Black-odor Water Research Articles

Preliminary study on the effect of Fenton oxidation on black odor river sediment

沉积物中有机质的削减是黑臭水体治理的关键.Fenton（Fe²⁺+H₂O₂）试剂在有机污染废水和土壤原位修复中的应用广泛且效果良好；Fenton试剂也能很好地去除黑臭水体中的色度和浊度，但其氧化沉积物有机质的研究未见报道.为探究Fenton试剂对黑臭水体沉积物的氧化效果，本研究通过室内模拟实验用Fenton氧化法对黑臭河道沉积物进行处理，考察氧化过程沉积物特征和性质的变化；分析覆水后沉积物中污染物的释放特征，并和H₂O₂体系（无Fe²⁺）进行比较.结果表明：Fenton体系显著提高了沉积物与上覆水的氧化还原电位，对黑臭河道沉积物中的有机质具有很强的氧化效率.在温度为28℃、H₂O₂为20% Q（Q为体系中沉积物有机质完全矿化的理论H₂O₂用量）和Fe²⁺：H₂O₂（摩尔比）为0.5：1时，反应1 d，酸挥发性硫化物去除率为70.13%，沉积物总有机碳减少了22.14%，总有机氮减少了87.60%，生成了较多的铵态氮和硝态氮；由于铁对磷的钝化，沉积物中溶解性反应磷含量大幅减少.H₂O₂体系的氧化速度较Fenton体系慢，覆水后对体系中的Eh提高不明显.值得注意的是，Fenton体系会降低上覆水的pH，释放较多的铵态氮.需要联合其他技术（如微生物法），强化水体中有机质和氨氮的降解，以取得理想的修复作用.;The reduction of organic matter in the sediment is key to solve the issue of black odor river. Fenton (Fe^{2 +} + H₂O₂) reagent is effectively in the treatment of organic contaminated water or soil. Fenton reagent has been also found to remove the coloration and turbidity of black odor water effectively. But the research on the treatment of organic matter in sediment by Fenton reagent has not been reported until now. In order to explore the oxidation effect of Fenton reagent on the sediment of black odor river, in this study, Fenton reagent was used to treat black odor river sediment. The changes of sediment characteristics were investigated during the oxidation process, also the release of pollutants from the sediment was analyzed. In addition, the treatment of the sediment by H₂O₂ system (without Fe^{2 +}) was compared with Fenton treatment. The results showed that under the condition of T=28℃, input (H₂O₂) =20%Q (Q is the theoretical dosage to mineralize completely organic carbon in sediment), the molar ratio of Fe²⁺ to H₂O₂=0.5∶1, the Fenton treatment significantly increased the redox potential of the sediment and overlying water, and had a strong oxidation efficiency for organic matter in black odor sediment. During Fenton treatment, the removal of acid volatile sulfide, total organic carbon, and total organic nitrogen were 70.13%, 22.14%, and 87.60%, respectively. A substantial amount of ammonium nitrogen and nitrate nitrogen were produced. Due to the presence of iron, the concentration of soluble reactive phosphorus in the sediment was greatly reduced. Compared to Fenton treatment, the oxidation rate of H₂O₂ system was slower, and the improvement of redox potential in the system was not obvious. The release of organic acids and ammonium nitrogen to the overlying water during the Fenton treatment should be paid attention to. It is suggested that the post-treatment of the overlying water, such as biological methods, should be used to obtain the ideal repair effect.

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.

Characteristics of the chromophoric dissolved organic matter of urban black-odor rivers using fluorescence and UV-visible spectroscopy.

