Department of Mathematics and Applications "R. Caccioppoli", Via Cintia, Monte S. Angelo, 80126, Naples, Italy.
Department of Civil, Architectural and Environmental Engineering, University of Naples Federico II, Via Claudio 21, 80125, Naples, Italy.
Sci Rep. 2022 Apr 29;12(1):7008. doi: 10.1038/s41598-022-10944-z.
The aim of this study was to develop a mathematical model to assess the effect of soluble microbial products production and external carbon source addition on the performance of a sulfur-driven autotrophic denitrification (SdAD) process. During SdAD, the growth of autotrophic biomass (AUT) was accompanied by the proliferation of heterotrophic biomass mainly consisting of heterotrophic denitrifiers (HD) and sulfate-reducing bacteria (SRB), which are able to grow on both the SMP derived from the microbial activities and on an external carbon source. The process was supposed to occur in a sequencing batch reactor to investigate the effects of the COD injection on both heterotrophic species and to enhance the production and consumption of SMP. The mathematical model was built on mass balance considerations and consists of a system of nonlinear impulsive differential equations, which have been solved numerically. Different simulation scenarios have been investigated by varying the main operational parameters: cycle duration, day of COD injection and quantity of COD injected. For cycle durations of more than 15 days and a COD injection after the half-cycle duration, SdAD represents the prevailing process and the SRB represent the main heterotrophic family. For shorter cycle duration and COD injections earlier than the middle of the cycle, the same performance can be achieved increasing the quantity of COD added, which results in an increased activity of HD. In all the performed simulation even in the case of COD addition, AUT remain the prevailing microbial family in the reactor.
本研究旨在开发一种数学模型，以评估可溶性微生物产物（SMP）的产生和外加碳源对硫驱动自养反硝化（SdAD）过程性能的影响。在 SdAD 过程中，自养生物量（AUT）的生长伴随着异养生物量的增殖，主要由异养反硝化菌（HD）和硫酸盐还原菌（SRB）组成，它们能够同时利用微生物活动产生的 SMP 和外加碳源生长。该过程在序批式反应器中进行，以研究 COD 注入对异养物种的影响，并促进 SMP 的产生和消耗。该数学模型基于质量平衡考虑，由一组非线性脉冲微分方程组成，并通过数值方法求解。通过改变主要操作参数：周期持续时间、COD 注入天数和注入的 COD 量，研究了不同的模拟场景。对于超过 15 天的周期持续时间和在半周期后进行 COD 注入，SdAD 代表主要的过程，而 SRB 则代表主要的异养家族。对于较短的周期持续时间和比周期中期更早的 COD 注入，通过增加添加的 COD 量，可以实现相同的性能，从而提高 HD 的活性。在所有进行的模拟中，即使添加了 COD，AUT 仍然是反应器中占主导地位的微生物家族。
