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The ground water-source heat pump system for the plant factory lacks a scientific operation strategy to solve the problem of high energy consumption in winter and summer. It is very difficult and uneconomical to change the operation conditions by experimental means to obtain actual operation data. The current study aims to build a TRNSYS simulation model of the ground water-source heat pump system of Shanghai Chongming Natural Light Plant Factory. For the heating season, the simulation of energy consumption was 2315 GJ. Compared with the actual energy consumption, the relative error is -0.98%, which indicates that the simulation results are accurate and the simulation model developed is appropriate and usable. Numerical simulations for the whole year on this basis yielded that the plant factory energy supply system operates from November to March with a heating energy consumption of 3530.84 GJ and from June to September with a cooling energy consumption of 1126.24 GJ. In most cases, the indoor temperature fluctuates within a reasonable range, but in the summer high-temperature season, the plant factory temperature will reach above 40℃, which seriously affects plant growth. After optimization, the plant factory stops production in July and August, and the system stops running, the results are that the optimized system can save 56% of the annual cooling energy consumption, totalling 767.48 GJ, which can reduce the costs by 160,318.05 RMB.

Dairy slurry could be a significant source of nitrogen (N) for plants, but mismanagement can lead to atmospheric ammonia losses or nitrate leaching into groundwater. To make the use of dairy slurry efficient and reasonable, the loss of N pollution to the environment should be reduced. We used repacked lysimeters to comprehensively determine ammonia emission and N leaching losses in an alfalfa–soil system. The application of dairy slurry had no significant effect on alfalfa yield at the same rate of N application in comparison to chemical fertilizer, and adding humic acids significantly increased yield by about 12%. However, the application of dairy slurry increased the ammonia emission rate significantly, leading to an increase in the cumulative amount of ammonia emission, while the addition of humic acids reduced the ammonia emissions by 11%. Chemical fertilizer and dairy slurry application significantly increased nitrate leaching compared to the control treatment, while the addition of humic acids can significantly reduce ammonium N leaching. Dairy slurry was proven to be as effective as chemical N fertilizer in achieving the optimum biomass, and adding humic acids can significantly reduce N loss to the atmosphere and groundwater. This study showed the possibility of replacing chemical fertilizer with dairy slurry in alfalfa production and the advantages of humic acids' addition to alfalfa to maintain production yield and improve environmental friendliness. [ABSTRACT FROM AUTHOR]

In this paper, a novel amino-functionalized Fe3O4-MnO2-SiO2-NH2 adsorbent material was prepared by successive modifying Fe3O4 with KMnO4 and SiO2 to remove heavy metal ions in mixed solution of Pb(II), Cu(II), and Ni(II). The adsorption experiments showed that initial pH value had a significant effect on the adsorption capacity of the materials for heavy metals in solution. Moreover, the materials exhibited strong selective adsorption for Pb(II). Transmission electron microscopy (TEM) results showed that the innermost dark center was the Fe3O4 core with a thickness of about 200 nm, and the outermost light circle was a coated SiO2 shell with a thickness of about 30 nm, while MnO2 can be seen between the dark center and the light circle. Various factors affecting the uptake behavior such as contact time, temperature, pH, and initial concentration of Pb(II) were investigated. The kinetics were evaluated utilizing the Lagergren pseudo-first-order and pseudo-second-order models. The best interpretation for the equilibrium data was given by Freundlich isotherm. The recycling experiment showed that Fe3O4-MnO2-SiO2-NH2 kept its adsorption and desorption efficiencies constant over 5 cycles. Importantly, the Fe3O4-MnO2-SiO2-NH2 was able to selectively remove over 73% of Pb(II) not only in mixed solution of Pb(II), Cu(II), and Ni(II) but also remove 94.7% in only Pb(II) solution at pH 6 within 1 h. [ABSTRACT FROM AUTHOR]