The increasing number of cryptosporidiosis outbreaks over the last two decades has led to
concerns over the efficiency of conventional water treatment processes to remove
Cryptosporidium oocysts. A problem with chemical disinfection is that in many cases the use of
disinfectants would create high levels of byproducts because higher dosages and longer contact
times than now used would be required for the inactivation of Cryptosporidium. Since
Cryptosporidium oocysts are almost completely resistant to chlorine-based disinfectants at the
concentrations and contact times practical for water treatment, the physical-chemical removal
process including coagulation, clarification and filtration is of great importance, particularly for
those utilities using traditional treatment methods. Coagulation is employed in most surface
water treatment facilities, and is one of the most important steps for effective removal by
clarification and filtration. The parameters that affect coagulation efficiency and, therefore, the
optimum coagulant dose, include several raw water quality characteristics. One of the main
factors that control coagulation is natural organic matter (NOM). The objective of this study was
to evaluate the effects NOM on the removal of Cryptosporidium parvum oocysts during
coagulation and sedimentation using bench-scale experiments. The study was done for three
initial DOC concentrations and for several pH values and alum dose conditions. Materials and methods discussed include: jar tests; matrix water; natural organic matter; coagulant; cryptosporidium parvum oocysts; cryptosporidium parvum oocyst enumeration; dissolved organic carbon; and, ultraviolet absorbance.
Includes 16 references, figures.
| Edition : | Vol. - No. |
| File Size : | 1
file
, 300 KB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 13 |
| Published : | 11/01/2002 |
