セラミック複合木質炭化物によるＢｉｏｒｅｍｅｄｉａｔｉｏｎ‐難分解性有機塩素系農薬の吸着・分解‐

Abstract

For the purpose of recycling unused wood resources, such as thinned timber and discarded lumber, experiments were conducted on carbonized wood-ceramic composites made from cedar (Cryptomeria japonica D. Don) for their ability to serve as a microhabitat in bioremedial applications. The composites were inoculated with hard-to-degrade organochloric compound-degrading bacteria and were used to degrade two hard-to-degrade organochloric agricultural chemicals, 6-chloro-N2, N4-diethyl-1, 3, 5-triazine-2, 4-diamine (CAT, or commonly known as “simazine”) and pentachloronitrobenzene (PCNB, or commonly known as “quintozene”). Results of the CAT degradation experiments confirmed that almost all of the CAT-degrading bacteria were successfully inoculated on the composites and that the composites served as an excellent microhabitat for the bacteria. The rate of decline in CAT concentration began to increase after two weeks of refluxing, achieving nearly 100% of CAT degradation with steady production of chlorine ions as a by-product. Similarly, the PCNB degradation experiments showed that the composites served as an ideal and efficient microhabitat for nearly 100% of the inoculated PCNB-degrading bacteria. The rate of decline in PCNB concentration began to increase after two weeks of refluxing, achieving roughly 80% of PCNB degradation with steady production of chlorine ions as a by-product. In view of the high CAT and PCNB adsorption by the carbonized wood-ceramic composites used in the experiments, the results seem to indicate that the CAT and PCNB (which were the sole sources of carbon and nitrogen for the degrading bacteria) adsorbed primarily into the mesopores of the composites were degraded by the degrading bacteria aggregating mostly within the macropores of the composites. Therefore, the results showed efficient adsorption and degradation of agricultural chemicals by the bacteria in the meso- and macropores of the carbonized wood-ceramic composites.