Proceedings of the Annual Conference of The Japan Society of Waste Management Experts

Continuous hydrogen fermentation of dissolved starch and rice were examined and optimum culture conditions for hydrogen production were studied. Analyzing hydrogen yields under various experiment conditions, we found the following results, maximum hydrogen productivity from dissolved starch reached 2.13mol/mol-hexose at 35degrees in temperature, pH4 and 48hour HRT and maximum hydrogen productivity from rice reached 2.06mol/mol-hexose at 35degrees in temperature, pH4 and 60hour HRT.

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The combined system, methane fermentation of organic waste such as juicy garbage etc., incineration of waste with low moisture such as plastic etc., is recommended as a method of raising energy efficiency of the entire system during MSW processing. Although the separate collection of MSW is needed in the execution, the separate collection is difficult from an increase in the collection cost and the problem in an administrative procedure. However, the mechanical separate process such as complex separation system or solubilization system cannot achieve the purpose of the energy efficiency improvement because of their large energy consumption. From such a background, a simple type of mechanical separation technology is developed as pre-treatment equipment of dry methane fermentation that treats MSW. The parts of paper waste in MSW were collected at the separated –product side by the mechanical separation. The methane fermentation non-suitable materials (plastic and cloths etc.,) were removed. The biogas production amount from 1 ton of separated waste was 150m3N or more in dry methane fermentation. As a result, the mechanical separation technology of MSW was confirmed.

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On a survey for ordinary business waste in the Kitakyushu Central Wholesale Market, it is found that garbage accounted for about 80% of all, half of which was composed of some kinds of vegetable wastes. Possibility of co-digestion of the garbage waste containing the vegetables with sewage sludge was investigated through the methane fermentation experiments, on the assumption of use of the existing digestion tanks in the sewerage treatment facility.The characteristic of digestion of the vegetable was noted to be similar to that of sewerage sludge by conducting the batch experiments. The opposite effect against lowering of pH, etc. in the co-digestion was detected by comparison with the results of semi-continuous experiments using mixed substrate of sewerage sludge and vegetable.

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In cement industry, the powder, which contains a large amount of Ca with a small amount of Pb, occurs in cement manufacturing process. Therefore, the purpose of this research is the removal and separation of Pb from the powder by flotation for new resource and wastes treatment. The flotation was operated in the MS type flotator with 0.25 L capacity and FW flotator with 30 L capacity for continuous processing test under controlled pH, conditioning reagent (depressor and activator) and a certain amount of collector.The use of H2SO4 and NaOH did the pH adjustment. Sodium dodecyl sulfate (SDS) and amylxanthic acid potassium salt (PAX) were used as anionic collectors in flotation test 1 and test 2, respectively. Using SDS and lignine sulfonic acid as a depressor in flotation test 1 recovered Ca in float product and Pb in sink product. Flotation test 2, which recovered Ca in sink product and Pb in float product, was carried out by using PAX and sodium hydrosulfide (NaSH) as an activator and sulfurization process. In both flotation tests, over 60% of Pb were removed from the powder acidic region. Especially, in case of flotation test 2, almost all the Ca compound was distributed to the sink product and over 90% of Pb compounds were also removed in the float product. Moreover, the distribution and grade of recovery Pb in float product by sulfurization process (= procedure of flotation test 2) was over 60% and 17%, respectively, FW flotator with 30 L capacity during continuous flotation test.

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