What are the typical filtration rates for slow sand filtration?

The typical filtration rates for slow sand filtration are indeed in the range of 0.015 to 0.15 gallons per minute per square foot. Slow sand filters are characterized by their low filtration rates, which allow for effective removal of pathogens and particulates through a combination of biological processes and physical straining. This slow rate is essential because it provides sufficient contact time for organisms and materials within the filter media to effectively clean the water.

The ranges provided in the other choices exceed the typical operational rates for slow sand filters. Higher filtration rates would likely result in a loss of treatment effectiveness as the water would pass too quickly through the media, reducing contact time and compromising the filtration process. Understanding these specific rates is crucial for designing and operating water treatment systems effectively, ensuring both efficiency and safety in drinking water supplies.