Treatment of Arabian Sea Water for Industrial/Domestic Use

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I live in Karachi, which is a port city at Arabian Sea or the Indian Ocean. Karachi is a big industrial city and all the water comes from a Canal River Indus.

Can anyone suggest how we can treat the sea water for industry/domestic use in an economical way?

A few years ago Siemens Pakistan installed a Desalination/power plant but it failed soon due to some technical problems. Karachiates are facing serious water scarcity problems.

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15 Answers

  1. Why not treating the effluents for reuse, instead? Seawater desalination is one of the most energy- consuming treatments available and requires suitable infrastructures to operate ( jetty/intake stations, pretreatment and brine disposal) and huge energy consumption ( high CO2 footprint). Wastewater is often cheaper to treat and could give water ( almost-) endless lifecycle.

  3. How Arabian Sea water may be treated to use as Industrial/domestic purpose?
    An expert Prem Baboo replied:
    In view of the ​ever-increasing ​threat of ​marine ​pollution along ​Karachi coast ​and its ​possible danger ​to the coastal ​and marine ​environment. ​Although there ​have been a ​number of ​overviews on ​status of ​marine ​pollution in ​Pakistan, to ​quantify the ​level of oil ​pollution in ​the coastal ​environment of ​Karachi, ​Pakistan. Water ​and sediment ​samples were ​collected from ​various ​locations along ​Karachi coast ​bordering ​northern ​Arabian Sea. ​Water quality ​was assessed ​using the ​parameters ​salinity, ​dissolved ​oxygen, ​suspended load, ​organic matter (​in particulate ​carbon) and ​total oil and ​grease. The ​salinity in ​Karachi Harbour ​ranged between ​ 25.062–36.042 ppt in the Down ​Stream Lyari ​River Mouth and ​outside Manora ​Channel to open ​sea respectively.​ The dissolved ​oxygen values ​observed at all ​stations ranged ​between ​ 0–6.01 mg/l . Complete ​anoxic ​condition with ​zero oxygen ​value was found ​at Lyari River ​Mouth the ​discharge point ​of mostly ​untreated ​industrial and ​domestic wastes.​ The very high ​concentrations ​of suspended ​load have been ​found at ​Korangi creek ​and Gizri creek ​Tip which are ​ 177.6 ppm , and 100 ppm respectively. ​Concentrations ​of the ​suspended load ​in Karachi ​Harbour were in ​the range of ​ 28.30–61.60 mg/l however, ​higher values ​have been found ​in the Manora ​Channel and its ​surrounding ​area. The level ​of organic ​matter ranged ​between ​ 2.35–11.50 mg/l, with high ​values detected ​in Korangi ​creek and Gizri ​creek, which ​were 11.5mg/l and 7.15 mg/l respectively. ​The concentration ​of total oil ​and grease in ​seawater was ​detected in the ​range of ​ 0.9–49.9 mg/l . The highest ​concentration ​of total oil ​and grease ​ (49.9 mg/l) in seawater ​had been ​observed in ​Manora Channel. ​Similar results ​were also ​observed for ​total oil and ​grease in ​sediments. The ​highest ​concentration ​in sediment was ​found in Manora ​Channel, and ​Korangi creek ​which were ​ 115 mg/kg, and 81 mg/kg respectively. ​The lowest ​value ​ 0.9 mg/l was detected ​in water sample ​collected out ​side Manora ​Channel in the ​open sea, which ​clearly showed ​that the ​pollution level ​decreased from ​Karachi Harbour ​towards open ​sea, due to ​tidal flushing ​and mixing of ​pollutant with ​seawater. ​Karachi the ​largest ​industrial and ​thickly ​populated city ​of Pakistan ​which is ​situated at the ​north western ​boundary the ​Arabian Sea is ​highly ​vulnerable to ​flood damages ​either due to ​flash floods ​during SW ​monsoon or ​impact of sea ​level rise and ​storm surges ​coupled with ​cyclones ​passing through ​Arabian Sea ​along Pakistan ​Coast.​

    Comments From Mr.Anjum Alvi: An Ex Employee of Subject Plant.

