Studies Of Biological Nondegradale Organic Wastewater By Sub-Fenton Process

Photochemical oxidation process is developing fastly in the past twenty years for its mild reactional conditions and its superstrong oxidation. The applicational prospects are vast, especially for treating toxic hazardous biological nondegradale organic wastewater.Photooxidation experiments of TNT in an annular reactor were conducted by the application of three different photochemical processes (UV/H2O2, UV/Fenton and UV/Fe(C2O4)33-/H2O2). The effect of reaction conditions such as the dosage of H2O2,the dosage ferrious iron,initial pH,initial TNT concentration,reaction temperature were studied in terms of TNT concentration and chemical oxygen demand(CODcr).For UV/H2O2 system,under the condition of adding H2O2(2Qth),initial pH=3,88% TNT was degraded after 60min. For UV/Fenton system,the removal of TNT can be achieved over 97% only after 15min and the removal of COD can be achieved 84% after 60min under the condition of adding H2O2(lQth), H2O2:Fe2+=20:1,initial pH=3. For UV/Fe(C2O4)33-/H2O2 system,the removal of TNT can be achieved 98% after 30min under the condition of adding H2O2(0.25Qth), H2O2:Fe2+:C2O42-=20:1:5,initial pH=3. The role of oxygen in the reaction was evaluated in the UV/H2O2 and UV/Fe(C2O4)33-/H2O2 systems with a small dosage of H2O2 addition. From the experiments results,we can conclude that dioxygen continued the reaction as the mainly oxidant after H2O2 consumed entirely. Envidently,reducing the dosage of H2O2 addition can save the running cost to a certain degree and make the techniques more possible to apply in industry. Kineticmodels were established for UV/H2O2 and UV/Fenton systems respectively were well supported bythe experiment results.Moreover,a kind of high concentration biological nondegradale wastewater,which wasproduced in the process of printed circuit cards,was treated by UV/Fenton system. The change ofBOD5/COD was detected under different dosage of H2O2. The ecperiments showed that BOD5/CODwas raised from 0.19 to 0.35 and the biodegradabity of the wastewater was enhanced after 60minunder the condition of adding H2O2(1Qth), H2O2:Fe2+=20:1,initial pH=3.