Operator terms
Operator terms, explained plainly
The terms a Texas Class D candidate meets on the exam and the job, each explained in plain language. Read one, then practice it. No jargon for its own sake, and no promise about your result.
- What is BOD in wastewater?BOD (biochemical oxygen demand) is the oxygen microbes use to break down organic matter in water: a core measure of how strong or polluted wastewater is.
- What is TSS (total suspended solids)?TSS (total suspended solids) is the weight of solid particles suspended in water, in mg/L. Removing it is a main goal of wastewater clarifiers.
- What is return activated sludge (RAS)?Return activated sludge (RAS) is settled, microbe-rich sludge pumped from the clarifier back to the aeration tank to keep activated sludge treatment healthy.
- What is MLSS?MLSS (mixed liquor suspended solids) is the concentration of solids, mostly microbes, in an activated sludge aeration tank. It measures active biomass.
- What is a clarifier?A clarifier is a tank where water slows so solids settle to the bottom and clearer water flows off the top, used in water and wastewater treatment.
- What is effluent?Effluent is the treated water that flows out of a wastewater plant. It must meet the plant's permit limits before discharge. Influent is what comes in.
- What is coagulation in water treatment?Coagulation is adding a chemical like alum that neutralizes the charge on tiny particles so they can clump together: the first step in clearing cloudy water.
- What is flocculation?Flocculation is the gentle mixing after coagulation that lets particles collide and stick into larger clumps (floc) that settle or filter out more easily.
- What is sedimentation in water treatment?Sedimentation is letting water sit still so heavier particles and floc settle out by gravity before filtration, removing most of the suspended load.
- What is pH in water?pH measures how acidic or basic water is, from 0 to 14, where 7 is neutral. It affects coagulation, disinfection, and corrosion, so operators watch it closely.
- What is alkalinity in water?Alkalinity is water's capacity to neutralize acid, mostly from bicarbonate. It buffers pH so it stays stable when treatment chemicals are added.
- What is a cross-connection?A cross-connection is any point where drinking water can mix with a non-potable source, risking backflow contamination. Backflow prevention stops it.
- What is chlorine residual?Chlorine residual is the chlorine still active in water after demand is met. A measurable residual proves disinfectant reaches the customer.
- What is contact time (CT) in disinfection?Contact time is how long disinfectant stays in water before use; CT is time times concentration. Enough CT is what actually inactivates pathogens.
- What are coliform bacteria?Coliform bacteria are an indicator group used to screen water safety. Their presence signals that harmful organisms could be getting into the water.
- What is a maximum contaminant level (MCL)?A maximum contaminant level (MCL) is the enforceable legal limit for a contaminant in drinking water. Systems must stay below it and act if they exceed it.
- What is filtration in water treatment?Filtration passes water through sand or media to strain out the fine particles and floc that settling missed, a key barrier before disinfection.
- What is disinfection in water treatment?Disinfection kills or inactivates disease-causing organisms so water is safe, usually by chlorination with enough contact time and a lasting residual.
- What is aeration in wastewater treatment?Aeration adds air and oxygen to wastewater so the microbes in activated sludge can breathe and break down waste, controlled to keep treatment healthy.
- What is grit removal?Grit removal takes out heavy sand and gravel early in wastewater treatment to protect pumps and equipment and keep it from settling downstream.
- What is detention time?Detention time is how long water stays in a tank, found by dividing volume by flow. Enough time is what lets a tank settle solids or disinfect.