Fermentation Biosolids Dewatering via pH Conditioning and Flocculation
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Solution Overview
Problem
Existing methods for dewatering biosolids from fermentation processes result in cakes with unacceptably high moisture content and stickiness, leading to reduced solid recovery and efficiency, and the filtrate contains high total suspended solids, disrupting biological wastewater treatments.
Innovation Solution
A method involving the use of alkaline material to raise the pH of biosolids to 7 to 8.5, followed by the addition of a coagulant to reduce particle charge and an agglomerating polymer to increase particle size to at least 1 mm, facilitating efficient dewatering and separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional dewatering techniques are used on biosolids, then water removal is achieved, but the output cake has unacceptably high moisture content and stickiness
Solution Approach 1:
The patent applies preliminary chemical conditioning to the biosolids before dewatering. Coagulants and flocculants are added to the biosolids slurry prior to the dewatering process to modify the particle surface properties, promote aggregation, and reduce stickiness. This preliminary action prepares the biosolids for effective water removal while producing a cake with acceptable moisture content and reduced stickiness, preventing the problems that would occur with conventional direct dewatering.
2Quantity of substance
If conventional dewatering techniques are used, then some water is removed, but solid recovery is reduced and process efficiency diminishes
Solution Approach 1:
The patent changes the chemical parameters of the biosolids slurry by adding coagulants and flocculants, which alter the surface charge and aggregation state of the particles. These parameter changes enable more effective separation of water from solids during dewatering, increasing both the amount of water removed and the efficiency of solid recovery. The chemical conditioning optimizes the dewatering process to achieve higher productivity and better solid recovery compared to conventional mechanical dewatering alone.
3Quantity of substance
If conventional dewatering is applied, then water is separated, but the filtrate contains high total suspended solids that disrupt wastewater treatment
Solution Approach 1:
The patent uses coagulants and flocculants as intermediary substances that facilitate the separation of suspended solids from water. These chemical intermediaries cause the fine suspended particles to aggregate into larger flocs that can be more easily removed during dewatering. As a result, the filtrate produced has significantly reduced total suspended solids content, preventing disruption to subsequent wastewater treatment processes while still achieving effective water separation.
4Device complexity
If biosolids are dewatered without chemical conditioning, then the process is simpler, but cake stickiness reduces filtration unit efficiency
Solution Approach 1:
The patent modifies the chemical parameters of the biosolids by adding coagulants and flocculants, which fundamentally change the surface properties and aggregation behavior of the particles. This chemical conditioning reduces cake stickiness and improves filterability, thereby enhancing the ease of operation and efficiency of the filtration unit. Although this adds a chemical addition step, the overall process becomes more efficient and reliable, offsetting the slight increase in operational complexity.
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 produces a cake with higher solid content and a clarified stream with reduced solids, improving recovery efficiency, reducing microbial degradation, and minimizing the need for frequent cleaning, while allowing the recovered water to be recycled.
Implementation Method 1
treating the solid byproduct with alkaline material effective to increase the pH of the solid byproduct to a value of from about 7 to about 8.5
Implementation Method 2
adding coagulant to the alkaline-treated solid byproduct, the coagulant effective to reduce net charge of the particles
Implementation Method 3
adding polymer to the solid byproduct with reduced net charge, the polymer effective to agglomerate the particles so they have an average particle size of at least about 1 mm
Data Source
AI summary
Disclosed are methods of dewatering solid byproduct. In some embodiments, the solid byproduct contains particles and is produced from a fermentation process for making an oxygenated compound such as ethanol. The method comprises a chemical sequence for conditioning (pre-treating) the solid byproduct to be dewatered. The solid byproduct (in water) is treated with alkaline material to increase its pH to about 7-8.5. Coagulant is added to the alkaline-treated solid byproduct to reduce charge on the solid byproduct. An agglomerating polymer is then added to increase the average size of the solid byproduct particles to a desired size (e.g., at least about 1 mm). Dewatering can further use known technologies such as screw press, belt press, filter press, centrifuge, and/or a dryer to separate the conditioned or pre-treated byproduct from water. Also disclosed are methods of producing oxygenated product, as well as methods of producing animal feed and/or fertilizer, respectively.