Thermophilic Digester for Pathogen-Free Soil Remediant
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Solution Overview
Problem
Current methods for treating animal and vegetable waste to produce a pathogen-free soil remediant are costly due to high energy consumption and inefficiencies in pasteurization processes, which need to meet stringent EU regulations while reducing carbon-based fuel use and energy overall.
Innovation Solution
A method involving thermophilic aerobic digestion in a single digester vessel, where organic waste is maintained at 70°C or higher for at least one hour without external heat input, allowing for concurrent pasteurization and digestion, with controlled temperature and volume adjustments to maintain efficiency and pathogen destruction, using a microporous adsorbent to enhance the process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional pasteurization processes are used to meet EU standards, then pathogen destruction is achieved, but energy consumption increases
Solution Approach 1:
The patent combines pasteurization and digestion into a single integrated process occurring in one digester vessel. The thermophilic conditions (50-70°C) required for digestion also provide pasteurization, eliminating the need for separate heating and pasteurization steps. This merging of functions reduces overall energy consumption while maintaining pathogen destruction effectiveness.
Solution Approach 2:
The digestion process itself generates the heat required for pasteurization through microbial metabolism. The exothermic nature of thermophilic digestion provides self-heating, reducing or eliminating the need for external heat input. The system serves its own thermal needs through the digestion process, making the pasteurization energy-efficient.
2Reliability
If separate pasteurization and digestion processes are used, then pathogen destruction is ensured, but process complexity and equipment costs increase
Solution Approach 1:
The patent consolidates pasteurization and digestion into a single unit operation within one digester vessel. This eliminates the need for separate pasteurization equipment, heat exchangers, and process control systems, thereby reducing equipment costs and operational complexity while maintaining both pathogen destruction and organic matter stabilization.
Solution Approach 2:
The single digester vessel performs multiple functions simultaneously: it digests organic matter, pasteurizes the waste to destroy pathogens, and produces a stable digestate. This multi-functionality reduces the number of required equipment items and simplifies the overall process design.
3Use of energy by moving object
If thermophilic digestion is used without external heat input, then energy consumption is reduced, but maintaining temperature above 70°C becomes challenging
Solution Approach 1:
The thermophilic digestion process generates its own heat through microbial metabolism, creating a self-sustaining thermal system. The exothermic reactions maintain temperatures above 70°C without requiring external heating, as the biological process itself provides the necessary thermal energy.
Solution Approach 2:
The system operates in the thermophilic temperature range (50-70°C) where microbial activity is sufficiently high to generate adequate heat. By optimizing the biological parameters (microbial community, organic loading rate, retention time), the system maintains the required temperature through metabolic heat generation rather than external heating.
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 method effectively reduces energy consumption, meets EU pasteurization standards, and produces a pathogen-free soil remediant with enhanced agronomic benefits, including ammonia oxidation for plant nutrition, while minimizing equipment costs and energy use.
Implementation Method 1
thermophilic aerobic digestion in a single digester vessel
Implementation Method 2
temperature of the organic waste material in the digester vessel is at or above 70° C.... maintaining the organic waste material in the single digester vessel at a temperature of 70° C. or above for at least one hour such that the organic waste material is concurrently pasteurised and digested
Implementation Method 3
using a microporous adsorbent to enhance the process
Data Source
AI summary
There is disclosed a method of producing a soil remediant from liquid organic waste material in which the liquid organic waste material is concurrently pasteurised and digested by thermophilic aerobic digestion in the liquid phase in a single digester vessel. The organic waste material in the digester is maintained continuously at a temperature of at least 70° C. for at least an hour and the liquid organic waste material comprises at least 70% water and can be pumped. After a period of at least an hour a small amount of pasteurised organic waste material is removed and a corresponding amount of fresh organic waste material is added to the single digester vessel such that the temperature is maintained in a comfort zone of the thermophilic bacteria. In a preferred embodiment the thermophilic aerobic digestion is facilitated by micro-organisms including crenarchaeota. The liquid organic waste material can be combined with a microporous adsorbent. Also disclosed is a soil remediant comprising a microporous adsorbent and liquid organic waste material from the novel method. The microporous adsorbent may be a volcaniclastic sedimentary rock or diatomite or of vegetable origin such as biochar. The microporous adsorbent may be a powder or a granular material and may have particle sizes up to 2000 microns.