterns and succession process in the blackening process of black-odor water

Human-imported pollutants could induce water black, changing microbial community structure and function. Employed 16S rRNA high-throughput sequencing, field-scale investigations and laboratory-scale experiments were successively conducted to reveal mechanistic insights into microbial community assembly and succession of black-odor waters (BOWs). In the field-scale investigation, livestock breeding wastewater (56.7 ± 3.2%) was the most critical microbial source. Moreover, fermentation (27.1 ± 4.4%) was found to be the dominant function. Combined with laboratory experiments, the critical environmental factors, such as total organic carbon (30–100 mg/L), ammonia nitrogen (2.5–9 mg/L), initial dissolved oxygen (2–8 mg/L) and chlorophyll a (0–90 mg/L), impacted the intensity of blackening. The differentiation of ecological niches within the microbial community played a significant role in driving the blackening speed. In laboratory-scale experiments, the microbial ecological niche determined the blackening timing and dominations of the stochastic processes in the microbial assembly process (88 - 51%). The three stages, including the anaerobic degradation stage, blackening stage and slow recovery stage, were proposed to understand the assembly of the microbial communities. These findings enhance our understanding of microorganisms in BOWs and provide valuable insights for detecting and managing heavily organic polluted waters.

Research on water quality improvement effects of China’s Battle against Black-Odor water bodies

Given the sustained momentum of China's urbanization, the proliferation of black and odorous water bodies has emerged as a foremost predicament within urban settings. Since 2015, China has enacted a succession of policies aimed at mitigating the predicament of black and odorous water bodies. Nevertheless, there is a paucity of research assessing the impact of black-odor governance on water quality at the monitoring-section level. This study constructs the Black and Odorous Comprehensive Index (BOCI) to appraise the efficacy of remediating black and odorous water bodies at the monitoring-section level in China. Utilizing monthly water quality data from national monitoring sections spanning 2016 to 2018, the BOCI index is applied to evaluate the improvement in water quality within black and odorous water bodies, the enhancement of water quality in associated sections, and to quantitatively analyze the remediation effects resulting from the battle against black and odorous water bodies. The results indicate that a significant enhancement in the water quality of black and odorous water bodies in China. Notably, this improvement is most pronounced in water bodies facing more adverse environmental conditions. The Battle Against Black-Odor Water Bodies initiative has effectively compelled local governments to address issues associated with black and odorous water bodies by means of inspections, investigations, and other measures, leading to favorable outcomes.

Remediation of the black-odor water body by aquatic plants with plant growth-promoting Rhizobacteria: Lab and pilot tests

To explore an effective, environmental, rapid operating method to repair black and odor water bodies, water samples and sediment samples collected from a polluted municipal lake in Daqing, China, were directly tested in transparent barrels (10 L). Seven groups of optimizing parameters obtained the optimal operating method, and the max removal rate of COD, NH4+-N, NO3−-N, and TP were achieved (89.18%, 59.65%, 69.50%, and 75.61%) by using aquatic plants with plant growth-promoting Rhizobacteria (PGPR). To further verify the method's effectiveness, lager scale tests were conducted based on a water tank (216 L), and similar removal rates were obtained within 48 h. The water quality index and microbial community structure analysis revealed the mechanisms of the interaction among plants, microorganisms, and pollutants and the main biological processes during water body remediation. Finally, the cost of water body remediation by using this method was estimated.

The blackening process of black-odor water: Substance types determination and crucial roles analysis

Black-odor water is a serious environmental issue in many developing counties. Iron sulfides and chromophoric dissolved organic matter are considered possible blackening substances. However, the specific type of blackening iron sulfides and the contributions of blackening substances are unclear. This study performed a laboratory simulation experiment to identify the blackening iron sulfides and quantify the contribution of blackening substances. The environmental conditions for forming blackening substances and their blackening process were also determined. We demonstrated that the black iron sulfide was mackinawite. Humic acid is another substance that absorbs light. The equivalent contributions of mackinawite and humic acid were 18.94m-1/mg Fe2+ and 1.11m-1/mg DOC, respectively. A pH of more than 6 is a precondition for producing mackinawite. The production of black substances is the foundation of the blackening process, but the suspension of black substances is essential in causing water blackening. Fulvic acid stabilizes the suspension by changing the surface charge of blackening substances. Moreover, blackening substances can also be suspended with microbial flocs. Determining blackening substances and their role during the blackening process would allow for developing precise and targeted control technologies, improving urban water over the long term.

