A Study On Dilute Phenol Degradation Using Photocatalysis Combined With Biological Treatment

The paper used combined reactor for dilute phenol degradation, which consisted of photocatalysis unit and biological membrane unit, In the photocatalysis unit, a 30W UV lamp(254nm) was used as light source, and TiO2 film by sol-gel method was loaded on the suface of lightweighty-Al2O3 sphere. In the biological membrane unit, a new kind of porous lightweight ceramic carrier was adopted to load microorganism. Phenol was selected as study object, and the regularity of phenol degradation and COD removal under photocatalysis alone, biofilm alone, and coupling of photocatalysis and biofilm, respectively. The reacot was performded under intermittent and continuous flow state, respectively.Experimental results showed that:(1) The degradation of phenol by photocatalysis was not fully accomplished, most of which was oxidized to intermediate prducts. Only in the low concentration load, can photocatalysis reach a high removal efficiency. The biofilm alone was better than photocatalysis for phenol degradation.(2) Although the phenol removal efficiency was lose to each other, phenol removal rate and COD removal efficiency are better under the coupling process by synergetic effect of photocatalysis and biofilm. Under continuous flow state, the phenol removal efficiency by coupling process reached approximately to 100%, which approached full mineralization. As HRT is 6hr, the COD removal efficiency of A, B, C phenol solution were about 78%,87%,93%, respectively.(3) Under the coupling process of photocatalysis and biofilm, the degradation mainly relied on microorganism. During the photocatalysis process, biofilm still keeped high biological activity.(4) The phenol volumetric removal rate(VRR) increased with increasing initial concentration of phenol, but decreased with increasing HRT. Under continuous flow state, the sequence of VRR was as follows:the coupling process>biofilm process> photocatalysis process. As HRT is 2h, and initial concentration were 200mg-L"1 phenol,480mg-L-1 COD, respectively, it reached the maximum value(102mg phenol·L-1h-1,239mg COD-Ih-1).