Atlas of Contaminated Sites

Notable case, Biên Hòa, Đồng Nai, Vietnam

Bien Hoa Airbase

Sân bay Biên Hòa

The airbase near Ho Chi Minh City where Agent Orange and other herbicides were stored during the Vietnam War. It is the largest dioxin hotspot left in the country, with almost four times the volume remediated at Da Nang.

Microbial bioremediation

Status
Remediation under way
Media
soil, sediment, surface water, living organisms
Kind of site
military, agrochemicals
  1. Area. No overall contaminated area in the sources read. The volume to be remediated is put at almost 500,000 m³ of soil and sediment (2016 USAID assessment); in 2019, 37 hectares in the western part of the base were handed over to the project and by January 2025 work had covered 13 hectares on and around the base.

Contaminants

Organic compounds

Status

Remediation under way

By January 2025 more than 107,000 m³ of soil out of about 500,000 had been excavated and treated or secured; the thermal treatment plant was scheduled for April 2025. According to Wikipedia the work was affected in 2025 by the cuts to USAID ordered by the US administration.

Story

During the war Bien Hoa was one of the depots from which defoliant-spraying aircraft flew. Agent Orange, a mix of the herbicides 2,4-D and 2,4,5-T, carried dioxin (2,3,7,8-TCDD) as an impurity; leaks and spills at the storage and loading points left it in the soil, from where it moved to the lakes and channels on and off the base.

From 1999 a team at the Institute of Biotechnology of the Vietnam Academy of Science and Technology, led by Dang Thi Cam Ha, studied biological treatment of the soil here. In 2016 a USAID assessment put the soil and sediment needing remediation at almost 500,000 m³. The joint project of USAID and Vietnam's Ministry of National Defence was approved in April 2019 and work began on 5 December 2019, planned to last ten years with an initial US contribution of 183 million dollars, later raised to 430 million.

The first phase (2019–2025) covers 150,000 m³. In 2022 an off-base lake, a first on-base area and the long-term storage facility were completed; in November 2024 the design of the thermal treatment plant was approved.

Timeline

  1. 1999The Institute of Biotechnology in Hanoi starts research on biological treatment of soil with herbicides and dioxin.
  2. 2016USAID assessment: almost 500,000 m³ to be remediated.
  3. 2019April: the project is approved. 5 December: work starts and 37 hectares are handed over.
  4. 2022An off-base lake, the first on-base area and the long-term storage facility are completed.
  5. 2025January: more than 107,000 m³ excavated and treated. Later in the year the USAID cuts affect the work.

Remediation

  1. 2019excavation and containmentExcavation of contaminated soil and sediment and placement in a long-term storage facility, starting with the areas from which dioxin could leave the base: more than 107,000 m³ by January 2025.
  2. 2025thermal treatmentThermal treatment plant for the most contaminated soil, design approved in November 2024 and start-up planned for April 2025; whether it started was not verified.

Plants and fungi at this site

Microbial bioremediationField pilot

"Active landfill" developed by the Institute of Biotechnology of the Vietnam Academy of Science and Technology (Dang Thi Cam Ha) with the Ministry of National Defence: contaminated soil is confined in cells and the activity of the microorganisms already present is stimulated so that they break down herbicides and dioxin.

Outcome According to VietNamNet (2012), after 27 months of treatment and periodic checks at four points dioxin residues were below the limit allowed for agricultural and non-agricultural land. The source is a news report and gives neither volumes nor concentrations; the method was not taken up for the full-scale clean-up, which relies on excavation, containment and thermal treatment.

Microbial bioremediationLaboratory, with soil from the site, 2021

Pseudomonas aeruginosa, Sphingomonas histidinilytica, Bordetella petrii, Achromobacter xylosoxidans

Laboratory study on soil taken from the base: four bacterial strains were isolated from enrichment cultures fed with 2,4-D and 2,4,5-T (the two herbicides in Agent Orange).

Outcome All four strains degraded both herbicides, with complete removal within 10 days of culture; three used them as sole carbon source, building 33–46% of the carbon into biomass. The study concerns the herbicides, not dioxin.

From the literature

Species that acted on one of this site's contaminants in at least one study. The list is automatic and takes no account of this site's soil, concentrations or climate.

Plants

Fungi

Sources

  1. VN kicks off first phase of dioxin remediation at Bien Hoa Airbase Area, Government of Viet Nam (Báo Chính phủ), 2019
  2. Dioxin remediation project kicked off at Bien Hoa Airbase, Vietnam Television (VTV), 2019
  3. Over 107,000 cubic meters of dioxin-contaminated soil treated at Vietnam's Bien Hoa Airbase, Tuoi Tre News, 2025
  4. Detoxifying the land and people, VietNamNet, 2012
  5. Species and Metabolic Pathways Involved in Bioremediation of Vietnamese Soil From Bien Hoa Airbase Contaminated With Herbicides, Frontiers in Sustainable Cities, 2021
  6. Bien Hoa Air Base, Wikipedia, 2026

Draft compiled from public sources, not yet reviewed.