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.
Renewable Fresh Water Availability Per Person in the Southern Mediterranean Countries, 1990 to 2050 Annual renewable fresh water Annual renewable fresh water per capita per meters) (cubic capita (cubic meters)4000 1990 20253500 2050300025002000 1700-Periodic Water Stress1500 1000 - Chronic Water Stress1000 500-Absolute Water Stress 500 0 Algeria Cyprus Egypt Israel Jordan Lebanon Libya Morocco Syria Tunisia Turkey
The Mediterranean Region: Water Demand in 1990 and ForeseenDemand for the years 2010 and 2025 [in km3/year] Waa te rD ee man dd [in km 33 /ye a r] W te r D m an [in km /ye a r] 4411 4.5 4 .5 33 566 .9 5 .9 44 5 0 50 44 0 0 00 22 788 7 33 5 0 50 33 0 0 00 22 5 0 50 +49% related +28% 22 0 0 00 to 1990 11 5 0 50 11 0 0 00 55 0 0 00 11 999 0 9 0 2200 100 1 22 022 5 0 5
A more rational management of water resources can permitconsiderable savings, of the order of at least 30%, but it is noteasy to achieve, nor is it sufficient to solve the problems ofwater scarcityTherefore the use of non-conventional water resources ismandatory In particular, reusing non-conventional water resources is awin-win solution because it is possible to solve two problemssimultaneously: safe wastewater disposal and more water toirrigation
The ChallengesCan agriculture make use of non-conventional waterresources in a way which is technically sound,economically viable and environmentally nondegrading?What are the applicable techniques and managementpractices required for the sustainable use of thenon-conventional water resources in agriculture?
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.
Intensive vs. Extensive Treatments(e.g. lagooning, constructed wetlands and Soil Infilteration)
Extensive treatmentsExtensive treatments Looking for a reasonable trade-off between cost and Risk risk ? There’s no point in pushing treatment beyond reasonable limits even in wealthy communities: you pay more to have less and damage Cost the environment (it is the Italian case) Intensive treatmentsIntensive treatments
Constructed wetlandsStabilization ponds and constructed wetlands are a low-costalternative for the treatment of domestic wastewater. Theyprovide water for irrigation in urban agriculture and forwatering green spaces.Detention and retention ponds, lined up with reeds andother wetland plants, perform well in purifying run-offrainwater from quite streets. More polluted water requiresconstructed wetlands designed for horizontal or verticalflow, filtering, adsorption and uptake of nutrients. Gooddesign and maintenance are vital.
poplar plantation for depuration of domestic wastewater
inlet outlet tap water Visual comparison of water depurated in a constructed wetlandOutlet water is not intended for domestic uses, but can be used –and further depurated- in irrigation
Standards for the UseIt is not true that standards are more advanced when morestringentExceedingly stringent standards –like those adopted in mostindustrialized countries- imply a waste of resources (organicmatter, nutrients) precious for the agriculture and theenvironment, a waste of energy, and release CO2 to theatmosphereThe only solution is to find out a way for taking advantage ofsuch resources instead of spending money to eliminate themThe challenge is: how to determine the correct level oftreatment? which is the permissible load of pollutants inirrigation water under any specific condition?
Which Solution can We Suggest ?Abandon unreasonably restrictive, universal standardsLook for a trade-off between costs and benefitsBut never abandon the bottom-line level of safety
USING TREATED WASTEWATER AS SUPPLEMENTAL IRRIGATION FORSTABILIZING 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