盐胁迫条件下好氧颗粒污泥生长模式研究

Growth Model of Aerobic Granule Under Different Salinities

研究了含盐量分别为1%、2.5%、5%条件下颗粒污泥成长特性,对其表面结构、粒径分布与稳定性进行了评估。结果表明,在颗粒成长初期颗粒较为疏松,粒径和离散度均呈增大趋势；颗粒成熟后粒径密实度增大,粒径大多稳定在0.3-0.5mm左右。成熟的颗粒污泥在含盐量1%下颗粒孔隙率较大,离散度较小,菌胶团细菌占优势,微生物通过胞外多聚物相互聚集,其稳定性较好；而在含盐量5%下其孔隙率和离散度呈现相反趋势,丝状菌占优势,颗粒通过丝状菌的相互缠绕形成,其稳定性较差；但在含盐量2.5%下由于菌胶团细菌与丝状菌均未成为优势菌群,难以维持稳定结构,颗粒发生膨胀自溶,其离散度也变大。研究提出了同质和异质2种生长模式,颗粒粒径分布较窄的成长模式称为同质生长,其颗粒的生长及基质利用条件基本相同,故系统稳定；而颗粒粒径分布较宽的成长模式称为异质生长,其颗粒生长和基质利用条件差异性大,故系统不稳定。

The stability of aerobic granules that developed under salinities of 1%, 2.5% and 5%, respectively, was evaluated using microscopic observations and size distribution. It was found that the size of granules increased and the diversity of size distribution became wider during the granulation period, and the size of mature granules distributed mainly in the range of 0.3-0.5 mm. Granules under the salinity of 1% showed high porosity and narrow size distribution and extracellular polymeric substances （EPS） linked the particles in the granules. In contrast, those under the salinity of 5% showed low porosity and wide size distribution and entanglement of filaments formed the frame work of granules. Disintegration of aerobic granules was found under the salinity of 2.5 %, and the size distribution was found became wider, which may due to the unbalance growth between floc-forming and filamentous microorganisms. Therefore, it is reasonable to conclude that size distribution could effectively describe the stability of aerobic granules, namely, narrow size distribution indicates stability of aerobic granules. Furthermore, granules under low salinity were predominated by the floc-forming bacteria and thus EPS-linking was the main mechanisms of granulation, on the other hand, those under high salinity were predominated by filamentous microorganisms and thus the entanglements of filaments was the main mechanisms of granulation. Two models have been proposed for the growth of aerobic granules. One is heterogeneous growth of which the granule size distributes in a narrow spectrum and the granules growing with this model are stable because the conditions of growth and substrate utility are similar for all granules. Another is homogenous growth of which the granule size distributes in a wide spectrum and granules with this model are unstable.