Green-Engineered Mulch for Stormwater Pollutant Removal
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Solution Overview
Problem
Current stormwater treatment technologies require significant resources, labor, and expertise, and alter land extensively, while existing methods for metal removal from stormwater runoff are inefficient and costly, with aluminum-based water treatment residuals (Al-WTR) having low hydraulic conductivity.
Innovation Solution
Process Al-WTR into a fine powder, mix it with a biopolymer solution, and coat mulch chips with an ionic cross-linker to create green engineered mulch, which can be used as a retrofit material in bioretention systems to enhance pollutant removal without altering existing BMPs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Al-WTR is used as a retrofitting material for stormwater treatment, then pollutant removal capability is improved, but hydraulic conductivity deteriorates due to low permeability of Al-WTR
Solution Approach 1:
The patent combines Al-WTR with mulch chips to create a composite material system. The Al-WTR provides pollutant removal capability while the mulch chip matrix provides hydraulic conductivity and structural stability, resolving the contradiction between pollution control and water permeability.
Solution Approach 2:
The mulch chip-based composite structure creates porous pathways that maintain hydraulic conductivity while allowing Al-WTR particles to be distributed throughout the matrix for effective pollutant adsorption and removal.
2Productivity
If conventional stormwater BMPs are implemented, then stormwater quantity reduction is achieved, but pollutant removal capability remains limited and requires significant resources and land alteration
Solution Approach 1:
The composite material is designed to be applied directly to existing BMPs without requiring complex redesign or construction modifications. The material itself provides both quantity reduction and pollutant removal functions, eliminating the need for additional complex design elements.
Solution Approach 2:
The Al-WTR/mulch chip composite serves multiple functions simultaneously: it reduces stormwater quantity, removes pollutants, provides structural stability, and maintains hydraulic conductivity, replacing the need for separate specialized components.
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 green engineered mulch effectively removes metals and nutrients from stormwater runoff, is cost-effective, and can be implemented without additional expertise, minimizing environmental impact and maintenance.
Implementation Method 1
The powder is subsequently mixed with a biopolymer solution, such as alginate. Mulch chips are then coated by soaking them in the solution.
Implementation Method 2
The coated mulch is then added individually into an ionic cross-linker, such as calcium, to produce a green engineered mulch product.
Data Source
AI summary
A green-engineered mulch product and methods for making same are disclosed. The mulch product includes a coating of aluminum-based water treatment residuals which makes the product “green.” Furthermore, coating aluminum-based water treatment residuals on mulch eliminates the problem of the low hydraulic conductivity of aluminum-based water treatment residuals and makes it feasible to utilize its pollutant removal potential without requiring any modification to existing best management practices or additional maintenance.