污水处理厂尾水的电化学脱氮技术

摘要

It is difficult to achieve biological deep denitrification of wastewater due to low content of biodegradable organic matter in tail water from sewage treatment plant. If the tail water discharged into rivers, the eutrophication could be produced due to higher concentration of total nitrogen. Therefore, the study on deep denitrification technology is of important significance for tail water treatment. In this paper, the total nitrogen (TN) removal efficiency of a catalytic electric-oxidation technology and its influence factors, such as electric-current density, HRT, influent pH, etc. , were studied and analyzed. The results showed that total nitrogen can be decreased to 11. 91 mg·L-1 from 26. 40 mg·L-1 (54. 9%) , NO-3-N to 4. 90 mg·L-1 from 18. 03 mg·L-1 (72. 8%) by the catalytic electric-oxidation technology at conditions of current density 32. 67 mA·cm-2, pH 6. 25-7. 02, and HRT 30 min. The NO-3-N removal is dominating in the TN removal of tail water from urban wastewater treatment plant. The results indicate that TN of tail water can be removed efficiently by this technology. The catalytic electric-oxidation technology is of the advantages of operation stability and shock resistance etc. , and could be a basis for advanced nitrogen removal of tail water from wastewater treatment plant.%污水处理厂尾水中因可生物降解的有机物含量较低,无法实现生物深度脱氮,外排仍含有较高浓度的总氮,若排入河流会引起富营养化,因此深入研究尾水的深度脱氮技术具有重要意义.采用催化电氧化技术,以污水处理厂尾水为研究对象,研究了在电流密度、水力停留时间(HRT)、进水pH值等因素的影响下,尾水中总氮的去除.结果表明,催化电氧化技术在电流密度为32.67 mA· cm-2、进水pH值为6.25～7.02、HRT为30 min时,总氮(TN)从26.40 mg·L-1降至11.91mg·L-1,NO3-N从18.03mg· L-1降至4.90 mg·L-1,去除率分别可达到54.9％和72.8％; TN的脱除主要以硝氮(NO3--N)的去除为主.催化电氧化技术能高效去除污水厂尾水中的总氮,且具有运行稳定和抗冲击等优点.为污水处理厂尾水的电化学深度脱氮提供了理论基础.