Black Odorous Water Research Articles

Construction and Application of Recognition Model for Black-Odorous Water Bodies Based on Artificial Neural Network

In the water environment, construction, and civil engineering industries, digital twins have gradually become a popular solution in recent years, and in digital twins, accurate data prediction and category recognition are important parts of it. Artificial neural network (ANN), a widely used data-driven model, can accurately identify nonlinear relationships in the water environment. In this paper, a recognition model for black-odorous water bodies based on ANN was established to directly identify the sensory description of water bodies. This study used water quality data and sensory description (color and odor) as samples to train backpropagation (BP) neural networks. The training results show that the accuracy of the color and odor models reaches 86.7% and 85.8%, respectively. It can thus be suggested that the sensory description can be accurately recognized by BP neural network. The application results indicate that all seven rivers had black-odorous phenomenon within a year. The recognition models have been instrumental in water resource management. Meanwhile, the models provide a reference for the evaluation and early warning of black-odorous water bodies in other regions.

Preparation and application of embedded and immobilized Achromobacter sp. agent for effective removal of ammonia nitrogen from water.

A novel wastewater-quality-improver, Sodium Alginate Embedded Microbe-treated Zeolite (SAEMZ), was proposed. The strains used are screened from black-odorous water and have high-efficiency NH4+-N degradation performance. The Gram-positive bacteria, belonging to Achromobacter sp., was determined through the screening and identification for this strain, whose removal rate of NH4+-N can reach 88.06%, to decrease the NH4+-N concentration from 61.83 mg/L to 7.80 mg/L, and its optimal growth conditions are pH 7-8, rotation speed 150-210 r/min, temperature 25-35 °C. The SAEMZ's removal effect on NH4+-N was considered in this research from aspects of reusability, storage stability, and the effects of dosage, coexisting ions, and wastewater's concentration. The increase of the SAEMZ's dosage effectively improved the NH4+-N removal rate; Ca2+ in the solution promoted the NH4+-N removal rate, while Mg2+ and Mn2+ inhibited it. Also, the NH4+-N removal rate improved slightly with Fe2+ concentration's increase and then decreased significantly; with the increase of the wastewater dilution factor, the NH4+-N removal rate showed an upward trend and with the increase of the SAEMZ's reuse times, it decreased. Therefore, recycle times should be controlled to less than 3 times in practical application; the SAEMZ still maintains its physiological stability, high mechanical strength, and good storage stability after being stored at 4 °C for 120 days.

Surface water quality assessment based on the Integrated Water Quality Index in the Maozhou River basin, Guangdong, China

Rivers are a vital component of both urban and rural aquatic ecosystems, and the rapidly increasing pollution in rivers severely threatens the security of these ecosystems. In this study, the surface water quality in the Maozhou River basin, Guangdong Province, China, was assessed from 2018 to 2020 using multivariate statistical techniques and the Integrated Water Quality Index (IWQI). In addition, spatial trends in surface water quality were studied using a geographic information system. The results indicated that the water quality in 82.17% of the studied section met the Class V standard for surface water quality, with IWQI values ranging from 12.157 to 3.650. The surface water quality was clustered into eight groups and further divided into unsuitable (low quality) and suitable (acceptable quality) according to standard surface water quality thresholds (China in Environmental quality standards for surface water, 2002). Four groups (G1, G2, G3, and G4) were classified as unsuitable, because they fell short of the Class V standard for surface water quality. In these groups, industrial sewage, endogenous pollution, domestic sewage, and rainfall runoff, were the primary sources of pollution, and the main background pollutants for the water quality target of the functional zones were COD, NH3-N, TP, and LAS. The other four groups were classified as suitable. In these groups, endogenous pollution and rainfall runoff were the primary sources of pollution, and the main background pollutants for the water quality target of the functional zones were NH3-N and TP. Among them, NH3-N and LAS were recognized as responsive and sensitive to the surface water quality and spatio-temporal variability. Owing to pollution treatment and management measures undertaken by the Chinese government, the black-odorous water in the Maozhou River basin has disappeared, and the water quality in the Maozhou River basin has been maintained at the “medium and good” level. However, the surface water quality in the estuary region and the southwest tributary in the basin requires further improvement. This calls for further efforts to improve surface water quality and to properly deal with various sources of pollution in the watershed. This combined method has proved to be effective for surface water quality evaluation and management at river or basin scales. The results of this work are expected to provide a scientific foundation for aquatic ecosystem management and planning.

