Control measures to reduce clogging in a St. Lawrence River water treatment process using slow sand filtration

Description

Previous studies showed that measures were required to control populations of E. coli and zebra mussel larva in water from the St. Lawrence. A system using slow sand filtration and an aerated pond was therefore installed at a farm on Île d'Orléans. Although this system has been proven to be effective for resolving both these problems, the sand filter can become clogged due to increased turbidity levels in the river at certain times of year and algal blooms in the water column above the filter. To manage this clogging risk, the project automated pumping based on water turbidity and cover the filter to prevent light from entering the water and thus reduce algal bloom. These control measures will improve technology transfer to other farmers who want to draw water from the river.

Objective(s)

• Determine the impact of methods of controlling suspended solids and algae on clogging of the sand filter
• Measure the effect of water turbidity on clogging of the sand filter in the lab
• Automate pumping from the river based on water turbidity
• Determine the effectiveness of covering the filter for algae control