Pulp Thermal Hydrolysis Recirculation for Biogas Yield
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Solution Overview
Problem
Thermal hydrolysis processes for pulp treatment face challenges in minimizing investment costs, maximizing biogas production, stabilizing bacterial populations, and managing ammonia toxicity, particularly due to fluctuating loading conditions and equipment underutilization.
Innovation Solution
A method involving aerated or non-aerated hydrolysis of pulp, optional dilution, mesophilic or thermophilic digestion, dehydration, and recirculation of dehydrated pulp to maintain constant loading conditions, using thermal hydrolysis with controlled temperature and pressure, and pH management to optimize biogas production and equipment utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If thermal hydrolysis is implemented to improve biogas production and digestion efficiency, then the investment costs are high, but the return on investment is long-term
Solution Approach 1:
The patent implements dynamic control of the hydrolysis process by adjusting temperature, pressure, and residence time parameters based on real-time monitoring of biogas production and substrate characteristics. This allows optimization of the balance between investment costs and biogas production efficiency, enabling the system to adapt to varying operational conditions and maximize return on investment.
2Productivity
If feed concentration is increased to improve volumetric loading, then the rheological constraints are overcome, but ammonia toxicity increases
Solution Approach 1:
The patent employs parameter changes by adjusting pH levels, temperature, and hydraulic retention time to control ammonia speciation and toxicity. By modifying these parameters, the system can maintain high volumetric loading while preventing ammonia from becoming toxic to methanogenic bacteria, thus resolving the contradiction between productivity and harmful factors.
3Productivity
If pH is increased to improve biogas production, then the proportion of dissolved NH3 increases, but ammonia toxicity increases
Solution Approach 1:
The patent implements feedback control mechanisms that continuously monitor pH, ammonia concentration, and biogas production rates. Based on this feedback, the system automatically adjusts operational parameters such as alkalinity addition, hydraulic retention time, and mixing intensity to maintain optimal pH levels that maximize biogas production while preventing ammonia toxicity buildup.
4Adaptability or versatility
If loading variations are allowed to occur, then operational flexibility is improved, but bacterial population stability decreases
Solution Approach 1:
The patent applies beforehand cushioning by maintaining a buffer inventory of active bacterial populations and establishing reserve capacity in the digester system. This cushioning effect allows the system to absorb sudden loading variations without compromising bacterial population stability, thus enabling operational flexibility while protecting against shocks to the microbial consortium.
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 minimizes investment costs, maximizes biogas production, stabilizes bacterial populations, and effectively manages ammonia toxicity by maintaining consistent loading and pH levels, ensuring efficient use of thermal hydrolysis and digestion equipment.
Implementation Method 1
thermal hydrolysis which combines the effects of heating at high temperature and generally of abrupt depressurization
Implementation Method 2
heating at high temperature
Implementation Method 3
The most common heating mode of these methods is steam injection, which is used to bring the sludge to the temperature required for the hydrolysis
Implementation Method 4
thermal hydrolysis which combines the effects of heating at high temperature and generally of abrupt depressurization
Implementation Method 5
improve its capacity for digestion by anaerobic bacteria for the purpose of producing biogas
Implementation Method 6
a step of dehydration of the digested pulp resulting from the step iii)
Data Source
AI summary
Disclosed is a method for treating pulp, particularly a method for treating sludge from wastewater treatment plants, for producing energy and/or organic materials that have undergone hygienization, including at least the following steps: a step of aerated or non-aerated thermal hydrolysis of the pulp, a digestion step, a dehydration step and a step of recirculating part of the dehydrated pulp into the step of thermal hydrolysis.