Evaluation of Slow Sand Filter

Efficient filtration

This project aimed to ascertain the efficiency of removing Giardia cysts, coliform bacteria and other measurable indicators at 100 Mile House.

The study also reviewed the operation of the plant focusing on such aspects as filter run lengths, cleaning procedures and annual costs. The plant has three slow sand filters, each 43m long x 6m wide with a hydraulic capacity of 3.6 ML/d.  Also used in the evaluation were three pilot slow sand filters.

Of 21 raw water samples taken over the study year, 11 detected cysts that varied between 14 and greater than 300 cysts per 4500 litres. No cysts were detected in the filtered water. Similar removal efficiencies were found with other micro-organsisms.

The filter runs were 60-200 days. The research findings and plant features were presented in the AWWARF “Slow Sand Filter Design Manual”.