Urban black-odor water (BOW) is a typical phenomenon seen in the urban water environment; it is caused by excessive pollution by organic matter and other pollutants, such as nitrogen and phosphorous. Chromophoric dissolved organic matter (CDOM) is a major optical fraction of dissolved organic matter. In this study, optical properties and components of CDOM were obtained from 178 river samples collected from five cities in China, the sample were investigated using absorption and fluorescence spectroscopy. The collected included 89 ordinary water (OW) samples, 63 mild BOW (MBOW), and 26 heavy BOW (HBOW) samples. Significant differences were found in the absorption spectra of the HBOW, MBOW, and OW samples, particularly in their optical parameters (the slope of the spectrum (S275-295), and the ratio of two absorption coefficients of CDOM (E2:E3)). Additionally, the fluorescence intensity of the humic acid-like component (F5) and soluble microbial by product-like component (F4) obtained via the fluorescence regional integration (FRI) method were 3 and 4.2 times higher in HBOW than in OW, respectively; this could be used as an indicator to distinguish OW from BOW in urban rivers. The results obtained using the redundancy method and the strong negative correlation between F4 and dissolved oxygen (DO) (r=- 0.56) suggested that the composition of CDOM could change significantly under different urban water environments (p<0.01). Different correlations were also found between F5, and a355, E2:E3, S275-295 in different BOW levels, suggesting that the optical parameters of CDOM were mainly determined by the polluted organic matter originating from terrestrial sources with large molecular humic acid-like compounds; optical parameter a355 could distinguish BOW from OW. These findings are conducive in understanding the dynamics of organic matter pollution and to discover the composition and optical properties of the CDOM in urban BOW and OW, thereby providing an effective method for tracking the spatial characteristics of BOW in urban rivers using remote sensing technologies in areas with multiple sources of pollution.

Removal of Nitrogen and Phosphorus from Black-Odor Water by Different Submerged Plants

In general, nitrogen and phosphorus in eutrophic water are absorbed by submerged plants for growth, which is considered as a feature and frequently applied in sustainable wastewater treatment. These plants are entirely submerged at the bottom of the water, absorbing nitrogen and phosphorus by roots, stems, leaves and epidermal cells. Compared with other species of aquatic plants, submerged plants show certain advantages in the aspects of planting area, total biomass and total removal of nitrogen and phosphorus. Rational utilization of submerged plants is an effective way to remove nitrogen and phosphorus from eutrophic water. Submerged macrophyte has been at the focus of attention in recent years as an alternative system for aquatic plant wastewater treatment with several applications in eutrophication. Aiming at the pollution control scheme of inland lakes, in this study, the removal of nitrogen and phosphorus by Hydrilla verticillaya (H. verticillaya) and Vallisneria natans (V. natans) were studied and compared in monoculture and mixed-culture plantings, thus screened the best submerged plants. Results showed that the removal capacity for ammonium (NH+4–N), Nitrate (NO–3–N) and total phosphorus (TP) from high to low was NH+4–N, NO–3–N, and TP. Reasonable allocation of plants can improve the removal efficiency of nitrogen and phosphorus. The order of removal capacity for different submerged plants to pollutants was: mixed culture V. natans and H. verticillaya &gt; H. verticillaya &gt; V. natans. The transformation of NO–3–N to NH+4–N was considered as the NH+4–N removal mechanism.

The Influence of Key Elements in Black-Odor Water

Currently, the progress for the treatment of black-odor rivers is not optimistic. One of the main reasons is that the public understanding of the influence of key elements for the formation of black-odor water still remains unclear. Studying the key elements in black-odor water is important to determine the water quality conditions, evolution process, and mechanism underlying the formation of black-odor water, as well as to quantify the degree of black-odor water. In this study, the effect of total organic carbon on dissolved oxygen (DO) and oxidation–reduction potential (ORP) values was studied by artificially simulating black-odor water. The contribution of inorganic sulfur (IS) and organic sulfur (OS) to the formation of black-odor water was discussed. The obtained results show that pure organic pollutants do not cause black-odor water. When the DO content is below 1 mg/L and the ORP value decreases to –200 mv, metal sulfides begin to appear, followed by pungent odors such as H2S and volatile organic sulfur compounds (VOSCs). Both IS and OS contribute to the black-odor water. IS is more likely to form metallic sulfides than OS; however, OS is more likely to produce pungent odors than IS.