A collaborative effect of algae-bacteria symbiotic and biological activated carbon system on black odorous water pretreated by UV photolysis

In this study, UV photolysis was deemed as the pretreatment, degrading initially the black odorous water, and the algae-bacteria symbiotic system combined with biologically activated carbon (BAC) column technology was employed to degrade black odorous water. The addition of sodium acetate promoted the proliferation of microalgae and bacteria, enhancing the degradation effect of microorganisms. In the process of adsorption and biodegradation, BAC had a large specific surface area and pore structure, which was good for adsorbing macromolecular dissolved organic matter (DOM) and providing a nutrient environment for microorganisms. Mutant strain M1 could survive in the black odorous water after pretreatment, which was proved to have great application potential. In order to evaluate the optimal removal efficiency, an indoor-scale column study was performed using black odorous river sediment, activated carbon and algae-bacteria mixed solution. The results show that the combined treatment achieved a COD removal of 83 ± 1 %. The treated water could be used for green land irrigation and ecological water supplement. That played a major role in restoring the self-purification function of the ecosystem and improving the hypoxic environment of water bodies.

Isolation and degradation characteristics of bacteria in black and odorous water

Abstract Bioremediation is one of the treatment technologies for the black-odorous water, and obtaining functional bacteria is the key step to its success. In this study, a number of highly efficient pollutant degrading strains were isolated from the sediment of black-odorous river, and were identified by phenotypic and phylogenetic analysis. The composite bacterial agent J1 was mixed by strains A1, A2, A5 and A7, with a volume ratio of 4:4:2:1. And the final compound bacteria injected into black-odorous water were composed of J1 and NS3, with the volume ratio of 1:1. Optimized degradation conditions of compound bacterium agent were as follows: pH 7.5, DO 2.5 mg/L, temperature 30 °C. Under optimized conditions, add 1% by volume to the black-odorous water for a 50-day experimental operation. Finally, the overlying water ammonia nitrogen, chemical oxygen demand (COD), and total phosphorus has been significantly degraded. The research is expected to contribute to the use of bioremediation methods to repair black-odorous water, and the application of isolates can be carried out in situ for water types similar to pollute waterways.

Study on the Spectral Characteristics of Black-Odorous Water: A Case Study of Shenzhen City, China

ABSTRACT The occurrence of black-odorous water (BOW) in urban waters is a common problem in China that has occasional, seasonal, and perennial rules. The treatment of urban has become an important task for water managers in China. Based on field BOW spectra and 13 types of water quality parameters measured in Shenzhen City, in this study, we processed three types of spectra, including normalized, difference, and ratio spectra, to reveal the correlation between the spectra and the water quality parameters, especially for the spectra and four indicators that are used to distinguish BOW. The four indicators include Secchi depth (SD), dissolved oxygen (DO), oxidation-reduction potential (ORP), and ammonia nitrogen (NH3-N). Furthermore, we analysed the spectral sensitivity of the different water quality parameters to build a quantitative regression model between the water quality parameters and the portrait spectrum. The results showed the following: (1) Of the four indicators, both SD and NH3-N were significantly related to the spectrum of mild and severe BOW, and the ORP was only significantly related to the spectrum of severe BOW. The correlation between DO and BOW was not significant. (2) For mild BOW, the sensitive bands were 404 to 572 nm and 704 to 864 nm for the SD and 705 to 717 nm for NH3-N. For severe BOW, they were 499 to 606 nm and 730 to 900 nm for the SD, 556 to 664 nm for NH3-N, and 642 to 709 nm for the ORP. (3) The SD had the strongest correlation with the BOW spectrum. The correlation between the SD and the BOW spectrum was symmetrically distributed in the range of 404 to 572 nm near 489 nm, whereas 545 nm appeared as the centre in the range of 499 to 606 nm. (4) The best regression relationship between the SD and BOW was R 489/ R 714 (coefficient of determination R 2 = 0.8806) and R 545 (R 2 = 0.4868) for the mild and severe grades, respectively. The best regression relationship was R 489- R 607 (R 2 = 0.7598) between NH3-N and mild BOW. The results of this study provide important guidance significance and application value regarding the selection of bands, model construction, and result verification for urban BOW using remote sensing.

