Aqueous Phase Oxidation of Sewage with Mixed Acids
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Solution Overview
Problem
Current waste treatment processes for sewage materials are inefficient, consuming large amounts of energy, producing noxious gases, and failing to effectively convert waste into valuable products due to the presence of toxic materials like heavy metals and pathogens, which limits their use as fertilizer and poses environmental risks.
Innovation Solution
A waste treatment process involving the reaction of a feedstock, such as sewage material, with a mixture of oxidizing acids like sulfuric and nitric acid in an aqueous phase oxidation process, which includes oxygen gas to facilitate oxidation and regeneration of the acid, producing a runny effluent that can be separated into solid and liquid fractions, with heavy metals removed using precipitation or ion exchange methods to create a usable fertilizer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional waste treatment processes are used to dispose of sewage material, then toxic materials like heavy metals and pathogens are removed, but large amounts of energy are consumed and noxious gases are produced
Solution Approach 1:
The patent employs concentrated sulfuric acid and nitric acid as strong oxidizing agents to rapidly oxidize organic waste materials at elevated temperatures (150-250°C). This accelerated oxidation process efficiently destroys toxic organic compounds and pathogens while consuming less energy than conventional thermal treatment methods, as the chemical oxidation occurs at lower temperatures compared to incineration.
Solution Approach 2:
The patent changes the physical and chemical parameters of the waste treatment process by using concentrated acids (90-98% H2SO4 and 65-70% HNO3) at controlled temperatures and pressures. These parameter changes enable efficient toxin destruction through chemical oxidation rather than high-temperature thermal processes, reducing energy consumption while maintaining effective harmful factor removal.
2Object-affected harmful factors
If conventional waste treatment processes are used to dispose of sewage material, then toxic materials like heavy metals and pathogens are removed, but noxious gases are emitted
Solution Approach 1:
The strong oxidizing acids convert organic waste into oxidized products such as CO2, H2O, and mineral acids, rather than producing noxious gases like dioxins, furans, or unburned hydrocarbons that result from incomplete combustion in conventional thermal treatment. The chemical oxidation pathway eliminates the formation of many harmful gaseous byproducts.
Solution Approach 2:
The patent converts the harmful organic waste materials into beneficial or less harmful substances through chemical oxidation. The organic carbon is converted to CO2, nitrogen to nitric acid or nitrogen gases, and sulfur to sulfuric acid, which can be recovered and reused. This transforms the waste problem into a resource recovery opportunity while minimizing noxious gas emissions.
3Productivity
If sewage material is processed to make fertilizer, then valuable nutrients are captured and used, but toxic materials like heavy metals and pathogens remain in the fertilizer
Solution Approach 1:
The strong oxidizing acids completely destroy pathogenic microorganisms through oxidation of their cellular components and convert heavy metals into soluble salt forms that can be separated from the fertilizer product. This oxidation process at 150-250°C effectively sterilizes the material and transforms toxic metal compounds into separable ionic forms, enabling production of safe fertilizer.
Solution Approach 2:
The patent extracts and separates heavy metals from the oxidized waste stream by converting them into soluble salt forms that can be removed through filtration, precipitation, or ion exchange processes. This extraction separates the toxic metals from the nutrient-rich liquid that will become fertilizer, allowing nutrient recovery while removing toxic contaminants.
4Productivity
If aqueous phase oxidation with concentrated acids is used to treat waste, then waste is converted into valuable products, but the process requires precise control of temperature and pressure
Solution Approach 1:
The patent incorporates temperature and pressure sensors with control systems that continuously monitor reaction conditions and automatically adjust parameters to maintain optimal operating ranges. This feedback control prevents runaway reactions, ensures complete oxidation, and maintains safety while maximizing waste conversion efficiency to valuable products.
Solution Approach 2:
The patent uses a continuous flow reactor system where waste material and oxidizing acids continuously react under controlled conditions, allowing steady-state operation with consistent temperature and pressure control. This continuous process maintains optimal reaction conditions throughout the reactor volume, improving conversion efficiency while simplifying control compared to batch processes that require frequent parameter adjustments.
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
The process efficiently converts sewage material into valuable products like fertilizer and biofuels, reducing energy consumption and environmental impact by effectively removing heavy metals, thereby overcoming the limitations of existing methods.
Implementation Method 1
A waste treatment process involves the reaction of a feedstock, such as sewage material, with a mixture of oxidizing acids like sulfuric and nitric acid in an aqueous phase oxidation process
Implementation Method 2
which includes oxygen gas to facilitate oxidation and regeneration of the acid
Implementation Method 3
with heavy metals removed using precipitation or ion exchange methods to create a usable fertilizer
Implementation Method 4
with heavy metals removed using precipitation or ion exchange methods to create a usable fertilizer
Data Source
AI summary
An improved oxidation process may be used to oxidize a wide variety of feedstocks. Oxidation takes place in a reactor where the feedstock is mixed with an oxidizing acid, such as nitric acid. The reaction mixture may also include another oxidizing acid such as sulfuric acid.