Abstract
Metal contamination in drinking water, particularly mercury, iron, aluminium, and hexavalent chromium remains a pervasive public-health and environmental challenge, with the heaviest burden borne by communities that have the least access to advanced treatment. POSEIDON (Phytoprotein-Optimised System for Environmental Ion Detoxification) is a selective, low-energy filtration approach that combines engineered metal-binding peptides with biodegradable alginate beads to capture toxic metals at low concentrations and under mixed-contaminant conditions. Rationally selected phytochelatin synthase (PCS) and a tailored metallothionein (MT) are expressed in E. coli, purified, and covalently immobilised onto alginate via aqueous EDC/NHS chemistry to yield robust, regenerable adsorption units. These beads are deployed in a modular packed-bed cartridge whose performance is predicted using competitive Langmuir isotherms and breakthrough modelling, enabling data-driven choices of bead loading, bed height, flow rate, and regeneration schedules. The system is designed for decentralised, field-friendly operation: low pressure drop, straightforward cartridge swaps, and closed-loop regenerant handling that supports metal recovery and minimises secondary waste. A stepwise validation path covering peptide expression and loading, single- and multi-metal isotherms, packed-bed breakthrough, and multi-cycle regeneration anchors the technical claims in measurable metrics (capacity, affinity, pressure drop, service life). Biosafety is integral: no live organisms are present in the deployed device; only purified, immobilised peptides are used. Beyond technical performance, POSEIDON foregrounds social access and policy alignment, emphasising affordability, community co-design, and links to SDG-3⤴︎(Good Health And Well Being), SDG-6⤴︎ (Clean Water), SDG-8⤴︎ (Decent Work And Economic Growth), SDG-9⤴︎ (Industry, Innovation And Infrastructure), SDG-11⤴︎ (Sustainable Cities And Communities), and SDG-14⤴︎ (Life Below Water), SDG-15⤴︎ (Life On Land), SDG-17⤴︎ (Partnerships And Goals). By targeting the operational regimes where conventional methods struggle with trace levels, mixed metals, and resource-constrained settings, POSEIDON offers a practical path toward cleaner water, reduced environmental load, and scalable green employment through cartridge manufacture, regeneration, and responsible metal recovery.
Across India, recent reports keep reinforcing the urgency of metal contamination in water: villages near a thermal power plant in Ropar, Punjab, show children’s blood lead above safe limits alongside uranium in groundwater; nearly four decades after the Bhopal gas disaster, heavy metals like manganese and zinc persist in aquifers around the defunct plant; nationwide monitoring by the Central Water Commission flags extremely high concentrations of metals (e.g., arsenic, mercury, chromium) in 81 rivers and tributaries, while CGWB syntheses continue to highlight widespread groundwater contamination (nitrate, fluoride) with pockets of arsenic and uranium. WHO’s drinking-water guidelines underscore the health risks and the need for preventive risk management from source to consumer. Illustrative case studies show the human and ecological stakes: Odisha’s Sukinda Valley, one of the world’s most polluted zones, faces long-standing hexavalent chromium contamination tied to chromite mining, with documented health burdens and ongoing legal-regulatory action; Kodaikanal’s mercury episode stemming from a thermometer plant’s historic waste handling, left soil and water contamination, health impacts among workers and families, a landmark settlement, and still-ongoing remediation to reach safe standards.
Background and Description
Our project responds with a selective, low-energy, and field-deployable approach that integrates synthetic biology, materials chemistry, and device engineering. In brief, engineered metal-binding peptides are immobilized on biodegradable alginate beads and deployed in a modular packed-bed cartridge designed for simple operation, regeneration, and end-of-life handling. The system is guided by competitive adsorption modeling and validated through a stepwise experimental pipeline, aligning technical performance with affordability, safety, and equitable access.
Problem Statement
Scope of Contamination
Ground and surface waters in industrial, mining, and agricultural regions frequently contain mercury (Hg), iron (Fe), aluminum (Al), and hexavalent chromium (Cr(VI))- often co-occurring at trace-to-low ppm levels. Mixed-metal streams reduce the effectiveness of single-target treatments.
Operational Realities
- Selectivity at low concentration: Many methods lose efficiency near guideline limits and in competitive matrices.
- Secondary waste: Chemical precipitation and some membrane processes generate sludge or concentrates that require safe handling.
- Energy and infrastructure: High-pressure or reagent-intensive systems raise operating costs and demand skilled oversight.