Roles of magnetic coagulation in black-odor water restoration: An insight into dissolved organic matters

The black-odor water body restoration is an unfinished business in protecting and maintaining the ecological functions of natural water systems in China. Magnetic coagulation (MC) had found a vast application prospect for its high-efficient separation. In this work, the performance of MC was analyzed to explore its role in natural water protection, with a focus on identification and removal mechanisms of the dissolved organic matters (DOM) by absorption and fluorescence spectroscopy in terms of the spectroscopic indices, two-dimensional correlation spectroscopy (2D-COS), and parallel factor analysis (PARAFAC) methods. MC presented an excellent performance for suspended and colloidal matters, phosphorus, and DOMs, and showed high adaptability in pollution interception and water restoration. Tryptophan-like, tyrosine-like, and humics were identified as the key components in the wastewater, which were mainly recently produced or microbial-derived. The targeted pollutants were DOMs with high molecular weight, hydrophobicity, polarity, and aromaticity for the high affinity with the hydrolyzed Al species. Polyaluminum chloride (PAC) was the key in dissolved pollutants removal, while the mix stage is crucial for DOMs with low MW or humic-like substances as PAM facilitated the flocs formation and the absorption process. However, the residual PAM and the redissolved DOMs from the recycled magnetic seeds also act as the DOM source. This work identified the DOM composition and removal mechanism in MC, which would promote its application in natural water protection.

Monitoring of Urban Black-Odor Water Using UAV Multispectral Data Based on Extreme Gradient Boosting

During accelerated urbanization, the lack of attention to environmental protection and governance led to the formation of black-odor water. The existence of urban black-odor water not only affects the cityscape, but also threatens human health and damages urban ecosystems. The black-odor water bodies are small and hidden, so they require large-scale and high-resolution monitoring which offers a temporal and spatial variation of water quality frequently, and the unmanned aerial vehicle (UAV) with a multispectral instrument is up to the monitoring task. In this paper, the Nemerow comprehensive pollution index (NCPI) was introduced to assess the pollution degree of black-odor water in order to avoid inaccurate identification based on a single water parameter. Based on the UAV-borne multispectral data and NCPI of sampling points, regression models for inverting the parameter indicative of water quality were established using three artificial intelligence algorithms, namely extreme gradient boosting (XGBoost), random forest (RF), and support vector regression (SVR). The result shows that NCPI is qualified to evaluate the pollution level of black-odor water. The XGBoost regression (XGBR) model has the highest fitting accuracy on the training dataset (R2 = 0.99) and test dataset (R2 = 0.94), and it achieved the best retrieval effect on image inversion in the shortest time, which made it the best-fit model compared with the RF regression (RFR) model and the SVR model. According to inversion results based on the XGBR model, there was only a small size of mild black-odor water in the study area, which showed the achievement of water pollution treatment in Guangzhou. The research provides a theoretical framework and technical feasibility for the application of the combination of algorithms and UAV-borne multispectral images in the field of water quality inversion.

