Gwadar Needs Research on Water

By Tassadduq Rasool*, Mujahid Ali**

*Agronomy, **Horticulture; University of Agriculture Faisalabad

The port city of Gwadar has got more attention after being a part of China-CPEC program. This Sino-Pak project is expected to give unprecedented economic benefits to the region. The real estate personal skyline its future as a Dubai like city and Govt. is committed to making it a modern port city. However, despite many positive initiatives, still, it has an alarming issue and ground realities are quite different. Gwadar port city was hit by an acute water shortage this year when the main supply source “Akara Kaur Dam” dried out, that is located 25 km from Gwadar city. A team of researchers led by Shahid Naseem from the University of Karachi assessed water quality of Akara Dam and found its composition suitable for use as fresh water. However, it is influenced by calcium sulfate dissolution and might deteriorate its quality in near future. Water is a versatile resource for a human being that fulfills its domestic, agricultural and industrial needs. About 100000 local residents of Gwadar need access to this basic life facility. They are dependent on costly portable water supplied by tankers from a distance of 80 km. Gwadar, being projected a well growing port city, will have its water requirement increased in the coming days. According to Leonardo da Vinci “Water is driving force of all nature”. The government has prioritized to establish new desalinization plants under CPEC-project, to make fresh water available for the better future of this city. These plants will supply 5 million gallons of water per day at a rate of 80 cents per gallon. These plants will be inaugurated in January-2018 and people will have access to clean drinkable water. The development of the city is strongly correlated to access of basic life facilities. We need research that should prioritize the use of water according to its quality. Moreover, domestic use can be cut down by developing water conservation tools by domestic engineering. The ocean can be a good resource for an endless supply of drinkable water. The research should be based on desalinization of seawater, use of brackish groundwater and reuse of wastewater. The most prominent techniques for desalinization are thermal desalinization adopted in the Persian Gulf and pretty much common is “the reverse osmosis” everywhere in the world. Water is taken through intake pipes from the ocean, filtered from largely sized contaminants or sea living creatures and passed through pressurized reverse osmosis system, to screen salts through membranes. The only issue is that, membranes pores are choked by microbial colonization and it makes it costly to periodically clean the membranes. Recently a breakthrough in the membrane technology has been made, that utilizes the lava stone to capture microbes, before they reach the membranes. There are several other possible technologies of future like “Spin cycle” developed by Palo Alto Research Center (PARC) in California; membrane screening under low hydraulic pressure, forward osmosis, and microbial fuel cell etc. Another cost-effective technology is “Biosantizer” developed by Dr. Uday S. Bhawalkar in INDIA to treat waste-water. This technique is an ecological-based and has shown sustainability for the last 12 years. Recently a group of scientists in Australia has developed a salt tolerant wheat by incorporation of gene “TmHKT1;5-A”; a big breakthrough in the food production in the salt-affected areas. Moreover, Israel is meeting 60% of its domestic water needs by desalinization of water. The research on efficient use of water in homes has cut down to halves than actual needs. They have prioritized the research on drip irrigation, water treatment and desalinization. The major driving force behind all this effort is that, Israel is in one of the driest regions and has faced the challenge of severe drought in 2008. So, turning ocean into drinking water is not out of future now. The Sorek desalinization plant in Israel is the largest facility in the world, working on reverse-osmosis principle. It supplies 1.5 million people with drinkable water. There would be seven desalinization plants working by 2020, in Los Angeles and Orange counties of USA. Another important facility is in Carlsbad desal, that is supplying 50 million gallons of water per day to San Diego, USA.  The cost estimates show that fresh drinkable water has no alternative. The cities near the ocean have limited access to fresh water, and they meet their need either from imported supply or from desalinization. According to estimates, desalinization costs might range from Rs. 209000 to Rs. 221000, per 326000 gallons of water (Costs converted from Dollars to Pak currency). There are many disasters due to water shortages. Recently in Syria, more than a million farmers made strikes in Aleppo because drought affected severely the agriculture and wells eventually dried out due to extensive pumping deeps in the water table. The efficient household water use can be a game changer as well. Israel recaptures the 86 % of the water going down into drains and utilize it for agriculture. Another most efficient country is Spain that has the capability to capture almost 18% for utilization. The modern world has developed the efficient toilet and shower systems, and innovative treatment systems that make them reusable. Water conservation has become essential even in areas of abundant water supply. Overall, I can say, it’s not easy to make all waters drinkable especially from the sea that contains salts within a range of 30000-40000 ppm as compared to freshwater 1000 ppm. Still, there are a lot of option and a hope. The desalinization era has been started by Israel.

What is Reverse Osmosis?

Although Reverse Osmosis seems like a complex system it is really a simple and straightforward water filtration process. And it’s not a new process. High-pressure (pump driven) reverse osmosis systems have been used for years to desalinate water – to convert brackish or seawater to drinking water. Having a better understanding of how a reverse osmosis system works will eliminate the mystery and confusion you may feel when you look at a reverse osmosis system — with its many colored tubes and multitude of filters. Read on to enhance your knowledge of residential reverse osmosis systems.

The most important points to remember:

  • All RO Systems work the same way.
  • Most RO (Reverse Osmosis) systems look alike.
  • All RO Systems have the same basic components.
  • The real difference is the quality of the filters and membranes inside the RO.

reverse osmosis diagram

How the Reverse Osmosis System Works?

Reverse Osmosis is a process in which dissolved inorganic solids (such as salts) are removed from a solution (such as water). This is accomplished by household water pressure pushing the tap water through a semi permeable membrane. The membrane (which is about as thick as cellophane) allows only the water to pass through, not the impurities or contaminates. These impurities and contaminates are flushed down the drain.

