壳聚糖联合酶诱导碳酸盐沉淀处理铜废水的劣化现象和强化机理研究

Implication and enhancement mechanism of chitosan-assisted enzyme-induced carbonate precipitation for copper wastewater treatment

已有研究表明,酶诱导碳酸盐沉淀法在加固软黏土和钙质砂方面有很大潜力。然而,这一方法在稳定、固化重金属离子方面的应用却十分有限。此外,在铜离子作用下,碳酸盐沉淀形态及其处理效率的关系尚不清楚。提出一种壳聚糖联合酶诱导碳酸盐沉淀法进行铜废水处理,结果表明此方法可以显著提高脲酶活性,保证尿素能够充分得到水解。通过一系列试管试验和模拟试验发现,较高与较低的脲酶活性均会劣化处理效率。当pH高达9时溶液会大量产生铜氨络合物,降低处理效率。壳聚糖和钙源的添加能够有效抑制pH的升高,防止铜离子对脲酶活性的抑制作用,具有良好的应用前景。

Studies have shown that enzyme-induced carbonate precipitation(EICP)has great potential for strengthening soft clays and calcareous sands.However,the applications of the EICP method to solidification and immobilization of heavy metal ions are remarkably limited.In addition,the speciation of carbonate precipitation and its linkage to the degradation of the treatment efficiency when subjected to the effect of Cu^(2+) remain unclear.In this study,a chitosan-assisted enzyme-induced carbonate precipitation measure to improve the copper wastewater treatment efficiency by securing the urease activity was proposed.The results from the test tube experiments and numerical simulations showed that both higher and lower NH^(+)_(4) concentrations,corresponding to higher degrees of urea hydrolysis,have implications for treatment efficiency.When the pH is as high as 9,the solution will produce a large amount of copper ammine complexes,reducing the processing efficiency.The calcium source and chitosan additions are considered useful in modifying pH surrounding conditions and preventing the urease activity from degrading by the effect of Cu^(2+).