Filtratklarhet

Filtratklarhet, literally 'filtrate clarity' in Swedish, is a measure of how clear or transparent the liquid is after it has passed through a filtration process. It reflects the removal of suspended solids and colloidal material and is an important quality parameter in water treatment, pharmaceuticals, and food processing.

Measurement: Clarity is typically quantified by turbidity using nephelometric methods expressed in NTU; visual inspection is sometimes used for quick checks; spectrophotometry can assess color/clarity; transmittance can be reported as percent transmitted at a given wavelength.

Influencing factors: pore size and type of filtration media; filtration method (gravity, pressure-driven, cross-flow); upstream fouling; feed particle load and size distribution; coagulants/flocculants; color and dissolved substances that affect appearance.

Improvement: proper pretreatment, coagulation and flocculation, selecting appropriate filtration step and media, controlling filtration rate, regular cleaning (backwashing or CIP), and protecting from fouling; for cross-flow filters, maintaining shear and flow to reduce cake formation.

Applications and standards: in drinking water and wastewater treatment, a low turbidity is typically required; in pharmaceuticals and bioprocessing, filtrate clarity relates to downstream filtration, with strict acceptance criteria for sterile filtration and product appearance; regulatory bodies specify turbidity limits and testing methods.

Limitations: turbidity measures suspended particles, not dissolved substances or color; visual assessment is subjective; correct sampling and calibration are essential.