FILAMENTIOUS BACTERIA IDENTIFICATION & PROCESS CONTROL A Simple Approach

INTRODUCTION Under normal conditions in activated sludge, bacteria occur singly, in small chains or clumps. Under adverse conditions however, bacteria that grow in filaments begin to form longer chains called filamentous bacteria or “filaments”. Filaments can dominate in the wastewater treatment system under a variety of conditions. These conditions are usually less favorable for the floc-forming bacteria so, this allows the filaments to gain an advantage. The presence of some filaments in the activated sludge is advantageous. They aid in settling by providing a “back-bone” for floc-forming bacteria to attach to. However, when filaments begin to grow in excess amounts, extending from the floc into the bulk fluid, they can interfere with settling and my cause foaming upon aeration. Different types of filaments dominate under different conditions. Identifying which filaments are dominating in the system will help the operator to understand the condition in the treatment system so that corrective changes can be made. Microscopic evaluations to identify filamentous bacteria can be complicated and time consuming. This lesson will provide a simple approach to identifying filaments in the activated sludge as well as provide suggestions for corrections.