Improvement of Black-Odor Water by Pichia Strain GW1 under Optimized NH3-N Degradation Conditions.

In this study, a yeast strain with an outstanding NH3-N degradation ability was isolated from the sediment of a black-odor water channel in Guangdong Province, China. Based on phenotypic and phylogenetic analysis, this strain was identified as Pichia kudriavzevii GW1. The optimum conditions for NH3-N degradation by the GW1 strain were as follows: 0.3% inoculum concentration, 1.5 L/min aeration, pH 7, and a temperature of 35°C. Under optimized conditions, the GW1 strain degraded 95.5% of the NH3-N. The strain was then added to simulated black-odor water under optimal degradation conditions to investigate changes to the bacterial community over time. 16S rRNA sequencing of samples collected on days 0, 7, 14, and 21 showed that, in the presence of the GW1 strain, the relative abundances of the phyla Proteobacteria, Bacteroidetes, Chloroflexi, and Firmicutes increased in the black-odor water. In addition, the relative abundance of Propionivibrio, a known NH3-N degrading genus, increased. This study will facilitate the use of microbiological methods to repair black-odor water.

Ex-situ treatment of sediment from a black-odor water body using activated sludge

Sediment containing numerous nutrients and pollutants has become an important consideration when treating black-odor water. Excessive activated sludge produced in wastewater treatment plants contains a large number of microorganisms, which is beneficial for removing organics and nutrients from the black-odor sediment. In this study, three types of sludge from a secondary sedimentation tank (SST), a digestion tank (DT), and an aerobic tank treating landfill leachate (AT_leachate) were used to treat black-odor sediment, respectively. All the three types of activated sludge enhanced the treatment performance of sediment. The SST sludge worked the best with the optimal dosage of 2.56 g/(kg sediment), and the removal of nitrogen and organics reached 57.03 and 28.14%, respectively. Illumina MiSeq sequencing revealed that the activated sludge significantly affected the microbial community of the sediment. In particular, SST sludge resulted in significant increase in the number of microorganisms related to nitrification and sulfur metabolism to 10.68 and 10.97%, respectively. This was found to be important for degrading organics and promoting nitrogen removal. This study provides an efficient strategy for the treatment of black-odor sediment, and also realizes the complete utilization of waste activated sludge.

Characteristics of Nitrogen Metabolism by Denitrifying Bacterial Agents in Low Dissolved Oxygen Black Odor Water

In order to deal with low dissolved oxygen black odor water body of Guangdong-Hong Kong-Macao Greater Bay Area, the nitrogen metabolic capacity of ammoniated bacteria, nitrifying bacteria and denitrifying bacteria under low dissolved oxygen concentration was studied, and the relationship between denitrification efficiency and nitrogen conversion of different bacteria was clarified, which provided theoretical basis for the treatment of black odor water of Guangdong-Hong Kong-Macao Greater Bay Area. Nitrogen conversion characteristics of ammoniated bacteria (Staphylococcus sp. Ay), nitrifying bacteria (Microbacterium sp. Xw), and denitrifying bacteria (Arthrobacter sp. Fy) in simulated wastewater were detected by different concentration of bacteria and different concentration of substrates. The nitrogen metabolism of Ay, Xw and Fy in black odor water at the same concentration under low dissolved oxygen condition and the characteristics of nitrogen metabolism in different concentrations of black odor water were studied. The results showed that the bacterial concentration of Ay bacterium agent increased three times, but the ammoniation efficiency did not multiply. It indicated that increasing the concentration of ammoniated bacterium was not the best way to increase the ammoniation rate. Xw bacteria have a significant effect on the change of nitrate concentration. At 60 h, the nitrate concentration was increased 180% at low bacterial concentration, was 231% at a high bacterial concentration. Fy denitrification efficiency was high, that nitrate nitrogen can be removed quickly at lower concentration. Appropriate increase of total nitrogen concentration can increase the ammoniation efficiency of Ay microbial agent, but too high would inhibit the nitrogen metabolism efficiency of Ay microbial agent. The concentration of nitrate nitrogen of Xw bacterium reagent was increased (3736%) when the total nitrogen was 25 mg·L-1. The Fy microbial agent has no obvious effect on ammonia nitrogen removal. When the total nitrogen concentration was 25 mg·L-1, the removal rate of nitrate by Fy bacterium was the best. Overall, the results showed that the concentration of ammoniated bacteria and denitrifying bacteria could meet the need of nitrogen metabolism, and the nitrifying bacteria could increase the nitrate nitrogen synthesis rate with the increase of the concentration of nitrifying bacteria. In a certain range, increasing the concentration of substrate could increase the efficiency of nitrogen metabolism of bacterial agents, and excessive concentration would inhibit the effect of nitrogen metabolism. The study provides data support for the problem of black odor water in Guangdong-Hong Kong-Macao Greater Bay Area.

