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Commonly used methods to simulate the oxidation−reduction (redox) titration curves include the three-step method and the rigorous method. The simple three-step method simulates the redox titration curve with the assumption that the reaction is complete, which is widely used in undergraduate quantitative analysis courses. For the rigorous simulation method, the concentrations of the components are obtained throughout the titration by solving the equilibrium equation, and then the potential is obtained based on the Nernst equation. However, both methods have certain defects. In this work, a user-friendly program that uses an optimized rigorous algorithm to simulate the redox titration curve of a simple system with n 1 = n 2 = 1 at different potentials was built with LabVIEW. The program was then applied to the teaching of redox titration, and questionnaires from 15 students were used for evaluation. The results showed that the program improved students' understanding of the principles of redox titration and deepened their graphical impression of Nernst equations.

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BACKGROUND Biological aerated filter (BAF) is an efficient and economical treatment process to cope with the rapid increasing drainage of aquaculture wastewater. Here, GAC and ceramic, which have the combination advantage, was used as filters of BAF system to treat the aquaculture wastewater. The effect of filters in different sequences was also compared. The BAF with GAC at the bottom is named as GAC‐down BAF, and the BAF at the top is named as GAC‐upper BAF. RESULTS Results showed that the removal efficiency of total nitrogen (TN) in GAC‐down BAF was 54.2 ± 1.2% higher than that in GAC‐upper BAF, when the HRT was 3 h and the gas‐water ratio was 5:1. Additionally, it had better phosphorus and COD removal performance in the GAC‐down BAF than those in the GAC‐upper BAF. Microbial community analysis of biofilm attached to different filter layers indicated that the abundances of functional microorganisms like Zoogloea spp., Acinetobacter spp., Pseudomonas spp., Nitrospira spp. on GAC of the GAC‐down BAF were higher than those attached to ceramsite at the same site of GAC‐up BAF. CONCLUSION It was demonstrated that GAC could provide a suitable niche for the growth of functional microbes at the up‐flow BAF system, and plays a key role in pollutant removals from aquaculture wastewater. © 2022 Society of Chemical Industry.