Keynote Speakers

Prof. Xueying Liu, Zhejiang University of Water Resources and Electric Power, China

Title: Analysis of Water Engineering Heritage and Its Value System

Abstract:Water engineering heritage is a engineering heritage closely related to water . It is a specific part of human cultural heritage. It has both cultural attributes and specific engineering attributes. This paper introduces the basic characteristics and types of water engineering heritage, discusses the definition of water engineering heritage and the basic framework of heritage composition,  analyzes the scientific and technological value, cultural and artistic value, environmental and ecological value of water engineering heritage, so as to provide reference ideas for the protection of water engineering heritage. Meanwhile, it will share various categories encountered in recent field investigation and exploration. We are looking forward to exploring and communicating with experts and scholars at home and abroad.

 

Vice Dean/Prof. Zheng Chen, Guangxi University, China 

Title: The effect of microenvironmental conditions on the formation of passive film of steel bar in concrete

Abstract: The corrosion of steel bar is the most significant cause resulting in the deterioration of steel bar concrete structures. However, it is generally accepted that the highly alkaline environment produced by concrete could promote the formation of passive film on the steel bar surface, thereby protecting the steel bar from corrosion. In addition, there exists the CaOH+ in the concrete pore solution, and the CaOH+ with high activity could adsorb easily on the steel surface to change the properties of surface. Nevertheless, the effect of CaOH+ on the passivation of steel bar was received less attention in previous studies. In this work, the passivation mechanisms of steel bar with considering the effect of CaOH+ were studied by experiments and DFT simulations. The differences in the electrochemical behavior of the steel bar in the NaOH solution and Ca(OH)2 solution indicate that the CaOH+ is the important factor affecting the passivation of steel bar. The zeta potential test suggests that not only OH but also CaOH+ could adsorb on the steel surface in the concrete environment. The DFT simulations were conducted to investigate the adsorption of OH and CaOH+ on iron surface. The results show that the interaction of iron surface with CaOH+ is stronger than OH, and the adsorption of CaOH+ could obviously decrease the spin value of iron surface and thereby weakening the interaction between iron surface and O2. This work provides the deeper understanding of the passivation mechanism of steel bar in concrete.

 

Prof. Hongguang Liu, Shihezi University, China 

Title: Research and Prospect of subsurface drainage technology in arid area

1. Background
The cultivated land area of Xinjiang is about 78 million mu, of which the saline alkali cultivated land accounts for about 40% of the cultivated land area. At present, the non saline alkali soil is also in danger of becoming salinization in the future. After the extensive application of drip irrigation under mulch film in Xinjiang, it has played a role in saving water, increasing production and controlling salt. However, the original drainage channel has been gradually abandoned, and the mode of "drip irrigation without drainage" has been formed. Drip irrigation under mulch can moisten the root layer in a short time and make the root layer desalting temporarily, but it will aggravate the soil secondary salinization in Xinjiang in the long term. The drainage measures of drip irrigation and leaching are very effective methods for saline alkali land improvement, among which open ditch drainage and concealed pipe drainage are most commonly used. Compared with open ditch drainage, subsurface drainage not only has the advantages of less land occupation, zero pollution and long service life, but also meets the development trend of agricultural mechanization and intensification. The application prospect of subsurface pipe drainage in Xinjiang is broad.


2. Application
Under the condition of drip irrigation under plastic film, the use of subsurface pipe drainage has been tried for nearly 10 years. At present, the total area is about 666.67 ha(hectare). The study area is located in AnJiHai irrigation area, which is located in the area of West Bank canal and Anxia alkali drainage canal built in 1960s. In 2010, three ditches and one branch (buried depth of 2.3-2.4 m) were excavated in the test site, with the spacing of 518.9 m, 502 m, 519.1 m, 510.6 m and 898 m, respectively, connected with the branches for drainage and salt drainage. From 2012 to 2020, the experiment was carried out. The samples were distributed in the experimental site, the groundwater level and soil salinity were monitored, and the total soil salt content was analyzed.


3. Research and main conclusions
First ,The combination of drip irrigation under plastic film and subsurface pipe drainage makes the desalination effect of soil root layer remarkable. The maximum RMSE(Root Mean Square Error) value and minimum R2 of salt content are 0.7274 and 0.8765 respectively, which are in the acceptable range.
Second, Under the condition of subsurface drainage and drip irrigation under plastic film, the average desalination rate of 0 ~ 80 cm soil layer reached 42.67%, and on the whole, the total salt content of 0 ~ 80 cm soil layer decreased by 13.50%. After cotton harvest, the salt content in the upper layer of soil increased significantly. Compared with the harvest period before the formation of frozen soil, the salt content of 0 ~ 80 cm soil increased by 9.79%.
Third, Compared with that before sowing, the salt content of 0-80cm soil decreased by 5.02%, and that of 0-200cm soil decreased by 2.53%, indicating that the total salt content in soil would continue to decrease after long-term use of drip irrigation leaching and subsurface pipe salt drainage.


4. Prospects and Prospects
First, modern agriculture requires high yield, high efficiency, intensification and mechanization, which will make the underground pipe drainage have more application space. Second, the development of industrial technology provides strong support for the development of subsurface drainage. Then, Further research and practice are needed. In practice, the production units are eager for success, eager for quick success and instant benefit, and deny the underground pipe drainage. In the future, we have to think about it : Water shortage and soil salinization coexist. How much water is used to wash salt and how to wash salt is reasonable? Salt washing period and non salt washing period are the alternation process of soil drying and wetting. How is salt movement? The problem of silting up after years of use needs to be studied continuously.

 

Prof. Tao Zhang, China Agricultural University, China 

Title: Biomass Stabilization: Phosphorus Fixation and Utilization

Abstract: One of the reality before us today is the increasingly exhausted of phosphorus (P) resource. Animal manure, produced from livestock and poultry production, contains large amount of P. The treatment of P recovery from animal manure is regarding as a promising technical for food security. Recently, numbers methods to treat waste agricultural biomass have been considered. Amongst, pyrolysis to generate biochar has attracted attention. Biochar, has a rich surface chemistry, interesting nanostructures, abundant oxygen-containing functional groups, and a large porous structure, regarded as a potential sorbent. Due to the limitation of P-solubilization and selectivity recovery processes caused by the existing of organic phosphorus, sparingly soluble P, and many other kinds of substances, we have conducted a series of explorations on phosphorus solubilization and selectivity adsorption. For P solubilization, organic phosphorus and sparingly soluble P can be decomposed, dissolved, and released under thermal conversion (ultrasound, hydrothermal process, microwaves digestion). Coupling degradation and oxidation process, such as microwaves digestion and NaOH (or H2O2-HCl), ultrasound/H2O2, and hydrothermal assisted process have been developed. For P fixation, cation loaded biochar, such as magnesium modified corn biochar, ferric oxide hydrate modified biochar, calcium modified biochar, can be synthesized to enhance P adsorption selectivity. The adsorption isotherm, adsorption kinetics, thermodynamics have been investigated. The P saturated adsorbed modified biochar could continually release P in soil environment and its fertilizer property has been analysis.