Activated Sludge vs Primary Sludge Key Differences Explained
Activated sludge is the living, aerated mix of microbes that devours dissolved organics after primary settling. Primary sludge is the raw, heavy stuff—grit, grease, and settleable solids—removed before any biology begins. Operators and students swap the names because both are “sludge” pulled from tanks. One looks chunky and smells earthy, the other is lighter, frothy,…