S3 - Presentation 7 - Nurul Akhand

Assessment of Pathogens and
Heavy Metals Contamination in
Vegetables Grown with Treated
Wastewater in the UAE
Conference on
The Use of Treated Wastewater in the Agricultural
Production in the Arab World: Current Status
and Future Prospective
Nurul Akhand
Irrigation Management Scientist
International Center for Biosaline Agriculture
15 January 2014
Dubai, UAE

Presentation Outline
‣ Introduction
• Importance of TSE in the UAE
‣ Experiments on vegetables
‣ Results and discussion
• Pathogens and heavy metals in vegetables
• Heavy metals in soil profile/root-zone
‣ Conclusions
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Team-Members
‣ ICBA Research Team
• Dr. Nurul Akhand
• Dr. Nanduri Rao
• Dr. Shabbir Shahid
• Dr. Mohamed Shahid
• Basel AlAraj
‣ In collaboration with
• MOEW
• DM
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Treated Sewage Effluent
Desalination
People, commerce
and industry
Reused for irrigation –
agriculture, forestry
and landscape
Treated

Water Generated in UAE
Annual volume – 2410 MCM
Water
Volume (MCM)
Desalination (sea water) 1700
(70%)
Treated sewage effluent 600
(24%)
Groundwater recharge 10
(

Wastewater Status in UAE
Indicator
Quantity
Treated Effluent
Reused effluent
Treated effluent lost
Projected wastewater in 2030
Treatment design
600 MCM/yr
352 MCM/yr
248 MCM/yr
1400 MCM/yr
Very good
Source: ICBA, 2010 (2009 data)
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Treatment Plants in UAE
‣ Existing WWTPs have relatively good
technical efficiency (mostly equipped with
advanced tertiary treatment process) with
regards to effluent quality complying with
standards for use in restricted irrigation
100%
75%
Septic
tanks and
local
systems
50%
Sewered
25%
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0%
Abu Dhabi
Al Ain
Fujairah
Dubai
Shajah
RAK
Ajman
UAQ

Treated Wastewater at ICBA
‣ Tertiary-level treated water received from Dubai
Municipality
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Treated Water Quality
Parameter Unit Result (≈)
E.Coli CFU/100 ml 2
Fecal streptococci CFU/100 ml 3
Total coliform CFU/100 ml 460
BOD mg/l 9
Ammonia Nitrogen mg/l 9.7
Nitrate-Nitrogen mg/l 16.6
Phosphate mg/l 2.42
Potassium mg/l 20.7
Chromium mg/l 0.2
Copper mg/l 0.2
Zinc mg/l 0.27
Residual Chlorine mg/l 2
Salinity dS/m 1.9
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Quality of Treated Sewage Effluent
‣ Variety of chemical, biological and physical
constituents
• Depends on sources of water, nature of
the industry or activity
• Type and degree of treatment

Quality of Treated Sewage Effluent
Recycled Water Regulations 2010 (RSB, Abu Dhabi)

Quality of Treated Sewage Effluent
Recycled Water Standards 2010 (RSB, Abu Dhabi)

Research Needed
‣ The current treated wastewater available in UAE
falls within the “restricted use”
‣ Thus there is a need for:
• Evaluating possible risks for both pathogens
and heavy metals transport to the vegetables
• Assessing possibility of accumulation of
heavy metals in the soil/root-zone
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Research Experiments
‣ Three vegetables i.e. carrot, lettuce and tomato were
evaluated in 2013
• the results will be presented today
‣ Additional three vegetables (i.e. radish, spinach and
egg plants) including the previous ones are being
conducted at ICBA experimental farm
‣ Also experiments are on-going on
• Fruit (date palm)
• Landscaping (Salvadora persica-miswak)
• Forage (Cenchrus ciliaris buffel grass)
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Research Experiments (Cont.)
‣ Irrigation is not only a disposal option but it also
provides increased agricultural yields
‣ For wastewater, irrigation method selection
depends on
• Quality of wastewater (in accordance with
reuse regulations, which may require higher
operating and management expertise)
• Many undesirable effects can be minimized via
right type of irrigation method
• Types of crops or forages to be grown
• Potential risk to the health of the farmers
• Wetting of foliage, fruits and aerial parts

Irrigation Methods
‣ Drip Irrigation
• Most promising and safe
• Minimum contact with farmers and crops
• No foliar injury
• Filtration is essential to avoid clogging (slimes,
bacteria, etc. cause clogging)
‣ Subsurface pipe, SDI
• Minimum health risk
• Psychologically and politically a very acceptable
method
• Eliminates odors, ponding and runoff problems

Results
‣ Completed first trial with vegetables (carrot,
lettuce and tomato)
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Results (Cont.)
‣ Test results on lettuce
• Pathogens
Parameter TSE Low-saline water
E.Coli
(conventional)
Not detected
Not detected
E.Coli (157) Not detected Not detected
Coliform (cfu/g)

Results (Cont.)
‣ Test results on lettuce (Cont.)
• Heavy metals
Parameter TSE Low- saline water
Surface drip
Sub-Surface
drip
Surface drip
Cu (mg/kg) 3.44 2.9 2.27
Fe (mg/kg) 16.25 23.33 96
Zn (mg/kg) 3.71 1.31 5.43
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Results (Cont.)
‣ Test results on carrot
• Pathogens
Parameter TSE Low-saline water
E.Coli
(conventional)
Not detected
Not detected
E.Coli (157) Not detected Not detected
Coliform (cfu/g)

Results (Cont.)
‣ Test results on carrot (Cont.)
• Heavy metals
Parameter TSE Low- saline water
Surface drip
Sub-Surface
drip
Surface drip
Cu (mg/kg) - 1.26 1.46
Fe (mg/kg) 5.16 5.28 3.31
Zn (mg/kg) 2.24 2.69 4.17
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Results (Cont.)
‣ Test results on tomato
• Pathogens
Parameter TSE Low-saline water
E.Coli
(conventional)
Not detected
Not detected
E.Coli (157) Not detected Not detected
Coliform (cfu/g) >10 >10
Salmonella Not detected Not detected
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Results (Cont.)
‣ Test results on tomato (Cont.)
• Heavy metals
Parameter TSE Low- saline water
Surface drip
Sub-Surface
drip
Surface drip
Cu (mg/kg)

Results (Cont.)
Heavy metals in soil profile
(0-30 cm)
Parameter TSE (mg/l) Soil (mg/kg)
Original SD SSD
Chromium 0.2 16.7 14.9 15.2
Copper 0.2 5.3 5.4 5.2
Lead

On-Going Experiments
2014
‣ Carrot, lettuce and tomato
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On-Going Experiments (Cont.)
2014
‣ Radish, spinach and egg plant
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Conclusions
‣ Results obtained from the first set of experiments
with three vegetable (i.e. carrot, lettuce and tomato)
were found to be free from tested pathogens
‣ The concentration of heave metals (i.e. Cu, Zn, and
Fe) in the TSE treatments was more or less similar to
the control treatments
‣ The concentration of heavy metals in soil profile (0-
30 cm depth) was not increased during the
experimental period
‣ Further testing is on-going with more vegetables
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Thank You