- Reliability in the field: Variable feed quality, fouling, and intermittent power challenge consistent performance in decentralized settings.f
Health and Equity Dimension
Exposure to these metals is linked to neurological, renal, and carcinogenic outcomes. Burden clusters in communities with limited treatment access, amplifying existing social and economic vulnerabilities.
What Must Be Solved
- Low-level, mixed-metal removal with predictable performance near regulatory thresholds.
- Minimal secondary waste and feasible metal recovery to avoid shifting the pollution burden.
- Low-energy, modular operation that tolerates variable water quality and intermittent power.
- Simple maintenance and regeneration with clear end-of-life pathways for materials.
- Affordability and access to ensure uptake in resource-constrained contexts.
- Promoting education and awareness while contributing to science
Design Target
A selective, regenerable adsorption system that performs under mixed-metal competition, is sized and operated using transparent modeling, and delivers consistent outcomes with modest energy, minimal waste, and straightforward field workflows.
Motivation
Confronted with mounting evidence of metal-laden waters, where conventional treatments often falter at trace levels or create secondary wastes- we looked for a path that is both scientifically rigorous and field-realistic. Water safety is a climate and justice issue: contamination clusters in communities with the least access to stable power, skilled operators, or high-capex systems.
We turned to bio-derived chemistry because engineered peptides can be selective, modular, and low-energy. Immobilizing such binders on biodegradable alginate beads allows us to separate biological production from deployment: no live cells in the field, just robust, regenerable adsorption units that work under mixed-metal competition.
Our goal is to pair this biology-to-device bridge with transparent modeling (competitive Langmuir and breakthrough sizing) so sizing, operation, and regeneration are predictable. The outcome we seek is practical: decentralized cartridges, simple swap-and-service workflows, recoverable metals, minimal secondary waste, and affordability, so the solution scales where need is greatest.
Existing Solutions & Limitations
What’s in use today
Common approaches for metal removal include reverse osmosis/nanofiltration, ion-exchange resins, chemical precipitation with coagulation–flocculation, activated carbon or specialty adsorbents (e.g., biochar, metal oxides), membrane filtration (UF/NF/RO), electrocoagulation/electrodeposition, and nature-based systems (constructed wetlands, bioreactors).
| CHEMICAL PRECIPITATION | PHYTOREMEDIATION | MICROBIAL REMEDIATION |
|---|---|---|
| Large volumes of sludge. | Dependent on the growing conditions of the plant, hence success depends on tolerance of the plant to the pollutant. | Difficult to scale-up |
| Metal hydroxides-increasingly soluble, even a slight pH adjustment to precipitate one metal may put another back into solution. | Possibility of environmental damage due to leaching of soluble contaminants. | Success is highly dependent on the presence of metabolically capable microbial populations and environmental growth conditions. |
| Corrosive chemicals used. |
Source: Fenglian Fu & Qi Wang (2010)
Where they help
These methods can achieve high removals in controlled settings, handle moderate loads, and, in centralized plants, benefit from skilled operation, steady power, and engineered waste handling.
Key limitations in the target use-case
- Trace-level selectivity: Performance drops near guideline limits and under mixed-metal competition; co-ions (e.g., Ca/Mg, sulfate) and speciation (e.g., Cr(VI) vs. Cr(III)) complicate removal.
- Secondary wastes: Precipitation creates sludge; membranes generate brines/concentrates; resin regeneration produces spent regenerants, each requiring safe treatment and disposal.
- Energy and consumables: High pressure (RO/NF), frequent chemical dosing (precipitants, pH control, regenerants), and replacement media increase operating cost and logistics.
- Fouling and uptime: Scaling, organic fouling, and variable feed quality reduce flux/capacity and demand frequent maintenance.
- Operator dependence: Tuning pH, dosing, and regeneration cycles needs trained staff and reliable monitoring, often scarce in decentralized contexts.
- Field robustness: Intermittent power, fluctuating contaminant profiles, and limited spare-part chains hinder consistent performance outside centralized plants.
Why these gaps matter
Rural and peri-urban deployments need predictable trace-level performance in mixed matrices, minimal secondary waste, low energy, and simple, repeatable field workflows- conditions under which many conventional options become costly, maintenance-heavy, or unreliable.
