HCH contaminated soils and nature-based solutions for site cleaning

HCH or hexachlorocyclohexane is a toxic substance found in approximately 300 production or processing sites, waste deposits and landfills, storage facilities and treatment centres in 22 EU countries. A large number of these sites still need to be remediated. Several current EU funded innovation projects within the framework of HORIZON Europe, LIFE and INTERREG are focusing on nature-based approaches to removing soil and groundwater contaminants. Our MIBIREM project is one of them.

(C)Tauw: HCH damp site

HCH relevance and contamination in Europe

HCH is an abbreviation of hexachlorocyclohexane, a group of isomers[1] of which the most famous is lindane. HCH consists of a six-carbon ring with to each carbon one chlorine and one hydrogen as illustrated bellow. Lindane was used as an insecticide for agriculture as well as in pharmaceuticals (to treat lice, scabies etc.). Between 1950 and 2000 about 600,000 tons of lindane were produced globally. During the production of lindane, an estimated 4,000,000 tons of other HCH-isomers were produced in Europe as a byproduct. This byproduct, a white solid with a musty odor, was dumped on landfill sites with some level of containment, dumped on waste deposits without any proper containment, or stored in facilities awaiting final disposal. The alpha, beta-HCH-isomers and Lindane (gamma-HCH) are known as POP’s (persistent organic pollutants). Besides their persistence, they are toxic for the environment and for humans, affecting the nervous system, liver, and kidneys, and are, additionally, a suspected carcinogen.

(C) ResearchGate: Structure of the five major isomers of HCH. (Adapted from Lal et al. (&)

The ‘Inventory of sites potentially impacted by HCH in EU Member States’, an EU-project to which TAUW significantly contributed, records approximately 300 sites spread across 22 EU countries where HCH was handled at production or processing sites, waste deposits and landfills, storage facilities and treatment centres. A large number of these sites still need to be remediated. For a quick overview of the problem there is a video of the EC inventory project.

[1] Isomers are molecules with the same molecular formulas, but different arrangements of atoms

HCH Forum and our project participation

The International HCH and Pesticides Forum is a technical forum, open for discussions and interactions among the pesticides manufacturing industry, international, national and regional authorities, NGOs, Research and Development Institutes, contractors, consultants and other knowledgeable and interested parties. The aim of the Forum is to find technical solutions to the problems arising from the former production and application of pesticides. TAUW was an official sponsor of the 14th International HCH & Pesticides Forum, held in Zaragoza, Spain from 21-24 February 2023. Both MIBIREM partners TAUW and DND Biotech gave talks on lab and field research, nature-based technologies regarding HCH, and the scope of the MIBIREM-project during this event. The presentations can be found and downloaded via the following links on the Forum website:



(C)DND Biotech: Cosimo Masini presenting MIBIREM at the 14th HCH and Pesticides Forum in Zaragoza, Spain, February 2023

Initiatives and projects tackling the HCH problem

Regarding measures to tackle high concentrations of HCH in the environment, traditional intensive and high-tech techniques, like excavation and in situ chemical oxidation, can only solve a part of the problem. This is due to the high cost, the scale of sites, the restriction of access to contaminated areas (due to depth, hindrance caused by the presence of buildings and infrastructure etc.), and the impact on sustainability indicators like landscape disturbance, nuisance, and biodiversity. Therefore, the environmental, social, and economic value of the remediation work should be optimized[1]. Nature-based solutions (NBS) are often essential for a sustainable approach to site decontamination. In general, the NBS-approach is cheaper, less disturbing, and emits less CO2. Furthermore, operational maintenance is less extensive, which makes NBS approaches advantageous for remote sites and large sites with diffuse contamination.

(c)TAUW: Field work at an HCH site

According to John Vijgen, Director of International HCH & Pesticides Association (IHPA): “Another issue, often not taken into account for technology development is that the focus for the treatment of HCH is mainly on the highly contaminated materials and/or the waste, but in terms of quantities the largest quantities are the lower contaminated materials, and that is where nature-based solutions can make a huge impact and major difference for the real solution of this huge problem!”

Several current EU funded innovation projects within the framework of HORIZON Europe, LIFE and INTERREG are focusing on the NBS-approach to remove soil and groundwater contaminants. NBS-mechanisms for removal, like adsorption by green adsorbents or plants, aerobic/anaerobic biodegradation, reductive dechlorination by residual iron chips, and phytoremediation (phytocontainment, rhizo-degradation), are promising for HCH-isomers (and other chlorinated pesticides). These NBS-mechanisms are the basis for the EU-projects (Life) POPWAT as well MIBIREM, both of which are focused on HCH (MIBIREM also deals with cyanide and PHC).

[1] ISO 18504, ‘Soil quality – Sustainable Remediation’, 2017-07

MIBIREM nature-based solutions for soil decontamination

One of the goals of the MIBIREM project is to investigate the specific microbiomes and corresponding environmental conditions present on HCH-contaminated sites and how they can be used for natural attenuation, bio-stimulation, and/or bio-augmentation for soil and groundwater contamination, with biodegradation as common NBS-mechanism. In situ biodegradation can be improved by the addition of upscaled or upgraded microbiomes and/or by creating the right environmental conditions by adding nutrients, electron acceptors/donors, or even vitamins to soil and groundwater.

One of the first steps in the MIBIREM project is to take samples of soil and groundwater at five preselected HCH-sites in Germany, France, Italy, Spain and Poland at which microbiomes will be characterized and isolated. In particular, at the site in Poland, TAUW is cooperating with the partners of Life POPWAT. The isolated microbiomes and possible additions will first be tested on lab scale and, after that, on pilot scale under real field conditions. The MIRIBEM project aims to show that specific microbiomes are present at contaminated sites and that they can be added and stimulated to significantly reduce HCH-contamination in soil and groundwater. This is why TAUW, as an environmental consultancy, joined this innovation project: to to help our clients find and use a new sustainable solution for environmental issues. The presence of HCH in the environment is a negative heritage and we would like to contribute to reducing its risks.


Author: Tobias Praamstra, senior consultant at TAUW

Text editing by RTDS Group

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