Discussion on Urban Black Odor Water Body Treatment and Long-term Management and Maintenance

In view of the increasingly serious pollution of urban rivers, seasonal or end-age black odor, not only affects the urban landscape, but also affects the daily life of the surrounding residents, in order to eliminate urban black and smelly rivers and improve the quality of urban water environment. This paper proposes the treatment technology of urban black and odorous water from the aspects of controlling source pollution, water pollution control and ecological restoration technology. Strengthen management from the long-term improvement system of water quality and policy guarantees to achieve the long-term clear effect of urban water bodies.

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.

Monitoring of Urban Black-Odor Water Based on Nemerow Index and Gradient Boosting Decision Tree Regression Using UAV-Borne Hyperspectral Imagery

The formation of black-odor water in urban rivers has a long history. It not only seriously affects the image of the city, but also easily breeds germs and damages the urban habitat. The prevention and treatment of urban black-odor water have long been important topics nationwide. “Action Plan for Prevention and Control of Water Pollution” issued by the State Council shows Chinese government’s high attention to this issue. However, treatment and monitoring are inextricably linked. There are few studies on the large-scale monitoring of black-odor water, especially the cases of using unmanned aerial vehicle (UAV) to efficiently and accurately monitor the spatial distribution of urban river pollution. Therefore, in order to get rid of the limitations of traditional ground sampling to evaluate the point source pollution of rivers, the UAV-borne hyperspectral imagery was applied in this paper. It is hoped to grasp the pollution status of the entire river as soon as possible from the surface. However, the retrieval of multiple water quality parameters will lead to cumulative errors, so the Nemerow comprehensive pollution index (NCPI) is introduced to characterize the pollution level of urban water. In the paper, the retrieval results of six regression models including gradient boosting decision tree regression (GBDTR) were compared, trying to find a regression model for the retrieval NCPI in the current scenario. In the first study area, the retrieval accuracy of the training dataset (adjusted_R2 = 0.978), and test dataset (adjusted_R2 = 0.974) was higher than that of the other regression models. Although the retrieval effect of random forest is similar to that of GBDTR in both training accuracy and image inversion, it is more computationally expensive. Finally, the spatial distribution graphs of NCPI and its technical feasibility in monitoring pollution sources were investigated, in combination with field observations.

Urban black-odor water body dynamic analysis with high-resolution remote sensing image

The black-odor water has significant negative impacts on the sustainable development of society and survival of mankind. The paper presents a new Urban Black-Odor Water (UBOW) model to identify the urban black-odor water body from high-resolution remote sensing image Gaofen-2(GF-2), to help monitor and control urban black-odor water bodies. The new UBOW model is derived from the analysis of the in-situ observation data and the spectral characteristics of GF-2. It takes advantage of the spectral difference at the blue band, the green band and the red band and has certain theoretical ground. The UBOW model can effectively identify the severe black-odor water and the mild black-odor water. The model is validated by the observation and the overall accuracy can be up to 81%. The UBOW model is used to analyze the dynamics of the urban black-odor water bodies of Beijing China, with monthly GF-2 images from March 2017 to October 2018. Results show that the urban black-odor water bodies, whether it is mild black-odor water bodies or severe black-odor water bodies, have been reduced significantly, which is consistent with the governmental report. This confirms that the Beijing government takes effective measurements to remedy the urban black-odor water bodies.