    To begin ​seawater ​desalination ​water treatment,​ a stable, high ​quality feed ​water is ​required –​ this optimises ​membrane ​durability. ​Depending on ​the water ​purification ​system, from ​here water ​heads either to ​the distillation ​solution or ​membrane ​solution.

    What the writer is writing is true for R.O. plants. The coastal sea water along Karachi beach is even worst.

     In the urban belt, even raw sewage is dumped directly into sea as no sewage treatment plant is operational for 14-15 million people. This sea water is NOT suitable for R.O. intake unless extraordinary pre-treatment is designed and installed, raising the capital and production cost. That is why we have seen and know very well that big R.O. plant is not and has never been feasibly successful for Karachi beach water when it is meant for bulk supply to the consumers. Small size R.O. units for bottling mineral water or supplying for any industrial needs may be technically or financially feasible but when comes to plants for supplying in bulk to any community of say ¼ to many million GPD, then none of the desalination plants are profitable. In Europe and Middle East and all over the world it is Government’s responsibility to subsidize the cost and supply Desalinated Water to public where natural streams are in scarcity. That is why there is no Desalinated Plants supplying bulk water to communities in private sector all over the world. In Pakistan, the production cost alone comes out around Rs.650-700 per 1000 gallon which is too much for a consumer to pay. Depending upon the quality of feed water, the capital and production cost of R.O. water may vary further.

    For ​distillation ​processes, the ​technology used ​to vaporise ​is ​Multiple Effect ​Distillation(​MED), a low ​temperature sea ​water ​distillation ​process used to ​evaporate ​seawater in ​numerous stages ​– up to ​14 stages in ​some instances ​– at ​temperatures of ​70° C or ​lower to ​produce clean ​distillate ​water. ​

    Mr.Anjum Alvi : Replied.

    That is why the Cogen Plant was considered and installed with MED unit, which is a hot distillation process. It has a series of evaporation and condensation process and hence does not require very stringent feed water quality. It operates on waste heat available from any source at 65-70 degree C. The Cogen plant gets spared steam from a combined cycle power plant. The MED plant produces distillate and also in return supplies condensate and make up water to the HRSG of power plant to continue its operation. That is the operation of both the plants are dependent to each other, if one is shut down the other will also not work. However, it is a wrong perception that Cogen Plant is shut down due to problem in Desalination /MED Plant. There has NOT been serious issues with the MED Plant. The Plant is shut down due to problems in the main prime mover (GT) of the power plant which has nothing to do with quality of sea water. The plant is still technically doable and can be rehabilitated if some investor comes forward and invest money. However, ever rising liabilities on the company due to long shutdown are getting enormous, that is making the financial model unattainable for getting allowable power tariff from NEPRA.

    Make the water ​suitable for ​drinking ​purposes the ​following ​procedures ​should e ​carried out:​

    Removal of suspended matter.e
    ​Decolourisation ​and oxidisation ​of the ​inorganic ​material and ​killing of all ​pathogenic ​micro-organisms ​by adding ​chlorine (pre-​chlorination).​
    Aeration of water.
    Oil removal by ​gravity settler ​Or disc oil ​system.​
    ​Flocculation of ​colloidal/​organic matter ​with aluminium ​sulphate and ​anionic ​polyelectrolyte.​
    Sedimentation.
    Filtering.
    Addition of lime. .
    Post chlorination

    Mr.Anjum Alvi Replied:

    In April, 2008 when the plant was commissioned and operating for 9 months there has been some problem in operating MED unit due to excessive silt coming in with the sea water feed. At that time, DHA was dumping thousands of tons of sand/earth every day to reclaim area for the Emaar housing project located next to Cogen. With the result the heavy silt ingress in feed was requiring excessive cleaning and/or replacement of filters. Considering the silting issue as a long term problem for this area, a sedimentation tank at the sea water intake was planned and a model testing was carried out successfully in 2009 in Germany to execute the same. That proposal is still available to resolve the silting issue, if it reappears in future.

    If you let me know the intention of your interest in this field, maybe I can assist you further.

    Regards.

     

    Anjum

  4. Hello Muhammad, I would suggest a Multiple-effect distillation (MED) system powered by Solar such as Focal Line Solar, to achieve a high quality potable water at the least expensive possible cost.  The short video is a proposal from Focal Line Solar to supply potable water and electricity for the Trans Africa Pipeline (TAP).  A similar setup would work well for you.  TAP will provide fresh water for drinking and irrigation across an 8000 kilometer strip of land just south of the Sahara and also provide water to refill Lake Chad.  Please be welcome to contact me for more information.

