基于碳源条件的燃料乙醇生产废水脱氮工艺优化

某厂稻谷燃料乙醇DDG废水处理工艺因好氧进水碳氮比失调，导致出水TN难以达标。通过对反硝化系统碳源种类的筛选，寻找适宜的碳源并对废水处理系统工艺进行调整，以提升反硝化脱氮效率。碳源筛选实验在葡萄糖、乙醇和清液(原废水)，3种碳源条件下进行。通过考察实验系统pH和TN浓度的变化，对反硝化系统投加不同碳源时TN去除速率，以及相应碳源条件下的运行成本进行对比。结果表明：乙醇作为碳源时系统的TN去除速率最大，为8.33 mg·(L·h)⁻¹，是清液为碳源时的1.1倍、葡萄糖为碳源时的1.18倍；而清液作为碳源的运行成本是乙醇为碳源的9%、葡萄糖为碳源的37%。综合对比反硝化投加不同碳源情况下的脱氮反应速率和运行成本，以清液作为碳源来调整脱氮工艺是最佳方案。经现场工艺验证，当A/O系统进水TN为300~600 mg·L⁻¹、投加清液量使废水中COD/TN达到12.1以上时，可确保该厂废水处理系统经处理外排废水TN稳定在50 mg·L⁻¹以下。上述研究结果可为DDG废水的处理提供经济合理的碳源补充方案，并能为可生化性较好的发酵行业废水处理提供参考。

Optimization of denitrification treatment process of fuel ethanol wastewater based on carbon source

The C/N ratio in the A/O influent of the the rice fuel ethanol DDG wastewater treatment process in a plant was too low to meet the the discharge standard of total nitrogen for the effluent. In this study, the carbon sources in the denitrification system were screened, and a suitable carbon source was determined and the wastewater treatment process was adjusted for the increase of denitrification efficiency. The carbon source screening test was conducted among the three carbon sources of glucose, ethanol and clear liquid (raw wastewater). The changes of pH value and total nitrogen concentration in the the reaction system were invetigated, then the total nitrogen removal rates and operating costs were compared when different carbon sources are added to the denitrification system. The results showed that the when ethanol was taken as carbon source, the fastest removal rate of total nitrogen occurred with a value of 8.33 mg·(L·h)−1, which was 1.1 or 1.18 times of the carbon source of glucose or clear liquid (raw wastewater), respectively. The operating cost with the carbon source of raw wastewater was 9% of ethanol and 37% of glucose, respectively. Through the comprehensive analysis and comparison of denitrification reaction rate and operating cost among different carbon sources additions for denitrification, the best choice was to add raw wastewater to adjust A/O denitrification process in this wastewater treatment plant. After verification in field process, when the total nitrogen in the influentt of A/O system was about 300~600 mg·L−1 and the COD/TN ratio in the wastewater was above 12.1 by adding raw wastewater, the effluent total nitrogen concentration could be stablized lower than 50 mg·L−1. The research provides an economic and reasonable carbon supplement scheme for DDG wastewater treatment, and provides a reference for fermentation wastewater treatment with good biodegradability.