Abstract
Availabilities of biodegradable plastics as a carbon source for biological denitrification process were studied. Four kinds of biodegradable plastics (poly-β-hydroxybutyrate, CELLGREEN, LACTY BIONOLLE) were used for batch denitrification experiments with activated sludge and continuous denitrification experiment using soil column. The denitrification activities and weight-losses before and after experiments were compared. The highest denitrification activity was obtained in the experiment with PHB (bacteria produced plastic) as a carbon source, and 90.2% of initially added 10g of PHB pellets was degraded. CELLGREEN (natural compound) was also utilized in denitrification process, and 32.6% of initially added 10g of CELLGREEN pellets was degraded. On the other hand, the weight-loss was not observed in LACTY and BIONOLLE (both are chemical synthesis palstic), which indicated that these types of biodegradable plastic were not easily degraded by activated sludge and soil microorganisms. The decomposition of surface of PHB plastic pellet in soil column was slower than that in activated sludge, which suggested the advantage of PHB for long-term bioremediation in nitrate-polluted soil and ground water. After the continuous denirtrification experiment, the total number of bacteria and the number of PHB-utilizing denitrifier was counted to be 3.4×109cells⋅wet-g-1 and 8.5×106cells⋅wet-g-1 respectively.
