SUSTAINABLE USE OF

TREATED URBAN

WASTEWATER IN

AGRICULTURE

(BARI INSTITUTE EXPERIENCE)

Prof. Atef Hamdy

CIHEAM – Mediterranean Agronomic Institute of Bari

Water Scarcity in Arid and Semi Arid Countries

of the Mediterranean and Arab World : The

Dilemma

• Nowadays, many countries in the region are approaching

the limit of water resources development and others reeling

under sever supply shortage; the problem of water scarcity

is turning into crisis. The dilemma those countries already

are facing is how to balance the increasing water demand

with the limited fragile water supply?; how to avoid water

crisis?; and what are the alternative options to ease the

situation?. there are potential ways to ease the burden

of water scarcity by trapping non conventional water

resources like sewage and industrial effluents, which

have traditionally been neglected.

Why Non-Conventional Waters?

0

500

1000

1500

2000

2500

3000

3500

4000

Algeria Cyprus Egypt Israel Jordan Lebanon Libya Morocco Syria Tunisia Turkey

1990

2025

2050

Annual renewable fresh water per capita (cubic meters) Annual renewable fresh water

per capita

(cubic meters)

1700-Periodic

Water Stress

1000 - Chronic

Water Stress

500-Absolute

Water Stress

Renewable Fresh Water Availability Per Person in the

Southern Mediterranean Countries, 1990 to 2050

The Mediterranean Region:

Water Demand in 1990 and Foreseen

Demand for the years 2010 and 2025 [in km3/year]

278

356 .9

4 14 .5

0

50

100

150

200

250

300

350

400

450

1990 2010 2025

W ate r D em and [in km3/ye ar]

278

356 .9

4 14 .5

0

50

100

150

200

250

300

350

400

450

1990 2010 2025

W ate r D em and [in km3/ye ar]

+28% +49%related

to 1990

A more rational management of water resources can permit

considerable savings, of the order of at least 30%, but it is not

easy to achieve, nor is it sufficient to solve the problems of

water scarcity

Therefore the use of non-conventional water resources is

mandatory

In particular, reusing non-conventional water resources is a

win-win solution because it is possible to solve two problems

simultaneously: safe wastewater disposal and more water to

irrigation

Can agriculture make use of non-conventional water

resources in a way which is technically sound,

economically viable and environmentally non

degrading?

What are the applicable techniques and management

practices required for the sustainable use of the

non-conventional water resources in agriculture?

The Challenges

Tha main non-conventional water resources

Non Conventional water resources and its use in

the region : Main Obstacles

• The efficient reuse of this vital water source is still

facing many technical, economical, environmental

and social constrains which are still seeking

sustainable solutions.

• Most countries of the region don’t have national

policies and strategies related to waste water

management in general and waste water for

agriculture in particular.

• Health fears and hazard due to the absence of well

defined waste water treatment technology to be

adapted.

URBAN

WASTEWATERS

The problems and The Risks

Bari Institute Program : Focusing elements

Intensive vs. Extensive Treatments

Intensive vs. Extensive Treatments

(e.g. lagooning, constructed wetlands and Soil

Infilteration)

Cost

Risk

Extensive treatments Extensive treatments

Intensive treatmentsIntensive treatments

There’s no point in pushing

treatment beyond reasonable limits

even in wealthy communities: you

pay more to have less and damage

the environment (it is the Italian

case)

Looking for a reasonable

trade-off between cost and

risk

?

Constructed wetlands

Stabilization ponds and constructed wetlands are a low-cost

alternative for the treatment of domestic wastewater. They

provide water for irrigation in urban agriculture and for

watering green spaces.

Detention and retention ponds, lined up with reeds and

other wetland plants, perform well in purifying run-off

rainwater from quite streets. More polluted water requires

constructed wetlands designed for horizontal or vertical

flow, filtering, adsorption and uptake of nutrients. Good

design and maintenance are vital.

poplar plantation for depuration of domestic wastewater

Reed beds

monitoring water in a constructed wetland

inlet outlet tap water

Outlet water is not intended for domestic uses, but can be used –and

further depurated- in irrigation

Visual comparison of water depurated in a

constructed wetland

Standards for the Use

It is not true that standards are more advanced when more

stringent

It is not true that standards are more advanced when more

stringent

Exceedingly stringent standards –like those adopted in most

industrialized countries- imply a waste of resources (organic

matter, nutrients) precious for the agriculture and the

environment, a waste of energy, and release CO2 to the

atmosphere

Exceedingly stringent standards –like those adopted in most

industrialized countries- imply a waste of resources (organic

matter, nutrients) precious for the agriculture and the

environment, a waste of energy, and release CO2 to the

atmosphere

The only solution is to find out a way for taking advantage of

such resources instead of spending money to eliminate them

The only solution is to find out a way for taking advantage of

such resources instead of spending money to eliminate them

The challenge is: how to determine the correct level of

treatment? which is the permissible load of pollutants in

irrigation water under any specific condition?

The challenge is: how to determine the correct level of

treatment? which is the permissible load of pollutants in

irrigation water under any specific condition?

Which Solution can We Suggest ?

Abandon unreasonably restrictive, universal standardsAbandon unreasonably restrictive, universal standards

Look for a trade-off between costs and benefits Look for a trade-off between costs and benefits

But never abandon the bottom-line level of safetyBut never abandon the bottom-line level of safety

USING TREATED WASTEWATER AS

SUPPLEMENTAL IRRIGATION FOR

STABILIZING RAIN FED WHEAT YIELD

Impact of Treated Wastewater as

Supplemental Irrigation

• Using 2410 m3 per hectare for wheat

production can save 30 – 35 % of the

nitrogen fertilizer, 10 % of P fertilizer, and 70

– 82 % of K fertilizer, of the whole plant

exported nutrients and increase the farmer

income.

Impact of Treated Wastewater as

Supplemental Irrigation

• Equal amount of supplemental irrigation (125

mm) at flowering and grain filling stages

produced satisfactory yield (41.4 q/ha)

• Maximum yield (48.1 q/ ha) were obtained

when 70 % of supplementary irrigation ( 175

mm) is applied at the flowering stage.

• Less than 50 mm at flowering stage recorded

a drastic reduction in the grain yields.

• Flowering stage is the most critical growth

stage

Wheat Production Under supplementary

irrigation

• Wheat production in arid regions of Morocco

depends on rainfall.

• Drought periods took place during the spring,

which corresponds to flowering or gain filling

stage according to the planting date.

• Supplementary irrigation is widely practiced

in several mediterranean countries to

stabilize and improve the crop yield

Sustainable Safe Use : Major Needs

THANK YOU FOR YOUR

ATTENTION