Monitoring urban black-odorous water by using hyperspectral data and machine learning.

Economic development, population growth, industrialization, and urbanization dramatically increase urban water quality deterioration, and thereby endanger human life and health. However, there are not many efficient methods and techniques to monitor urban black and odorous water (BOW) pollution. Our research aims at identifying primary indicators of urban BOW through their spectral characteristics and differentiation. This research combined ground in-situ water quality data with ground hyperspectral data collected from main urban BOWs in Guangzhou, China, and integrated factorial data mining and machine learning techniques to investigate how to monitor urban BOW. Eight key water quality parameters at 52 sample sites were used to retrieve three latent dimensions of urban BOW quality by factorial data mining. The synchronically measured hyperspectral bands along with the band combinations were examined by the machine learning technique, Lasso regression, to identify the most correlated bands and band combinations, over which three multiple regression models were fitted against three latent water quality indicators to determine which spectral bands were highly sensitive to three dimensions of urban BOW pollution. The findings revealed that the many sensitive bands were concentrated in higher hyperspectral band ranges, which supported the unique contribution of hyperspectral data for monitoring water quality. In addition, this integrated data mining and machine learning approach overcame the limitations of conventional band selection, which focus on a limited number of band ratios, band differences, and reflectance bands in the lower range of infrared region. The outcome also indicated that the integration of dimensionality reduction with feature selection shows good potential for monitoring urban BOW. This new analysis framework can be used in urban BOW monitoring and provides scientific data for policymakers to monitor it.

Mechanistic insights into organic carbon-driven water blackening and odorization of urban rivers

With rapid global urbanization, massive anthropogenic inputs of organic matter and inorganic nutrients are resulting in severe pollution of urban rivers and consequently altering the structure and function of their aquatic microbial communities. In contrast to nutrient-induced eutrophication of freshwaters, water blackening and odorization of urban rivers, as well as their microbial communities, are poorly understood at a mechanistic level. Here, in a one-year field study on the taxonomic composition, predicted function and spatiotemporal dynamics of water and sediment microbial communities in seven black-odorous urban rivers in a megacity in southern China, combined with laboratory water-sediment column experiments, we pinpointed organic carbon as a key parameter driving the overgrowth of aquatic heterogeneous microorganisms. These microorganisms are major constituents of suspended black flocs that mediate methanogenic digestion of organic carbon and consequent water blackening and odorization. Source tracking analysis revealed a strikingly high contribution of sewage communities to black-odorous water microbial communities, in which emerging pathogens are enriched. Our results provide mechanistic insight into organic carbon-driven water blackening and odorization of urban rivers, which brings up current remediation strategies in questioning and sheds light on the future sustainable management of urban aquatic ecosystems.

Remote Sensing Classification of Urban Black-odor Water Based on Decision Tree

Remote sensing monitoring of black-odor water is an important method for understanding the current status of urban water quality, and comprehensively evaluating the effect of urban water environment treatment. A total of 171 samples were collected in Nanjing, Changzhou, Wuxi, and Yangzhou cities and water quality parameters and optical parameters were measured simultaneously. Based on the analysis of the water color and optical characteristics of the black-odor water and non-black-odor water (denoted as general water), a decision tree was constructed to identify the severe, mild black-odor water, and general water as green and yellow water. The results found that:①According to the water color, the water bodies can be divided into six types. Among them, type 1 to 4 water bodies are black-odor water, which are gray black, dark gray, gray, and light gray water, respectively, and type 5 and 6 water bodies are general water, which are green and yellow water, respectively; ②Type 1 water body contains high contents of non-pigmented particulate matter and colored dissolved organic matter(CDOM), however, the absorption of pigmented particulate matter is not dominant. Type 2 and 5 water bodies are dominated by pigmented particulate matter. Type 3, 4, and 6 water bodies are dominated by non-pigmented particulate matter; ③After water color classification, and according to the differences of the reflection spectrums of the six types of water bodies, the difference of black-odorous water index (DBWI), green-red-nir area water index (G-R-NIR AWI), the green band reflectance and the normalized difference black-odorous water index (NDBWI) were used to construct a decision tree to identify the severe, mild black-odor water, and general water; ④The decision tree was applied to the PlanetScope satellite image of Yangzhou City on April 9, 2019, and 10 synchronous sampling points were used for verification. The overall recognition accuracy reached 80.00%, and the K value reached 0.67. The urban water classification model, after water color classification, can be applied to other similar water bodies, and provides a technical method for the supervision of black-odor water bodies.

