Endocrine disruptors in sewage treatment are a significant concern because they can interfere with the hormonal systems of humans and wildlife, even at very low concentrations. Here’s a breakdown of what they are, how they get into wastewater, and how they’re dealt with in treatment plants:
What Are Endocrine Disruptors?
Endocrine-disrupting compounds (EDCs) are chemicals that mimic, block, or otherwise interfere with the body’s hormones. Common EDCs include:
- Pharmaceuticals (e.g., birth control pills, hormone replacement therapy)
- Personal care products (e.g., parabens, phthalates)
- Industrial chemicals (e.g., bisphenol A or BPA, PCBs)
- Pesticides (e.g., DDT, atrazine)
- Plasticizers and flame retardants These compounds can mimic hormones like oestrogen, testosterone, and thyroxine, disrupting biological processes
How Do They Get into Wastewater?
EDCs enter the sewage system through:
- Human excretion (after metabolizing medicines or hormones)
- Washing off personal care products
- Industrial discharges
- Agricultural runoff (in combined systems or via illegal connections)
- Improper disposal of pharmaceuticals or chemicals
Detection and Monitoring
EDCs are typically present in very low concentrations (ng/L to µg/L) but are biologically active. Monitoring involves:
- Advanced analytical techniques (GC-MS, LC-MS/MS)
- Bioassays to detect hormonal activity (e.g., yeast oestrogen screen)
Removal in Sewage Treatment Plants
Conventional wastewater treatment plants (WWTPs) are not specifically designed to remove EDCs, but they do achieve partial removal through:
- 1. Primary Treatment:
- Minimal removal – mostly suspended solids
- 2. Secondary Treatment (biological processes):
- Moderate removal – some EDCs are broken down by microbes or adsorb to sludge
- Activated sludge and extended aeration can help biodegrade certain compounds
- 3. Tertiary/Advanced Treatment:
- More effective at removing EDCs, including:
- Activated carbon filtration (adsorption)
- Advanced oxidation processes (AOPs) – ozone, UV/H₂O₂
- Membrane filtration – nanofiltration, reverse osmosis
- Constructed wetlands – useful in decentralised systems
Environmental & Health Concerns
EDCs are a risk to aquatic life, causing:
- Feminization of male fish
- Reduced fertility and altered reproductive behaviour
- Developmental abnormalities
In humans, long-term exposure to EDCs (even in trace amounts) has been linked to:
- Hormonal imbalances
- Infertility
- Developmental delays
- Certain cancers (e.g., breast, prostate)
Mitigation Strategies
- Upgrading treatment plants with tertiary processes
- Source control – proper disposal of meds, industrial pretreatment
- Regulatory frameworks – setting limits for discharge
- Public education to reduce harmful chemical usage