Anaerobic Digester Self-Delivery of Floating Solids
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Solution Overview
Problem
Household anaerobic digesters face frequent clogging issues due to the accumulation of lignin-based floating solids, leading to high maintenance requirements and inefficient operation, especially in smaller designs intended for the U.S. market.
Innovation Solution
The design incorporates a self-delivery mechanism that automatically moves accumulated solids from the primary vessel to a secondary treatment vessel, utilizing a top-mounted dual output component with a gas output path and a solids output path, preventing clogging and allowing for easy removal of solids, along with a gas recirculation system to maintain efficient operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If smaller digester designs (50-100 gallons) are used to reduce aesthetics and heating requirements, then the digester becomes more suitable for U.S. households, but clogging occurs much more quickly due to accumulation of lignin-based floating solids
Solution Approach 1:
The digester is divided into two separate vessels: a primary digestion vessel and a secondary treatment vessel. The dual-vessel segmentation allows solids to be separated from the digestion process, with the secondary vessel collecting floating solids that would otherwise cause clogging in smaller digesters.
Solution Approach 2:
A dual output component acts as an intermediary between the primary and secondary vessels. This component includes both a gas output path and a solids output path, mediating the separation of biogas and floating solids, preventing clogging of the gas collection system.
2Device complexity
If traditional single-vessel digesters are used, then the design is simpler, but frequent draining and re-inoculation are required when floating solids accumulate
Solution Approach 1:
By segmenting the digester into primary and secondary vessels with separate output paths, the system automatically separates solids from the digestion mixture. This segmentation eliminates the need for frequent manual draining and re-inoculation, significantly reducing maintenance requirements.
Solution Approach 2:
The dual-vessel design with automatic solids separation enables the digester to self-manage solid accumulation. The system continuously separates and redirects floating solids to the secondary vessel, performing self-maintenance without requiring user intervention for draining and re-inoculation.
3Reliability
If larger digesters are used to operate effectively, then heating requirements increase and aesthetic issues arise, but clogging occurs less frequently
Solution Approach 1:
The segmentation into dual vessels with separate solids handling allows smaller digester volumes to operate effectively without the clogging problems that previously required larger designs. This eliminates the need for excessive heating that would be required in larger digesters while maintaining reliable operation.
4Reliability
If frequent draining is performed to remove accumulated solids, then clogging is prevented, but the bacterial ecosystem must be re-established each time
Solution Approach 1:
The dual-vessel segmentation continuously separates solids from the digestion process, preventing accumulation that would require draining. The bacterial ecosystem remains undisturbed in the primary vessel, eliminating the time loss associated with re-establishment after draining.
Solution Approach 2:
The continuous solids separation mechanism maintains uninterrupted digestion operation. By continuously removing floating solids through the dual output component, the system prevents clogging without interrupting the bacterial ecosystem, maintaining continuous useful action without time loss for re-establishment.
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 solution reduces maintenance needs by preventing clogging and allowing for continuous operation, increasing the effective working volume of the digester, and enabling smaller, more efficient designs that can handle waste effectively, contributing to reduced fossil fuel use and improved food waste management.
Implementation Method 1
The anaerobic digesters described herein self-deliver accumulated solids and sunken sludge for easy periodic removal by the end-user
Implementation Method 2
lighter floating solids can be delivered through an upper outlet
Data Source
AI summary
Self-delivering digester 100s with self-delivery of accumulated solids are described. A primary waste vessel includes a feeding port for kitchen waste, and an upper output component that connects to a top of the primary waste vessel. The upper output component includes a gas output path from a top of the upper output component, and a floating solids output path that delivers floating solids that overflow from the top of the primary waste vessel to a secondary vessel thereby preventing clogging of the gas output path.