Thin-Stillage Digestate Decarbonization for Ammonium Removal
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Solution Overview
Problem
The production of bioethanol is hindered by the presence of ammonium bicarbonate in digestates from thin stillage, which increases ammonium concentration, requires additional sulfuric acid use, and leads to high sulfur levels, necessitating further treatment and affecting ethanol production efficiency.
Innovation Solution
A process involving heating the digestate to decompose ammonia bicarbonate into ammonium and bicarbonate, followed by counter-current contact with air to form carbonates, which are then settled out, reducing the ammonium load and minimizing the need for sulfuric acid.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If digestate containing ammonium bicarbonate is introduced to the bioethanol production process, then the digestate can be reused as process water, but the ammonium concentration increases which has a harmful and inhibiting effect on ethanol generation reactions
Solution Approach 1:
The patent extracts and removes ammonium bicarbonate from the digestate through a decarbonizer system before the digestate is reused in the bioethanol production process. This extraction eliminates the harmful ammonium component while preserving the utility of the digestate as process water.
Solution Approach 2:
The decarbonizer system acts as an intermediary treatment unit between the digestate source and the bioethanol production process. It mediates by treating the digestate to remove harmful substances before introduction to the fermentation system.
2Loss of substance
If ammonium bicarbonate containing digestate is used as process water, then water reuse is achieved, but additional sulfuric acid must be added to adjust pH which increases sulfur load
Solution Approach 1:
The patent removes ammonium bicarbonate from the digestate before pH adjustment is needed. By extracting the harmful substance first, subsequent pH adjustment requires minimal or no sulfuric acid addition, thereby eliminating the sulfur load problem.
Solution Approach 2:
The decarbonizer performs preliminary treatment by removing ammonium bicarbonate before the digestate enters the bioethanol process. This preliminary action prevents the need for subsequent acid addition and sulfur management.
3Loss of substance
If digestate with high ammonium bicarbonate levels is introduced to the bioethanol process, then water reuse is maximized, but further treatment of products such as biogas is required to remove compounds like H2S
Solution Approach 1:
The patent extracts ammonium bicarbonate from digestate before reuse, which prevents the formation of H2S and other problematic compounds during subsequent processing. This extraction eliminates the need for additional biogas treatment systems.
Solution Approach 2:
The decarbonizer performs preliminary anti-action by removing the precursor substance (ammonium bicarbonate) that would lead to harmful byproducts. This prevents the need for corrective treatment measures downstream in the biogas processing system.
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 process effectively reduces the carbon and water footprint of ethanol production by minimizing ammonium bicarbonate levels, allowing for the reuse of treated digestate in bioethanol plants with reduced acid consumption and improved efficiency.
Implementation Method 1
contacting the heated stream with air, wherein a first portion of the ammonia is desorbed from the heated stream to mix with the air so as to form a gaseous effluent stream
Implementation Method 2
a first portion of the bicarbonate reacts with metals in the digestate to form carbonates which settle out from the heated stream during the counter-current contact
Implementation Method 3
heating the digestate stream so as to form a heated stream, wherein the heating is to a temperature of at least about 194° F. (90° C.) to decompose ammonia bicarbonate contained in the digestate stream into ammonium and bicarbonate
Data Source
AI summary
Processes, systems and equipment are for treating a digestate resulting from the thin stillage of a bioethanol plant. They can include a decarbonizer system to reduce the carbon and water footprint in an ethanol plant and associated biogas plant by treating a digestate stream resulting from a thin stillage digester. The treatment includes heating the digestate stream to decompose ammonia bicarbonate contained in the digestate stream into ammonium and bicarbonate; and contacting the heated digestate stream with air so that a first portion of the ammonia is desorbed from the heated stream to mix with the air.