ABSTRACT
Testing of field-scale bag filtration systems yielded results indicating that 4 to 6 micron polystyrene microspheres can be a safe, less expensive, and reliable surrogate for determining Cryptosporidium oocyst removal. Particle counting is not likely to be widely used by small systems because of its cost and difficult operation and reliability. The studies were performed using turbidity to further characterize bag filtration. Different configurations of bag filtration systems are being challenged by varying turbidity levels and flow rates. The research is not intended to compare systems but to identify the most important design and operational characteristics that provide for the most economical application at various raw water situations. The raw water used in these experiments exhibited a preponderance of small particles whereas other water sources may be more amenable to bag filtration given a different size distribution. Also of concern is the removal efficiency just after installation.
