The construction of phases 7 and 8 of Tehran’s South Wastewater Treatment Plant requires at least $700 million in investment, but the procrastination of agent banks in extending funds has delayed the project, managing director of the provincial sewerage company said.
“With the completion of the project, 84 million cubic meters of wastewater will be added to the city’s annual sewage collection and processing capacity that currently stands at 675,000 cubic meters per day, which will play an important role in the development of agricultural lands in the vicinity of the plant,” