This review summarizes the latest research progress on the inhibition mechanism of different nanoparticles on algal bloom. We systematically analyze the influence of environmental factors on migration and transformation of nutrients and the cytotoxicity process regulated by nanoparticles. The future prospects for the immobilization of nanoparticles are explored, and the paper proposes ideas to realize the functional performance of nanomaterials while controlling environmental risks. This research sheds light on new strategies for the inhibition of algal bloom.
In this paper, we study land use change and its effects on water quality for 30 water bodies in the green-belt area of Shanghai; the analysis is based on the Markov transfer matrix and Pearson correlation analysis of field data and interpreted land use types. The results show that: the water quality is dominated by Grade Ⅳ and lower Grade Ⅴ; the proportion of water bodies with lower Grade Ⅴ is decreasing year by year; the buffer zone is dominated by construction land, forest, and grassland, with a total proportion of about 84.37%; the increase in construction land and decrease in bare land, accounted for 48.95% of the total reduced area and 50.85% of the total increased area, respectively; on the 300 m buffer scale, grassland had a positive effect on DO and Chla; on the 500 m scale, bare land was the main factor for CODMn deterioration; and cultivated land was positively correlated with multiple pollution indicators at two scales.
In this study, the rank evaluation method was used to comprehensively assess engineering applications for integrated multi-pond constructed wetlands (MPCWs) using a multi-dimensional evaluation system. We used pollutant purification performance, sewage storage capacity, vegetation ecological restoration, and economic investment as indicators for the evaluation. The results showed that the application of large-scale integrated MPCWs for controlling non-point source pollution was helpful for intercepting pollutants. Accumulated and purified reclaimed water was available for nearby rural agricultural water use. The implementation of MPCWs can result in water savings, pollution reduction, water resource allocation, and sewage reuse. The inclusion of vegetation within MPCWs was beneficial for ecological vegetation restoration and sewage purification. Given the economic investment requirement for MPCWs and the high potential security risks of deep-water MPCWs, we proposed application suggestions for different groups of MPCWs based on functional requirements. Shallow free water surface flow constructed wetlands could be used in populous areas with small volumes of highly polluted water, and eco-floating treatment wetlands could be used in sparsely populated areas with large volumes of highly polluted water. The scientific application of different groups of MPCWs also requires consideration of other factors, such as local special land resource endowments, pollution source structures, and the allocation of rural agricultural water resources.
In this paper, we consider the rainwater runoff prevention and control technology demonstration area of the Jinze water source area in Qingpu District, Shanghai - Dalian Lake; the research area is a national major water project from the “13th Five-Year Plan”. Our study includes systematic research analysis on the type and slope of the riparian zone, the nature of the riparian soil, and the species of indigenous plants in the demonstration area; the study provides essential data to support subsequent research on the use of experimental rainwater gradient control technology in the riparian zone. The analysis shows that the riparian zone in the demonstration area is comprised of near-natural and rigid riparian, with gentle slopes. The aquatic and terrestrial plants in the zone with the largest population include lotus, reed, and herbaceous plants, respectively. Among the sampling sites in the study area, the average total nitrogen content of the soil in the adjacent farmland fluctuated around 0.95 g/kg, while the soil near the inlet gate was measured at 0.42 g/kg. The total phosphorus content of the soil in the adjacent residential living area, fish pond culture, and farmland area was more than 1.58 g/kg, while the soil at the lakeshore berm was measured at 1.10 g/kg. The average organic matter content was 11.30 g/kg, with higher values recorded in the densely planted area. These results confirm that local fishpond farming and agriculture have contributed to pollution of the soil environment.
In this paper, we use hydrology and water quality survey data around Dalian Lake to assess the environmental status of the water and surface runoff pollution in the Dalian Lake demonstration area. The results show that the water quality of the Jinze water source can largely satisfy class Ⅲ standards for surface water; however, given seasonal differences for some indicators, the water quality of the Jinze water source fails to meet the standard on a consistent basis. The water body surrounding the Dalian Lake demonstration area is predominantly slow flow (flow rate: 0 - 0.03 m/s), with low transparency and neutral or slightly alkaline water (pH = 6.63 - 9.67); these conditions render the area susceptible to forming water bloom. Pollution from nitrogen and phosphorus nutrients at each sampling point was significant, and seasonal differences were noticeable; the water quality in spring and summer is generally better (class Ⅱ—Ⅲ), and some water bodies meet class Ⅴ standards in autumn and winter. The concentration of rainwater runoff in the Dalian Lake demonstration area has a noticeable initial effect. The average concentration of nitrogen and phosphorus in the underlying water is higher than the class Ⅴ standard for surface water, and the pollution is likewise more significant.
This paper provides an overview of the technical achievements in A2/O upgrading during the 11th and 12th Five-Year Plans as well as the current successful operation of the improved A2/O process. We summarize the measures used for upgrading the A2/O process of municipal wastewater treatment plants under high discharge standards with respect to in-situ optimization and advanced treatment. Finally, we review the operating state of representative A2/O upgrade demonstration projects and offer suggestions for optimization and promotion of the A2/O process.
