Hard Chrome Treatability Bench Tests and Report
KB-1 Treatment Results on Stripper Tank and Floor Waste Process Water
Bench Test No. # 4TT0514 and # 5TT0514
The following illustrations and photos are of the KB-1
Treatment results of the Hard Chrome Process Waste Water samples that were
taken from the Stripper tank and Floor water tank at the Hard Chrome Industries
Hard Chrome facility located in
On this series of tests, the stripper tank waste water and the floor waste water were mixed together into two beakers. Each beaker was set up as follows :
Beaker #4TT0514 - as shown in Figure 1. and Figure 2
#4TT was a mix of 500 ml Raw Stripper Waste water that included 100 grams of sludge waste, 500 ml floor waste water with no sludge and 3000 ml of tap water. This gave the mixture a treatment ratio of 1 to 3 use of contaminated water to tap water.
The raw water results of the mixture can be found in Figure 1, below. The metal concentration was high in Cr3 and Cr6. The resulting high chrome concentration was from the sludge that was mixed into the beaker from the stripper sample. Once the Raw Water samples were taken from the beaker for lab analysis, treatment of the water was started. The treatment process is described on page 4 and with Figure 4, showing the colour changes during the Cr6 reduction to Cr3, using Sodium Meta-bisulfite, prior to treatment of the sample with SME KB-1.
Beaker #5TT0514 - as shown in Figure 1. and Figure 3
#5TT was a mix of 500 ml Raw Stripper Waste water, ( no sludge waste ), 500 ml floor waste water with no sludge and 3000 ml of KB-1 Treated Decant water. This gave the mixture a treatment ratio of 1 to 3 use of contaminated water to KB-1 Treated Decant water.
The raw water results of the mixture can be found in Figure 1, below. The metal concentration was not as high in Cr3 and Cr6. The resulting lower chrome concentration was because there was no sludge mixed into the beaker from the stripper sample. Once the Raw Water samples were taken from the beaker for lab analysis, treatment of the water was started. The treatment process is described on page 5 and with Figure 5, showing the colour changes during the Cr6 reduction to Cr3, using Sodium Meta-bisulfite, prior to treatment of the sample with SME KB-1.
The following IME Certificate of Analysis is shown in Figure
1. of the heavy metal concentrations in the raw water of the two treatment
samples, along with the comparative metal concentrations after KB-1 treatment
of the waste water, which are then compared to the City of
The Composite Sludge is a mixture of all of the sludge that has been generated from 5 to 6 samples being treated with KB-1. This is to verify that the sludge would meet MOE landfill leachate standards.
Figure 1 - IME Lab Certificate of Analysis Samples #4TT0514 and #5TT0514
The following photos Figure #2 and #3 are of the mixed raw water samples prior to KB-1 treatment of the Stripper Waste water and floor waste water. As stated above, sample #4TT had extra stripper sludge included and this affected the treatment process.
There were 3 treatment steps developed for these samples. These steps had been developed on previous samples with these two samples were to provide NEAT personnel with the verification that these waste streams could be mixed and treated. The above IME Certificate of Analysis provides the evidence that mixing the waste streams will allow for successful KB-1 treatment.
It is suggested that all waste water be cycled through a filter press prior to treatment. This would allow for fewer problems in treatment of the Stripper and Floor water.
The Stripper Tank Bottom sludge causes various treatment concerns, due to extremely high Chrome Concentrations. There are treatment reviews of the Stripper Tank Sludge in other sections of this report, which can be treated with KB-1, but may not be economical.
Figure 2 - #4TT0514 Raw - 500 ml Stripper Water w/ 100 g. Sludge & 500 ml Floor Water & 3000 ml Tap Water. Treatment @ 1:1:3 Ratio
Figure 3 - #4TT0514 Raw - 500 ml Stripper Water w/ 100 g. Sludge & 500 ml Floor Water & 3000 ml KB-1 Treated Decant Water. Treatment @ 1:1:3 Ratios
The 3 step treatment process is as follows : At all time, treatment is to be done in well ventilated area.
Step 1 - 3 to 1 water dilution of the mixed waste water and pH adjustment to pH 2.0
The requirement for the water dilution is to provide enough water for the Sodium Meta-bisulfite reaction for the Cr6 reduction to Cr3. By reducing the Hexavalent Chrome to Trivalent Chrome, which will allow for optimum KB-1 treatment and encapsulation conditions. The pH adjustment is required if the waste water pH is lower or higher that pH 2.0, to allow for the Cr6 reduction to Cr3 and then be at the pH 4.0 range to start the KB-1 Treatment. In the following bench tests, HCL acid was used for pH adjustment.
