Water treatment glossary.

The terms engineers use, explained in plain language.

A

AOP: Advanced oxidation process. Treatment that generates hydroxyl radicals to destroy organic pollutants that resist biological treatment.

BOD: Biochemical oxygen demand. The oxygen bacteria use to break down organic matter in water; a measure of biodegradable pollution.

CIP: Clean-in-place. Cleaning equipment or membranes with chemical solutions without dismantling them.
Coagulation: Adding chemicals that neutralise the charge on fine particles so they can clump together.
COD: Chemical oxygen demand. The oxygen needed to chemically oxidise all organic matter; always higher than BOD.

DAF: Dissolved air flotation. Separation process in which micro-bubbles float oil, grease and solids to the surface.

EC: Electrocoagulation. Coagulation using metal ions released from electrodes by an electric current.
Effluent: Wastewater leaving a process, a factory or a treatment plant.
Equalisation: A tank that evens out variations in flow and concentration before treatment.
ETP: Effluent treatment plant. A plant treating industrial wastewater.

Flocculation: Gentle mixing, usually with a polymer, that grows small particles into larger flocs.
FOG: Fats, oils and grease.

MABR: Membrane aerated biofilm reactor. Biological treatment in which oxygen is supplied through membranes to a biofilm, saving aeration energy.
MBR: Membrane bioreactor. Biological treatment combined with membrane filtration in place of a clarifier.
MEE: Multi-effect evaporator. Thermal system that concentrates brine by reusing steam across several stages.
MLSS: Mixed liquor suspended solids. The concentration of biomass in a biological reactor.

Permeate: Water that has passed through a membrane.
Produced water: Water brought to the surface with oil and gas during production.

Reject (concentrate): The stream of concentrated salts and impurities left behind by a membrane.
RO: Reverse osmosis. Membrane process that removes dissolved salts from water under pressure.

SDI: Silt density index. A measure of how likely water is to foul reverse osmosis membranes.
Sludge: The solids removed during treatment, which need thickening, dewatering and disposal.

TDS: Total dissolved solids. The concentration of salts and other dissolved substances.
TSE: Treated sewage effluent. Sewage treated to a quality suitable for reuse, typically for irrigation.
TSS: Total suspended solids. Particles suspended in water that can be removed by settling, flotation or filtration.

UF: Ultrafiltration. Membrane filtration that removes suspended solids, bacteria and turbidity.

ZLD: Zero liquid discharge. A treatment approach where all water is recovered and salts leave as a solid, so no liquid is discharged.

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