Study On Comprehensive Treatment Of Lurgi Coal Gasification Wastewater

Lurgi coal gasification wastewater after the initial recovery of phenol and ammonia was researched in the article with comprehensive treatment. Pre-oxdation technology and efficient biochemical treatment was adopted to insure the effluent meet the discharge requirements.The intermittent aeration SBR reactor with shortcut nitrification-denitrification technology was adopted and different factors on degradation, including discussions on impacts of temperature, pH and DO etc were studied. Conclusions:The target influent was a high concentration of wastewater with COD of 5198 mg/L, NH3-N of 219 mg/L, TN of 385 mg/L, phenol of 1277 mg/L, B/C of 0.31.When the reactor was controlled at the temperature of 25±1℃, DO was 0.5 mg/L, the influent pH value was 7.50～8.00, and C/N was 5, shortcut nitrification-denitrification can be achieved with a sustainable nitrosation rate of over 89%, and in the effluent,the removal rate of COD, NH3-N and phenol were 79%、98% and 99% respectively. Two kinds of deep oxidation methods were further applied to this biochemical effluent. Research showed that:The COD、NH3-N、volatile phenol concentration of the Fenton effluent were 72 mg/L,0.5mg/L and 0.12mg/L respectively under the condition of m(H2O2)/m(COD)=1.6, n(H2O2)/n(Fe2+)=5, pH=3, reaction time=30min. However, the COD、NH3-N、volatile phenol concentration of the ozone reaction effluent were 56 mg/L、 1.0mg/L and n.d. under the condition of 45mg/min ozone dose, pH=10.5, reaction time =20min. Both oxidation technologies can ensure the effluent to meet the discharge requirements, and the effect of ozone oxdation was better.Meanwhile, "Ozone oxidation pretreatment+ SBR method" system showed that:Under the ozone pre-oxidation condition of 48mg/min ozone dose, pH=10.5, reaction time=20min, 63% of COD.29.7% of NH3-N and 95% of volatile phenol can be decreased and B/C can be increased to 0.45. Moreover,in the effluent of "Ozone oxidation pretreatment+ SBR method" system, COD. NH3-N and volatile phenol concentration were 150 mg/L、1.5mg/L and 1.Omg/L.The powder activated carbon biochemically enhanced experiment showed that when the optimum powder activated carbon dose was 500 mg/L,COD、NH3-N、volatile phenol of the last effluent were 64 mg/L、0.5mg/L and 0.10 mg/L, meeting the discharge requirements.