Understanding how algae fight back when water is cleaned
The Chlorine Conundrum
Every time you turn on your tap, you’re relying on chlorine to keep your water safe. But chlorine has a formidable opponent: algae, which have evolved a clever defense mechanism in the form of extracellular polymeric substances (EPS). These sticky layers shield algae from chlorine’s deadly effects, making water treatment a constant arms race.
Two Shields, Two Strategies
Scientists recently dissected the two main types of EPS to see how they withstand chlorine treatments:
- Loosely Bound EPS (LB-EPS)
- A flexible, protein-rich outer layer.
Reacts slower with free chlorine, allowing some algae to persist.
- Tightly Bound EPS (TB-EPS)
- A tough, sugar-based coating mixed with humic substances.
- Free chlorine dismantles it faster, while monochloramine attacks both types more evenly.
The Chemical Warfare Inside Your Water
Chlorine doesn’t just dissolve EPS—it rewires the algae’s defenses.
- Free chlorine speeds through TB-EPS, weakening protein structures and making algae vulnerable.
- Monochloramine works slower but triggers higher oxidative stress inside algae cells, forcing them to mount stronger antioxidant responses.
Without their EPS shields, algae face toxic superoxide buildup, crippling their ability to survive.
A Delicate Balance for Water Treatment
The research reveals a critical insight: EPS isn’t just a barrier—it’s a lifeline. By adjusting chlorine dosing based on EPS type, water treatment plants could weaken algae without total annihilation, preventing downstream contamination while minimizing chemical overuse.
The battle isn’t about eradication—it’s about strategic retreat.
