聚乙烯醇固定化微生物新方法的研究

为克服聚乙烯醇(PVA)固定化微生物存在的缺点,本文以聚乙烯醇(PVA)和海藻酸钠(SA)为固定化载体,采用5种不同固定化方法,即PVA-硼酸法、PVA-硝酸盐法、PVA-磷酸盐法、PVA-硫酸盐法、PVA冻融法,制备固定化活性污泥颗粒,研究了固定化微生物颗粒的机械稳定性及生物活性.结果表明,PVA-硫酸盐法制得的固定化微生物颗粒具有较高的机械稳定性和生物活性,该法为固定化微生物的较好方法.对PVA-硫酸盐法固定化条件进行了优化,当PVA浓度为12％、Na2SO4浓度为0.5 mo1·L-1,在含有2％ CaCl2的饱和硼酸中交联1h,Na2SO4溶液中交联4h,得到的固定化微生物颗粒活性较高.通过对PVA-硫酸盐法制备的固定化颗粒的稳定性考察发现,颗粒的机械稳定性和生物活性随时间变化,最后逐渐趋于稳定,使用寿命在30 d以上,具有良好的稳定性.

Immobilization of activated sludge in PVA matrix using innovative methods

The immobilization methods using polyvinyl alcohol (PVA) and sodium alginate (SA) as carriers was developed and used for entrapment of activated sludge. Mechanical stability and microbial activity was compared for five kinds of PVA-immobilized beads of activated sludge, which were PVA-boric acid beads, PVA-sodium nitrate beads, PVA-orthophosphate beads, PVA-sodium sulfate beads and PVA-freezing-thawing beads. The results showed that PVA-sodium sulfate method was the best immobilized one in terms of the microbial activity and mechanical stability. The immobilization conditions for ctivated sludge were optimized. With the PVA concentration of 12%, Na₂SO₄ concentration of 0.5 mol·L^-1, cross-linking in saturated boric acid containing 2% CaCl₂ for 1 h and cross-linking in Na₂SO₄ solution for 4 h, the formed immobilized beads had higher microbial activity. The long-term performance of the PVA-sodium sulfate beads was also studied. The physical characteristics and microbial activity of the beads changed with time and stabilized finally, with the service span more than 30 d.