Thermophilic Methane Digester pH and Temperature Control
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Solution Overview
Problem
Conventional anaerobic digestion methods for treating poultry manure face challenges such as suboptimal reaction rates and bacterial productivity due to pH, temperature, and chemical constituent conditions, particularly in broiler operations, leading to inefficient methane production and increased regulatory burdens on poultry farmers.
Innovation Solution
The method involves adding raw poultry manure to a mixing vessel with a thermophilic methanogenic digester liquid, maintaining a controlled pH and temperature between 7.0 and 7.5, and 120°F to 150°F, and agitating to produce a well-mixed slurry with a solids content of 1% to 10% to optimize methane production and nitrogen recovery, using thermophilic methanogenic bacteria like Methanosarcina barkeri, and employing a nozzle system for effective mixing and circulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional anaerobic digestion is used to treat poultry manure, then methane production occurs, but reaction rates and bacterial productivity are suboptimal due to non-optimum pH, temperature and chemical constituent conditions
Solution Approach 1:
The patent applies parameter changes by controlling pH within the range of 6.8-7.4 and temperature between 120-150°F to create optimal conditions for thermophilic methanogenic bacteria. This resolves the contradiction by adjusting environmental parameters to simultaneously improve reaction rates and stabilize bacterial productivity, preventing the suboptimal performance seen in conventional systems.
2Quantity of substance
If ammonia concentration is not controlled in the digester, then nitrogen recovery is reduced, but ammonia buildup becomes toxic and inhibits digestion
Solution Approach 1:
The patent implements feedback control by continuously monitoring ammonia concentration and adjusting digester conditions to maintain ammonia levels below inhibitory thresholds while maximizing nitrogen recovery. This resolves the contradiction by using real-time feedback to balance nitrogen utilization with prevention of toxic buildup that would inhibit digestion.
3Ease of manufacture
If poultry manure is directly digested without preprocessing, then treatment simplicity is maintained, but difficult-to-treat composition and high cellulose content reduce digestion efficiency
Solution Approach 1:
The patent applies preliminary action by pre-processing poultry manure to reduce cellulose content to less than 5% weight before digestion. This resolves the contradiction by performing preparatory treatment to improve digestibility and reaction rates, while the overall process remains simpler than conventional methods by eliminating complex pretreatment steps and enabling direct digestion of pre-conditioned material.
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 approach enhances methane production, reduces pathogen presence, and effectively manages ammonia levels, resulting in a more efficient and controlled poultry waste management process that addresses regulatory concerns and improves energy recovery from poultry manure.
Implementation Method 1
The present invention is directed to methods for treating manure which involve anaerobic digestion. Conventional anaerobic digestion technology has certain limitations in terms of reaction rates and the ability of the bacteria to be productive
Implementation Method 2
adding raw material to a mixing vessel containing a digester liquid which has been largely depleted of digestible organic materials... heating to an elevated range to produce ammonia and kill bacteria
Implementation Method 3
heating to an elevated range to produce ammonia and kill bacteria, removing the ammonia, cooling the remaining liquid to a digestion temperature
Implementation Method 4
maintaining a controlled pH and temperature between 7.0 and 7.5, and 120°F to 150°F
Implementation Method 5
removing the ammonia, cooling the remaining liquid to a digestion temperature
Implementation Method 6
agitating to produce a well-mixed slurry with a solids content of 1% to 10%
Data Source
AI summary
Compositions, methods and apparatus for the production of methane gas from poultry litter are provided. Particular features are selection of methanogens, well stirring of the digester, and control of critical parameters of digester temperature, pH, and solids content resulting in enhanced methane production and reduced nitrogen compositions. A benefit of the invention is the capability to maintain a closed system without waste by-products.