This study examined how pharmaceuticals behave in Swedish wastewater treatment plants (WWTPs) — how much of what we consume ends up in sewage, and how well different treatment designs remove them. It combined 8 years (2001–2009) of nationwide sampling data from research institutes, municipalities, and councils.

🎯 Main Aims

1. Identify which pharmaceuticals appear in wastewater.
2. Compare wastewater concentrations with Swedish sales volumes.
3. Evaluate how well different biological treatment systems remove them.

⚙️ Swedish Wastewater Treatment

Sweden’s WWTPs mainly use biological treatment systems:

• Activated sludge (AS) 🧫 — microbes in suspension; some have extended nitrogen removal (longer SRT & HRT).
• Trickling filters 🪣 — wastewater flows over a biofilm-covered medium.

Regulations:

• Plants south of a Norway–Baltic line (10,000+ people) must remove nitrogen.
• About 40% of wastewater volume comes from plants without nitrogen removal.

Total: ~470 WWTPs (>2,000 pe) treating 1.3×10⁹ m³/year ≈ 90% of urban wastewater.

🧪 Removal Mechanisms

Pharmaceuticals can:

• Strip to air (rare)
• Sorb onto biomass 🧫 (depends on Kd value)
• Degrade biologically ⚗️

💡 Key factor: Solid Retention Time (SRT)

• Above ~10 days → nitrification and better micropollutant removal.
• Short SRT → poor degradation.

📋 Data Collection & Processing

• Sources: 10+ major reports/databases (IVL, Stockholm Water, Region Skåne, etc.).
• Only non-antibiotic human pharmaceuticals included.
• Paired influent + effluent samples analyzed.
• < Reporting limit → handled by half-limit or exclusion.
• Plants categorized:
  1. AS + nitrogen removal
  2. AS – nitrogen removal
  3. Trickling filter
  4. Mixed (excluded from efficiency analysis)

💧 Influent Findings

• 70 pharmaceuticals detected (2 ng/L – 52 µg/L).
• Most common >1 µg/L:
  • 💊 Furosemide, metformin, paracetamol, ibuprofen, naproxen, ketoprofen, metoprolol, atenolol
• A few were widespread, others rare (<50 ng/L).

🧮 Only <20% of sold drugs reached WWTPs as dissolved parent compounds for most substances. ➡️ Suggests metabolism, degradation, or sorption before arrival.

⚗️ Removal Efficiencies

1. Activated Sludge (Nitrogen Removal)

• Tested 62 drugs.
• High removal: paracetamol, ibuprofen, naproxen 👍
• Low removal: furosemide, atenolol 👎
• Sometimes effluent > influent due to deconjugation (metabolites converting back to parent form).

2. Activated Sludge (No Nitrogen Removal)

• Tested 30 drugs.
• Similar results overall, but variable — some operated at longer SRT/HRT than designed, improving performance.

3. Trickling Filters

• Tested 50 drugs.
• Generally lower removal, especially for ibuprofen, naproxen, ketoprofen. ➡️ Activated sludge with nitrogen removal performed best.

🌊 Effluent Findings

• 60+ pharmaceuticals detected in treated water.
• Typical effluent: 1–500 ng/L, but a few near 1 µg/L:
  • atenolol, metoprolol, furosemide, hydrochlorothiazide
• Anti-inflammatories sometimes >1 µg/L at trickling filter or non-N plants.

🧠 Key Insights

• 💊 Only a small portion of sold pharmaceuticals survive to WWTPs.
• ⚗️ Removal efficiency depends heavily on treatment type and operating conditions (SRT/HRT).
• 🧫 Activated sludge with nitrogen removal → best at reducing pharmaceuticals.
• 🚫 Trickling filters → least effective.

🧩 Big Picture

Pharmaceutical residues are persistent micropollutants. While Sweden’s biological WWTPs remove many effectively, some — particularly β-blockers and diuretics — persist and may impact aquatic ecosystems.

🔬 Project Context

This research is part of MistraPharma, a Swedish strategic project on pharmaceuticals and the environment, funded by Mistra – The Foundation for Strategic Environmental Research.