Problems in existing solutions
| Sediment Filters | Activated Carbon Filters | UV Purification Systems | Reverse Osmosis |
|---|---|---|---|
| The most basic and widely available Acts like a sieve — to trap sand, silt, and rust Zero impact on dissolved contaminants | Commonly found in pitchers and faucet attachments Removes chlorine, pesticides, organic compounds Can become saturated May leach | Uses UV-C light to kill bacteria and viruses Doesn't remove metals, salts substances Doesn't remove metals, salts substances | Removes a wide range of contaminants Including: Dissolved salts, Nitrates Expensive High maintenance Waste water |
Design implication
A selective, regenerable adsorptive system that maintains capacity under competition, runs at low pressure, and has clear end-to-end waste handling aligns better with decentralized realities.
Proposed Solution - POSEIDON
Faced with mixed-metal contamination at trace levels and the practical limits of conventional treatments, we converged on a bio-derived, device-ready approach: POSEIDON. At its core are engineered metal-binding peptides- rationally selected phytochelatin synthase (PCS) and a tailored metallothionein (MT)- that chelate target ions (Hg, Fe, Al, Cr(VI)-related species) with high affinity under realistic water chemistries.
To separate biology from deployment, peptides are produced in E. coli, purified, and covalently immobilized onto biodegradable alginate beads via aqueous EDC/NHS coupling. The result is a robust adsorptive medium that preserves binding activity, avoids live organisms in the field, and supports regeneration with mild eluents for multi-cycle use and metal recovery.
These peptide-loaded beads are packed into a modular cartridge engineered for low pressure drop, stable hydraulics, and straightforward swap-and-service workflows. Competitive Langmuir and breakthrough modeling guide bead loading, bed height, flow rate, and regeneration schedules, enabling predictable performance near guideline limits, even in mixed-metal streams and variable feeds.
Variable Descriptions
- Mi: Adsorbed quantity of metal ion i at equilibrium (mg/g)
- Mmaxi: Maximum adsorption capacity (mg/g)
- KMi: Langmuir adsorption constant for ion i (L/mg)
- Ci: Equilibrium concentration of metal ion i remaining in solution (mg/L)
- Σj=1n (KMj · Cj): Competitive summation term accounting for all metal ions present
POSEIDON is designed for decentralized operation: compact form factor, minimal energy, minimal secondary waste, and clear end-of-life handling. By targeting the regimes where traditional methods struggle- trace concentrations, co-ion competition, intermittent power,it provides a practical bridge from synthetic biology to community-level water safety.
How It Works
Risk & Biosafety
Our design prioritizes safety at every stage, from lab development to field deployment. Genetic engineering is confined to controlled laboratory settings using non-pathogenic E. coli. The deployed product contains only purified peptides immobilized on biodegradable alginate beads, ensuring that no live organisms are released into the environment.
The chemistry underpinning bead preparation is carried out in aqueous, mild conditions. Covalent coupling secures peptides firmly to the bead matrix, and extensive rinsing steps prevent leaching. This makes the cartridge safe for contact with drinking water while maintaining binding efficiency.
Regeneration is handled through a closed-loop system: spent eluents are collected, sealed, and directed to recovery hubs for metal reclamation. This prevents secondary pollution and creates pathways for circular use of captured metals.
Operational safety is further reinforced by low-pressure cartridge design, simple swap-and-service workflows, and clear SOPs for handling, transport, and end-of-life disposal. By embedding biosafety into both the laboratory pipeline and the community deployment model, POSEIDON ensures a solution that is not only effective but also responsible and trustworthy.
Social Impact, Policy & Access
Communities facing mixed-metal contamination often have the least margin for complex, power-hungry treatment. Our focus is practical access: compact cartridges that run at low pressure, swap-and-service workflows that local operators can manage, and closed-loop regenerant handling that prevents secondary pollution while enabling responsible metal recovery. By keeping consumables simple and maintenance predictable, the system is designed to lower downtime and ownership cost where reliability matters most.
Policy alignment is built in, not retrofitted. The approach maps to national drinking-water norms and hazardous-waste rules, and supports WHO’s preventive risk management- from source protection to point-of-use verification. Framing cartridges as serviceable assets also creates pathways for public procurement, NGO deployment, and CSR partnerships, while aligning with [Sustainable Development Goals⤴︎:./sustainability], specifically, SDG-3⤴︎ (Good Health And Well Being), SDG-6⤴︎ (Clean Water), SDG-8⤴︎ (Decent Work And Economic Growth), SDG-9⤴︎ (Industry, Innovation And Infrastructure), SDG-11⤴︎ (Sustainable Cities And Communities), and SDG-14⤴︎ (Life Below Water), SDG-15⤴︎ (Life On Land), SDG-17⤴︎ (Partnerships And Goals). Traceable regeneration and take-back programs make compliance auditable and scalable.