Partial nitrification in free nitrous acid-treated sediment planting Myriophyllum aquaticum constructed wetland strengthens the treatment of black-odor water

Black-odor water pollution in rural areas, especially swine wastewater, can lead to the deterioration of water quality and thus seriously affect the daily life of people in the area. However, there is a lack of effective treatment measures with simultaneous attention to carbon, nitrogen and sulfur pollution in rural black-odor water bodies. This study evaluated the feasibility of an in-situ pilot-scale constructed wetland (CW) for the synchronous removal of COD, ammonium, and sulfur compounds in the swine wastewater. In this study, the operation strategy of CW sediment pretreated with free nitrous acid (FNA) and Myriophyllum aquaticum plantation was established. Throughout the 114-day operation, the total removal efficiencies of COD and ammonium nitrogen in experimental groups were 81.2 ± 4.2 % and 72.8 ± 1.8 %, respectively, which were significantly higher than CW without any treatment. Removal efficiencies of Sulfur compounds, i.e. sulfide, sulfate, thiosulfate, and sulfite, were 92.3 ± 1.9 % (61.2 % higher than the no-treatment group), 42.1 ± 3.8 %, 97.9 ± 1.7 %, and 42.7 ± 4.5 % respectively. High-throughput sequencing and qPCR revealed that experimental group significantly increased denitrification genes (nirK, nosZ) and sulfur oxidation genes (soxB, fccAB) and enriched the corresponding microbial taxa (Bacillus, Conexibacter and Clostridium sensu stricto). Moreover, metabolic pathways related to nitrogen and sulfur and the degradation of organic matter were up-regulated. These results indicated that partial nitrification in CW planted with M. aquaticum promoted sulfur oxidation denitrification and heterotrophic denitrification. Overall, the in-situ pilot-scale study revealed that the cultivation of M. aquaticum in FNA-treated CW can be a sustainable approach to treat black-odor water bodies.

Characterization, risk assessment and resource potential of sediments in the black-odor water in Hunan, China.

The black-odor water in urban water bodies is increasingly found, resulting in serious atrophy of water bodies and degradation of water ecosystems. At present, the pollution status of the sediments as an internal source still remains much unknown. In order to assess the pollution status of black-odor water sediments, the content of total nitrogen, total phosphorus, organic matter and heavy metals in the sediments were determined by taking the black-odor water sediments in urban areas of Hunan Province as the research object. Geoaccumulation and potential ecological risks index methods were used to evaluate heavy metal pollution in the sediments, and comprehensive pollution index method was used to evaluate nitrogen and phosphorus nutrient pollution in the sediments so as to provide pertinent information for urban black-odor water treatment. Finally, resource recovery potentials of sediments in black-odor water were revealed. The results could be beneficial for evaluation of sediments in black-odor water bodies.

Waste clay ceramsite supported Ti catalyst based on ozone/UV combination in treatment of black-odor waters

Black-odor water not only completely loses the function, but also seriously affects the environment landscape and human health. Aiming at the problems of high cost and low activity of catalysts for black-odor waters treatment by catalytic ozonation technology, this paper fabricated a stable Ti-based supported catalyst using the modified waste clay ceramsite (Ti/MC1). Combined with the ozone/UV technology, this catalyst realized effective degradation of pollutants in actual black-odor waters. Based on the catalytic kinetics analysis, it showed that the prepared catalyst performance generally higher activity than those with other carriers or active components. As a kind of wastes reuse, waste ceramsite is environment-friendly with high economic efficiency, which gives it higher practical value and popularization prospect. Under the optimal conditions, the removal rates of NH3-N and COD in water have reached 72.08% and 80.07% respectively. In addition, by monitoring the physiological indexes of representative submerged macrophytes during the operation process, it could be concluded that the constructed technology will not hinder the normal growth of aquatic organisms in real water environment, which confirms the feasibility of its application. The results provided a new idea for the application of nature-based processes in aqueous environment management and remediation, while also provided a theoretical basis for efficient treatment of black-odor waters.

