Dissolved Air Flotation for Wastewater Solids Removal
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Solution Overview
Problem
Conventional wastewater treatment systems face inefficiencies in removing suspended solids and biological oxygen demand, leading to increased capital and operational costs, and require significant aeration and sludge disposal.
Innovation Solution
Incorporating a dissolved air flotation (DAF) unit between the contact tank and biological treatment unit to remove solids before they enter the biological treatment process, recycling a portion of the solids back to the contact tank, and utilizing an anaerobic digester to treat the remaining solids, reducing the biological oxygen demand and energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional wastewater treatment systems are used to remove suspended solids and biological oxygen demand, then treatment effectiveness is achieved, but capital and operational costs increase
Solution Approach 1:
The treatment system is divided into distinct functional segments: an anaerobic digester for solids treatment and a biological treatment unit for effluent treatment. This segmentation allows each unit to be optimized for its specific function, improving overall treatment effectiveness while managing system complexity through modular design.
Solution Approach 2:
Fermented solids act as an intermediary substance that transfers organic carbon from the anaerobic digester to the biological treatment unit. These fermented solids serve as both a product of anaerobic digestion and a substrate for biological treatment, creating an efficient link between the two treatment processes.
2Reliability
If conventional wastewater treatment systems are used, then suspended solids are removed, but aeration requirements increase
Solution Approach 1:
The anaerobic digester extracts and treats suspended solids separately from the main biological treatment process. By removing and concentrating solids in a dedicated anaerobic unit, the remaining effluent requires less aeration in the biological treatment unit, reducing overall energy consumption.
Solution Approach 2:
The system changes the oxygen parameter by creating an anaerobic environment in the digester for solids treatment. This parameter change allows solids to be treated without aeration, and the resulting fermented solids are then used in the aerobic biological treatment unit, optimizing aeration requirements.
3Reliability
If conventional wastewater treatment systems are used, then treatment is achieved, but sludge disposal requirements increase
Solution Approach 1:
The anaerobic digester converts what would be harmful waste sludge into beneficial fermented solids that can be used as substrate in the biological treatment unit. This transformation turns a disposal problem into a resource, reducing the volume of sludge requiring disposal while maintaining treatment effectiveness.
Solution Approach 2:
The system discards excess sludge from the anaerobic digester while recovering and utilizing the fermented solids as a valuable substrate for the biological treatment unit. This selective discarding and recovering approach minimizes waste disposal requirements while maintaining treatment performance.
4Volume of stationary object
If solids are removed before biological treatment, then biological treatment unit size decreases, but system configuration complexity increases
Solution Approach 1:
The system is segmented into an anaerobic digester for solids removal and a biological treatment unit for effluent treatment. This segmentation enables the biological treatment unit to be smaller since it receives pre-treated effluent with reduced solids load, while the overall system configuration is managed through clear functional separation.
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
This configuration reduces the size of the biological treatment unit, decreases aeration requirements, and increases biogas production, resulting in lower capital and operational costs while enhancing treatment efficiency and reducing waste sludge.
Implementation Method 1
The dissolved air flotation unit may be configured to treat the first mixed liquor with the gas to form the floated solids and the effluent
Implementation Method 2
The fermentation unit may be configured to treat at least a portion of the floated solids to form the fermented solids
Implementation Method 3
The biological treatment unit may be configured to treat the effluent with at least a portion of the fermented solids to form a second mixed liquor
Data Source
AI summary
A wastewater treatment system including a contact tank, a dissolved air flotation unit, a fermentation unit, and a biological treatment unit is disclosed. A method of retrofitting a wastewater treatment system by arranging the wastewater treatment system such that floated biosolids are fermented in an anerobic environment and fluidly connecting the biological treatment unit to receive at least a portion of the fermented solids is also disclosed. The method optionally includes providing a fermentation unit and fluidly connecting the fermentation unit to a biological treatment unit. A method of treating wastewater including combining the wastewater with activated sludge, floating biosolids from the activated wastewater, fermenting the floated biosolids, and biologically treating the effluent with the fermented solids is also disclosed. A method of facilitating delivery of soluble organic carbon to a biological treatment unit is also disclosed.