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The research status of nanofiltration technology to remove nitrate in water environment is reviewed. The mechanism of nitrate removal by nanofiltration membrane (including Donan effect, dielectric effect and steric hindrance effect） is introduced in detail, and the formation principle of its rejection mechanism is introduced. It focuses on the influencing factors of nanofiltration membrane in the process of nitrate rejection (nanofiltration membrane itself, pressure, temperature, salt concentration, pH and magnetic field, etc.） and analyzes in detail each influencing factor in the process of nitrate rejection by nanofiltration membrane. Finally, the retention mechanism and influencing factors of nanofiltration membranes are summarized. [ABSTRACT FROM AUTHOR]

The domestic nanofiltration membrane is used to remove nitrate ions in the water environment, and the factors affecting the retention performance and flux of the nanofiltration membrane，such as the concentration of the inlet liquid? the flow of concentrated water, the pressure? and the temperature are studied・ The results show that the increase in pressure is beneficial to increase the rejection rate and prod・ net water flux of the nanofiltration membrane, the optimal pressure is 0.7 MPa, and the rejection rate and product water flux can reach 75. 0% and 153.7 L/(m2 • h) ;Properly increasing the inlet water temperature can increase the rejection rate of the nanofiltration process, the best inlet water temperature is 39 ・ 3 °C ・ The feed concentration has a significant impact on the rejection process, the lower the feed concentration, the better the retention effect of the nanofiltration membrane. [ABSTRACT FROM AUTHOR]

The sources and characteristics of vegetable waste were discussed in the present study. The technical features, advantages, and disadvantages of different vegetable waste resource utilization modes, including aerobic composting of vegetable waste, association between "waste-fodder-fertilizer" and "waste-worm-fodder-fertilizer" planting and breeding, "waste-biochar-fertilizer" returning and soil amelioration, "waste-biogas-fertilizer" energy utilization, and "waste-mushroom-fertilizer" integrated utilization modes were analyzed. Furthermore, the limiting factors and development directions of the full utilization of vegetable waste were discussed. These can be provide a scientific basis for resource utilization of vegetable waste in China. [ABSTRACT FROM AUTHOR]

With rapid urbanization, underground pipeline systems are becoming more and more complex, and the risks of underground pipeline systems have increased significantly. The number of underground gas pipeline accidents in China is high, and the casualty consequences of their accidents are much higher than those of other underground pipelines. Risks posed by other underground pipelines to the underground gas pipeline system during operation are focused by those in the gas industry. In order to perform a qualitative, quantitative and systematic risk assessment of underground pipeline systems, this paper integrates two system analysis methods, STAMP and BN, to establish a STAMP-BN model, to identify system risks and causal factors based on the STAMP model, and to perform a quantitative risk assessment using BN modeling based on STAMP results and safety control structures. The model of STAMP-BN was applied to underground pipeline risk assessment, the results show that the main intermediate cause of underground gas pipeline leakage is the earth moving operation of the third-party company, and reveal the root cause of the vulnerability of the third-party company and the gas company. It is concluded that strengthening the third-party company's operational level coordination and the gas company's ability to coordinate arrangements, incident response, and identification of chronic hazards posed to other underground pipelines is key to risk mitigation. [ABSTRACT FROM AUTHOR]

This paper systematically summarizes the main mechanism of the modified zeolite materials to remove nitrate from aqueous solution. The adsorption performance and influencing factors of different surfactants and metal modified zeolite materials in nitrate are introduced. The regeneration effect of modified zeolite materials is further analyzed. The future development trend of nitrate removal of modified zeolite materials is expected. [ABSTRACT FROM AUTHOR]