The performance of co-immobilized strains isolated from activated sludge combined with Scenedesmus quadricauda to remove nutrients and organics in black odorous water

In this study, three bacteria were isolated from activated sludge (Pseudomonas aeruginosa, Bacillus subtilis, and Dietzia maris). After that, isolated strains and Scenedesmus quadricauda that could degrade refractory organics, as co-immobilization species, were prepared gel beads to treat black odorous water. Under the optimized conditions, the removal rate of chemical oxygen demand (COD), ammonia nitrogen (NH3-N), total nitrogen (TN) and total phosphorus (TP) reached 94.36%, 95.7%, 91.22% and 95.27%, respectively, and organics (including aromatic proteins and microbial-by-product-like compounds) were also significantly removed. Microbial analysis reveals that the community structure had a significant difference before and after treatment, and the main dominant at the genus level was transformed from Nitrospirillum (approximately 18.03%) to Flavobacterium (approximately 17.64%). This study also found that the immobilized gel beads have excellent stability and reusability, which provided a feasible and robust bioremediation strategy for the treatment of actual black-odor water.

The Monitoring of Black-Odor River by Electronic Nose with Chemometrics for pH, COD, TN, and TP

Black-odor rivers are polluted urban rivers that often are black in color and emit a foul odor. They are a severe problem in aquatic systems because they can negatively impact the living conditions of residents and the functioning of ecosystems and local economies. Therefore, it is crucial to identify ways to mitigate the water quality parameters that characterize black-odor rivers. In this study, we tested the efficacy of an electronic nose (E-nose), which was inexpensive, fast, and easy to operate, for qualitative recognition analysis and quantitative parameter prediction of samples collected from the Yueliang River in Huzhou City. The E-nose sensors were cross-sensitive to the volatile compounds in black-odor water. The device recognized the samples from different river sites with 100% accuracy based on linear discriminant analysis. For water quality parameter predictions, partial least squares regression models based on E-nose signals were established, and the coefficients between the actual water quality parameters (pH, chemical oxygen demand, total nitrogen content, and total phosphorous content) and the predicted values were very high (R2 > 0.90) both in the training and testing sets. These results indicate that E-nose technology can be a fast, easy-to-build, and cost-effective detection system for black-odor river monitoring.

Impact of increasing sulfide addition on the nitrogen removal and microbial community of CANON process in membrane bioreactor

Simultaneous removal of nitrogen and sulfur pollutants was an urgent issue since they coexisted in many kinds of wastewater and led to the black-odor water. In this study, sulfide was step-wise increased and added to the completely autotrophic nitrogen removal (CANON) system, to investigate its impact. Results showed that autotrophic denitrification was successfully induced and then improved the total nitrogen removal efficiency (TNRE) to 91.9 % from 83.7 %, when 0−5 mg L−1 sulfide was supplied. However, 50 mg L−1 sulfide significantly decreased TNRE to 42.9 %, together with the decrease of hydroxylamine oxidoreductase activity to 1.05 from 1.77 EU g−1 SS and Heme-c to 0.15 from 0.28 μM g−1 SS. CANON system can resist the sulfide shock after acclimatization, the TNRE slightly decreased to 82.9 % when 50 mg L−1 sulfide was supplied again. Prominent nitrogen removal was achieved in CANON system with 5 mg L−1 sulfide, by the cooperative contribution of CANON bacteria (5.77 % Nitrosomonas, 20.2 % Candidatus Kuenenia) and denitrifying bacteria (7.52 % Truepera, 1.79 % Denitratisoma and 3.72 % Arenimonas).

Occurrence and distribution of antibiotics in sediments from black-odor ditches in urban areas from China

Antibiotic levels in black-odor water could reflect the usage amount of antibiotics in population. On the other hand, these antibiotics are the source of antibiotics in the environmental water. Currently, researches on antibiotics in black-odor sediments are still lacking. In this study, 174 black and odor sediment samples from 74 cities in 28 provinces in China were collected for analysis. Among 44 targeted antibiotics, 13 antibiotics were detected in more than 30% of sediment samples. Fluoroquinolones and tetracyclines were the predominant antibiotics in these field samples, with average concentrations of up to 2074 and 1902 ng/g dry weight (dw), respectively, followed by macrolides (87.9 ng/g dw), lincosamides (8.06 ng/g dw) and sulfonamides (8.38 ng/g dw). High antibiotic contamination levels were almost always detected in black-odor sludges from economically less developed small cities; however, the difference in antibiotic concentrations between well-developed and small cities in China was not statistically significant. In addition, among the seven regions within China, no significant difference in concentrations was observed for the most antibiotics. Variances in antibiotic composition patterns in the 28 provinces of China may be due to differences in bacterial resistance, prescription habits, efficacy, and sediment carbon concentrations among various regions. There were significant positive correlations among some antibiotics in the same or different classes.

