进水N/S值对同步脱硫反硝化特性的影响

Effect of Influent N/S Ratio on Characteristics of Simultaneous Desulfurization and Denitrification

研究了不同进水N/S值条件下,不同接种物的厌氧体系的同步脱硫反硝化特性。结果表明:在N/S为0.6或0.4的条件下,3个体系对硫化物的去除率均达到90%以上,其中以进水N/S为0.4时产生的悬浮态硫最多;硝态氮的去除特性与硫化物不同,3个体系对硝态氮的去除率均在进水N/S为1.0时达到100%,且此时N2的产量也最大。可见,尽管同步脱硫反硝化工艺具备同时脱氮及除硫的能力,但其进水N/S的控制值却不相同。对于脱硫而言,最佳的进水N/S为0.4;对于脱氮而言,最佳的进水N/S为1.0。此外,研究发现3个不同接种物的厌氧体系对硫化物及硝态氮的去除途径不同,进水N/S值的影响也有差异。对于接种了厌氧污泥的体系,存在自养反硝化和异养反硝化的竞争,改变进水N/S值可调节二者的竞争,高N/S值会抑制硫化物自养反硝化过程,降低对硫化物的去除率;对于接种脱氮硫杆菌的纯菌体系,多硫自催化反应会与硫化物自养反硝化反应竞争硫化物,降低对硝态氮的去除率,高N/S值会导致出水硝态氮浓度较高;对于添加脱氮硫杆菌的强化厌氧污泥体系,以硫化物自养反硝化过程为主,最佳的N/S为0.4。

In three anaerobic systems with different inoculums, the effects of different N/S ratios in the influent on the characteristics of simultaneous desulfurization and denitrification were studied. The results show that the removal rates of sulfide in the three systems are all more than 90% when the influent N/S ratio is 0.6 or 0.4, in which the maximum suspended sulfur is produced at N/S ratio of 0.4. Whereas, as the influent N/S ratio is 1.0, the removal rates of nitrate nitrogen in the three systems are all close to 100% and the maximum N2 production is obtained. Although the process is capable of simultaneous desulfurization and denitrification, the control conditions of the influent N/S ratio are different. For desulfurization, the optimum influent N/S ratio is 0.4, and for denitrification, the optimum influent N/S ratio is 1.0. In addition, sulfide and nitrate nitrogen in three anaerobic systems with different inoculures are removed in different ways, the influence of influent N/S ratio also differs. For the system inoculated with anaerobic sludge, a competition exists between autotrophic denitrification and heterotrophic denitrification. The competition between two reactions is adjusted by changing the influent N/S ratio. High N/S ratio can inhibit sulfide autotrophic denitrification and reduce the removal rate of sulfide. For the reactor inoculated with pure Thiobacillus, the reaction of polysulfide may compete against sulfide autotrophic denitrification and reduce the removal rate of nitrate nitrogen, since sulfide is limited. High N/S ratio may lead to high-nitrate nitrogen effluent. For the enhanced anaerobic sludge system with Thiobacillus, sulfide autotrophic denitrification is the main reaction, and the optimum N/S ratio is 0.4.