Evaluating particle counters

Abstract

Comparisons of particle counts made by counters and counts made by microscopic processes suggest counters accurately indicate removal efficiency. Particle counting methods for use in a water treatment facility were analyzed to compare counts made by a particle counter with a forward‐angle light scatter (FALS) sensor with counts made with a scanning electron microscope and by microscopic particulate analysis. A separate study compared an FALS sensor with a light obscuration sensor when challenged with latex spheres and cultured microorganisms and when performing continuous in‐line counts of the facility's filter effluent. Log removal values were comparable among the particle counting methods and did not vary significantly across various size ranges of an FALS sensor. Microorganisms were undersized by both sensor types compared with sizes determined with an optical microscope. These results suggest counters accurately indicate facility particle removal efficiency. However, counts made by a particle counter within a specific size range should be interpreted after characterizing the nature of the particles in the source

Evaluation of Particle Removal at Water Treatment Plants in Nova Scotia

“…The need for enhanced resolution has grown increasingly in recent years by concerns about public risks associated with Giardia lamblia, Cryptosporidium parvum and other microbial pathogens. The size range for Giardia and Cryptosporidium is 8 to 12 µm and 4 to 5 µm, respectively (O'Shaughnessy et al 1997), which is in the detectable range for most commercially available on-line particle counters. Since concentrations of particles in this size range do not correlate with turbidity measurements, turbidity removal efficiencies by filtration probably do not correlate with particle removal (Kimbrough et al1998).…”

Advanced microscopy techniques to assess solid-state properties of inhalation medicines

“…The amount of voltage needed to return the detector to its original voltage increases with increasing particle size. Particles can thus be counted in specific size ranges [28]. This approach has been demonstrated by Niemann et al, which has shown this method meets International Pharmaceutical Aerosol Consortium on Regulation and Science (IPAC-RS) standards for the detection of foreign particles [29].…”

Concepção e estudo de uma unidade compacta para tratamento preliminar de esgoto sanitário composta por separador hidrodinâmico por vórtice e grade fina de fluxo tangencial

“…Os contadores de partícula têm sua utilização limitada à contagem de partículas mais finas (0,5 µm a 500 µm), distribuídas em faixas de tamanho estreitas, pois foram desenvolvidos para a contagem de glóbulos brancos e vermelhos do sangue (ALLEN, 1997). Na área de tratamento de efluentes líquidos, esses equipamentos têm sido utilizados para estudo de unidades de tratamento de água, como filtros rápidos, flotadores etc., uma vez que, as faixas de tamanho de partícula, mormente observadas nos afluentes e efluentes dessas unidades permitem sua utilização (LEWIS et al, 1992;O'SHAUGHNESSY et al, 1997;GELDER et al, 1999). Todavia, os contadores de partícula não são indicados para determinação da distribuição granulométrica da areia presente nos esgotos, devido às faixas de tamanho dos grãos serem extensas e muito grossas (0,5 µm a mais de 1000 µm).…”