  6. Contact me through mail abdulgaffar557.ag@gmail.com And I'm not a seller bHai I have design RO plant own design with some engineer so you feel free to contact me I will send your sea water desalination RO plant projection you go through it and see what is problem in water and design like it.

    I'm doing this for free to gain knowledge thats it Iyas bHai.

     

    Whatsapp number +918608174649

  7. If the  correct pretreatment is selected then  a RO plant should be able to operate in a reliable manner with all seawater sources.  The pretreatment may require several process  steps depending on the level of none salt material in the source seawater.  

    If the source seawater has high suspended solids/ turbidity  sand or silt from rivers, then a lamella clarifiers process step are often used (eg Trinidad Point Lisas). 

    If the source seawater has high algae or oils and grease then Dissolved air Floatation is typically used (eg Fujairah) .  Dual Media Filters  are used for low levels of the turbidity (typically up to 10 NTU) (used on most desal plants) , and also a very deep pumice top layer is now often used in the DMF as  biofilter  to remove organic material that could other wise cause biofouling to the RO.  

    If there is  industrial organic pollution then another step is the granular active carbon filters.  (eg Carboneras Spain).  UF/MF membrane pretreatment although very good for particulate material is not effective for soluble material and tends to lead to biofouling of the RO membranes if there is no biofilter process added also to the pretreatment train. 

  8. Seawater RO treatment process is an alternate. Thermal desalination is also suitable if low pressure steam is available free from the process.

    Any system/plant will fail only if it is not designed properly or it is not operated as per the design. 

    It is difficult to suggest a solution for weage statements like "failed soon ​due to some ​technical ​problems

    1 Comment

    1. Good points Govindasamy.  I find it hard to believe Siemens would mis-design a plant like this given the amount of oversight that would have to make the project happen.  Not saying it is impossible, but more to the other point.  MOST likely it is service and operation and maintenance that would be the contributor to failure.  Things that could contribute to this is training, supply chain for spare parts etc.  

  9. Hi if there is sufficient wind (above 5m/sec) we can deliver wind driven desalination with a reverse osmosis system on wind energy, no grid needed. Capacities from 100m3/day to 800 m3/day. 

    pls send me winddata and if possible water specifications to h.tonningen@solteq.eu 

  10.  

    DEAR MUHAMMAD ILYAS KHAN , GOOD QUESTION

    In view of the ever-increasing threat of marine pollution along Karachi coast and its possible danger to the coastal and marine environment. Although there have been a number of overviews on status of marine pollution in Pakistan, to quantify the level of oil pollution in the coastal environment of Karachi, Pakistan. Water and sediment samples were collected from various locations along Karachi coast bordering northern Arabian Sea. Water quality was assessed using the parameters salinity, dissolved oxygen, suspended load, organic matter (in particulate carbon) and total oil and grease. The salinity in Karachi Harbour ranged between 25.062–36.042 ppt in the Down Stream Lyari River Mouth and outside Manora Channel to open sea respectively. The dissolved oxygen values observed at all stations ranged between 0–6.01 mg/l . Complete anoxic condition with zero oxygen value was found at Lyari River Mouth the discharge point of mostly untreated industrial and domestic wastes. The very high concentrations of suspended load have been found at Korangi creek and Gizri creek Tip which are 177.6 ppm , and 100 ppm respectively. Concentrations of the suspended load in Karachi Harbour were in the range of 28.30–61.60 mg/l however, higher values have been found in the Manora Channel and its surrounding area. The level of organic matter ranged between 2.35–11.50 mg/l, with high values detected in Korangi creek and Gizri creek, which were 11.5mg/l and 7.15 mg/l respectively. The concentration of total oil and grease in seawater was detected in the range of 0.9–49.9 mg/l . The highest concentration of total oil and grease (49.9 mg/l) in seawater had been observed in Manora Channel. Similar results were also observed for total oil and grease in sediments. The highest concentration in sediment was found in Manora Channel, and Korangi creek which were 115 mg/kg, and 81 mg/kg respectively. The lowest value 0.9 mg/l was detected in water sample collected out side Manora Channel in the open sea, which clearly showed that the pollution level decreased from Karachi Harbour towards open sea, due to tidal flushing and mixing of pollutant with seawater. Karachi the largest industrial and thickly populated city of Pakistan which is situated at the north western boundary the Arabian Sea is highly vulnerable to flood damages either due to flash floods during SW monsoon or impact of sea level rise and storm surges coupled with cyclones passing through Arabian Sea along Pakistan Coast.

