Greywater, or wastewater from sources other than toilets and kitchens, can be recycled to reduce water consumption by 35-40%. A case study examines recycling greywater from 225 apartments using a REVOSIS system to treat 49,500 gallons per day. This saves over $324,000 per year and pays for itself within 1.5 years. The treated greywater is used for toilet flushing and irrigation to significantly cut fresh water usage.
2. What is Greywater?
๏ต Greywater or sullage is defined as wastewater generated from
wash hand basins, showers and baths, (but not from a kitchen sink
or toilet) which can be recycled on-site for uses such as Water
Closet (WC) flushing, landscape irrigation and constructed
wetlands.
What is Blackwater?
P.I.: For the process of simplification, โGreywaterโ is abbreviated as โGWโ as needed
๏ต Greywater is distinguished from โBlackwaterโ which is wastewater
from WC flushing, kitchen sinks. Blackwater should not be reused in
the home because of high risk of contamination by bacteria,
viruses and pathogens.
3. What is GW treatment?
๏ต GW treatment is removal of unwanted suspended
material from the greywater collected and disinfecting
the same to make it useful for toilet flushing or irrigation
or discharging to sewer lines according to the local laws
applicable.
4. Why reuse GW?
๏ต GW Recycling can save upto 35-40% of water consumption
within a residential building by reusing shower & basin water for
the use of toilet flushing, irrigation, car washing, cleaning, etc.
๏ต Conventional plumbing systems dispose of greywater via septic
tanks or sewers. The many drawbacks of this practice include
overloading treatment systems, contaminating natural waters
with poorly treated effluent and high ecological/economic
cost
๏ต Instead, you can reuse this water. The most common reuse of
greywater is for irrigation.
๏ต Even a greywater disposal system has less negative impact
than septic/sewer disposal
5. 8 Advantages of GW Recycling & Reuse
1) Save water (30-35% reduction in consumption) and money
2) Reduce the demand on your reservoir/toilet distribution pumps
3) Increase the lifespan of your septic system
4) Less strain on public sewage treatment system
5) Reduction in energy use by the municipality
6) Increase points to reach LEED certification goals
7) Groundwater recharge
8) Reclamation of otherwise wasted nutrients
6. Reuse applications of treated GW
๏ต Watering Gardens
๏ต Fire hydrants
๏ต Field Irrigation
๏ต Toilet flushing
๏ต Cooling tower make-up
7. Case Study
๏ต REVOSIS GW System proposed for a building with an occupancy
of 225 Apartments, to treat approximately 49,500 Gallons / day
[180 m3/d] of greywater . REVOSIS GW System captures
greywater discharged from the buildingโs showers, bathtubs,
hand basins (All wastewater apart from toilet & kitchen).
Assumptions (Average):
๏ต Residents per apartment: 3
10. Feed Volume to GW system
Parameters Value Unit
Total volume of wastewater
generated from 1 apartment
240 Gal / day
Volume of Toilet Flushing 28 Gal / day
Volume of Greywater (actuals) 240 โ 28 = 212 Gal / day
Volume of Greywater (rounded
off)
220 Gal / day
No. of apartments in the building 225 Nos.
Total volume of Greywater for 1
building
220 x 225 = 49,500 Gal / day
49,500 x 30 = 1,485,000 Gal / month
Total capacity of GW Recycling System = 49,500 Gal / day = 180 m3 / day
12. Greywater Analysis (Typical)
Parameter Units Minimum Maximum Typical
pH - 7.2 9 7.5
Alkalinity (as CaCO3) mg/l 75 200 100
Total Suspended Solids mg/l 20 45 30
Conductivity uS/cm 1,000 1,600 1300
TDS (measured) mg/l 500 1,000 800
BOD5 mg/l 20 45 30
COD mg/l 60 400 200
Oil & Grease mg/l 10 20 15
Calcium mg/l 50 80 65
Magnesium mg/l 10 35 20
Sodium mg/l 150 760 390
Chloride mg/l 200 1,050 520
Fluoride mg/l 0.8 5 2
Potassium mg/l 30 60 50
Sulfate mg/l 10 70 50
Silica mg/l 60 75 70
Total Silica mg/l 75 100 85
Temperature deg C 20 30 25
System recovery, process scheme & design may change as per the detailed and actual water analysis parameters from the site
13. Savings Projection
Description Value Units
Freshwater required for GW usage
(before recycling)
1,485,000 Gal / month
Cost of water* 77,125 AED / month
Freshwater required for GW usage
(after recycling)
965,340 Gal / month
Cost of water* 50,095 AED / month
Savings 27,030 AED / month
324,360 AED / year
* Cost of water is based on the current water tariff
by DEWA
(http://www.dewa.gov.ae/tariff/newtariff.aspx)
14. Payback period
Description Values Units
RO System XXXXXX AED
Ancillaries (Tanks, Piping,
Commissioning, Civil)
XXXXXX AED
Total Investment 496,800 AED
Savings (from previous slide) 324,360 AED
Payback period 1.5 Years
15. Case Study Report
๏ต REVOSIS GW System recycles and saves 17,325 Gallons of drinking
water a day, over 6 million gallons per year
๏ต The recycled and treated water from the REVOSIS GW System is fed
in to the main water supply line to the toilet flushing lines, to
supplement the municipality feed line. Hence, reducing fresh water
consumption considerably.
๏ต GW is recycled and treated to the highest recycled water standards
approved by local Health authorities
๏ต Recycled water is distributed around the building for non-drinking
purposes apart from toilet flushing. For eg, district cooling, irrigation,
etc.
๏ต REVOSIS turn-key approach includes design, project management,
installation, commissioning, operations & service contracts.
16. Our Technology
๏ต The core technology at REVOSIS is a compact Reverse Osmosis
based Recycling Plant with specially coated Poly amide
membranes which are low fouling. After effective pre-treatment by
oil skimmers, sand filters and cartridge filters the influent is introduced
to the heart of the system which are the RO membranes. The
specialised RO membranes which are capable of handling high
influent characteristics segregates the purified water from the
concentrated reject. The purified effluent then passes through the
Ultraviolet undergoing disinfection and Chlorine to achieve a
chlorine residual. This multi-barrier treatment approach is what
ensures the treatment plant to confidently handle variable
wastewater qualities that are typical of decentralized greywater
schemes.
17. REVOSIS GW Recycling System
โ Key Benefits
๏ต Fast and consistent reduction of suspended solids
๏ต Occupies less space
๏ต Viable warranty conditions
๏ต Low maintenance & simple operation
๏ต Low energy consumption
๏ต Minimal use of chemicals
๏ต Delivered as a skid mounted package plant
๏ต Systems can be increased in capacity (in future) as a duplex plant
๏ต Low cost compared to conventional grey water systems
18. Your Queriesโฆ
Please feel free to contact us for any clarifications on the below contacts at all times.
REVOSIS Water Technology Solutions LLC,
P.O. Box 125082, Dubai, UAE.
T: +971 4 2520 617 | F: +971 4 2576 833 | M: +971 55 2308 194
E: info@revosis.com | W: www.revosis.com
Thank you!
