Three laboratory-scale slow sand filters containing sands of different effective sizes (170, 360 and 450 micrometres) were operated at treatment rates ranging from 100 to 500 mm/h at a constant temperature of 25 degrees Celsius.
|Title||A study of three slow sand filters at various flow rates with constant temperature|
|Publication Type||Journal Article|
|Year of Publication||1993|
|Authors||Ellis, KV, Aydin, ME|
|Pagination||p. 88-96: 5 fig., 4 tab.|
|Keywords||coliforms, denitrification, efficiency, flow rate, laboratory testing, nitrification, particle size, slow sand filtration, suspended solids removal, turbidity removal|
Three laboratory-scale slow sand filters containing sands of different effective sizes (170, 360 and 450 micrometres) were operated at treatment rates ranging from 100 to 500 mm/h at a constant temperature of 25 degrees Celsius. Removal rates were as follows: total coliforms: 1.74 to 3.4 log; faecal coliforms: 1.41 to 3.3 log; suspended solids: 0.76 to 1.77 log; turbidity: 1.16 to 1.76 log. There was a definite correlation between increasing rates of treatment and decreasing removal of total coliforms. This correlation was not nearly so evident with faecal coliforms. The number of 100 per cent removals of both faecal coliform and total coliform bacteria decreased as the treatment flows increased. A definite correlation was observed between increasing sand grain-size and an improved efficiency of suspended solids removal. High levels of nitrification and appreciable denitrification were also recorded. Some correlation was observed between increasing rate of treatment and decreasing percentage nitrification. No other sustainable correlation was discovered between sand grain sizes and the degree of removal of any other variable.