Brine Disposal Tamar OttolenghiPaula Barmaimon

Percentage of Israel’s drinking water:• 2014: 35% • 2015: 40% • 2050: 70%

Once unthinkable, Israel can now produce a surplus of fresh water with desalination, becoming one of the leading countries in the field.

The overall forecast of desalinated water needs are expected to be over 140 million m³/day by 2025.

DISADVANTAGES

• High cost

• Intensive energy consumption

• Direct environmental impact• Disposal of brine

ADVANTAGES

• Additional fresh water

• Does not depend on drought periods

• Produced close to consumption

• Environmental benefits

• Economical benefits

Where does the salt go..??

In wastewater treatment, brine waste is the super concentrated by-product that results from treating seawater.

WHAT IS BRINE?

SEAWATER BRINE

SALINITY 39.4 g/l 69 g/l

TEMPERATURE 24.5° 32°

The higher the salinity , the larger the density

The higher the temperature the lower the density

THE PROBLEM

WE DON’T WANT TO CREATE A SALTY DESERT UNDER THE SEA

Find the best alternative that will balance

Economic and Environmental issues

OBJECTIVE OF THE PROJECT

Current Situation at Ashkelon

• No pipe or diffusers are used for current brine discharge of 21,000 m3/hour.

• Brine disposed directly to the sea

• Designed for ≈ 50 MCM/year

• Currently supplying ≈ 100 MCM/year

WE DESIGNED FOR 42000 m3/hr of BRINE

Our Suggestion to Improve

• Introduce a pipe with a

diffuser

• Improving the dilutionwith lower environmental impact at lowest cost

Real Data Desalination plant at Ashkelon :

• Brine salinity: 69 g/L

• Seawater density: 39.4 g/L

• Average slope: 0.02

Assumed Data:

Hazen-Williams coefficient 135

Pump Efficiency 85%

Pipeline lifespan 40 years

Pipe operation 24 hours/day

Hours pumping/ year 8760 hours

Energy cost 0.02 $/kWh

Annual Interest 4%

Alternative Pipe length

1 1 Km

2 1.5 Km

3 2 Km

Pipeline Cost Calculation

• Investment Cost• Energy Cost• Operation and Maintenance Cost

Pipeline Cost Calculation• Investment Cost

• Only market diameters were used

• Total Pipeline Investment Cost

• Annual repayment for pipeline investment ($/year)[ -PMT(I,n,PV) ]

1 Km = 1 Million $

Pipeline Cost Calculation• Energy Cost

• Dynamic head Loss (m) [Hazen Williams]

• Total head Loss (m)[Dynamic HL+ Static HL+ Pressure requirements]

Pressure requirement= 1 atm= 10 m

• Power required (KW)Efficiency of 85%

• Energy required per year (KWh/year)8760 hours of pumping a year (24 hours)Average cost of of 0.02$/kWh as assumed

• Cost of energy required per year ($/year)

Pipeline Cost Calculation• O&M

0.75* Total Pipeline investment cost ($/year)

Pipeline Cost Calculation

MINIMUM COST

DiffusersThe ending point of an outfall pipe is generally made of a diffuser

This device separates the effluent fluid into several jets, so as to favor the process of dilution

Cost=1.1* Pipeline Investment Cost

Equal outlet velocity in nozzles2 m/s <velocity< 5.5 m/s

Distance between nozzles = Y/5

Dilution Calculations

Near field dilution: It occurs near the outlet into the sea.

Far field dilution: It occurs further away from the effluent outlet.

Comparison 1 Comparison 2

Same number of nozzles in the diffuser

Same dilution So

Different dilutions So Different number of nozzles in the diffuser

3 alternatives 3 alternatives

COMPARISONS

COMPARISON 1- Same # nozzles

Alternative Lengthpipe[Km]

# nozzles

Outletvelocity

Ratio Diffuser/

main pipeline

Dilution So

Cost[c/m3/ye

ar]

1 1200

5.16 m/s 0.81 43.140.44

2 1.5 200 5.16 m/s 0.81 98.84 0.63

3 2 200 5.16 m/s 0.81 171 0.82

Alternative Lengthpipe[Km]

# nozzles

Outletvelocity

RatioDiffuser/

main pipeline

Dilution So

Cost[c/m3/ye

ar]

1 1 450 2.29 m/s 1.85 94.6 0.49

2 1.5 194 5.32 m/s 0.79 95.8 0.63

3 2 110 9.38 m/s 0.45 95.9 0.78

COMPARISON 2- Fixed Dilution

13 $2

CONCLUSION

Alternative 2 gives us the most suitable result to get potable water,

diluting back to the environment our waste at the most economical price.

1.5 km long

200 nozzles

So= 98.8

Cost=0.63 cents/m3/year

THANK YOU