@article {ahmad1998effects,
	title = {Effects of backwashing on biological filters},
	journal = {Journal-American Water Works Association},
	volume = {90},
	number = {12},
	year = {1998},
	pages = {62{\textendash}73},
	author = {Ahmad, Rasheed and Amirtharajah, A and Al-Shawwa, A and Huck, Peter M}
}
