EDR Vs ​RO for Water Treatment

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What is the ​best water ​treatment ​method for ​water with the ​following given  ​specifications ​to use water ​for Drinking ​and Cooling ​purposes?  ​

We get our ​water from two ​brackish water ​surface wells.​  ​

Which method ​will give ​better results -​ Electrodialysis ​Reversal or ​Reverse Osmosis ​and why? ​

Water Specification

Well 1 -

For Drinking water 

Well 2 -

Plant cooling

pH

7.35

7.42

conductivity ​ [µS/​c]

5290

5057

Salinity (as ​NaCl)  [mg/​L]

2138

1981

Chlorides (Cl ​-)  [mg/L] ​

1453

1200

Sodium (Na+)  [mg/L]

685

781

Total Hardness  [F.D.]

19

15

Calcium (Ca2+)  [mg/L]

40

30

Magnesium (​Mg2+)  [mg/​L]

21

18

B.O.D  [mg/L]

60

60

Carbonates (​CO3-2)  [​mg/L] ​

Traces

Traces

Bicarbonates (​HCO3)  [mg/​L]

159

146

Suphates (SO4-​2)  [mg/L] ​

940

840

Nitrites (NO3-​)  [mg/L] ​

1.6

2.2

Nitrites (NO2-​)  [mg/L] ​

0.021

0.035

Silicate (​SiO2)  [mg/​L]

17

15

Ammonia (NH3)  [mg/L]

0.64

1

T.SUSP Solids  [mg/L]

6

2

T. Dissolved ​Solids (T.D.S) ​ [mg/L] ​

3386

3236

Turbidity  [FTU]

0.004

0.01

Dissolved (​Fe2+)  [mg/​L]

0.08

0.45

Chemicals  [ppm]

0.5

0.35

 

 

Taxonomy

20 Answers

  1. TSS and Turbidity does not match, TSS probably will be much lower. Measurement of TSS for low levels is very difficult.

    SDI15 should give a better understanding of the quality, but probably should be lower than 1.

    As other people mentioned, EDR will give you a higher recovery (85-90 %) but every stage will reduce the TDS 50% average. It's very easy to calculate the number of stages you need knowing the quality you want to achieve. Two stages is ideal, three stages is the higher economical number. Advantages: No biofouling, even during standby time,Chlorine gas production (You save a lot of money in hypo to sterilize the product water) No membrane replacement in many years. Membranes are chlorine resistant. No sand filters for this water, only cartridge filters as pre treatment. 

    RO is also a good option. Perhaps you do not need sand filters as well. It will depend on the amount of colloids. A measurement of SDI15 will give you the answer. 

    CAPEX and OPEX data is needed to take a decision

  3.  I have a project near this analysis ,the wells in the desert,the wells are deep (160 m),the BOD of raw water is 60-110 mg/l ,I use the water for power plant and the water treatment used d.m.f with Ro. after 6 month accidentally I found the  BOD is high and research for pretreatment to reduce of BOD.

    OZON plant suggested for reduce to BOD.

    1 Comment

  4. Such high BOD with unspecified COD or TOC and SDI will definitely result in fast irreversible (bio)fouling of RO membranes. Hence I recommend to first reduce the BOD by at least 90% for an acceptable economic service life of the RO membranes. We achieve BOD < 3 mg/l by advanced biological treatment for high grade water reuse.

  5. if BOD of 60ppm is right, it means the water is contaminated by some organics. but turbidity is very low, so RO will be preferred against EDR as it also removes organic and produce good water quality for drinking water but BOD may cause fouling issue at RO.

  6. The well water chemistries are similar. Both EDR and RO would work, it would however depends on what you want to achieve. The EDR would give you high recovery without any pretreatment. For the  RO  option would  however need pretreatment and achieve less recovery. The EDR option normally comes at a premium price but is a very robust solution.

  7. The well water chemistries are similar. Both EDR and RO would work, it would however depends on what you want to achieve. The EDR would give you high recovery without any pretreatment. For the  RO  option would  however need pretreatment and achieve less recovery. The EDR option normally comes at a premium price but is a very robust solution.

    1 Comment

  9. If you send me your email I will send you a paper that is backed up by a working proof of concept plant that can be viewed at anytime.

    4 Comments

    1. Hello Aubrey, could please send me the paper as well. Thanks 

  11. I use magnesium oxide (MgO) prill beads to purify any water. The prill beads come from a deep mine in Nevada. They are processed at 700 degrees which turns them into ceramic beads that do not dissolve in water.

    The beads place a positive charge in the water that shatters the magnetic bond that holds together any contaminants or pollutants (chlorine, fluoride, heavy metals: zinc, copper, lead, chromium-VI, pesticides, radiation, pharmaceuticals, mold, Ecoli, bacterias, etc) and gasses them out of the water. It raises the water pH to 8.7, high alkalinity, high oxygen, and thins the water so that can penetrate the cell membranes and flush out your toxins. As to hydration: 3 Glasses of prill water is equal to drinking 1 gallon of water.

    Great for acid conditions: acid-reflux, heartburn and acne. 

    http://www.PrillyPureWater.net Never dissolves, Never wears out, and Never needs to be re-purchased. One-time investment of $40

    1 Comment

  12. The two waters are not very different. EDR or RO will work for both. However, one of your major concerns will be the corrosivity of the product water. It will be aggressive  toward the pipes and fixtures and leach metals, so you will need to stabilize it by pH adjustment and hardening with lime or limestone.

    1 Comment

    1. Afraid about corrosion use PE 100 in drinking water quality for water transport?

  13. For drinking water, use EDR plus pre-treatment and disinfection on the final stage (ex-chlorine or ozone gas). For Cooling System EDR plus post treatment to reduced silica and metal conditioner when circulating. RO could be applicable on both application but the low recovery on reject/concentrate is too much and the fact that high silica would clogged the RO membrane ( there is a solution on high reject by using high efficiency RO membranes and to address silica, very expensive de-ionization process on top of expensive membranes at post & pre-treatment). Hope this will help.

  17. For cooling water I would recommend Capacitive Deionisation (CapDI). It is an electrcally driven membrane process, that removes hardness without chemicals for regenertion like the use of HCl or NaOH normally used for regenration of IX softeners. It does not increase salinity. Reccommend to go to the Voltea website. Gives a good explanation and it increases the recycle ratio for cooling waters very well against acceptable cost. Good reference base.

    For drinking water it is usually a matter of cost. For this salinity RO and ED are both in the same ball park. So you need other considerations like operability, recovery, scaling and sanitary or pathogen removal.

  18. That much sodium will give all of you high blood pressure. Are you in a desert or semi-desert climate? see www.suns-river.com

    2 Comments

  19. Your BOD is kind of high for water (vs. wastewater) I would use RO as EDR does not remove the BOD (organics).  The silica is not very high so EDR does not have an advantage.  What is F.D. for total hardness?

     

    1 Comment

    1. By using HVCF Technology it is possible to remove BOD.  With MF, UF and RO by using membranes in disc arrangement rather than tubular where there is a dead end that does not allow for a higher permeate.

  20. I am interested to explore the differences between the two waters. They are similar enough to be coming from one aquifer but I'd say there is a reason for the disparities - perhaps one is closer to a recharge source? (e.g. a leaking lake, river or canal).

    Hydrogeological issues aside, if the quality of the two waters is stable then a water treatment system could be designed around an analysis of the blended mix. The treated water (with TDS approaching