The treatment of black-odorous water using tower bipolar electro-flocculation including the removal of phosphorus, turbidity, sulfion, and oxygen enrichment

The large amount of municipal wastewater discharged into urban rivers sometimes exceeds the rivers’ self-purification capacity leading to black-odorous polluted water. Electro-flocculation has emerged as a powerful remediation technology. Electro-flocculation in a bubble column tower with a bipolar electrode (BPE) was tested in an attempt to overcome the high resistance and weak gas-floatation observed with a monopolar electrode (MPE) in treating such water. The BPE reactor tested had a Ti/Ta2O5-IrO2 anode and a graphite cathode with an iron or aluminum bipolar electrode suspended between them. It was tested for its ability to reduce turbidity, phosphate and sulphion and to increase the concentration of dissolved oxygen. The inclusion of the bipolar electrode was found to distinctly improved the system’s conductivity. The system’s electro-flocculation and electrical floatation removed turbidity, phosphate and sulphion completely, and the dissolved oxygen level improved from 0.29 to 6.28 mg/L. An aluminum bipolar electrode performed better than an iron one. Changes in the structure of the microbial community confirmed a significant improvement in water quality.

Black odorous water concentrating by forward osmosis (FO) with aquaporin biomimetic membranes: Pollutants concentrating and membrane fouling characteristics

This study aimed to investigate pollutant concentration and membrane fouling characteristics of a forward osmosis (FO) process using aquaporin biomimetic membrane (ABM) for concentrating black odorous water. The membrane cells were operated in active layer facing feed solution (ALFS) mode with 2 M NaCl solution as the draw solution. The system was continuously performed for 64 batch cycles, and each cycle duration was 24 h. At the end of each cycle, physical cleaning with deionized water was employed as the membrane recovery strategy. The results showed that the rejection ratios of chemical oxygen demand (COD), total phosphorus (TP) and nitrate (NO3−-N) could reached 97.2%, 98.0%, and 85.0%, respectively, while most NH4+-N penetrated into the draw solution due to cation exchange. The total nitrogen (TN) rejection ratio was largely dependent upon the NH4+-N/TN ratio. At high NH4+-N/TN ratio, the successions of ammonia oxidizing bacteria (AOB) communities enriched in the biofouling layer in different experimental stages would affect the transformation degree of NH4+-N, and thus lead to much fluctuations of TN rejection. The average initial water flux reached 9.84 L/(m2·h), and the average water flux of each cycle kept stable especially in the later stage of the experiment. In the biofouling layer, polysaccharides enhanced while proteins decreased in the later period. P, Mn, Fe and Na also accumulated on the surface. Norank_f__Reyranellaceae, Erythrobacter, SM1A02, Pirellula, and Hydrogenophaga were the predominant genera enriched in the fouling layer, which would lead to complex pollutants transformations, especially nitrogen transformation, during the FO process.

Mechanism of Urban Black Odorous Water Based on Continuous Monitoring: A Case Study of the Erkeng Stream in Nanning

