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.
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.
