N/S值和电子受体对厌氧生物脱氮除硫的影响

Effect of N/S Ratio and Electron Accepter on Anaerobic Biological Denitrification and Desulfurization

分别以NO_3^-和NO-2为氮源,在9个不同N/S值条件下进行厌氧脱氮除硫试验。结果表明:当N/S值>0.67时,硝酸盐体系的出水硫化物浓度均小于1.0 mg/L,硫化物去除率达99%,脱硫速度明显高于亚硝酸盐体系,即N_3^-是脱硫最佳的电子受体。硫化物加速了对NO-2的去除,即使将N/S值提高为4,对NO-2的去除率仍高达99%,硫化物是去除NO-2适宜的电子供体。硝酸盐体系的出水单质硫浓度明显高于亚硝酸盐体系,亚硝酸盐不利于单质硫富集。硝酸盐体系的N/S值从0.2增大为1时,大部分的N_3^-被转化为N2(产生氮气14~58 m L);而当硫化物不足时(N/S值从1继续增大为4),NO_3^-不能被全部转化为N2。对于亚硝酸盐体系而言,去除的NO-2基本全部生成N2。当NO-2受限时(N/S值<0.4)产生了大量的N2(48 m L),此时部分进水氨氮可能被去除。硝酸盐、亚硝酸盐体系中,硫化物过量时(N/S值=0.2),电子数的差均较高,分别为59%和66%;二者分别在N/S值为1、2时,电子数的差为零,电子得失达到平衡。

The experiments of anaerobic biological denitrification and desulfurization were conduc- ted under 9 different N/S ratios when nitrate and nitrite were chosen as nitrogen source respectively. The results showed that sulfide concentration in the effluent from the nitrate system was less than 1.0 mg/L when the N/S ratio was higher than 0.67, and 99% of sulfide was removed. However, the desulfuriza- tion rate was slower when nitrite acted as electron acceptor, The nitrate was the most suitable electron ac- ceptor for desulfurization. Sulfide accelerated the removal of nitrite. The removal rate of nitrite was higher than 99% even the N/S ratio was increased to 4. Therefore, sulfide was a suitable electron donor for denitrification in the nitrite system. Nitrite could resist generation of sulfur because element sulfur con- centration in the effluent from the nitrate system was obviously higher than that in the nitrite system. When N/S ratio was increased from 0.2 to 1 in the nitrate system, the majority of nitrate could be trans- ferred into nitrogen gas （ 14 mL to 58 mL）. When the N/S ratio continued to be increased from 1 to 4, not all nitrate could be transferred into nitrogen gas. While in the nitrite system, almost all the removed nitrite was transferred to nitrogen gas. A large amount of nitrogen gas was generated （48 mL） when ni- trite was limited （ N/S ratio less than 0.4） since ammonia nitrogen could be removed. In the nitrate and nitrite systems, the difference between the number of electrons was as high as 59% and 66% when sul- fide was excessive （N/S ratio of 0.2）. The difference between the number of electrons was zero with a balance between electron gain and loss when the N/S ratio was increased to 1 and 2 in the nitrate and ni- trite systems, respectively.