Hydrodynamic Separator for High MLSS Wastewater Treatment
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Solution Overview
Problem
The high capital costs associated with operating activated sludge process (ASP) wastewater treatment plants at mixed liquor suspended solids (MLSS) concentrations above 3,000 mg/L, primarily due to the non-linear increase in clarifier costs, make it economically prohibitive to maintain efficiency and capacity.
Innovation Solution
Implementing a Hydrodynamic Separator (HDS) system between bioreactors and clarifiers to separate MLSS, allowing for higher MLSS concentrations while reducing the size and cost of bioreactors and clarifiers, and enabling the recycling of biomass, thus lowering overall treatment costs and increasing operational capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If activated sludge process operates at higher MLSS concentrations (above 3,000 mg/L), then treatment capacity and efficiency are improved, but capital cost of clarifiers increases non-linearly making it economically prohibitive
Solution Approach 1:
The patent divides the clarifier into multiple zones with different functions: a first zone for initial settling and a second zone for final clarification. This segmentation allows each zone to be optimized for specific MLSS concentration ranges, enabling the system to handle higher overall MLSS concentrations without requiring a single oversized clarifier, thus controlling capital costs while maintaining treatment capacity.
Solution Approach 2:
The patent introduces a vertical dimension to the clarifier design by creating stacked zones at different heights. The first zone operates at a lower elevation for bulk solids removal, while the second zone operates at a higher elevation for final effluent clarification. This vertical arrangement allows the system to process higher MLSS concentrations without increasing the horizontal footprint, thereby controlling capital costs.
2Ease of manufacture
If secondary clarifier size is reduced to lower capital cost, then ease of manufacture is improved, but ability to handle high MLSS concentrations deteriorates
Solution Approach 1:
The clarifier is segmented into functional zones that handle different aspects of solids separation. The first zone handles bulk solids removal at lower cost, while the second zone provides enhanced clarification for high MLSS streams. This segmentation allows the overall system to handle high MLSS concentrations with a compact footprint, achieving both cost reduction and maintained productivity.
Solution Approach 2:
The patent introduces an intermediary recycling stream that returns a portion of the settled sludge from the first zone back to the bioreactor. This intermediary flow helps maintain the biological activity needed for high-rate treatment while allowing the clarifier to operate at reduced size, thus achieving both capital cost reduction and sustained MLSS handling capacity.
3Device complexity
If clarifier size is minimized for cost effectiveness, then device complexity is reduced, but operational capacity to process high influent flow deteriorates
Solution Approach 1:
The clarifier is divided into functional segments that handle different flow rates and solids concentrations. The first zone processes the bulk of the influent flow at a simplified configuration, while the second zone handles the concentrated MLSS stream with enhanced separation capability. This segmentation allows the system to process high influent flows with a compact overall structure, achieving both reduced complexity and maintained productivity.
Solution Approach 2:
The patent implements dynamic flow distribution between the two zones based on operational conditions. During high flow periods, the system can adjust the flow split to optimize performance, allowing the compact clarifier to handle variable influent flows effectively without requiring oversized design capacity, thus maintaining both simplicity and operational flexibility.
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 HDS system enables ASPs to operate at higher MLSS concentrations, reducing capital costs by minimizing clarifier size and cost, and increasing treatment capacity without the need for extensive expansions, thereby making wastewater treatment more economically viable.
Implementation Method 1
a hydrodynamic separator (HDS) system, where MLSS separation operations are performed
Data Source
AI summary
A wastewater treatment plant that employs an activated sludge process and a method of operating the same is described. Wastewater influent is provided to a bioreactor configured to perform activated sludge processing to develop mixed liquor suspended solids (MLSS). The MLSS is passed from the bioreactor to a hydrodynamic separator (HDS) system, where separation operations are performed on the MLSS. The separation operations generate a low concentration MLSS stream and a high concentration MLSS stream. The low concentration MLSS stream is passed from the hydrodynamic separator system via a first output to a clarifier, and the high concentration wastewater stream is passed via a second output back to the bioreactor. The clarifier performs clarification operations on the cleaned wastewater stream and then outputs an effluent flow.