ABSTRACT
Polyhydroxyalkanoate (PHA) producer selection is a key step in mixed culture (MC) production. This study focused on incompatibility between PHA storage and floc settling of MCs in the selection process. In a selector using fermented waste activated sludge as substrate under varying organic loading, average maximum PHA content obtained in batch assays increased by â¼ 22 wt% and biomass concentration increased by â¼ 34% with the increasing of organic loading. However, poor floc settling occurred, causing decreased batch PHA production and costly downstream process. A flank community which can corporately use non-VFA organics existed in the selector. When organic loading increased, PHA producers had stronger negative interactions, but not cooperation with the flank community members. Thus, high PHA storage of MCs was bounded to the domination of core PHA producer. But the domination of Thauera bacteria under high organic loading indirectly induced a bloom of filamentous bacteria.