Black odorous water seriously endangers urban ecological functions. The "Water Pollution Prevention Action Plan" promulgated by the State Council has attached great importance to this issue and set a timetable for achieving the goal of pollution remediation of the urban black odorous water problem. However, in the process of managing the city's black odorous water, we found that the apparent governance effect is not sustainable. Many of the urban waters that have been treated to become clear have returned to a black odorous state. This problem has constrained the completion of the black odorous water control plan, and urgently needs to be resolved. To explain the reason for this phenomenon, we chose the Erkeng Stream in Nanning as the research object, which is a water body that returns to a black odorous state after treatment. We used a multi-parameter water quality tester and chemical analysis method to carry out daily continuous monitoring for 24 h and monthly dynamic monitoring of the water body. The results showed that the rainfall process was significantly correlated with the ammonia nitrogen concentration in the water (P<0.01), and the temperature was positively correlated with the trend of ammonia nitrogen concentration in the water (r=0.23, P<0.05), which in turn was negatively correlated with the change trend of water transparency (r=-0.33, P<0.01). The above results show that the return of the black odorous state may be related to the microbial degradation of endogenous pollutants and the input of external pollutants. The reason may be:① The microorganisms are driven by light and temperature to promote the development of water in the direction of the black odorous state; ② Contaminants carried by rainfall promote the formation of black odor in water bodies. In short, in the context that internal pollution cannot be completely eradicated and external pollutants are difficult to control effectively, to prevent the treated urban water body from returning to a black odorous state, attention should be paid to endogenous pollutants such as river sediment and its control technology. Moreover, ecological control measures should be comprehensively adopted to reduce the input of external source indicators.

Ultraviolet-B radiation of Haematococcus pluvialis for enhanced biological contact oxidation pretreatment of black odorous water in the symbiotic system of algae and bacteria

Black odorous water contains abundant organics and nutrients, such as nitrogen and phosphorus, which would lead to eutrophication of the water body and affect the water environment. In this study, the eutrophic water body in the campus landscape was taken as the research object, and the biological contact oxidation (BCO) method and co-cultivated indigenous microorganisms were adopted to pretreat black odorous water. Inoculating mutant strain M1 through ultraviolet-B radiation formed algae-bacteria symbiosis system in optimal effluent. The results showed that under the conditions of dissolved oxygen (DO) concentration of 5 mg/L, light intensity of 3000 Lx and inoculum size of 125,000 cells/mL, the optimal organic migration effect was achieved by the combined process. In addition, the ability of H. pluvialis to transform from green vegetative cells to red cyst cells under stressful conditions (strong light, nitrogen starvation, etc.) made it as an indicator for monitoring the degradation status of pollutants in black odorous water.

Pollutant degradation behaviors in a heterogeneous Fenton system through Fe/S-doped aerogel

To prepare a heterogeneous Fenton catalytic material with high pollutant degradation efficiency, Fe/alginate acid hydrogel was used as a template to obtain a Fe/S-doped aerogel (GFe2) and a Fe/O aerogel (GFe3). GFe2 and GFe3 exhibit different iron component crystal patterns; from our results, we deduced that S-doping improves the electron transportation in the Fenton reaction. GFe2 also exhibits a better spherical structure and a higher specific area than GFe3 due to the support of the FeS nanospheres. To further increase structural advantage, polyvinyl alcohol (PVA) was added to alginate hydrogel during in-situ pyrolysis, which further converts GFe2 into a more porous structure (PGFe). Experiments show that the organic removal efficiency of the samples are ordered as GFe3 < GFe2 < PGFe, which acts as additional evidence for the importance of S doping and the structural support that PVA offers which produces more active sites and faster electron transportation. PGFe shows a high reusability after 5 runs of repetitive use in tetracycline (TC) and perfluorooctanoic acid (PFOA) degradation. The removal rate of PFOA increased from 15.4% to 21.6% using PGFe; though not as significant as its effects on TC. The C7, C8, F23, and O24 atoms of PFOA are found easier to be attacked by hydroxyl radicals. Having used drinking and black odorous water to further evaluate the practical properties and industrial potentials of the aerogel, PGFe also shows a significant effect in degrading a variety of pollutants, both organic and heavy metal. This clearly demonstrates the promising potentials of Fe/S-doped carbon aerogel.

Analysis and Prospect of Treatment Measures for Black - odorous Water Sediment in China

In recent years, black-odorous water bodies have been seriously polluted, and the release of endogenous pollution from sediments has once again caused harm to water bodies. How to deal with the black-odorous water sediment has become a widespread concern in the process of building ecological civilization . This article analyzes the sources, hazards, types, and treatment technologies of sediment pollution, including dredging and dredging technology, dredging and post-treatment technology, sediment cover technology, chemical agent dosing technology, microbial remediation technology, and aeration recovery oxygen technology, submerged phytoremediation technology and so on . The article gives suggestions and measures for the treatment of sediment from the aspects of external pollution control, implementation of measures according to local conditions, and development of new technologies.rocesses.