Occurrence and distribution of antibiotics and antibiotic resistant genes in water and sediments of urban rivers with black-odor water in Guangzhou, South China

Urban rivers in some countries have been heavily polluted and the water became black and odor. Nevertheless, only few studies reported the occurrence of antibiotics and their corresponding antibiotic resistant genes (ARGs) in urban rivers with black-odor water with and without remediation. In this study, nine antibiotics (belonging to sulfonamides, tetracyclines, quinolones, and macrolides) and their corresponding ARGs in water and sediments of six urban rivers in Guangzhou, South China were analyzed to investigate their spatial distribution and the influence of water remediation. The concentrations of individual antibiotics varied from ND (not detectable) to 2702 ng/L and ND to 449 μg/kg in surface water and sediments, respectively. Norfloxacin displayed the highest average concentrations, followed by ciprofloxacin. The relative abundance of quinolone-resistance gene qnrA (~103 ARGs/16S rRNA) was the highest, followed by tetracyclines-resistance genes tetC (~10−2 ARGs/16S rRNA). The antibiotics and ARGs in sediments from various rivers exhibited distinct spatial distribution with large variation from upstream to downstream. Generally, levels of antibiotics and tetracyclines-resistance genes (tetA, tetC and tetM) in urban rivers with black-odor water (affected by industrial and domestic sewage) were higher than those in remediated urban rivers. Significant positive correlations were observed only between the relative abundances of tetA (or tetC) with the concentrations of some antibiotics (e.g., ciprofloxacin and norfloxacin). TetA was also significantly positively correlated with the concentrations of Ni, Cr, and As in sediments. This study found that urban rivers remediated with dredging might lower antibiotic levels in sediment, but high relative abundance of certain ARGs (e.g., tetB, qnrA) may still exist.

Effect of calcium peroxide on the water quality and bacterium community of sediment in black-odor water

This study investigated how efficiently CaO2 could treat black-odor landscape water caused by low dissolved oxygen (DO) in a field experiment of 600 m2. The study demonstrated that CaO2 could significantly elevate the DO concentration in waters and the oxidation–reduction potential (ORP) level in sediments (p = 0.003 and p = 0), which is conducive to improving the anoxic environment of landscape water. The concentrations of total chemical oxygen demand (TCOD) and S2− in overlying and interstitial waters were considerably decreased. The average concentrations of TCOD in the overlying and interstitial waters of the test zone (TZ) were 52.98% and 66.05% of those of the control zone (CZ), and the average concentrations of S2− in the overlying and interstitial waters of TZ were 29.63% and 39.79% of those of CZ. Meanwhile, CaO2 could obviously reduce turbidity but increase the transparency in the overlying water. The mean value of turbidity in the overlying water of TZ was 39.46% of that of CZ, whereas the transparency in the overlying water of TZ was 2.07 times that of CZ. Furthermore, CaO2 changed the microbial community structure in the sediments, where the relative abundance of anaerobic bacteria was decreased but that of the aerobic bacteria was increased with some functional bacteria. In summary, CaO2 could significantly increase the DO and ORP in black-odor landscape water, obviously inhibit the release of pollutants from sediment, and increase the diversity of microbial strains. Consequently, the black-odor phenomenon of landscape water could be alleviated effectively by adding CaO2.

