生物膜强化推流式颗粒污泥自养脱氮反应器启动

Start-up of biofilm enhanced granular sludge process for autotrophic nitrogen removal in a plug-flow reactor

提出了一种推流式一体化短程硝化厌氧氨氧化颗粒污泥反应器的强化启动策略.第1步,在推流式反应器内接种活性污泥并投加固定生物膜填料,通过逐渐提高进水氨氮浓度和曝气量并控制溶解氧在0.2mg/L以下,自养脱氮反应器成功启动并稳定运行,总无机氮去除负荷达1.7kgN/(m^(3)·d).运行期间生物膜逐渐生长、成熟并出现脱落,同时悬浮污泥出现红色颗粒.第2步,填料填充比从20%降低至0,系统的总无机氮去除负荷短暂下降至0.85kgN/(m^(3)·d),平均污泥粒径从270μm降低至163μm.但系统脱氮负荷随着曝气量的增加可迅速恢复,且平均污泥粒径逐渐增加至195μm.结果表明,推流式反应器中悬浮絮体污泥与颗粒污泥可稳定存在,且悬浮污泥系统的脱氮负荷可达1.5kgN/(m^(3)·d),与固定生物膜-活性污泥系统相当.本研究为推流式厌氧氨氧化颗粒污泥工艺的启动提供了可行的方案.

In this study,a novel start-up strategy for single-stage partial nitritation-anammox(SPNA)process was developed in a plug-flow granular sludge reactor.The activated sludge inoculum and biofilm-fixing carriers were simultaneously added into reactor firstly to start up as integrated fixed-film activated sludge(IFAS)process with ammonium input.Under low dissolved oxygen(DO)concentration of<0.2mg/L,the influent ammonium concentration and aeration rate gradually increased until the autotrophic nitrogen removal system performance was stable and a total inorganic nitrogen removal rate around 1.7kgN/(m^(3)·d)was achieved.As the biofilm was formed,matured,and detached repeatedly during the start-up period,red-brown granules were observed in mixed suspended sludge liquid.Then the media filling ratio was adjusted from 20%to 0%,resulting in a temporary decrease of granular size from 270μm to 163μm and total inorganic nitrogen removal rate to 0.85kgN/(m^(3)·d).However,the removal performance was rapidly recovered following the increment of aeration and the average sludge particle size gradually increased by 195μm.The experimental results showed that flocs and particles could be stable co-existed in the SPNA reactor,and the final loading rate of 1.5kgN/(m^(3)·d)could be achieved,which was comparable to that in IFAS mode.Therefore,the start-up method reported could be an effective pathway to fulfill high-rate autotrophic nitrogen removal in plug-flow granular sludge systems.