Step 2 - Sodium Meta-bisulfite ( MBS ) treatment for Cr6 reduction to Cr3
As shown below in Figure 4, during the MBS treatment, there will be substantial colour change in the waste water. This colour change is one of the best indicators, when the Cr6 has been reduced. There could be a requirement for the purchase of a Hack 4 unit to provide an accurate measurement of the reduction of Cr6 below 1.5 mg / L. Once the MBS treatment is reached, the pH of the waste water should be in the pH range of pH 3.5 to pH 4.5, which is the start pH range for KB-1 treatment. There was substantially more MBS used in Sample #4TT with the 100 g. of stripper tank sludge than in the Sample #5TT with no sludge.
Step 3 - Treatment of waste water with KB-1 in pH ranges of pH 4.0 to pH 10.9
The treatment of the waste water is all pH driven. Past experience has shown that there are three pH ranges that are involved in the treatment process. These ranges are : pH 4.0 to pH 7.5, pH 7.5 to pH 9.5 and pH 9.5 to pH 10.0 or pH 11.0. At the point of each pH range, it is recommended that the waste water be allowed to react with the KB-1 Silica Micro Encapsulation process for at least 1 hour. The amount of KB-1 required to reach each of the general ranges, will come with experience or by doing 1 liter bench tests. Once the treatment pH of pH 10.5 to pH 11.0 is reached, the treated solution should be allowed to react for at least 2 hours, prior to decanting and filter pressing the sludge.
Figure 4 - Colour changes during Treatment of Beaker #4TT0514,
with MBS for Cr6 reduction to Cr3, prior to KB-1 treatment.
Once the MBS treatment is completed by reducing the Cr6 to Cr3 and the waste water and sludge generated from the MBS treatment has changed from the yellowish / green colour to the deep bluish / green, the waste water is ready for KB-1 treatment. There will be a colour change of both the waste water and sludge during KB-1 treatment. This colour change will be from the deep blue to clear waste water and light blue sludge. The water colour change will be in the ph range of pH 9.5. At this pH range the flock will be heavier and will precipitate out quite quickly. Figures #5, #6 and #7 below, show the colour changes and the waste water colour changes.
The following are the steps for treatment followed for each sample and the amounts of MBS and KB-1 used during the treatment process and the grams / liter used on completion of the treatments :
Sample #4TT0514 w/Sludge Sample #5TT0514 no Sludge
4,000 ml sample 3,000 ml sample
pH adjustment from pH 6.19 to pH 1.98 pH adjustment from pH 6.09 to pH 2.01
add HCL 75 ml add HCL 96 ml
Start MBS Treatment @ pH 1.98 Start MBS Treatment @ pH 2.01
Add MBS Total 160 grams pH 3.64 add MBS Total 40 grams pH 2.38
Cr6 reduction from 6500 mg/l to 1.75 mg/l Cr6 reduction from 3700 mg/l to 1.25 mg/l
_______________________________ pH adjustment to pH 4.13 w/ 20 g. Caustic
Start KB-1 Treatment @ pH 3.64 Start KB-1 Treatment @ pH 4.13
Add KB-1 Total 120 grams pH 12.01 Add KB-1 Total 75 grams pH 12.17
MBS Treatment Grams / liter @ 40 g/l MBS Treatment Grams / liter @ 13.33 g/l
KB-1 Treatment Grams / liter @ 30 g/l KB-1 Treatment Grams / liter @ 25 g/l
pH was to high, so KB-1 could be reduced by at least 5 grams per liter on both treatments
Figure 5 - Treatment of Beaker Samples #4TT and #5TT with KB-1.
Figures #6 and #7 show the cleared water and the settled
sludge from the KB-1 treatments. Because
of the different camera angles, there would seem to be more sludge in #5TT than
in #4TT. It was actually very close to
the same amounts. Figure #7 also has the
reflections of another treatment in the background leaving a yellowish look to
the water. We have also found that the
yellowish water appears in the higher pH water, so it is best to keep the pH
close to discharge standards for the City of
Figure 6 - KB-1 Treated & Settled
Figure 7 - KB-1 Treated & Settled