Shigenobu Okajima

Catalytic destruction of PCDDs in flue gas

Abstract Many kinds of hydrocarbons are known to be decomposed by catalytic reaction at comparatively low temperatures. The technology of catalytic destruction is applied in many fields, for example, for automobile engine exhaust gas, deodorization from stack gas. We are trying to apply the catalytic destruction technology to reduce PCDDs concentration levels in the flue gas from municipal solid waste incinerators. Because the temperature of flue gas from the incinerator is comparatively low after the waste heat boiler and air pollution control units, 250 to 300 degrees Celsius, the final clean-up of the flue gas should be conducted at a low temperature. First, we had conducted laboratory experiments to confirm the reduction of PCDDs by catalytic destruction. And, at the next stage, we had conducted test plant experiments. Moreover, we have a plan to proceed to the pilot plant experiments. We present here the preliminary results obtained from these experiments, and the availability of the catalytic destruction for PCDDs in flue gas is reviewed in this short report.

Control of dioxins from municipal solid waste incinerator

Abstract The purpose of this study is to establish whether intermediate products, which are remained as unburned components and become the precursors to form the PCDD, can be reduced by improvement of the plant operation. The change of the PCDD levels was analyzed along the stream of the flue gas. Two test programs were conducted to reduce the emission levels of PCDD at municipal solid waste (MSW) incinerators. They were as follows; 1. (1) High temperature incineration to reduce unburned components. 2. (2) Investigation of the relationship between CO contents and PCDD levels at an incinerator which was operated by reductive two-step combustion mode to reduce NOx emission level.

Estimation of the environmental fate of PCDD emitted from municipal solid waste incinerators

Abstract Polychlorinated- p -dioxins (PCDD) have been detected within various media in Japan including air, sea water, river water, sediment and biota. Municipal solid waste incinerators are well-known as one of the major sources of these pollutants. In order to evaluate the effect of these pollutants, PCDD emission data published in Japan was collected and analyzed to estimate the release of PCDD from municipal solid waste incinerators into the environment. A compartmental model was used to calculate the environmental concentration of PCDD released from municipal solid waste incinerators and the predicted concentrations were then compared with the observed concentrations.