Experimental Study On Effluent From Sewage Treatment Plant Reuse For Sludge Incineration Flue Gas Purification

With the rapid economic development and the increase of population, the emission of urban wastewater was also increasing. The reasonable disposal and utilization of municipal sewage sludge was imperative. Sludge incineration was one of the most popular technologies in sewage sludge treatment for its advantages of high processing rate, maximum volume reduction. Sludge incineration flue gas includes a lot of harmful substances such as SO2, NOx, CO, Hg, dioxin, etc. While SO2was especially exceeded the state discharge standard, it was necessary to disposed the sludge incineration flue gas properly in order to avoid second pollution.In this study, the acid gas of sludge incineration flue gas was purified by the secondary effluent from the WWTP (wastewater treatment plant) in Shenzhen city. Then the emitted air could reach the state discharge standard. Experimental studied feasibility analysis and interfering factor of effluent from sewage treatment plant reuse for sludge incineration flue gas purification. The main conclusions were as follows:1The quality of the WWTP sludge could meet the requirements of The Disposal of Sludge from Municipal Wastewater Treatment Plant-sludge Quality for Separate Incineration (GB/T24602-2009), so the incineration technology could be used in this WWTP.2The SO2of the sludge incineration flue gas was especially exceeded the required emission limits of Standard for Pollution Control on Municipal Solid Waste Incineration (GB18485-2001), so the sludge incineration flue gas need to be purified.3The SO2of the sludge incineration flue gas could be absorbed effectively by the effluent from WWTP. The removal rate of SO2could reach92.8%when the inlet SO2concentration was1973mg/m and the gas-water ratio was5. The higher of the inlet water pH, the higher removal rate of SO2was got. The removal rate of SO2reached93.8%when the inlet water pH was11.4The NOx of the sludge incineration flue gas could be absorbed by the effluent from WWTP in a way. As the lower NOx concentration of the sludge incineration flue gas, the inlet NOx concentration was the controlling factor of the NOx removal rate. When the inlet NOx concentration was59.42mg/m3, the change of the NOx removal rate was insignificant while the gas-water ratio was changed. The highest NOx removal rate was86.7%and the outlet NOx concentration was about8mg/m3.5After treatment, the pollutants in emitted air are below the required emission limits of Standard for Pollution Control on Municipal Solid Waste Incineration (GB18485-2001), and the pollutants in absorption solution are below the required emission limits of Integrated Wastewater Discharge Standard (GB8978-1996).