Powell Water E-Cell Electrocoagulation of Heavy Oil Process Water
N.E.A.T. Environment, Inc. was requested to provide a treatability
study on Heavy Oil SAGD process water from a heavy oil operation in
Additional PW E-Cell treatments would be required to fully develop the treatment process for this oily water. The initial treatments were very good with reduction of heavy metals, TSS, Turbidity and extractable petroleum hydrocarbons. Treatment targets were the hydrocarbon removal and the heavy metals including Barium and Strontium.
Figure 1.0 Powell Water E-Cell 1.5 gpm Unit
Unit is processing Glacial Till Silty Construction Water
NEAT received samples of the oily water from a
Figure 2.0 SAGD Oily Water Samples used for treatability report
The above picture shows the samples that were obtained for the treatability report. The picture below shows the colour of the sample and its condition of settlement after 24 hours in a column and beaker.
Figure 3.0 Sample of SAGD Oily Raw Water prior to PW E-Cell Treatment
The raw water had an oily smell to it and there was no settlement of the suspended solids during the 24 hour period that the oily water was in the beaker and column. The following is a review on the PW E-Cell treatment of the Oily Water by Mr. Dennis Rasmussen, of Powell Water Systems Inc.
This is what the tests showed:
1) This water can be treated at nearly any current density setting and blade configuration---it is that reactive/conductive. Therefore, analysis will determine just how well the water has to be treated to achieve Company goals.
2) There is no indication of free oil or hydrocarbon in the EC treated water--no rainbows on the surface of the water in the beaker etc. I believe there is not enough free oil in the raw sample to recover using EC. As I have stated before, if the oil is 2,500 ppm or less, the EC seems to just break the chain/s down into new compounds and no hydrocarbon remains.
3) The amount of solids generated is enormous. The solids are heavy and dense enough that they appear not to settle at first---because they are busy trying to collapse on themselves--somehow. When the solids are settled, the floc will generally account for 50% of the container. The solids of course de-water well and do not represent a problem; the process system just needs to be designed to handle them from the start.
4) Water treats two ways--with a single chamber and with a double or split chamber. The double chamber worked by far the best. Current density was at 60 volts and 15 to 16 amps, flow rate set at 1 liter/min. Generation of foam may represent a problem when this stream is treated on large scale. The foam is not of a very dense, small size bubble, but there are a lot of bubbles. I would recommend that we design vacuum extraction of the foam from the chamber.
5) Filtration rate of the treated water is fast and the filter does not plug up (indicating a complete treatment). This particular water will treat well using gravity clarifiers, vacuum clarifiers (although there is no oil to recover), or just about any other means of separation. Solids aggregation is well developed, so de-watering is fast.
6) The filtrate thru a Whatman #1 is clear and very nearly colorless. There remains a very slight yellow color to the water, which I do not believe will affect the reuse or discharge of the water. If we take the time to run it again thru the EC, this color can be removed. Therefore it may be possible to slow down the flow rate and get the color. I also ran ozone in bottle of sample with good results. So, if there is a reason for the color to be completely gone, we can do so.
7) Visually, I believe the treatment was good enough on a single pass thru the chamber to remove the free oil and metals as Company desires. I do not think we will need to treat the water further. As I understand, the water is to be clean enough for reuse or injection. The visual results I saw should be good enough for these purposes. Analysis will provide the final word.
8) I am sending back a sample of the raw water, 3 - 16 oz bottles of the EC treated and filtered water and 1 EC treat, filtered and ozone treated water. I am also sending back the solids from filtration so they can be tested for oxide form etc.
9) If he has a problem with this water and its disposal at this time, he will really need to consider EC as a form of treatment, especially when the current density is at 60 volts and 15 amps. This should be quite economical.
There are a number of concerns raised by Mr. Rasmussen, which all were addressed by him and solutions were listed. As stated in the treatment review, there will be a requirement of additional test treatments to be done, in order to verify the treatment process, lab analysis of each treatment to obtain the best treatment results and the best economics for the treatment of the oily water.
Figure 4.0 Raw SAGD Oil water and PW E-Cell treated water
As shown in the above picture, there was no settlement in the raw water. The beaker of raw oily water also shows foam on top of the water, which would indicate some type of detergent. This could be the cause of the heavy foaming shown in the PW ecell treated water to the right. The PW ecell treated water indicates the heavy floc that was generated from the treatment. The heavier solids that were present in the raw water settles to the bottom and the lighter solids float to the top. This separation happens very quickly as the ECT water flows into the beaker.
Figure 5.0 Raw Oily water on left, EC Treated at center and Filtrated EC Treated water to right
On July 19, 2005, Mr. Scott Powell (
owner Inventor ) of the Powell Water E-Cell and Ken Gardner of NEAT, were
able to provide bench tests on the same oily water for Company in
The raw oily water was processed through the 1 liter per min. PW E-Cell using a single chamber and current treatment @ 100volt x 1.5 amps. The water treated very easily and filtered quickly. The water used for the treatment was mixed with 1500 ml of tap water to 500 ml of oily water. The reason for the mixture was to provide a sample large enough to provide the bench test demo.
Conclusion from the PW E-Cell Bench Tests :
1. The SAGD oily water treats with the PW E-Cell quickly and easily.
2. The power usage is low, with the use of one or two chamber treatment.
3. Target heavy metals : Barium Raw @ 0.13 mg/L was reduced to 0.02 mg/L
Strontium Raw @ 0.12 mg/L was reduced to 0.042 mg/L
Silica Raw @ 84 mg/L was reduced to 0.55 mg/L
These heavy metals can cause fouling in boiler water.
4 Extractable Petroleum Hydrocarbon was reduced in the heavy chain hydrocarbon. Additional tests are required to verify the best current density to use to provide higher reduction of the heavy oil in the process water
5 Total Suspended Solids and Turbidity was reduced and clear water was produced from the E-Cell treatment with fast floc separation and with filtration.
6 The ease of filtration of the E-Cell treated water will allow for water recycling.
7 Additional bench tests will be required, including lab analysis. The Powell Water E-Cell costs of operating were estimated @ $1.75 to $2.00 per 1000 gallons.
8 The Powell Water E-Cell can be scaled in size from 1.5 gpm to 2,500 gpm as skid units and larger units as modular built on site construction.
This treatability report was a joint effort of Mr. Dennis Rasmussen of Powell Water Systems Inc. and Ken Gardner, of N.E.A.T. Environment, Inc., the Canadian Distributor of the Powell Water E-Cell.