Analysis of Absorption Characteristics of Urban Black-odor Water

The urban black-odor water body has become a serious problem of urban water environment and identifying their optical characteristics in urban areas is the prerequisite and basis for their detection by remote sensing. A total of 85 samples of urban black-odor water, from Changsha, Nanjing, and Wuxi, were collected from 2016 to 2017, and a total of 80 samples were collected from non-black-odor (smelly) water samples. The water quality parameters such as suspended matter and the absorption coefficient were measured. The results showed that:①The total black-odor water body particulate matter absorption coefficients and non-pigmented particulate matter absorption coefficients were generally higher than those for non-black-odor water bodies and they had a certain degree of discrimination at 440 nm, but their effect was not significant. The absorption of relatively high levels of particulate matter in black-odor water was mainly due to high absorption of non-pigmented particles. In the data collected, non-pigmented particles in black-odor water accounted for more than 50% of the total particles. ② The Colored Dissolved Organic Matter (CDOM) absorption coefficients for black-odor water bodies and non-black-odor water bodies differed. The average absorption coefficient of CDOM at 440 nm for black-odor water bodies was 1.7 times higher than that for non-black-odor water bodies. Thus, the black-odor water body can be distinguished by using the slope of the absorption coefficient curve fitted in the characteristic wavelength band of 440 nm, as well as in different wavelength bands; the overall effect is good. However, as the wavelength increases, the discrimination effect decreases. Analysis of the absorption characteristics of urban black-odor water bodies will provide effective technical support for their detection by remote sensing and supervision, and the density of CDOM in black-odor water was generally high, which could be used as an important reference for identification.

Remote Sensing Identification of Urban Black-Odor Water Bodies Based on High-Resolution Images:A Case Study in Nanjing

The identification of urban black-odor water bodies plays an important role in monitoring and controlling black-odor water bodies. In 2016, a ground survey was conducted on the urban reach of Nanjing, and 55 samples from the West Shazhou River, Tuwei River, Xuanwu Lake, and Jinchuan River were obtained. The spectral characteristics of urban black-odor water bodies and other water bodies were analyzed. Recognition algorithms for GF-2 data were proposed in order to analyze the spatial distribution and environmental factors of urban black-odor water bodies. These algorithms were single-band thresholds based on reflectance of the green band, the difference between the blue band and green band, the ratio of the green band and red band, and the chromaticity value. The results indicate that:① compared with other types of water, the urban black-odor water has the smallest spectral slope in the range of 400-500 nm and lowest reflectivity, and the peaks and valleys are not prominent in the whole visible range; ② based on the verification, the accuracy of the ratio algorithm is the highest; and ③ using the ratio algorithm to calculate the GF-2 data of November 3, 2016, a total of 11 black river sections are identified. The entire length is 40.7 km, and the area is 0.749 km2.The black-odor water sections are distributed over a wide range but are not continuous, and they are concentrated in the densely populated areas. Domestic sewage, industrial waste water, and broken river channel are the main reasons.

Black-odor water analysis and heavy metal distribution of Yitong River in Northeast China.

The black-odor mechanism of Yitong River was analyzed based on survey and monitoring results. We found that organic matter is the main pollution source of Yitong River and its tributaries. A black-odor evaluation model that can describe the pollution of the Yitong River water system was developed, and this model has the parameters I = 0.21 [CODCr] + 0.18 [DO] - 0.36[NH3-N] + 0.91. The model performance was satisfactory with a black-odor defining accuracy of 69%. Moreover, we found that CODCr, NH3-N, and DO are the influential factors of the Yitong River black-odor water body and that their threshold values when the water body transitioned to black odor were 109.2, 1.90, and 7.50 mg·L-1, respectively. We found that most of the Yitong River was polluted by six heavy metals, namely, As, Cd, Cr, Cu, Pb, and Zn. We used the Nemerow method to calculate the heavy metal pollution degree of each sampling point and found that 60% of the points were seriously polluted. Furthermore, we drew the heavy metal pollution distribution map of the Yitong River. Finally, we proposed an effective measure called new-type multistep constructed wetland to improve the water quality of Yitong River.

