WASTEWATER - By Rick Lallish
During an afternoon plant walk-through, you notice a thin, light-tan foam covering approximately 10% to 25% of the aeration basins. What condition does this indicate?
A. Normal conditions
B. Startup conditions
C. Nocardia filaments
D. Old sludge (long solids retention time, low food/microorganism ratio)
Answer: A. The ability to interpret visual conditions in an activated sludge facility is vital to successful operations. A thin, light-tan foam is normal. The startup condition is usually a thick, white, billowy foam; Nocardia typically appears as a thick, greasy and dark-tan foam. Old sludge usually presents thick, scummy and dark-brown foam. Knowing these conditions will
