Steel slag is the solid waste produced by the steelmaking process. At present, there are differences in the treatment and utilization of this waste among countries around the world. The massive accumulation of steel slag not only occupies land, but also the heavy metal elements in steel slag leached by rainwater cause serious pollution to the soil and groundwater, both which threaten the life and survival of the surrounding residents. More and more attention has been paid to the resource utilization of slag because of the gradual promotion of energy saving and emission reduction all over the world. Currently, the fields that utilize slag focus on recycling of steel waste, acting as sinter raw material, dephosphorization of hot metal, road and water conservancy project construction, wastewater treatment material, application of CO₂ capture and flue gas desulfurization or agriculture. Many researchers have carried out research and explorations on the effects of slag on microalgae’s growth and found that slag has enormous potential algal biomasses and huge advantages for promoting microalgae’s growth and the accumulation of metabolites. Under suitable conditions, slag can effectively promote microalgae’s growth and reproduction, as well as promote microalgae’s accumulation of metabolites, especially lipid accumulation. Thus, slag can be used as an ideal nutrient for microalgae. Culturing microalgae with slag can lower the cost and solve the problem of lacking Fe during the process of marine microalgae’s growth. Meanwhile, it can alleviate the phenomenon of the substantial stacking of slag. This study provides new methods for slag’s resource utilization.

As a by-product of the iron and steel industry, steel slag is rich in catalytically active substances and can therefore be used as a solid catalyst. Many studies have shown that the application potential of steel slag in catalysis is huge, which provides new development space for its application, thereby increasing its additional utilization value. This article primarily reviews the research progress in catalytic fields such as catalytic pyrolysis, organic degradation, electrocatalysis, photocatalysis, transesterification, and carbon capture and storage, as well as the modification methods of steel slag. The catalytic performance of the modified steel slag has been further improved, and it has the meaningful characteristics of high efficiency, cleanliness, and low costs.

With the rapid development of deep learning, its application in the field of education has gradually attracted attention. This study introduces a deep learning-based moral education evaluation system for college students. The evaluation of the ideological and political education of college students is an important driving force to strengthen and improve the ideological and political education of college students, and its connotation is very rich. However, at present, there are many difficulties in the evaluation of ideological and political education in colleges and universities, such as narrow evaluation objectives, monotonous evaluation structures, lack of pertinence in the evaluation process, and subjective evaluation standards. The internal mechanism and external mechanism of the evaluation mechanism, the qualitative analysis and quantitative analysis of the evaluation method, the absoluteness and relativity of the evaluation standard, the dynamic and static evaluation process, and the systematic and specialized evaluation are combined to ensure the college students’ thinking the objectivity and effectiveness of political education evaluation.

As a by-product from the metallurgical industry, steel slag contains a large amount of metal elements. In many developing countries, the output of steel slag is huge and the comprehensive utilization rate is low, hence the development of a novel application method for steel slag is of great significance to increase its utilization rate to improve the environment. This paper reviewed the dissolution behavior of Fe, P, Ca and silicate of steel slag under seawater and acidic solutions as an application in the cultivation of different microalgae, such as diatoms, spirulina, and chlorella. This review clarifies that proper pre-treatment of steel slag can effectively increase the dissolved elements of steel slag in the solution and provide more nutrients for the growth of microalgae. Microalgae cultivated with steel slag as a nutrient can be used to produce biodiesel which has a very broad application prospects for cleaner production and environmental protection.

Argon oxygen decarbonization (AOD) slag refers to a byproduct of stainless steel (SS) production, which has caused considerable environmental stress. Finding an effective approach for recycling AOD slag is essential to environmental safety. In this work, batch leaching tests were carried out to explore the leaching behavior of AOD slag and soil. Pot experiments was conducted to analyze the fertilization effect of AOD slag for tall fescue (Festuca arundinacea Schreb) planting. The plant height, biomass, total root length (TRL), root surface area (RSA), root tips (RT), root hairs (RH)), chlorophyll content, malondialdehyde (MDA) content, and antioxidant enzyme activities of the tall fescue seedlings were measured. As indicated from the results, adding AOD slag into soil increased soil pH. The leaching concentration of Ca, Si, Al, Cr of the AOD slag was higher than the original soil, while that of Mg, Mn, and Fe was lower. Low addition rate (≤1%) of AOD slag fertilization was good for plant height, biomass, root growth, and chlorophyll synthesis, whereas high addition rate (≥2%) exerted an opposite effect. Elevating the rate of AOD slag fertilization increased the Cr accumulation in the tall fescue seedling that aggravated damage of reactive oxygen species (ROS). When the AOD slag fertilization was at a low rate (≤1%), ROS scavenging was attributed to the synergistic effects of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) defense systems, while at a high rate (≥2%) of AOD slag fertilization, scavenging of excessive ROS could be mainly due to the CAT defense system.

In this study, Chlorella pyrenoidosa was cultured with different concentrations of Cr(III) and Cr(VI), and the changes in biomass, lipid content, protein content and total sugar content of Chlorella pyrenoidosa under different culture conditions were detected. The effects of Cr(III) and Cr(VI) on the intracellular antioxidant system and related key enzymes of lipid synthesis were analyzed. The results showed that appropriate Cr(III) and Cr(VI) concentrations could make Chlorella pyrenoidosa regulate the contents of SOD, POD, ASA, CAT and GSH in cells, improve the enzyme activity of ACC and promote lipid synthesis. The aim was to investigate the mechanism of lipid synthesis by analyzing the distribution of Cr(III) and Cr(VI) in algal cells. The lipid content of Chlorella pyrenoidosa reached its highest level at 50.43 wt% and 38.00 wt% when both Cr(III) and Cr(VI) concentrations in the culture environment were 0.5 mg/L. These values were 1.37 and 1.03 times higher than the control group, respectively. The addition of appropriate Cr(III) and Cr(VI) concentrations can increase ME enzyme activity and decrease PEPC enzyme activity, shorten the biomass accumulation cycle and prolong the lipid synthesis cycle.