A client read me his STP contract over the phone the week before he signed it: two pages, a list of tanks, and 90 per cent of the money paid before the plant ever saw sewage. These are the four plain-language questions I would ask before signing — none of them about equipment.
Your STP can pass BOD and TSS and still fail ammonia, because the bacteria that remove ammonia are slow, alkalinity-hungry, oxygen-hungry and easy to kill. Field notes on the four things that quietly wipe them out, the food processing plant where I created my own nitrification problem with one piping decision, and what I check before anyone orders more bacteria.
Bacteria dosing is a real tool for commissioning, restarts and shock recovery. It is not a fix for low DO, solids washout, short retention time or an ongoing toxic input. Field notes on when I recommend probiotics for a sewage treatment plant, when I refuse to, and the food processing plant that taught me the difference.
Field notes on what a sewage treatment plant operator actually does, why plants fail weeks after a good operator resigns, and how to tell an operator problem from a design problem.
A healthy sewage treatment plant smells like wet soil. When it smells like rotten eggs, ammonia, or spoiled food, it is telling you where to look, usually weeks before the lab report does. Field notes on reading an STP by smell, including the food processing plant that taught me the hard way.
Small STPs fail more often than large ones, and not because they are cheap. Field notes from Cebu on why 5 cubic meters a day is harder to operate than 500 — and how I design small sewage treatment plants differently now.
Field notes on why the company that sizes your sewage treatment plant is usually the company that profits from the size, the arithmetic a bid comparison table hides, and what to ask for before you sign — written by someone who sits on both sides of the conflict.
Field notes from an early food processing plant project: emulsified FOG I underestimated, a combined waste stream that tightened my own compliance target, a second-floor plant that took odour complaints from the Barangay to the DOH, and the flotation and fixed-film retrofit that finally held.
Zero sludge is a sales line, not a design. Field notes from a Cebu wastewater engineer on why every biological STP produces sludge, what Extended Aeration really reduces, and the four questions that expose a false claim.