Research on the Technique of Multistage Functional Filtration to Repair Black and Odorous Water

It is of great significance for environmental protection to carry out in-depth research on the treatment of black and odorous water body and form effective water remediation technology. The ecological technology of multistage functional filtration for water restoration can be used as a new and reliable combined filtration process for advanced treatment of black and odorous river, which can effectively intercept pollutants from point sources and purify watershed water. In this paper, a new type of water purification device consisting of cobblestone, quartz sand, activated carbon and PP cotton is developed, which is used to deeply treat black odorous water body and study the filtration and adsorption performance of filter materials on target pollutants. The filtration and adsorption performance of the filter material to the target pollutants, and the influence of the thickness of the filter layer and the particle size of the filter material on the filtration efficiency were studied. The water quality was effectively improved and the purpose of treating the black odor water body was achieved.

Study on Purifying Effect and Mechanism of "Combined Artificial Floating Island" on Black-odorous Water

In the process of traditional ecological floating island purification, floating plants have limited absorption capacity. And it also have limited effect on deepwater treatment. Because of the shortcomings of the traditional floating island, the "Combined Artificial floating island" device, which combines the ecological floating island, activated carbon fiber and aeration, is proposed to study its purification effect on black-odorous water. After 22 days of experiment, the removal rates of COD, TN and TP reached 83.9%, 50.2% and 26.4% respectively for the "Combined Artificial floating island" combined treatment unit, while it reached 70.5%,39.2%and 17.5% respectively for the traditional ecological floating island. The experimental results show that the removal rates of COD, TN and TP in water body are increased by 13.4%, 11% and 8.9% respectively for the treatment of "Combined Artificial floating island" combined treatment unit, and the purification effect is greatly improved compared with the traditional ecological floating island. The “Combined Artificial floating island” uses synergistic effect of particle sedimentation, plant absorption, microbial degradation and activated carbon fiber adsorption to purify water. Therefore, it can adapt to water bodies with different water quality and water depth, and has wider application range and stronger adaptability.

Experimental study on combination of microbial flocculants with PAC in in-situ remediation of black odorous water and sediment

This study, the sediment of black and odorous water body in Xinyang main flood drainage channel of Xiamen City was taken as the research object, and the effect of in-situ remediation of black and odorous water body sediment by microbial flocculant (MBF) and polyaluminium chloride (PAC) in different proportions was studied through laboratory static simulation test. The experimental results show that: (a) The MBF dosage of 20 mg/L has a good effect on the remediation of the sediment in the black-odor river. The removal rates of TP and COD in the overlying water are 86.5% and 87.37% after 15 days of experiments, respectively. The removal efficiency of acid volatile sulfur in sediment (AVS) is not very good, the removal rate is only 27.1%. 100 mg/L PAC is added to remedy the black-odor river sediment, and the overlying water under the same experimental conditions. The removal rate of TP was 51%. (b) The combination of MBF and PAC has a good effect on the remediation of the sediment and overlying water of the black and odorous river in the city. The optimum dosage scheme is PAC with 20 mg/L and microbial flocculant with 10 mg/L. Under this scheme, the removal rates of NH4+-N, TP and COD in overlying water were 92.37%, 70.82% and 64.52% respectively after 15 days of restoration experiment. AVS in sediment was reduced by 52.21%, which basically eliminated the black odor in overlying water.

Remediation of Black-Odorous Urban Rivers by Using Biostimulants Combined with Low Intensity Aeration

Abstract. Biostimulant and low intensity aeration were used to restore black-odorous water body in Zhupai Creek, Nanning. After 60 days’ experiment, results showed that the removal rate of CODCr、NH3-N and TP were 46.8%、98.7%and 73.3% respectively. The pH value of overlying water changed from 7.61 to 7.92 which would be beneficial to the release of P in the sediment. And the reduction of sediment reached to 5.49 cm. Hence, the remediation effects and speed of biostimulants to the black-odorous urban rivers can be improved greatly by using low intensity aeration.