Performance Appraisal of Controlled Low-strength Material Using Sewage Sludge and Refuse Incineration Bottom Ash

This research evaluated the use of sewage sludge and refuse incineration bottom ash to replace calcium sulfoaluminate cement （CSA） in making controlled low-strength material （CLSM）. Various properties of CLSM mixtures were characterized in terms of unconfined compressive strength, microstructure and leachability. It was found that the strength of tested CLSM mixtures ranged from 3.6 to 9.0 MPa, over the upper excavatable limit of 2.1 MPa. The micro-structural analysis revealed that sewage sludge and bottom ash were crystallochemically in- corporated within CLSM system_s by forming the needle-like ettringite （C3A＇3CS＇_H32） with exiguous tu.bers via the typical Pozzolanic Reaction, leading to a dense and low-porosity microst;＇ucture. Furthermore,-the toxicity characteristic leaching procedure evidenced that the cumulative leachable metals in the leachate were much below the regulatory thresholds. The potential for us!ng sewage sludge and bottom ash!n CLSM makin.g was thus confirmed.

The Optimal Plan for WTE Plants in an Urban Area Considering Refuse Collection and FIT

Burnable municipal solid waste is disposed sanitarily at incinerator plants, which leads decrease of environmental load. At the same time, WTE （waste-to-energy） is realized as recovery of energy. WTE, however, has weakness of low generation efficiency and output in Japan due to smaller capacity of incinerator plants. To overcome above weakness, high efficient WTE is necessary with total integration and scaling up of incinerator plants. In addition FIT （feed-in tariff） has been started recently in Japan. When planning, we must consider totally both cost of incinerator plants and cost of refuse collection which is important role for the waste disposal. The planning method whose target is an urban area has formulated in this study. Considering the situation of the decrease trend of refuse volume and the strict finance condition of a local government, so that the proposed method is very effective.

Study on Catalytic Decomposition of Dioxins by Supported CeO_2-TiO_2-V_2O_5 Composite Catalyst

Loaded on the cordierite, the rare earth doped composite catalyst was prepared by sol-gel method combined with dipping technique. Taking Orthodichlorobenzene as model, the catalyst was used to remove the dioxins of the waste gas. The results showed that at 280 ℃ and gas space velocity being 8000 h-1, the orthodichlorobenzene could be removed effectivily by the prepared CeO-TiO2-V2O5 composite catalyst whose activity was remarkably enhanced by the doping of Ce, while the industrial side-stream test of dioxins from refuse incineration smoke indicated that the decomposition rate could reach above 93% under the same conditions.

Electrochemical oxidation of recalcitrant organic compounds in biologically treated municipal solid waste leachate in a flow reactor

Biologically-treated municipal solid waste （MSW） leachate still contains many kinds of bit-recalcitrant organic matter. A new plate and frame electrochemical reactor was designed to treat these materials under flow conditions. In the electrochemical oxidation process, NH3 and color could be easily removed by means of electro-generated chlorinefaypochlorite within 20 min. The effects of major process parameters on the removal of organic pollutants were investigated systematically. Under experimental conditions, the optimum operation parameters were current density of 65 mA/cm^2, flow velocity of 2.6 cm/sec in electrode gap, and initial chloride ion concentration of 5000 mg/L. The COD in the leachate could be reduced below 100 mg/L after 1 hr of treatment. The kinetics and mechanism of COD removal were investigated by simultaneously monitoring the COD change and chlorine/hypochlorite production. The kinetics of COD removal exhibited a two-stage kinetic model, and the decrease of electro-generated chlorine/hypochlorite production was the major mechanism for the slowing down of the COD removal rate in the second stage. The narrowing of the electrode gap is beneficial for COD removal and energy consumption.