I agree with the description and measurement of turbidity in (treated) wastewater. This turbidity is caused by colloids which are microscopic particles suspended in water and subject to random Brownian motion. As a result, without upstream (electro)chemical coagulation-flocculation, these colloids will only be marginally removed by gravity sedimentation (in conventional clarifiers or inclined/parallel plate settlers) or by media filtration (using AFM or sand). However as indicated these colloids will be retained by ultra-filtration (UF) membranes (with backwashing and CIP) which could be quite expensive. Fortunately there is a far more efficient and less expensive solution to remove and biodegrade these colloids in both municipal sewage and most industrial wastewater. This is achieved by upgrading the widely used activated sludge (AS) biotreatment as to capture (adsorb/absorb, enmesh), crack (by bacterial enzymes) and biodegrade these colloids by regenerated AS. In this way, we obtained less than 0.3 NTU turbidity without any post treatment.

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I agree with the description and measurement of turbidity in (treated) wastewater. This turbidity is caused by colloids which are microscopic particles suspended in water and subject to random Brownian motion. As a result, without upstream (electro)chemical coagulation-flocculation, these colloids will only be marginally removed by gravity sedimentation (in conventional clarifiers or inclined/parallel plate settlers) or by media filtration (using AFM or sand). However as indicated these colloids will be retained by ultra-filtration (UF) membranes (with backwashing and CIP) which could be quite expensive.

Fortunately there is a far more efficient and less expensive solution to remove and biodegrade these colloids in both municipal sewage and most industrial wastewater. This is achieved by upgrading the widely used activated sludge (AS) biotreatment as to capture (adsorb/absorb, enmesh), crack (by bacterial enzymes) and biodegrade these colloids by regenerated AS. In this way, we obtained less than 0.3 NTU turbidity without any post treatment.