吡啶在紫外光辐射下的生物降解

吡啶是一种难降解的含氮杂环化合物,难以用单一的生物方法使其有效降解.本研究采用气升式内循环紫外光辐射与生物膜一体化反应器,通过单独紫外辐射降解(photolysis,P)、单独生物降解(biodegradation,B)以及紫外辐射与生物同步耦合降解(photobiodegradation,P&B)3种方法对吡啶进行间歇降解和连续降解,以比较吡啶的降解规律.结果表明,间歇降解过程中,方法 P&B对吡啶的降解速率最快,其次是方法 B,而方法 P的速率最慢.初始浓度为100 mg.L-1的吡啶溶液分别采用方法 P、B和P&B进行间歇降解,其去除速率分别是:4.95、10.2和14.58 mg.(L.h)-1.根据Monod模型求解出吡啶在方法 B和方法 P&B降解下的动力学方程,其饱和常数KS从1 920.4 mg.L-1下降至1 094.1 mg.L-1.采用连续流方式对进水浓度分别为50、100和300 mg.L-1的吡啶溶液分别采用方法 P、B和P&B进行降解,其单位体积平均体积去除速率分别是:15.8(P)、23.1(B)和24.9 mg.(L.h)-1(P&B),且高于间歇降解方法.研究结果表明,紫外辐射与生物膜同步耦合,可以缓解吡啶对生物膜的抑制,并且生物仍能保持其降解吡啶的生物活性,从而提高吡啶生物降解的速率.

Biodegradation of Pyridine Under UV Irradiation

Pyridine, a complex nitrogen-containing heterocyclic compounds, is usually difficult to degrade by means of single biological method. The internal loop photobiodegradation reactor (ILPBR) was used for degradation of pyridine in batch and continuous experiments following three protocols: photolysis alone (P), biodegradation alone (B), and intimately coupled photolysis and biodegradation (P&B) to investigate the regularity of pyridine degradation. The experimental results indicated that pyridine removal rate by P&B was fastest among three protocols in batch experiment, in which protocol B was faster than P. For initial pyridine concentration of 100 mg·L^-1, the pyridine removal rates were respectively 4.95, 10.2 and 14.58 mg·(L·h)^-1 corresponding to protocol P, B and P&B. Pyridine degradation kinetic equations were established based on Monod model, and the saturation constants decreased from 1920.4mg·L^-1 for protocol B to 1094.1 mg·L^-1 for protocol P&B. Protocols P, B and P&B were also used for pyridine degradation in continuous flow and influent pyridine concentration increased from 50 to 300 mg·L^-1, and their average removal rates were respectively 15.8 mg·(L·h)^-1 for protocol P, 23.1 mg·(L·h)^-1 for protocol B and 24.9 mg·(L·h)^-1 for protocol P&B, in which the removal rates were higher than that in batch. Experiments suggested that the inhibition of pyridine to biofilm could be relieved due to UV irradiation in process of intimately coupled UV photolysis and biodegradation, and biofilm had kept its bioactivity degrading pyridine and enhanced pyridine removal rates.