Title: Application of Ecotechnology for Freshwater Treatment and Storage to Mitigate Saltwater Intrusion in the Coastal Zones of the Mekong Delta
Authors: Kiet Pham Tan , Trang Vuong Thi Huyen
Volume: 9
Issue: 12
Pages: 261-272
Publication Date: 2025/12/28
Abstract:
Saltwater intrusion is increasingly constraining freshwater security in the Mekong Delta, where conventional hard-infrastructure responses are energy-intensive and ecologically disruptive. This study develops and evaluates an ecotechnology framework that integrates low-energy modules, including Eco-Intake, a multi-material Eco-Filter (sand-biochar-clinoptilolite-laterite), hybrid constructed wetlands (HF?VF), and Eco-Storage, with optional managed aquifer recharge (MAR), to produce fit-for-purpose water for irrigation and non-potable domestic uses. Through laboratory characterization, mesocosm trials, and pilot plants at household/cluster (H1, 30 m³·d?¹) and commune (C1, 450 m³·d?¹) scales, EC, TDS, major ions, SAR, trace metals, and E. coli were monitored under controlled hydraulic loadings, along with standard QA/QC and basic life-cycle costing. Across eight weeks of pilot operation, the treatment train consistently reduced EC/TDS by 33-38%, Na? by 38-43%, and shifted SAR from high risk (~9-10) to a moderate band (~6-7), while stabilizing pH-alkalinity and polishing Fe/Mn; energy use remained ?0.06 kWh·m?³. A shallow MAR test (? 0.8 m, screened 6-10 m bgs) achieved 71% recovery efficiency (EC ?3.5 mS·cm?¹) without geochemical penalties (Fe <0.10 mg·L?¹; As <5 µg·L?¹; pH 7.3-7.6). Operational simplicity, duty/standby resting, light back-rinsing, and quarterly vegetation harvests supported reliable community operation at low OPEX. Findings indicate that partial yet purposeful salt reduction, rather than full desalination, can deliver substantial agronomic and household value at one to two orders of magnitude lower energy than membrane systems and support a tiered service model in which ecosystems supply bulk water and limited point-of-use (POU) treatment/polishing meets potable water needs.