Sustained-Release Calcium Peroxide Nanoparticles for Wastewater Nitrogen Removal
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Solution Overview
Problem
Conventional wastewater treatment plants fail to efficiently reduce endocrine disrupting toxicity and meet stringent nitrogen discharge standards, particularly due to low carbon and nitrogen ratios in secondary effluent, which necessitates additional treatment processes and costly carbon source additions.
Innovation Solution
The method involves synthesizing sustained-release calcium peroxide nanoparticles (SR-nCPs) using calcium sulfate and hydrogen peroxide under alkaline conditions, encapsulating them with polyvinyl alcohol, sodium carboxymethyl cellulose, and stearic acid, and applying them in a bioreactor to create a slow-release oxygen and carbon source, enhancing nitrogen removal and reducing endocrine disrupting toxicity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If direct carbon source addition is used to increase carbon and nitrogen content, then nitrogen removal capability is improved, but operating cost increases due to continuous addition requirement
Solution Approach 1:
Carbon sources are encapsulated in calcium peroxide particles before being added to the system. The encapsulation pre-prepares the carbon release mechanism, allowing controlled release over time without requiring continuous external addition, thus reducing operating costs while maintaining nitrogen removal capability
Solution Approach 2:
The calcium peroxide particles serve as self-contained carbon release units that automatically provide carbon sources to the system as needed. The particles self-regulate carbon release based on environmental conditions, eliminating the need for continuous manual intervention and reducing operational expenses
2Use of energy by moving object
If calcium peroxide is directly added as oxygen-releasing material, then oxygen supply is improved, but pH value rises sharply and free radical content increases
Solution Approach 1:
Calcium peroxide is encapsulated within a carrier matrix that acts as an intermediary between the calcium peroxide and the aqueous environment. This intermediary layer controls the dissolution rate and moderates the release of oxygen and calcium ions, preventing sharp pH increases and excessive free radical formation while still providing adequate oxygen supply
Solution Approach 2:
The encapsulation modifies the physical and chemical parameters of calcium peroxide by controlling its dissolution rate. The carrier material creates a controlled release mechanism that changes the concentration profile and release kinetics, transforming the abrupt parameter changes into gradual, controlled changes that avoid harmful effects
3Productivity
If anoxic environment is used for biological denitrification, then nitrogen removal capability is improved, but endocrine disrupting toxicity reduction effect deteriorates
Solution Approach 1:
The system merges the anoxic conditions required for denitrification with controlled oxygen release from calcium peroxide particles. This creates a hybrid environment where bulk anoxic conditions support nitrogen removal while localized micro-oxygen zones enable endocrine disrupting substance degradation, achieving both objectives simultaneously
Data Source
AI summary
A method for intensification of advanced biological nitrogen removal and reduction of endocrine disrupting toxicity, and belongs to the technical field of advanced wastewater treatment includes the steps of utilizing the reaction of calcium sulfate and hydrogen peroxide solution under alkaline conditions to prepare nano-calcium peroxide (n-CP) oxygen-releasing materials, then the polyvinyl alcohol is used as a framework material, the sodium carboxymethyl cellulose is used as a bonding agent, the stearic acid is used as buffering agent and stabilizing agent, the prepared n-CP is used as an oxygen-releasing material, and the quartz sand is used to increase the material density to the sustained-release calcium peroxide nanoparticles (SR-nCPs) through the encapsulation method.