高负荷厌氧氨氧化EGSB反应器的运行及其颗粒污泥的ECP特性

高效性是厌氧氨氧化(anaerobic ammonium oxidation,anammox)生物脱氮工艺的优势,污泥颗粒化则是生物反应器高效性的重要原因。控制进水亚硝酸盐浓度为360mg·L-1,回流比为0.5,经过230d的连续运行,逐步将厌氧氨氧化膨胀颗粒污泥床(expanded-granular sludgebed,EGSB)反应器(1.1L)的水力停留时间由6.9h缩短至0.30h,获得的容积基质氮去除速率为50.75kg.m-3·d-1,是原有世界最高水平的2倍。在此工况下获得的高负荷厌氧氨氧化颗粒污泥的平均粒径为(2.51±0.91)mm,比污泥厌氧氨氧化活性为1.899kg·(kgVSS)-1·d-1,胞外多聚物(extracellular polymers,ECP)总含量达143.00mg·(gVSS)-1。随着反应器容积基质氮去除速率的提高,反应器内厌氧氨氧化颗粒污泥胞外多聚物含量增加,其中蛋白质含量增加更快,蛋白质的"超量产生"致使颗粒污泥的PN/PS增大,易随水流失。

Granulation and characteristics of extracellular polymers of anammox sludge in high-load EGSB reactor

High effectiveness is one of the most attractive advantages of the anaerobic ammonium oxidation (anammox) process for nitrogen removal from ammonium-rich wastewater.Granulation is considered to play a vital role in development of high-load bioreactors.The hydraulic retention time (HRT) of the 1.1 L anammox EGSB (expanded-granular sludge bed) reactor was progressively shortened from 6.9 h to 0.30 h; while the influent nitrite concentration was fixed at 360 mg·L~(-1) and the effluent recycling was maintained at 0.5 constantly.A super high nitrogen removal rate, 50.75 kg·m-3·d~(-1) was recorded, which was 2 times of the highest value reported before.Granulation of the anammox microorganisms occurred in the high-load anammox EGSB reactor.The average diameter of the high-load anammox granules was (2.51±0.91)mm and the specific anammox activity reached 1.899 kg·(g VSS)~(-1)·d~(-1).The extracellular polymers (ECP) content was 143.00 mg·(g VSS)~(-1), which was amazingly high when compared to heterotrophic microbial granules.The extracellular proteins increased at a higher rate along with the increase of hydrodynamic shear stress, resulting in over-production of extracellular proteins.Thus the stability of the anammox granules decreased and sludge washout became inevitable.