Understanding the impact of dissolved organic matter (DOM) on the denitrification process is critical to addressing the challenges associated with nitrogen removal in urban river treatment. In this paper, we show that DOM in urban rivers are mainly comprised of small-molecule fulvic acids. The humic acid content and aromaticity of the DOM, moreover, were found to be low. Compared with the control case, DOM can promote the denitrification process; specifically, the removal efficiency of TN and NO3–-N in the DOM-added group increased by 7.24% ± 0.36% and 23.52% ± 1.17%, respectively. DOM with an acetate group had an even better effect on the removal of TN and NO3–-N, reaching 74.48% ± 1.29% and 98.62% ± 0.07%, respectively. Microbiological analysis showed that the DOM-added group can significantly increase the diversity and richness of the bacteria community compared with the control case. However, the relative abundance of the heterotrophic denitrifiers Pseudomonas and Brevundimonas as well as the nirK-type denitrifier Paracoccus in the DOM-added group was less than that of the DOM with an acetate group. Additionally, a relatively high concentration of NH4+-N (> 3.7 mg/L) was observed in the DOM-added group. The addition of DOM can significantly increase the relative abundance of Anaeromyxobacter related to dissimilatory nitrate reduction to ammonium (DNRA) functional genes. It is speculated that DOM promotes the denitrification process and induces the DNRA process simultaneously.
In this paper, we provide an overview of the development of emission permit systems domestically and globally, and analyze the problems and technology requirements for an emission permit management system at the initial stage of the National Major Science and Technology Program for Water Pollution Control and Treatment (referred to hereinafter as the “Water Program”) in the Taihu Basin. Based on a summary of technical achievements from the 11th and 12th Five-Year Plans for the Taihu Basin Water Program, a comprehensive set of industrial point source emission permit management technology methods was developed for unit division, control unit pollution load verification, control unit water environmental capacity calculation, assessment of water pollution control and management for key industries, allocation of emission permits, and dynamic monitoring. Furthermore, the effects of implementing a complete set of technologies in Taihu Lake Basin were explored and will serve as a reference for the implementation of a pollution permit management system.
Since the eleventh five-year plan, the National Major Science and Technology Program for Water Pollution Control and Treatment (referred to as the “Water Program”) has developed more than 20 key technologies to assist in restoring the lakeshore zone of Taihu Lake Basin. These solutions overcome the application limitations of a single technology in ecological restoration of the lakeshore zone. This includes technologies for: rebuilding the upwind bank slope to eliminate wave and algae in the ecological restoration area; rapid settlement of sediment for lasting improvements in water quality; multi-level reconstruction technology for aquatic vegetation in an open water area; large-scale cultivation and community construction for optimal allocation and stabilization of aquatic plants; and utilization of aquatic vegetation resources for long-term operation and management, based on the technical requirements for improving soil stability, improving the wetland habitat, and restoring the aquatic vegetation in the restoration area. Hence, a comprehensive technology solution for ecological restoration of different lakeshore zones in Taihu Lake Basin (titled “investigation and assessment of lakeshore zone status, wetland habitat improvement, wetland aquatic vegetation restoration, and long term management”) was formed. The complete technology solution for vegetation restoration in the dike-type lakeshore zone has been successfully applied in Zhushan Bay of Taihu Lake, with the wind wave reduced by 64% and the vegetation coverage rate exceeding 30%. The complete technology solution for vegetation restoration in a gentle slope lakeshore zone was also successfully applied in Gonghu Bay of Taihu Lake; the implementation resulted in coverage of aquatic plants reaching 57%, water depth transparency of more than 110 cm, and a greatly improved biodiversity index. In summary, the research results provide a practical basis for aquatic vegetation restoration and water quality improvement.
In this paper, we propose the concept of “LID (low impact development) Index” and “LID Runoff Reduction Efficiency” based on an analysis of runoff cutting efficiency for different LID technical measures. A map was designed to help quickly select the appropriate LID facility and its proportions according to the pollution reduction target in a built-up area. It shows that when the‘LID index’ increases, surface runoff and pollutants exhibit a similar exponential function form; the larger the LID index, the lower the “LID runoff reduction efficiency”. The model data is easy to obtain and flexible, rendering potential applications worthy of exploration.
To improve the environmental tolerance and nitrogen removal efficiency of an aerobic denitrifier, polyvinyl alcohol (PVA), sodium alginate (SA), and rice hull powder were used as immobilized carriers for an aerobic denitrifier and the performance was subsequently evaluated. The results showed that the optimal ratio of immobilized particles was a mixture of 12% PVA, 8% sodium alginate (SA), 0.5 g rice hull powder, and 10 mL bacterial solution. The immobilized particles had strong stability and mass transfer capability; the removal efficiency of TN was 89.35% ~ 90.12% over 48h. The immobilized particles had good tolerance to pH and rotating speed. When the pH was 11, the removal efficiency of TN was 90%. The removal efficiency of TN and NH4+-N was the highest (91.29% and 93.30%, respectively) when the speed was 120 r/min. The immobilized particles were not resistant to low temperatures (10℃ and 15℃), and the TN removal efficiency was only about 20% at 10℃. The TN removal efficiency, however, achieved 90.59% at 30℃.