Study on the governance of black-odor water in Chinese cities

With China's rapid urbanization and the improvement of living standards, the number of black-odor water bodies in cities increase over time bring a huge threat to urban environment, city image, and the health of residents. Although water quality of rivers has achieved remarkable improvements due to a series of related policies, there are still some unreasonable mechanisms and insufficient supervision. In this paper, using descriptive statistics, we introduce the current situation of black-odor water bodies and analyze the governance mechanisms of black-odor water bodies at the national and provincial levels. We found that there are more black-odor water bodies in east and south-central China, compared to other areas. The causes of black-odor water bodies varies from economic development and natural environment. Then, we explore measures taken by governments at different levels in the treatment of black-odor water bodies and their governance performance. As the largest developing country, China's experience in the treatment of black-odor water bodies may be a reference for other developing countries.

Photocatalysis and Biodegradation Coupled Intimately for Treatment of the Black-Odor Water

Black-odor water remains an important problem of water pollution control in China. An increasing number of studies have thus investigated combined technologies for water pollution. Among them, many researchers prefer the intimate coupling of photocatalysis and biodegradation (ICPB) for its characteristics of high efficiency and high removal rate for refractory organics. In this study, porous cellulose-TiO2, which has advantages of good responsiveness, stability, and friendliness towards microorganisms, was introduced into the ICPB system as a crucial carrier for cleaning black-odor water. The key factors of this system were changed to obtain the optimum conditions (carrier mass 4 g, pH 7, and light intensity 25 W), and three comparison protocols including UV-responsive photocatalysis (UPC), biodegradation (B), and the coupled (PB) were carried out. The results showed removal rates of 59.06% (UPC), 68.20% (B), and 92.06% (PB) for COD, 59.96% (UPC), 82.36% (B), and 97.16% (PB) for NH3–N, and 69.00% (UPC), 85.61% (B), and 94.83% (PB) for TP. Obviously, the coupled treatment exhibited the maximum removal rates for the three indexes. Moreover, with the coupled treatment, the effluent water quality could meet the requirement of Class III water of the Environmental Quality Standard for Surface Water (GB3838-2002).

Urban Black-Odor Water Remote Sensing Mapping Based on Shadow Removal: A Case Study in Nanjing

Urban black-odor water is a serious water environmental problem worldwide that seriously affects the living environment and the health of residents. The detection of black-odor water is a primary problem of centralized governance. Remote sensing is an effective means for water-quality monitoring. However, in most urban areas, with their complex underlying conditions, black-odor water always shows an uncertain distribution and small area. Furthermore, because of similar spectral characteristics, it is easily confused with dark objects such as asphalt roads, dark roofs, bridges, river levees, and building shadows. In this article, we propose a new black-odor water detection method, without shadow misjudgment, for complex urban conditions. A remote sensing image from the Chinese high-resolution satellite Gaofen-2 (GF-2) was used for detection. Using in situ water-quality measurement data for verification, the results showed that the proposed method achieved an accuracy of 85.7% while reducing the false alarm rate to 3.5%. Compared to four other existing methods, the proposed method proved to be more practical because it can reduce the false extraction of nonblack-odor water to the greatest extent possible while ensuring accuracy The method proposed in this article has a good effect on the extraction of black-odor water in Nanjing City. Therefore, our method can be applied widely to screening and management of large-scale urban black-odor water and can provide reliable data for centralized treatment.