Small or big treatment plant? For single house septic tank (in this case it has function of equalization tank) + filter with P-removal media can be good solution. If the water contain enough nutrients, biofilter can be used between these stages.

Thank you so much Dr.Marta

http://oaktrust.library.tamu.edu/bitstream/handle/1969.1/ETD-TAMU-1447/KADUVINAL-VARGHESE-THESIS.pdf?sequence=1

Thank you so much Dr.Aamal

In any given region before taking up the implementation of waste water (including grey water) treatment plant, one will have to consider how to re-use the treated water and how to dispose the ultimate "WASTE". One of the re-use purposes of treated waste water is for domestic use for gardening, washing, etc (non-drinking purposes), which indirectly recharge groundwater. Other re-use of treated waste water is in artificial ground water recharge. But in both cases, the determinants are the regional groundwater level and its quality. In your case, as the groundwater level is shallow, further recharge is not feasible as it is expected to cause water logging. You have also mentioned that the groundwater is saline. In that case you can plan to mix this saline groundwater with the treated waste water, thereby reducing the salinity, and use for some domestic purposes.

hello

Thank you very much for your excellent explanation  Dr.N B Narasimha Prasad 

regards

Dear Dr Ali Hadi

Different types grey water treatment systems have been developed and installed, such as sand filtration, activated sludge systems, aerobic and anaerobic bio-filters, bio-rotors and submerged aerated filters, bio-rolls . However, implementation of grey water systems with simple installation, operation, maintenance, cost and energy requirements will assist in rural community adoption of these systems for reuse of a portion of their effluents for irrigation.

A few shining examples of conservation and waste recycling exist. In some Asian and African countries controlled wastewater use is practiced with significant positive impact on those countries’ water budgets. Outside the Middle East and North Africa region, other countries have employed a proactive policy of reclaiming wastewater for productive use including the USA (California and Arizona) and Australia.Recycling treated wastewater for food production is less common than reusing treated wastewater for municipal uses, such as public parks, schools and golf courses . Yet, use of recycled water by agriculture is common in some countries of the world, particularly where water is simply unavailable or the economic incentive to reuse is substantial. It is estimated that 20 million farmers worldwide use untreated or partially treated wastewater .

Best regards

Dear Dr. Ali hadi Ghawi, below is the precise definition of (GREY WATER) :-

Grey water, which is the water that comes out of the drains of showers, baths, sinks, and washing machines, is distinctly different from black water, which is what gets flushed down the toilet. Grey water can be used for watering houseplants, landscaping, or even flushing the toilet, so it's a resource we can use twice. The problem is that our modern plumbing doesn't distinguish between the two, but instead combines them and sends onward as sewage, so unless we manually divert or capture it, grey water essentially becomes black water, rendering it useless until it goes through the municipal water treatment process.

Please refer to the link below for details:-

https://www.treehugger.com/green-home/how-reuse-grey-water-home-and-yard.html

I selected also the following for REUSE:-

The ideal method of grey water reuse requires some thought, as a level of filtration or settlement, as well as a method of discharging it either below the surface or in a location where it can slowly filter through the soil without human contact, may be required. If you'd like to implement a larger-scale grey water system at your home, be sure to thoroughly evaluate your options, consult with a grey water professional, and consider investing in a system that complies with local regulations and is appropriate for your needs and your landscape.

Hello Dr.

Please see the following link

http://oaktrust.library.tamu.edu/bitstream/handle/1969.1/ETD-TAMU-1447/KADUVINAL-VARGHESE-THESIS.pdf?sequence=1

Thank you so much Dr.Parisa and Dr.Nabeel and Dr.Mohamed

Regards

Dr. Ali Hadi being an Environmental Engineer himself, I am sure he knows the definition of grey water and also the use of waste water treatment plants & programmes. The main stress of the question is how the waste water treatment plants have to be established in "shallow groundwater level areas with salinity". Something similar to island or coastal region conditions. One thing I would like to repeat is that even the 'Grey Water' is to be treated before using for gardening or irrigation or any other purpose (other than flushing in toilets), as this water ultimately infiltrates into the ground,  and gradually pollutes the groundwater (most importantly in shallow ground water level regions).

All answers above related to grey water with slightly brackish or brackish water, so with mixing of high groundwater level associated with salty or brine water, in this case the groundwater must be dewatered or discharged to drain canals then to ponds using evaporation mechanisms such as solar radiation, etc. away from sewage net( separated and not mixed with grey water).

thanks 

I think dewatering of groundwater from areas with high groundwater level (shallow level) is very very difficult (almost impossible) suggestion. If you start dewatering, then the vacuum created will be immediately filled with upstream water. Using evaporation mechanism is still difficult proposal. I am not in a position to even visualize the proposal / suggestion. As I have indicated the area is similar to coastal region. How can any body dewater from such regions and evaporate so much of water through solar radiation !! Kindly consider the groundwater hydrology.

Thank you very much Dr. N B Narasimha Prasad  and Dr.Bayan Hussien For this explanation and adequate answer to my question