Circulation Sludge Fermentation with Moisture Feedback and Carbonization
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Solution Overview
Problem
Existing sewage sludge recycling systems face challenges in producing usable compost efficiently, with some materials being discharged in an unripe state and requiring lengthy processing times, while also being costly due to microorganism usage.
Innovation Solution
A sewage sludge-to-resource recycling system that incorporates dehydration, primary and secondary fermentative treatment, carbonization, and controlled distribution and mixing processes to produce compost and activated carbon efficiently, utilizing aerobic thermophiles and controlled water content management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If sewage sludge is fermented using conventional single-stage systems, then processing time is reduced, but the compost quality is insufficient and materials are discharged in an unripe state
Solution Approach 1:
The fermentation process is divided into two distinct stages: primary fermentation (3-7 days) and secondary fermentation (7-14 days). Each stage has specific temperature ranges, microbial communities, and operational parameters optimized for its purpose. This segmentation allows rapid initial decomposition followed by thorough maturation, resolving the contradiction between speed and quality.
Solution Approach 2:
The primary fermentation stage performs preliminary decomposition and pathogen reduction before the secondary stage completes maturation. By pre-processing the sludge to reduce moisture content to 60-70% and eliminate harmful organisms in the first stage, the system prepares material for final composting in the second stage, achieving both speed and quality.
2Productivity
If microorganisms are added to accelerate decomposition, then processing time is reduced, but system cost increases
Solution Approach 1:
The system generates its own microbial population through the fermentation process itself. Indigenous thermophilic and mesophilic microorganisms naturally present in the sludge proliferate during primary fermentation and are then distributed throughout the secondary fermentation material. This self-generated microbial inoculum eliminates the need for expensive external microorganism additions while maintaining rapid decomposition speeds.
Solution Approach 2:
The system recycles the fermented compost from the secondary stage back to the primary fermentation stage as inoculum material. This circular approach continuously builds and redistributes microbial populations within the system, eliminating external microorganism purchases while sustaining high decomposition rates indefinitely.
3Ease of operation
If water content is not controlled during fermentation, then operation is simpler, but fermentation efficiency decreases and processing time increases
Solution Approach 1:
The system implements water content monitoring and control through a feedback mechanism. A water content meter continuously measures moisture levels in the sludge, and this information feeds back to the dewatering equipment to adjust processing parameters. This automated feedback loop maintains optimal water content (60-70%) without requiring manual intervention, resolving the contradiction between operational simplicity and fermentation efficiency.
4Device complexity
If single-stage fermentation is used, then device complexity is reduced, but processing time increases and compost quality is insufficient
Solution Approach 1:
The fermentation system is segmented into two separate functional units: a primary fermentation device for rapid initial decomposition (3-7 days) and a secondary fermentation device for maturation (7-14 days). Each device is optimized for its specific stage requirements, enabling parallel operation that reduces total processing time while maintaining simple, modular device structures that are easy to construct and maintain.
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 produces compost and activated carbon efficiently, reducing processing time and microorganism costs, and enhances sewage treatment by normalizing fermentation and reducing BOD/COD, while ensuring high-quality output.
Implementation Method 1
the fermentative treatment is performed while the fermentative treatment container is rotated about a central axis thereof to cause the raw material to gradually move within the fermentative treatment container from the one end side toward the other end side
Implementation Method 2
configured to fermentatively treat organic waste as a raw material by aerobic hyperthermophiles
Implementation Method 3
decomposition and fermentation unit for delivering the solid waste subjected to the crushing and mixing by the crushing and mixing unit into a decomposition and fermentation mechanism for decomposing and fermenting the delivered soil waste by the activity of the microorganism
Data Source
AI summary
A sewage sludge-to-resource recycling system of circulation-type is provided for recycling sewage sludge as organic waste into a useful product. The sewage sludge-to-resource recycling system of circulation-type comprises: dehydration means to dehydrate sewage sludge to form a raw material; primary fermentative treatment means comprising a horizontal cylindrical shaped fermentative treatment container configured to be rotated about a central axis thereof; raw material supply means provided on the inlet end side of the fermentative treatment container and configured to receive the raw material from the dehydration means and supply the received raw material into the fermentative treatment container; primary fermented product discharge means provided on the discharge end side of the fermentative treatment container and configured to discharge the primary fermented product outside the fermentative treatment container: secondary fermentative treatment means to receive the primary fermented product from the primary fermentative treatment means, and additionally ferment the received primary fermented product to produce a secondary fermented product having a second set water content value or less, the second set water content value being less than a water content of the primary fermented product; carbonization means to receive the secondary fermented product from the secondary fermentative treatment means, and subject the received secondary fermented product to carbonization treatment to produce a carbide; mixing means to receive the secondary fermented product from the secondary fermentative treatment means and the carbide from the carbonization means, and mix them together to produce a mixture; and water content measurement means to measure the water content of the primary fermented product discharged from the primary fermentative treatment means; wherein the mixing means is connected to third distribute and supply means, the third distribution and supply means being configured to distributively supply at least part of the mixture to the raw material supply means and/or third useful resource processing means to perform processing into a third useful product of a third form.