Thanks for the nice answers, I think :

firstly adsorption technique and then for long term remediation using phytoremediation !

Dear Deep Shikha

Adsorption; Application of adsorbent like magnetic biosorbent or biochar, some composite like clay with biochar can be applied. Also, you can think of membrane filtration, ionic exchange, electro-coagulation, methods for the same. Hope this could help you to initiate.

@Deep Shikha: The answer depends which heavy metals shoul be treated, what is the quality of contaminated soil, what are the pollutant concentrations in soil and groundwater etc.

It is very imposrtant also if the remediation should be performed in-situ or ex-situ.

There exists more possibilities for soil treatment (solidification/stabilization, soil washing, ......) as well as for groundwater remediation (coagulation, biological reduction, .....).

So, please give more detailed information, then you can get reliable naswers.

Best regards

Vit

Follow these links, I hope this will be useful:

Article Scientific and technical journal «Technogenic and Ecological...

http://repositsc.nuczu.edu.ua/bitstream/123456789/7800/1/3-12-Sandra%20Nonyerem-Bunmi.pdf

Article Nutrient Dispersion Modeling of Coal Overburden Dumps for Re...

Hi Deep Shikha , I agree with Vit Mateju that more info is required however my experience in dealing with mining companies with legacy contamination issues is they prefer methods that can target a suite of metals that are relatively simple (and of course, cost effective) to apply. This will be in part influenced by how these companies do business, the metals of primary concern and the existing policies/regulations (not all metals are subject to the same discharge limits).

Broadly speaking, the strategies breakdown as follows:

- Immobilization

- Precipitation

- Redox chemistry (this can work to solubilize and recover metals, or, change them to a species that will bind to ligands in the environment more readily)

What I have seen is the most widely used in situ tends to be precipitation approaches. This typically involves the use of sulphide-bearing salts to precipitate metals such that they are much less soluble in water and/or saturated soil. Something important to keep in mind is how adding sulphide can change the redox chemistry of the environment and in the case of some metals, like mercury, can actually create a substrate that leads to the production of more toxic organic mercury species. That being said, this one tends to be popular because it's simple, it scales and there are firm regulations in place (at least in Canada).

Immobilization can take many forms but what I have seen is that ion exchange is most commonly used. This relies on using a charged ion exchange column where the cationic (positive charge) metals can exchange with the charged substrate on the column. This again is useful because it can have a small physical footprint particularly for ex situ treatment. The downside is it creates hyper concentrated brines and is only good for targeting charged metal species, which don't tend to diffuse through cell membranes readily and are thus not as worrisome as neutrally-charged complexes. Sulphur-impregnated activated carbon is also use to much the same effect, however strong acids are required to regenerate the adsorptive material and this can create secondary waste. Immobilization can also rely on biomass from microbes and/or plants although in my experience this type of approach is much less widely used (unfortunately) and tends to be used for more diffuse pollution vs highly concentrated point source pollution.

Lastly, redox chemistry approaches taken many forms but generally speaking they try to maintain reducing conditions more favourable to the formation of sulphide to induce precipitation, or, they will solubilize metals strongly bound to soil matrices to recover them more readily with in situ (pumping and treating) or ex situ treatments. Microbes can also play an important role in dictating the redox chemistry of metals that can be used for remediation purposes, such as iron, arsenic and mercury, however these types of approaches have yet to gain widespread traction. This is what I advocated for as part of my PhD thesis which focused on developing sustainable bioremediation methods to remove mercury from water and soil (articles and thesis provided below):

Article A physiological role for HgII during phototrophic growth

Article Heliobacteria Reveal Fermentation As a Key Pathway for Mercu...

Thesis Photosynthetic and Fermentative Bacteria Reveal New Pathways...

I hope this information helps and I look forward to continuing the discussion in this thread.

Daniel

Nano scale zero valent iron with it's mobile form applied to treat the contaminated soil and water

Stabilized nZVI with some polymers such as CMC is more efficient and more mobile than bare nZVI for soil remediation and heavy metals adsorption

But of course the type of contamints and quality of soil determine the remediation method.

As far as contaminated soil is concerned stabilisation and secured land fill is the most economic and viable option. Where as treatment of contaminated ground water depends upon the behaviour of heavy metal at the particular site, concentration of the pollutant, area of contamination and redox nature of the heavy metals before and after treatment. Each method has its own advantage and disadvantage. However, the selection of methodology depends on the aim and target of the treatment and further disposal.

I would like to recommend to treat it by Soil washing method after excavation of soil. However If we can not excavate of soil because of industrial area, we can appling the soilidification or Stabilisation by stabilizer like Hematite, ZVI, slag, lime stone...

I prefer phytoremediadtion which can absorb heavy metals by their root system

Thanks to all of you for such a nice contributions.

What I would recommend in this case is to check the contaminant first through an analysis of the water and soil. Based on what is the contaminant or the pollutant the remediation process can be designed.

Thanks for the nice answers, I think :

firstly adsorption technique and then for long term remediation using phytoremediation !