Access is more than hardware- it’s participation. We emphasize community codesign, training for women and youth operators, and locally viable business models: village-level cartridge exchanges, regional regeneration hubs, and micro-enterprise roles for logistics and QA. Metal recovery adds circular value, helping subsidize operations and building green jobs around maintenance, testing, and safe end-of-life handling.
Case Studies (India) - Snapshot Cards
Sukinda, Odisha
The Sukinda Valley, home to most of India’s chromite reserves, has faced decades of contamination from open-cast mining. Hexavalent chromium (Cr(VI)) has leached into groundwater and the Brahmani River, with reports linking exposure to cancers, gastrointestinal illness, and respiratory diseases. Despite interventions by regulatory bodies, the scale and persistence of pollution make remediation complex. This case highlights the challenge of removing toxic metals from widespread, mixed sources where predictable, low-level performance is essential.
Kodaikanal, Tamil Nadu
In 2001, mercury waste from a thermometer factory was discovered in surrounding soils and water bodies, triggering one of India’s most visible industrial contamination cases in the city of Kodaikanal. Mercury exposure caused neurological and renal problems among workers and nearby residents, leading to a landmark settlement and ongoing site cleanup. This underscores the importance of safe waste handling and recovery pathways to prevent long-term environmental and health burdens.
Ropar, Punjab
Villages near a thermal power plant in Ropar, reported elevated uranium in groundwater and unsafe lead levels in children’s blood, attributed to fly ash and industrial emissions. The contamination drew national attention, raising concerns over both environmental safety and children’s health. This example illustrates the urgent need for decentralized, point-of-use solutions that can protect vulnerable populations while broader source-control measures are pursued.
Bhopal, Madhya Pradesh
Nearly four decades after the Bhopal gas tragedy, 1984, groundwater around the abandoned Union Carbide site remains contaminated with heavy metals such as manganese and zinc. Communities continue to face exposure risks, with remediation and monitoring efforts still in progress. This case reflects the enduring legacy of industrial waste and the need for resilient, long-term treatment options in peri-urban settings.
Comparative Analysis (At-a-Glance)
Purpose
Quickly contrast conventional metal-removal options with a cartridge of immobilized peptides (POSEIDON) for trace-level, mixed-metal, decentralized use.
Key takeaways
Conventional methods can excel in centralized plants but tend to be energy- or reagent-heavy, produce secondary wastes, and lose selectivity near guideline limits, especially under mixed-metal competition. POSEIDON targets this gap with selective adsorption at low pressure, predictable sizing via modeling, closed-loop regenerants, and swap-and-service workflows.
Comparison Matrix
| Aspect | Conventional Metal Removal (RO, precipitation, activated carbon, etc.) | POSEIDON Cartridge (Immobilized Peptides) |
|---|---|---|
| Performance at low concentration | Often underperform below ppm levels; poor selectivity at trace levels | High affinity of peptides enables effective binding at low ppm/ppb levels |
| Multi-metal streams | Struggles with competition; selective removal is difficult | Designed via competitive Langmuir modeling to handle Hg, Fe, Al, Cr(VI) together |
| Energy & infrastructure | High capital cost, power-hungry (pumps, membranes, sludge treatment) | Low-energy, gravity/low-pressure compatible, minimal auxiliary equipment |
| Waste & regeneration | Generates sludge or brine requiring safe disposal | Regenerable with mild eluents; spent regenerant can be processed for metal recovery |
| Operation & usability | Requires skilled operators, centralized plants | Cartridge-based, modular, easy to swap, suitable for decentralized/rural contexts |
| Durability & reusability | Membranes foul, precipitates clog; high maintenance | Beads are stable, reusable over multiple adsorption–desorption cycles |
| Cost & accessibility | Expensive setup, not feasible for marginalized communities | Affordable, locally manufacturable, aligned with community-scale deployment |
| Inclusivity & context fit | Suited to industrial/urban settings; less adaptable to local needs | Co-designed for vulnerable communities; inclusive, modular, and biodegradable |
What this means for deployment
For rural/peri-urban or intermittent-power contexts, a low-pressure, regenerable adsorption cartridge with modeled breakthrough and take-back logistics offers a clearer path to predictable performance, lower operational complexity, and auditable waste management.