Dale

Clarifier weir stringing means the sludge blanket is already high

Secondary clarifier, routine walk-round

• Thin strings of solids trailing over the weir
• Water still looks clear from the walkway — this is the trap

Blanket is within a foot of the weir even though the surface looks fine

Take a blanket depth reading now, not at end of shift → Raise return rate before you touch wasting

• A brand new weir plate sheds strings for the first week and means nothing

If the digester gas flare is pulsing, check the condensate trap first

Anaerobic digester, flare visibly pulsing

• Flare flame pulsing in a slow rhythm rather than steady

Condensate is slugging the gas line — drain the trap before touching the pressure settings

Drain the condensate trap → Watch the flare for ten minutes

A rising pH at the headworks on a dry morning means an industrial dump

Headworks, dry weather, early shift

• Influent pH climbing past 8.5 with no rain in 48 hours
• Flow is normal — that is what rules out infiltration
• A faint solvent smell at the grit channel before the probe confirms

Someone upstream is dumping. This is not a sensor drift.

Grab a sample bottle now — evidence disappears in an hour → Call the pretreatment coordinator before you adjust anything → Do not neutralise blind; find out what it is first

• First Monday of the month the brewery does a permitted caustic clean — check the schedule before you call anyone

In 2019 I neutralised first and sampled after. We never identified the discharger and ate the fine ourselves.

When aeration foam turns from white to chocolate brown ✔

Activated sludge aeration basin, steady influent, no storm event

• Foam goes tan then chocolate brown and stops breaking up
• Sludge blanket creeping up while dissolved oxygen holds normal
• Smell shifts from earthy to wet cardboard — you get this before the microscope confirms it

Sludge age is too long and filaments are taking over. This is not an organic overload.

Increase wasting rate about 10% → Pull a sample and look for Nocardia under the scope → Hold return rate steady — do not chase it with returns

• After heavy rain the same brown appears from washed-in road grit and clears within a day — do not waste on that
• In the first two weeks after a plant restart the colour means nothing yet

In 2014 I read it as an overload and chased it for two weeks. Ended in a bulking event and a permit violation that cost us the quarter.