Preface	6
	Contents	8
	1 Introduction	11
	Abstract	11
	General Scope	12
	Variation Driven by Precipitation	13
	Ecotechnologies	14
	References	15
	2 Treatment Techniques for Variable Flows	17
	Abstract	17
	Treatment Systems	18
	Stormwater Ponds and Basins	18
	Constructed Wetlands	21
	Surface-Flow Constructed Wetlands	22
	Floating Treatment Wetlands	23
	Subsurface-Flow Constructed Wetlands	27
	Bioretention Filters	30
	Swales and Buffer Strips	34
	References	35
	3 Nutrient Removal from Variable Stormwater Flows	41
	Abstract	41
	Treatment Mechanisms for Nutrient Removal	42
	Concentrations of Nutrients from Stormwater, CSOs and Agricultural Diffuse Pollution	46
	Stormwater from Separate Sewer Systems and Highway Runoff	46
	Combined Sewer Overflows	46
	Agricultural Diffuse Pollution	49
	Treatment Systems	51
	Stormwater Sedimentation Ponds and Basins	51
	Constructed Wetlands	52
	Surface-Flow Wetlands	52
	Floating Treatment Wetlands	54
	Subsurface-Flow Constructed Wetlands	55
	Bioretention Filters	58
	Swales and Buffer Strips	60
	References	60
	4 Microbial Loads and Removal Efficiency Under Varying Flows	66
	Abstract	66
	Introduction	67
	Treatment Mechanisms	67
	Concentrations of Pathogens from Stormwater, Combined Sewer Overflows and Agricultural Diffuse Pollution	69
	Stormwater from Separate Sewer Systems	69
	Combined Sewer Overflows	71
	Agricultural Diffuse Pollution	72
	Treatment Systems	74
	Stormwater Ponds and Basins	74
	Constructed Wetlands	75
	Surface-Flow Constructed Wetlands	75
	Subsurface-Flow Constructed Wetlands	77
	Bioretention Filters	77
	References	79
	5 Metals: Occurrence, Treatment Efficiency and Accumulation Under Varying Flows	84
	Abstract	84
	Introduction	84
	Treatment Mechanisms	85
	Metals in Stormwater from Separate Sewer Systems and Combined Sewer Overflows	86
	Seasonal Variations	86
	Variation Between Catchments	87
	Variations Over Time	87
	Treatment Systems	89
	Stormwater Ponds and Basins	89
	Constructed Wetlands	91
	Surface-Flow Constructed Wetlands	91
	Floating Treatment Wetlands	92
	Subsurface-Flow Constructed Wetlands	92
	Bioretention Filters	93
	Swales and Buffer Strips	96
	References	96
	6 Emerging Contaminants: Occurrence, Treatment Efficiency and Accumulation Under Varying Flows	101
	Abstract	101
	Introduction	102
	Concentrations of Selected Emerging Contaminants	104
	Treatment Systems	108
	Stormwater Ponds and Basins	108
	Constructed Wetlands	109
	Bioretention Filters	112
	Swales and Buffer Strips	113
	References	113
	7 Modelling Under Varying Flows	118
	Abstract	118
	Modelling of Treatment Systems	118
	Modelling Hydraulics of Variable-Flow Constructed Wetlands	119
	Modelling Treatment Performance of Variable-Flow Constructed Wetlands	122
	Design-Oriented Models for CSO-CWs	122
	First-Order Kinetic Model	124
	Process-Based Model	126
	Future Perspectives	127
	Novel Approaches for Design of Variable-Flow Constructed Wetlands	127
	Process-Based Models as Design Tools	127
	Limitations of the Wider Application of Models for Variable-Flow Constructed Wetlands	131
	References	133