Parallel Biological and Dissolved Air Flotation Storm Water Treatment
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Solution Overview
Problem
Conventional municipal wastewater treatment systems face challenges in handling excess wastewater during storm events, leading to untreated overflow that contaminates water bodies with high concentrations of pollutants like suspended solids and fats, oils, and grease (FOG), which can exceed discharge limits and impact water quality and public health.
Innovation Solution
A parallel wastewater treatment system comprising a biological treatment unit and a dissolved air flotation (DAF) unit, where overflow wastewater is directed to a contact tank and then to a DAF unit for effective removal of FOG, utilizing a return activated sludge recycle and valves to manage flow rates and contaminant concentrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional municipal wastewater treatment systems are used, then standard treatment capacity is maintained, but untreated overflow occurs during storm events leading to water contamination
Solution Approach 1:
The system divides the single wastewater treatment stream into two parallel streams: a primary treatment path for normal flow and an overflow treatment path for excess storm water. This segmentation allows the system to handle both standard capacity and peak storm events simultaneously, preventing untreated overflow contamination while maintaining standard treatment operations.
2Reliability
If overflow wastewater is treated through the primary biological treatment unit, then treatment quality is maintained, but treatment time and system overload increase
Solution Approach 1:
The overflow treatment sub-system acts as an intermediary pathway that receives and treats excess storm water separately. This intermediary system prevents the primary biological treatment unit from becoming overloaded during storm events, maintaining treatment quality in the primary system while providing rapid treatment capacity for overflow through the parallel DAF-based path.
3Adaptability or versatility
If a parallel overflow treatment system is added, then storm water treatment capability is improved, but system complexity increases
Solution Approach 1:
The overflow treatment sub-system is designed with multi-functionality to handle various storm water conditions and can operate independently or in conjunction with the primary system. The dissolved air flotation units and contact tanks serve multiple purposes including FOG removal, suspended solids separation, and rapid treatment of variable flow rates, reducing the need for additional specialized equipment.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system effectively treats overflow wastewater, meeting municipal discharge requirements by removing FOG and suspended solids, reducing capital and operational costs, and enhancing environmental sustainability.
Implementation Method 1
a biological treatment unit configured to biologically break down organic components of the wastewater
Implementation Method 2
a dissolved air flotation unit configured to separate suspended matter from a portion of the second mixed liquor and form a second solids-lean effluent, floated solids, and waste solids
Implementation Method 3
a contact tank configured to mix the overflow wastewater with the return activated sludge to form a second mixed liquor
Data Source
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AI summary
A wastewater treatment system includes a first sub-system having a biological treatment unit and a second sub-system having a dissolved air flotation unit. A method of treating wastewater includes directing a first stream of wastewater to a biological treatment unit and directing an overflow stream of wastewater to a dissolved air flotation unit. A method of facilitating treatment of overflow wastewater in a biological treatment system includes connecting an overflow treatment system in a parallel configuration with the biological treatment system, the overflow treatment system having a dissolved air flotation unit, and directing a fraction of activated sludge from the biological treatment system to the overflow treatment system.