Proceedings

Wet Weather Strategies for Treatment

Outline
• Managing peak wet weather in the catchment
• Case Studies: CSO Abatement; Catchment Approach
• Impacts of wet weather on wastewater characteristics
• Equalization / Storage
• High-Rate primary treatment
• High-Rate sidestream treatment

Wet Weather Peak Flow Management
• Split flows (passive or active control) into parallel trains
• Passive: vortex, orifice, fixed weir
• On-line equalization and/or off-line storage
• Return-pumping of stored flows for subsequent treatment

Effective Primary Treatment
Performance Essential
• Wet weather solids are:
• larger in size;
• settleability is typically good
• Highly variable in characteristics
• Wet weather loadings are:
• High during first flush
• Highly variable during event
• Higher in total dissolved solids
• Temperature typically colder
Generally, as flow increases, percent removal efficiency decreases
Significant impact on downstream processes