8/3/2019 A Water Treatment Solution for heavy metals

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An innovative Water Treatment Solution for Heavy Metals

ZwolleThe Netherlands

ResultsThe First lab results showed that the water contained

mainly Crhomium6. The concentrations showed to be

much lower than earlier levels: 25-36.000 g/l. We found

out that a three-staged treatment with chemicals was

needed to get the best results. Phase 1 was a pH

correction. Then the Chromium was precipitated with

iron3chloride and the last step was to ad a polymer for

optimal settlement of the created sediments. In the lab we

could reduce the water concentrations below 100 g/l.

Also visible results where good: a good defined

sedimentation with on top a brightened water.

The lab results where then translated to the full scale

application. In the field the water in the old cellar is been

treated with the same recipe by spraying the different

chemicals over the water surface. Due to the wet autumn

the total amount of water was raised from 600 to 1.500

m and in the end we had to treat the water several

times. Each treatment lasted 1-2 days. But the results

were very good: like in the lab we were able to reduce theChromium6 concentrations below 100 g/l.

Beside the on-site water treatment we also took care of

the discharging of the water in the cellar. Discharging this

water without the sediments was done by floating pumps.

To be sure, we also installed a small water treatment

unit to prevent any sediments from discharging to the

local sewer (sand filtration).

ChallengeIn the Summer of 2011 HMVT was asked to provide a

practical solution for the treatment of 600 m polluted

water in an old cellar in Zwolle, The Netherlands.

On this project old buildings were being demolished and also a

soil remediation was carried out. The location was severelypolluted with Chromium3, Chromium6 and Nickel. As a result

of the very wet Summer the old and still to demolish concrete

cellar stood full of polluted water with Chromium6

concentrations of 400.000 g/l. A temporary water treatment

plant based on ion-exchange was having a lot of problems due

to clogging and was not capable of treating the water to meet

the discharge levels.

SolutionOur solution was based on precipitation of the heavy metals to

the bottom of the cellar and additionally discharging the

cleaned water to the local sewage system. The residual

polluted sediments could then be removed together with the

demolishing of the cellar and the soil excavations and for

treatment transported from the site.

Before executing this plan, we first collected water from the

location and tested this water in our lab facility. The aim was to

find a recipe of needed chemicals which could meet the local

water discharge levels (