Frequently Asked Questions

Fractured aquifer

Rock masses are commonly fractured with a different degree of fracturing. When fractures are saturated with water, they constitute a fractured aquifer. Due to the small amount of water that these aquifers can storage, this groundwater is not usually used. Their importance is limited to mining, tunnel construction or to contamination problems due to the existence of dense phase or contaminated water. The former one is the case of Bailin site, where there is a sandstone layer that occupies the 10% of the site’s surface, whose fractures reach 40m depth. 

Detritic aquifer

The undersoil of the river flood plains is usually composed by deposits of sand and gravel. Big basins and plains can be also formed by these materials.

The water contained inside the sand and gravel pores constitute a detritic aquifer.


What is the lindane production waste bioremediation about?

It is a process that uses microorganisms, fungus, yeast, plants or plant enzymes to bring back an environment negatively modified by contaminants to its natural condition. Contaminants are usually degraded to obtain energy for the living organisms.

Stockholm Convention

The Stockholm Convention on Persistent Organic Pollutants is an international agreement that regulates the treatment of some toxic substances. The United Nations Program for the Environment backs this Convention. It entered into force in 2004. The signatory countries are obligated to eliminate more than twelve persistent organochlorinated products that are harmful for the environment. The lindane production waste are regulated by this Convention.




The so called “grasshopping” determines that the persistent organic pollutants turn into gas and are moved by the wind. When temperature drops, they form aggregates again and they are deposited in the soil. They can travel from the Equator to the Poles and from the bottom of the valleys to the mountains.

Dense phase

What is the dense phase or the DNAPL?

They are liquid contaminants, denser than the water. Therefore, they move to deeper areas. In the case of the lindane, they are the result of the obtention of distillation tails during the production process. They can also be produced during the failed reactions or during the emptying of the production pipes. Therefore, their production ended around 1989, once the lindane production was stopped.


Pumpable dense phase


The dense phase is a viscose liquid, which can be pumpable for its management and elimination. Due to its high content in chlorinated compounds, the only feasible way to manage it is the incineration. In Bailin landfill, the pumpable dense phase is almost exhausted. In Sardas landfill, the main objective is its detection and its pumping.

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Residual dense phase

The dense phase movement is determined by the gravity. When it reaches a rock mass whose fractures are saturated with water, the dense phase displaces the water and reach the deepest areas. Boreholes are drilled up until these deep areas to pump the dense phase. Once the pumpable dense phase is exhausted, a residual dense phase can be found adhered to the first millimetres of the rock fractures. If this residual dense phase is not eliminated, the water that goes through these fractures will be contaminated.


Oxidation of an organic contaminant

An organic contaminant is that one formed mostly by carbon, oxygen and hydrogen, as well as other secondary compounds such as phosphorus, nitrogen or chlorine.

An organic contaminant is oxidized when it gains an oxygen or other electronegative atoms (it loses electrons) and the result of the reaction is CO2, water and ions with phosphorous, nitrogen or chlorine.

Reduction of an organic contaminant

An organic contaminant is that one formed mostly by carbon, oxygen and hydrogen, as well as other secondary compounds such as phosphorus, nitrogen or chlorine.

An organic contaminant is reduced when it loses oxygen or other electronegative atoms (it gains electrons) and it is degraded in minor molecules, loosing contaminant capacity.

Train of technologies

The remediation technologies are usually effective in a specific concentration range. That is why trains of subsequent technologies are used. The train of technologies consist in the application of one technology after the other, as concentrations are being reduced in the contamination matrix (water, air, soil or rock).