Operator Articles
Long-form answers to the questions operators ask most.
Why Is My SVI Increasing?
A practical guide to rising sludge volume index: how to confirm the number, what the settleometer and microscope tell you, the common causes, and how to protect your clarifiers while you fix it.
1,586 words, about 7 min read
What Causes Rising Sludge in a Secondary Clarifier?
Why sludge floats to the surface of a secondary clarifier, how to tell denitrification from other causes, and how to fix it with RAS rate, blanket control and upstream denitrification.
1,259 words, about 5 min read
How Much RAS Should I Return?
Four practical ways to set return activated sludge flow (mass balance, settleometer, SVI and blanket depth), plus state point analysis, with worked examples and the mistakes to avoid.
1,380 words, about 6 min read
How Do I Calculate Sludge Age?
Sludge age, SRT and MCRT explained with worked examples, which numbers to use, common mistakes, and how to use SRT to control nitrification and settling.
1,306 words, about 6 min read
Why Is My Effluent Ammonia High?
A step-by-step guide to diagnosing loss of nitrification: DO, alkalinity, pH, SRT, temperature, ammonia load and toxicity, with worked calculations and recovery tips.
1,311 words, about 6 min read
What Does Brown Foam Mean in an Aeration Basin?
How to read aeration basin foam by color and texture, what causes stable brown foam (Nocardioforms and Microthrix), and how to control it with SRT, foam removal, grease control and selectors.
1,231 words, about 5 min read
How Do I Know If I'm Wasting Too Much Sludge?
The warning signs of over-wasting and under-wasting, how to check your SRT and WAS data, and a practical method to set and adjust wasting without upsetting the process.
1,275 words, about 6 min read
How Much Air Does My Aeration Basin Need?
Calculate the oxygen requirement for BOD removal and nitrification, convert it to air flow with transfer efficiency, and use DO control to deliver the air without wasting energy.
1,323 words, about 6 min read
How Do I Run a Settleometer Test?
Step-by-step settleometer procedure, how to read the settling curve and supernatant, how to calculate SSV, SVI and RAS ratio, and how to avoid the most common errors.
1,266 words, about 6 min read
How Do I Read My Microscope Slide?
A practical routine for activated sludge microscopy: preparing a wet mount, what to look for at 100x and 400x, floc and filament ratings, indicator organisms, and how to connect what you see to process data.
1,216 words, about 5 min read