Construction of Microbial Consortium and Its Directly Treatment for the Black-odor Water

Recently, how to efficiently treat the black-odor water in China has become an urgent issue. In this study, a microbial consortium which consisted of yeast, actinomyce and nitrobacteria isolated from East Sha River located in Beijing was constructed and used to directly treat black-odor water, and the removal efficiency was also investigated. The experimental results showed that the microbial consortium exhibited more significant removal efficiency in comparison with single strains. The mixing proportion of single strains in the microbial consortium was then optimized. It was found that a high removal level of COD, NH3-N and TP could be achieved when the mixing proportion of yeast, actinomyce and mitrobactera was set at 1:1:1, and their removal efficiencies arrived at 60.2%, 81.7% and 85.7%, respectively. Furthermore, the optimizing microbial consortium was applied to treat other some black-odor water from Qing River, Qinghe Park and a pharmaceutical manufactory, respectively. With the exception of water sample from the pharmaceutical manufactory, the optimizing microbial consortium showed obvious potentials to treat the black-odor water, especially the water from urban rivers. Removal efficiencies of NH3-N, TP and chroma in the water sample from Qing River were above 95%.

Research on an emergency treatment technology for black-odor water caused by macrophytes decaying

水草腐烂加速水体耗氧和水体还原性物质的溶出进程,在夏、秋季高温条件下极易引发局部水体黑臭.以太湖沉水植物优势种马来眼子菜(Potamogeton malaianus)、苦草(Vallisneria natans)及浮叶植物优势种莕菜(Nymphoides peltatum)为受试材料,利用太湖原位底泥培养模拟水草腐烂形成的黑臭水体,考察不同的环境材料处置方式(壳聚糖(CTS)、聚合氯化铝(PAC)、聚丙烯酰胺(PAM)、CTS+PAC和PAC+PAM)对黑臭水体浊度、溶解氧浓度、挥发性硫化物等黑臭水体特征污染物的絮凝沉降规律及去除机理.结果表明:(1)絮凝处理24 h后,CTS+PAC组合对黑臭水体的浊度去除效果最佳,浊度去除率达70.3%,上覆水溶解氧浓度明显提高,增加率为261.5%;(2)加石英砂悬浊液加速絮体沉淀,形成絮体之后加石英砂使水体浊度稳步下降,4 h之后,浊度去除率达74.9%,显著高于与絮凝剂一起加入的处理组(29.8%);(3)植物腐烂释放的含硫特征嗅味物质主要为硫化氢(H₂S)、甲硫醚和二甲基三硫醚.不同植物体腐烂释放的含硫挥发性有机物浓度差异显著,马来眼子菜释放的4种含硫有机物总和分别为莕菜和苦草释放的319.8%和252.2%;(4)CTS+PAC处理后苦草及马来眼子菜腐烂水体中挥发性有机硫化物浓度较对照组分别降低了18.6%和44.5%.PAC+PAM组合絮凝处理组对莕菜腐烂水体中H₂S有较好的去除效果,去除率达到52.4%.CTS+PAC絮凝剂组合处理的H₂S浓度均低于对照组,苦草、马来眼子菜和莕菜腐烂后黑臭水体中H₂S浓度分别降低了27.4%、41.0%和28.6%.CTS+PAC组合对H₂S和二甲基硫醚类物质等致臭物释放的抑制效果优于PAC+PAM组合絮凝处理.;Aquatic plants decaying will accelerate the process of dissolved oxygen depletion and promote the dissolution of reducing substance, which can easily lead to partial water black-odor in a hot summer. In this study, dominant species of submerged plants Potamogeton malaianus, Vallisneria natans and floating-leaved dominant species Nymphoides peltatum in Lake Taihu were selected as test material. Then the macrophytes decayed in cylindrical sediment in the culture system in which simulated conditions in situ. The black-odor waters were formed to study the flocculation and sedimentation kinetics, removal mechanism of water turbidity, volatile sulfide, dissolved oxygen and other water and soil interface characteristics which were treated with different environmental material disposals(chitosan(CTS), poly aluminum chloride(PAC), polyacrylamide(PAM), CTS+PAC and PAC+PAM). The results suggest that:(1) After 24 h, the turbidity removal of black smelly water treated by CTS+PAC was optimal, when turbidity removal rate was 70.3%. The CTS+PAC combination can increase the dissolved oxygen in overlying water more significantly than other environmental material disposals, and the increase rate is 261.5%.(2) Taking flocculation experiments by joining flocculants in the black smelly water with different flocculants, the suspension of quartz sand was added at different timing. Quartz sand suspension can accelerate flocculant precipitation, adding quartz sand before flocculant is significantly better than after it with turbidity removal rate 74.9% compared to 29.8%.(3) Sulfur characteristic odor compounds released by decay aquatic plants are mainly hydrogen sulfide(H₂S), dimethyl sulfide and dimethyl trisulfide. volatile organic sulfur compounds(VOSCs) released by difference decayed plants was significantly different. The sum of the four forms of organic sulfur released from Potamogeton malaianus were 319.8% of Nymphoides peltatum and 252.2% of biter grass.(4) Volatile organic sulfur compounds contents of Vallisneria natans and Potamogeton malaianus decaying water treated by CTS+PAC was reduced by 18.6% and 44.5%. Treatment PAC+PAM has a good deodorizing effect on Nymphoides peltatum for the removal rate of H₂S reached 52.4% when treatment CTS+PAC affected both three kind of plants. The content of H₂S reduced by 27.4%, 41.0% and 28.6% in Vallisneria natans, Potamogeton malaianus and Nymphoides peltatum, respectively. The inhibitory effect of odorant(such as H₂S and dimethyl sulfide) in treatment CTS+PAC was higher than that in treatment PAC+PAM.

