强化厌氧污泥体系同步脱硫反硝化特性研究

以硫化物为电子给体的自养反硝化厌氧体系是代替传统异养反硝化工艺处理低C/N比含氮废水的有效工艺,可以同时去除硫化物和硝酸盐.将脱氮硫杆菌菌悬液接种到厌氧污泥体系中,脱氮硫杆菌快速富集,采用5组进水比N/S比不同的反应瓶进行试验,运行15d后,测定不同时段的出水硫化物、硝酸盐、亚硝酸盐、硫酸盐浓度等指标,考察强化厌氧污泥体系去除硫化物和硝酸盐的特性,并对生化反应机制进行初步研究.结果表明,强化厌氧污泥体系运行3h后,进水中90%的硫化物被去除,硫化物的去除与进水N/S比无关,硫化物(以S计)去除速率高达20～24g·(m3·h)-1,是相关文献报道的10倍左右;运行6h后,进水中65%的硝氮被去除,硝氮的去除负荷随着进水N/S比的提高而增大,最高达到940g·(m3·h)-1,约为硫自养反硝化体系硝氮去除负荷的2倍,此时体系中亚硝氮积累,最高浓度达到93mg·L-1,进水N/S比低的条件下,6h后亚硝氮消失,进水N/S比较高时,21h后出水中未检测到亚硝氮.表明强化厌氧污泥体系停留6h后可以实现同时去除硫化物和硝酸盐,但硝酸盐首先转化为亚硝氮.与以往不同的是研究发现硫化物与生物硫粒产生多硫化合物的链式反应,是硫化物迅速转化的主要途径,此外,还原硝氮的电子给体并不来源于硫化物,可能主要来源于体系中产生的单质硫.

Characteristic of Autotrophic Denitrification in Bioaugmented Anaerobic System

An autotrophic denitrification process using reduced sulfide as electron donor in anaerobic system is proposed as an efficient and cost effective alternative to conventional heterotrophic denitrification for low C/N ratio wastewaters and for simultaneous removal of sulfide and nitrate. A suspended culture of Thiobacillus denitrificans bacteria was fast and efficiently established in anaerobic system. 5 series bioaugmented anaerobic systems with different N/S ratio synthetic influent were set up. Sulfide, nitrate, sulfate, and nitrite concentration in the effluent at every 3 hours were measured after 15 day. The primary objective was to investigate the characteristic of autotrophic denitrification and sulfide oxidation, and to reveal the mechanism of autotrophic denitrification process using reduced sulfide as electron donor in bioaugmented anaerobic system. 90% removal efficiency of sulfide was observed after 3 hours and removal efficiency of sulfide had no reference to N/S ratio. The rate of sulfide oxidation was 20-24 g·(m³·h)^-1, which was 10 times higher than that have been reported in the literatures. Maximum removal efficiency of nitrate was 65% after 6 hours, which enhanced with increasing N/S ration of influent. The result showed bacteria reduced nitrate to nitrite at first step, and resulted in accumulation of nitrite to 93 mg\5L^-1 to the large extent. Accumulated nitrite was disappear on low influent N/S ratio condition after 6 hours, and need 21 hours on high influent N/S ratio condition. So, complete sulfide and nitrate removal was achieved during 6 hours. The results revealed that the sharp decreasing of sulfide concentration attributed to the reaction between sulfide and biosulfur particles to form polysulfide anions. In addition, biosulfur produced in 3 hours was the main source of electron donor for reducing nitrate.