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好氧颗粒污泥(aerobic granular sludge, AGS)是微生物在好氧环境中自凝聚形成的一种生物聚集体[1-2],其具有沉降性能优良、生物量高、耐有机负荷、同步脱氮除磷等优点[3-4]。这也使得AGS技术在污水处理领域有着广阔的应用前景[5]。关于AGS的理化特性、影响造粒的因素以及形成机理也有了广泛研究[6-7]。但AGS经长期储存后,颗粒污泥结构破坏、发生解体、微生物活性降低甚至丧失[8]。因此,探索可长期维持AGS储存稳定性及AGS储存后的活性快速恢复的方法是解决该技术工程化应用的关键和技术瓶颈[9-10]。
AGS的储存方法主要为湿式储存和干式储存。在蒸馏水中储存8个月的AGS大多数发生解体,且微生物几乎完全失去活性[11]。湿式储存方法因营养物质匮乏使AGS中的微生物内源呼吸作用增强,促进蛋白分解菌对蛋白质的降解,从而导致其结构稳定性丧失[12]。HU等[13]表明使用纯丙酮溶液干燥AGS可保持其结构完整性,但大部分微生物同样失活。LV等[14]采用丙酮梯度法将AGS干燥储存40 d后,其颗粒状立体结构保持较好,但颗粒内部微生物数量减少且活性显著降低,且使用丙酮干燥好氧颗粒污泥会造成二次污染,在实际工程应用中并不可取。
固定化微生物技术[15]是将特选的微生物固定在选择的载体上,使其高度密集并保持生物活性,有利于微生物抵抗不利环境的影响,其中包埋法在微生物固定化中最为常用,而海藻酸钠作为包埋材料对微生物毒性小且固定化密度高。赵珏等[16]采用琼脂包埋AGS,在4 ℃环境中储存30 d后,经过22 d的重新曝气才完全实现AGS的活性恢复。
因此,本研究为探究在4 ℃下海藻酸钠凝胶储存AGS的可行性,以海藻酸钠凝胶为载体进行AGS的储存实验,考察了储存前后AGS理化特性变化以及储存后AGS恢复情况,以期为AGS储存和储存后AGS快速恢复方法的选择提供有价值的参考。
海藻酸钠凝胶储存好氧颗粒污泥及其活性恢复
Storage of aerobic granular sludge by sodium alginate gel and its recovery analysis
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摘要: 采用质量分数11.5%的海藻酸钠凝胶为载体,在4 ℃下避光储存好氧颗粒污泥(AGS) 7个月,并将储存后的AGS进行活性恢复。分析了储存前后AGS理化特性变化以及储存后AGS恢复情况,以期为AGS储存和储存后AGS快速恢复方法的选择提供有价值的参考。结果表明:部分AGS在储存过程中发生解体,颗粒粒径变小,沉降速度、MLVSS/MLSS和脱氢酶活性(DHA)分别下降了43.93%、22.22%和43.34%,说明在4 ℃下使用海藻酸钠凝胶储存AGS具有可行性,该储存方法在一定程度上可维持AGS 的结构完整性和微生物活性。经过9 d的再培养,AGS完全恢复到储存前水平。恢复后的AGS为黄褐色,表面光滑,整体呈球状或椭球状,颗粒粒径主要分布在1.3~2.5 mm,SVI30为31.9 mL·g−1,沉降速度为92.71 m·h−1,胞外聚合物(EPS)质量分数为75.05 mg·g−1,DHA为86.21 μg·(g·h)−1,表明恢复后的AGS沉降性能较好,微生物活性较高。恢复后的AGS对COD、NH4+-N、TN和TP的去除率分别为96.5%、97.8%、82.7%、73.5%,具有良好的除污效果。Abstract: Aerobic Granular Sludge (AGS) was stored at 4 ℃ in the dark for 7 months with 11.5% sodium alginate gel as carrier, and the activity of the stored AGS was recovered. The physical and chemical properties of AGS before and after storage as well as the recovery of AGS after storage were analyzed, in order to provide a valuable reference for the selection of AGS storage methods and rapid recovery of AGS after storage. The results showed that some AGS disintegrated during storage, their particle size became smaller, and the sedimentation velocity, MLVSS/MLSS and Dehydrogenase Activity (DHA) decreased by 43.93%, 22.22% and 43.34%, respectively, indicating that it was feasible to use sodium alginate gel to store AGS at 4 ℃. The storage method could maintain the structural integrity and microbial activity of AGS to some extent. After 9 days of recultivation, the AGS recovered completely. The recovered AGS was yellowish brown with smooth surface and spherical or ellipsoid shape, the particle size was mainly distributed in 1.3-2.5 mm, the SVI30 was 31.9 mL·g−1, the sedimentation velocity was 92.71 m·h−1, the extracellular polymeric substance (EPS) concentration was 75.05 mg·g−1 and the DHA was 86.21 μg·(g·h)−1, which indicated that the recovered AGS had a better settling performance and higher microbial activity. The recovered AGS had good removal effects of pollutants, and the removal rates of COD, NH4+-N TN and TP were 96.5%, 97.8%, 82.7% and 73.5%, respectively.
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Key words:
- aerobic granular sludge /
- sodium alginate gel /
- storage /
- reactivation /
- activity
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表 1 SBR反应器运行参数和条件
Table 1. Operating parameters and conditions of SBR reactor
运行时间/d 各阶段时长/min 曝气量/(m3·h−1) COD、氨氮、总氮和总磷/(mg·L−1) COD容积负荷/(g·(L·d)−1) 进水 曝气 沉淀 排水 闲置 COD NH4+-N TN TP 1 4 338 15 1 2 0.12~0.3 500 80 85 6.7 0.41 2 4 339 14 1 2 0.32 600 90 93 7.5 0.48 3 4 341 12 1 2 0.34 600 90 94 7.8 0.48 4 4 343 10 1 2 0.36 700 100 106 8.4 0.65 5 4 344 9 1 2 0.37 700 100 106 8.6 0.65 6 4 347 6 1 2 0.39 800 110 115 9.2 0.83 7 4 349 4 1 2 0.43 900 110 117 10.6 1.16 8 4 351 2 1 2 0.46 1000 120 124 11.7 1.36 9 4 351 2 1 2 0.5 1000 120 126 11.2 1.36 表 2 AGS储存前后理化特性指标变化
Table 2. Changes of physicochemical properties of AGS before and after storage
储存时间/d SVI30/(mL·g−1) MLSS/(mg·L−1) 沉降速度/(m·h−1) MLVSS/MLSS EPS/(mg·g−1) PN/(mg·g−1) PS/(mg·g−1) DHA/(μg·(g·h)−1) 0 28.7±1.95 24 140 94.63±1.27 0.72 68.60±6.13 41.86±4.61 26.74±2.85 82.65±3.02 210 61.4±2.06 15 720 53.06±2.41 0.56 37.48±5.61 21.96±3.05 15.52±2.56 46.83±2.74 -
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