Toxicity bioassays for water from black-odor rivers in Wenzhou, China

Following urbanization, a large number of urban rivers were contaminated and turned to black-odor rivers. The traditional approach for detecting water quality is based on chemical or physical analysis. However, biological toxicity of black-odor water has been less addressed. As two typical black-odor rivers, Jiushanwai River (JS) and Shanxia River (SX) are tributaries of Wen-Rui Tang River in Wenzhou (south of China). The eco-safety of the urban rivers was evaluated by bioassay for water toxicity in this study. Ten and 5 sampling sites were respectively set along JS and SX. Water samples were collected monthly from October 2010 to October 2011. The general physical and chemical parameters of river water were monitored. In order to investigate the ecotoxicological effects of black-odor water, the following bioassays were used: (1) Fish acute toxicity test (Danio rerio, comprehensive toxicity), (2) luminescent bacteria bioassay (Qinghaiensis vibrio, toxicity to bacteria), and (3) tropical claw embryo assay (Xenopus tropicalis, embryo toxicity). Biotoxicity of black-odor rivers water was demonstrated by D. rerio, Q. vibrio, and X. tropicalis embryos. Toxicological effects of black-odor water were respectively shown by mortality of zebrafish, and by the relative inhibitory light rate of luminescent bacteria. However, luminescent bacteria were more sensitive to inspect biotoxicity than zebrafish. In X. tropicalis embryos test, toxicological effects of black-odor water were mostly shown by embryos' survival rate and teratogenic rate. Bioassay results showed that toxicity of SX water was higher than that of JS water, especially in summer. Statistical analysis of luminescent bacteria toxicity test showed that biotoxicity of SX and JS was high in summer, but low in winter and spring. The seasonal changes of water toxicity of the black-odor river were positively correlative with changes of water temperature (p < 0.05), and related to pH and ammonium nitrogen of water. Typical black-odor river water displays different degrees of biotoxicity to D. rerio, luminescent bacteria, and X. tropicalis embryos. The ecotoxicological risk of black-odor rivers was demonstrated in urban area, which suggests bioassay is necessary for evaluation of water quality. In the present study, spatial and seasonal bioassay for toxicity of JS and SX provides a complete example for evaluation of urban rivers.