Filtration of Giardia cysts and other substances. Volume 3, Rapid rate filtration
Date
1985-02
Authors
Logsdon, Gary S., author
Al-Ani, Mohammad, author
McElroy, John M., author
Hibler, Charles P., author
Hendricks, David W., author
Department of Civil Engineering, Colorado State University, publisher
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Journal ISSN
Volume Title
Abstract
The efficiency of rapid rate filtration for removal of .Giardia lamblia cysts, standard plate count bacteria, total coliform bacteria, and turbidity was determined experimentally under a wide range of operating conditions. Percent removals were evaluated by means of a lab-scale pilot plant at temperatures of 4°C and 18°C, for low turbidity water, at hydraulic loading rates of 8 cm/min (2 gpm/ft2, 24 cm/min (5 gpm/ft2) and 33 cm/min (8 gpm/ft2), for "in-line" filtration, for three filter media, and using three chemicals. Testing was performed also using a 1.3 L/s (20 gpm) field-scale rapid rate filtration pilot plant. The range of testing was narrower and focused on ascertaining the findings at the lab-scale. The study has shown, that rapid rate filtration is a highly efficient treatment process for low turbidity waters when proper chemical pretreatment is used. Certain polymers, such as Magnifloc 572C® or Magnifloc 573C® in conjunction with alum will effectively coagulate low turbidity, low temperature water, i.e. when raw water turbidity level is less than 1 NTU, and when temperature is 0-4°C. Lab-scale results, for example, showed that using 5 mg/L of alum as Al2(SO4)3.14H20 followed by 1.5 mg/L Magnifloc 572C, Giardia cyst removals were 99 percent, and standard plate count bacteria and total coliform bacteria removals were greater than 99 percent. At the same time, corresponding turbidity removals of about 80 percent were obtained using raw water having less than 1 NTU turbidity. With no chemical pretreatment, removals of all substances, including Giardia cysts, ranged from only 10 percent to 70 percent. The results showed that rapid rate filtration will effectively treat low turbidity water, and will removal Giardia cysts if proper chemical pretreatment is used. Proper chemical pretreatment is difficult to determine and to evaluate for low turbidity waters since the usual measures of effectiveness such as turbidity removals and coliform bacteria removals are based upon very low amounts in the raw water. Pilot plant testing is imperative to ascertain proper chemical pretreatment, when using low turbidity waters. It covers the period March 1, 1981 to February 28, 1984, and work was completed as of February 28, 1984.
Description
Report 5847-85-1.
This report was submitted by Colorado State University to fulfill Cooperative Agreement No. CR808650-02, funded by the U.S. Environmental Protection Agency.
Includes bibliographical references (pages 103-110).
February 1985.
This report was submitted by Colorado State University to fulfill Cooperative Agreement No. CR808650-02, funded by the U.S. Environmental Protection Agency.
Includes bibliographical references (pages 103-110).
February 1985.
Rights Access
Subject
Drinking water -- Purification -- United States
Filters and filtration
Water -- Purification
Giardia lamblia