[Treatment of micro-polluted river water by immobilized microorganism technique].

The effect of immobilized microorganism technique on the micro-polluted river water was studied by four kinds of gaia-biological aerated filter (G-BAF), which were formed by special microorganism (BP35) and four different carriers, including haydite, FPUFS, aquamats flexible carrier and artificial aquatic mat. The removal rates of NH4(+) -N, chlorophyll and turbidity were 83.0%-89.0%, 77.5%-89.0% and 84.4%-95.2%, respectively, and they were all higher than the removal rates of COD, UV254 and TP. The FPUFS contained reactive groups, such as hydroxyl, epoxy and acylamide groups, which made FPUFS load a great amount of enzymes and microorganisms. Therefore, the removal rates of pollutants for FPUFS-G-BAF were higher than those for the other three kinds of G-BAF. Hydraulic retention time (HRT) had little effect on the removal rate of NH4(+) -N, while affected the removal rate of COD significantly. When the concentration of dissolved oxygen (DO) increased from < 2 mg/L to > 4 mg/L, for the four kinds of G-BAF, the removal rates of COD and NH4(+) -N increased 11.9%-18.0% and 12.7%-16.1%, respectively. The result of GC-MS showed that the technique of G-BAF could effectively degrade the macro-molecule refractory organics into small-molecule substance.

A novel method to synthesize polyaluminum chloride with a membrane reactor.

Al13 or Alb is usually regarded as the most efficient species of polyaluminum chloride (PAC), the performance flocculant for water treatment. This paper was intended to report a new method to synthesize PAC with high content Alb, by using the membrane reactor. NaOH solutions were managed to permeate slowly through the micropores of ultrafiltration membrane into AICl3 solutions under the suitable transmembrane pressure(TMP). Meanwhile NaOH drops size was limited to nano-scale, resulting in dramatical reduction of the characteristic diffusion time and great increment of contact interface between the strong base and Al ions in solution to favor the formation of Al(OH)4-, the precursor of Al13, so few precipitates and much Alb are produced. When the initial concentration of AlCl3/NaOH is 0.40/2.0 (mol/L), MWCO = 10000, TMP = 0.0085 MPa, T = 305 K and B (molar ratio of OH-/Al3+) = 2.25, the quantity of Alb attains about 80%. The results of 27Al-NMR determination showed that the Al13 content is equal to Alb content. And our PAC product has shown better flocculation effects than the commercial product.