Decentralized wastewater valorization with floating plant systems

Abstract

The Philippines, with its 7,000+ islands, faces severe pressures on coastal ecosystems from climate change, overfishing, and eutrophication1. Untreated wastewater from markets and food industries among others contributes high nitrogen and phosphorus loads, driving algal blooms and oxygen depletion 2. Centralized treatment infrastructure is scarce; most wastewater is discharged untreated or passes only through septic tanks, which remove solids but not nutrients3. Yet, these waste streams also contain valuable resources. Nutrient recovery can reduce environmental impacts while providing substitutes for mineral fertilizers and feed inputs such as soybean meal or fishmeal 4. Floating macrophytes like Azolla and Lemna, with fast growth and high nutrient uptake, offer potential for decentralized wastewater valorization.