    To begin seawater desalination water treatment, a stable, high quality feed water is required – this optimises membrane durability. Depending on the water purification system, from here water heads either to the distillation solution or membrane solution. For distillation processes, the technology used to vaporise is Multiple Effect Distillation(MED), a low temperature sea water distillation process used to evaporate seawater in numerous stages – up to 14 stages in some instances – at temperatures of 70° C or lower to produce clean distillate water. 

    Make the water suitable for drinking purposes the following procedures should be carried out:

     

    1. Removal of suspended matter.
    2.  Decolourisation and oxidisation of the inorganic material and killing of all pathogenic micro-organisms by adding chlorine (pre-chlorination).
    3.  Aeration of water.
    4. Oil removal by gravity settler Or disc oil system.
    5.  Flocculation of colloidal/organic matter with aluminium sulphate and anionic polyelectrolyte.
    6.  Sedimentation.
    7.  Filtering.
    8. Addition of lime. .
    9.  Post chlorination

     

    Regards,

    Prem Baboo

    2 Comments

    2. Nice presentation Mr. Baboo ; I agree completely with your assessment of the situation. The solution however has a few detrimental effects.  What you have suggested to do with chemicals nature already has microbes that eradicate all of the negative items you mentioned.  Microbes of various groups will bring the oil content to near 0 ppm. All of the perceived toxin will be chelated into their elemental/nutritional state. The desalination facility will not be needed. You can "clean" all water 100% and return it to your potable water reservoirs. Hopefully each home has their own elevated water tank and a subsurface cistern.  Setting up a rain water collection system is the key. Grinding all of your trash into compost will restore soil fertility. Crops and trees will grow healthy and "hold the water in the soil". Plant respiration will increase daily humidity levels. This will increase annual rainfall.  In addition one very special characteristic of these soil engineers they make oxygen more available.  Say goodbye to your coastal pollution and dead zones.   The only item that can stop nature from doing this job is chlorine.   

      2 Comment replies

      1. Mr. Kahn. I had worked with Dr Oppenheimer for 16 years. He is considered to be the father of modern microbiology. Now I only work with cutting edge technology. my email is biozomesales@biozome.com My skype is   guy_mcgowen .  We both seem to have acquired the same point value on the water network system.

  13. Dear Muhammad,

    Please see attached, floating desalination plants. Installed a bit offshore the intake water is of good quality and the plant performs well.

    Ronald.dehaas@modec.com

    mail for more info

  14. Dear Muhammad;

    Please forgive me if I am somehow rude, but the only way we can respond to such candid question is:

    1) Define Cheap

    2) What was the problem with SIEMENS

    3) What kind of water you have: Specs

    1 Comment

  15. Hi, our evaporator system can treat the brine water. It's for desalination and industrial wastewater treatment.

    May I have your detail data of your water, please? Like the PH, the content of calcium ion, Magnesium ion, chloride ion, fluorine ion or other composites. Also please tell us how many m3 of waste water you need to treat per hour. Then our engineer will make the technical proposal for your reference.

    Here is my Email: ms.fan@nomiamachinery.com. Or call me directly +8613003305050.

    Thanks in advance!

    Katharine

    3 Comments

    1. Dear Mohammed  A new  technology  for desalination from salty ( 2 x 3 times seawater) and/or polluted water which is made for point of use (household or small community level)  is slowly maturing and will the coming year come on the market . It is cheap, simple to use  and completely solar powered.  It is no alternative for large scale RO plants.  See www.SolarDew.com.  Perhaps useful.   

    3. We can dewater all solids [micro] as well as desalinate. Should make life easier.

      Brand new process---no additives

      jimquigley5@gmail.com