Stormwater treatment · tire-wear pollutants
Rheophylax captures tire-wear particles and 6PPD-quinone from road runoff, chemically fixes the toxin so it can't wash back out, and indicates its own remaining capacity - turning a blind filter into verifiable compliance.
The sentinel indicates breakthrough - so service happens on evidence, not a guess.
The problem
6PPD is added to nearly all tires to stop ozone cracking. As tires wear, it reacts with ozone to form 6PPD-quinone - washed into streams with the first rain, where it kills salmon at vanishingly small concentrations. The particles themselves are a leading microplastic. Regulators on three continents are now moving to control both.
Largest source of microplastics in the environment, after single-use plastic - most of it tire wear.
Tire-wear particles generated annually in Europe alone, the bulk reaching waterways untreated.
Today's sorptive controls give no signal when they saturate - and can release captured toxin downstream.
How it works
Rheophylax is not a single filter. It sequences three cooperating functions in one replaceable cartridge - sized to treat the high-load first flush and bypass extreme peaks.
Hydrodynamic pre-separation and a coarse screen remove sediment and large tire-wear particles, protecting the media from clogging. The reactive bed then partitions both particle-bound 6PPD and dissolved 6PPD-quinone out of the water.
The media is built on carbon recovered from end-of-life tires and carries immobilized nucleophiles that covalently bond 6PPD-quinone. The toxin isn't just held - it's chemically fixed, so it can't desorb and break through as the bed loads.
A sentinel layer watches for the first molecules of breakthrough and flips a visible indicator - by color front, viewport, or sensor signal. The cartridge announces when it's spent, so service is triggered by evidence, tied to the regulated contaminant itself.
Activated carbon and biochar adsorb the toxin physically. As the bed saturates - or under high flow and shifting water chemistry - captured 6PPD-quinone desorbs and breaks through as a pulse downstream. And nothing tells the operator it's happening.
Immobilized nucleophiles add covalently to the quinone, converting a mobile toxin into a bound, non-leachable adduct. Breakthrough is suppressed by chemistry - and when capacity finally runs low, the sentinel says so.
Proof of concept
A fixed-bed feasibility model built on the measured physicochemical properties of 6PPD-quinone. It sizes a curb-inlet cartridge, predicts how long effluent stays below the aquatic target, and shows why covalent immobilization outlasts a desorbing sorbent. Drag the design inputs.
Site & influent
Media
| Quantity | Value used | Basis |
|---|---|---|
| 6PPD-quinone molecular weight | 298.39 g/mol | Measured constant (CAS 2754428-18-5) [1] |
| log Kₒₙ (octanol–water) | 4.30 ± 0.02 | Measured; high hydrophobicity drives sorption to carbon [2] |
| Water solubility (20°C) | 38 ± 10 µg/L | Measured; upper bound on aqueous load [2,3] |
| Capture mechanism basis | organic-medium sorption | Transported by water until captured by an organic medium [4] |
| Uptake capacity, kinetics, desorption | design inputs | Engineering assumptions — to be measured per the validation protocol |
Physicochemical constants are cited literature values; capacity, kinetics, and desorption are engineering design inputs — the model predicts feasibility and sizing, not measured performance. Because 6PPD-quinone occurs at µg/L, capacity is ample and the binding consumable is solids and competitive organics, so effective in-matrix capacity sits below single-solute values. Empirical confirmation is defined in the Rheophylax Proof-of-Concept Validation Protocol.
Deployment
The replaceable module retrofits existing stormwater infrastructure and drops into new development - no access to vehicles or tires required.
Sits under the grate with a high-flow bypass weir; swap the module at service.
Larger-area treatment for collector lines and outfalls.
Polishes dissolved 6PPD-quinone the soil media leaves behind.
Installs beneath permeable pavement in parking and plazas.
The closed loop
End-of-life tires are an abundant, hard-to-value waste stream - and the origin of the contaminant. Rheophylax media is built on carbon recovered from those tires by pyrolysis, then functionalized to bind 6PPD-quinone. One waste problem is turned into the treatment for another.
Intellectual property & status
The defensible core is the combination no prior system pairs: an end-of-life-tire-derived media that covalently fixes 6PPD-quinone, plus an analyte-specific self-indicating sentinel - in an inspectable, replaceable cartridge.
U.S. Provisional Patent Application - App. No. 63/___,___, filed [DATE]. Inventor: Jeffrey D. Retherford. Intended assignee: Rheophylax, Inc. (Michigan). Parent: HeOntotita Corporation. A professional prior-art search precedes non-provisional conversion. Independent scope is maintained for tire-wear-particle capture and for the self-indicating function, so the portfolio does not rest on any single contaminant's regulatory fate.
Value creation
Risk-adjusted value rises as each gate clears and removes its risk. Clearing the proof of concept converts the asset from unproven to validated — the first hard de-risking that every later gate depends on.
Illustrative stage-gated model for internal planning — not a valuation, price, or investment advice. Values shown are risk-adjusted (unrisked NPV × cumulative probability of success) and flow from editable assumptions.
Get in touch
Rheophylax is a venture of HeOntotita Corporation, open to municipal and DOT pilots, stormwater-infrastructure licensees, and tire-recovery partners.