Particle count and online turbidity interference from bubble formation

Abstract

Bubble formation affects particle count and online turbidity measurements, but the water industry does not routinely employ a methodology for determining when bubbles are skewing measurements. In this study, bubbles were measured as particle counts in bench‐top laboratory experiments and at a full‐scale functioning utility. Particle counts decreased when the pressure in the measurement cell was increased during sampling, and in some cases, 46 ft (14 m) of water pressure was needed to suppress bubble formation. Failure to account for false particle counts can result in invalid conclusions about the efficacy of particle removal in water treatment. In laboratory experiments, bubbles caused spurious turbidity spikes, increasing turbidity and gas accumulation in the measurement cell of online turbidimeters. Instrument features such as electronic “bubble reject” and in‐line bubble traps can reduce the effect of bubbles on the measured turbidity, but in some cases they may aggravate the problem.

Online Quality Measurements of Total Suspended Solids for Offshore Reinjection: A Review Study

“…However, care should be taken if comparing turbidity measurement with TSS concentration, as turbidity is another parameter of measuring water quality. For instance, turbidity also depends on particle sizes, bubbles, color, organic matter ability to absorb light, and type of microorganism, all of which affect the correlation between turbidity measurements and TSS concentration [177,179,180]. Other conditions can affect the measurement, such as the light scattered by particles at the back of the sample volume, which can be blocked by particles closer to the detector [178].…”

“…It is well known in the field of turbidimeters that bubbles affect the turbidity measurement, where particles identical in size, but have different chemical composition, scatter different amounts of light [178]. Even some organic matter, such as colored dissolved organic matter (CDOM), can result in an artificially low turbidity measurement as it absorbs light instead of scattering it [179,180]. Nonetheless, it may be unreliable to use turbidimeters for measuring the true TSS concentration, but their strength of measuring the water's turbidity may have the potential in combination with other water quality monitors [178].…”

Uncertainty Analysis of Fluorescence-Based Oil-In-Water Monitors for Oil and Gas Produced Water

“…Gas bubbles’ influence on : Like turbidity monitors, the OiW monitors were suspected difficulties with interference from gas bubbles. For turbidity monitors, air bubbles are known to cause a false high turbidity reading when measuring the amount of light scattered [ 48 ]. However, results from another report testing a fluorescence-based monitor indicate that gas bubbles significantly reduce the measurement, as the gas bubbles potentially reduce the strength of both excitation light and fluorescence [ 22 ].…”

A signal analysis and identification scheme for an online multiphase micron-sized particle analyzer system

“…In bioprocesses, the condition of cells in biological reactors is usually tested to study the potential fluidmechanical cell damage, as well as the cell growth rate, and maximum cell density [5][6][7][8]. In addition, microparticle testing is also often used to measure the condition of water quality [9,10]. The online detection of microparticles can facilitate the understanding of the monitoring of non-uniform characteristics [11] in an industrial application, as well as the feedback, adjustment, and optimization of processes based on particle size variations.…”