For a definition of **Reverse Osmosis.

Ultimately, the factors that affect the performance of a Reverse Osmosis System are:

  • Incoming water pressure
  • Water Temperature
  • Type and number of total dissolved solids (TDS) in the tap water
  • The quality of the filters and membranes used in the RO System (see operating specs)

Diagram of a Reverse Osmosis Membrane:

Reverse Osmosis Membrane Diagram

What does a Reverse Osmosis System Remove?

A reverse osmosis membrane will remove impurities and particles larger than .001 microns.

Reverse Osmosis System Removals

TYPICAL REJECTION CHARACTERISTICS OF R.O. MEMBRANES
Elements and the Percent R.O. Membranes will remove

Sodium   85 – 94%
Sulfate   96 – 98%
Calcium 94 – 98%
Potassium 85 – 95%
Nitrate 
60 –75%
Iron
94 – 98%
Zinc 95 – 98%
Mercury 95 – 98%
Selenium
94 – 96%
Phosphate  96 – 98%
Lead 95 – 98%
Arsenic
92 – 96%
Magnesium 94 – 98%
Nickel 96 – 98%
Fluoride
85 – 92%
Manganese
94 – 98%
Cadmium 95 – 98%
Barium 
95 – 98%
Cyanide
84 – 92%  
Chloride 85 – 92%

% may vary based on membrane type water pressure, temperature & TDS

Basic components common to all Reverse Osmosis Systems:

  1. Cold Water Line Valve:   Valve that fits onto the cold water supply line. The valve has a tube that attaches to the inlet side of the RO pre filter. This is the water source for the RO system.
  2. Pre-Filter (s):   Water from the cold water supply line enters the Reverse Osmosis Pre Filter first. There may be more than one pre-filter used in a Reverse Osmosis system. The most commonly used pre-filters are sediment filters. These are used to remove sand silt, dirt and other sediment. Additionally, carbon filters may be used to remove chlorine, which can have a negative effect on TFC (thin film composite) & TFM (thin film material) membranes. Carbon pre filters are not used if the RO system contains a CTA (cellulose tri-acetate) membrane.
  3. Reverse Osmosis Membrane:   The Reverse Osmosis Membrane is the heart of the system. The most commonly used is a spiral wound of which there are two options: the CTA (cellulose tri-acetate), which is chlorine tolerant, and the TFC/TFM (thin film composite/material), which is not chlorine tolerant.
  4. Post filter (s):   After the water leaves the RO storage tank, but before going to the RO faucet, the product water goes through the post filter (s). The post filter (s) is generally carbon (either in granular or carbon block form). Any remaining tastes and odors are removed from the product water by post filtration.
  5. Automatic Shut Off Valve (SOV):  To conserve water, the RO system has an automatic shutoff valve. When the storage tank is full (this may vary based upon the incoming water pressure) this valve stops any further water from entering the membrane, thereby stopping water production. By shutting off the flow this valve also stops water from flowing to the drain. Once water is drawn from the RO drinking water faucet, the pressure in the tank drops and the shut off valves opens, allowing water to flow to the membrane and waste-water (water containing contaminants) to flow down the drain.
  6. Check Valve:   A check valve is located in the outlet end of the RO membrane housing. The check valve prevents the backward flow or product water from the RO storage tank. A backward flow could rupture the RO membrane.
  7. Flow Restrictor:   Water flow through the RO membrane is regulated by a flow control. There are many different styles of flow controls. This device maintains the flow rate required to obtain the highest quality drinking water (based on the gallon capacity of the membrane). It also helps maintain pressure on the inlet side of the membrane. Without the flow control very little drinking water would be produced because all the incoming tap water would take the path of least resistance and simply flow down the drain line. The flow control is located in the RO drain line tubing.
  8. Storage Tank:   The standard RO storage tank holds up to 2.5 gallons of water. A bladder inside the tank keeps water pressurized in the tank when it is full.
  9. Faucet:   The RO unit uses its own faucet, which is usually installed on the kitchen sink. In areas where required by plumbing codes an air-gap faucet is generally used.
  10. Drain line:   This line runs from the outlet end of the Reverse Osmosis membrane housing to the drain. This line is used to dispose of the impurities and contaminants found in the incoming water source (tap water). The flow control is also installed in this line.

Diagram of a Reverse Osmosis System with Basic Components:
Reverse Osmosis System Diagram

Quality of RO Membranes and Filters – They’re not all alike!

While one RO System may look just like the next in terms of design and components, the quality of those components can be very different. These differences can have a significant impact on the quality of the water the system produces.

Here are some examples of questions you might ask and consequences associated with “less than desirable” quality.

  • Has the manufacturer used sound methods? What types of welds have been used in these plastic products? Will they allow contaminated water to bypass the filtration system? Will they allow the system to leak?
  • How has this filter or membrane been created? Will it allow the water to ‘channel’ and, in effect, bypass the removal component of this device?
  • What about the quality of the ‘fill’? Are it’s contents of a high enough quality to produce the expected percentage of contaminant reduction? Carbon quality, for instance, can have huge variances in reduction capability, reduction capacity, and the sloughing of ‘fines’, which can prematurely clog or foul the RO Membrane.
  • What are the manufacturer’s controls on tolerances or variations in specifications? If this component is rated as a 1-micron filter will it truly filter out everything larger than 1 micron or will it only do the job 80% of the time? And, what if it actually filters at a .5-micron rate? That will stop the system from flowing — clogging it and forcing filter replacement? If this is a sediment filter and it fails the excess sediment will clog or foul the RO Membrane.
  • And in general – Are the materials used in this product FDA or NSF (National Safety Foundation) approved? If not, you might question their quality or performance ability.

Source: e.s.p water products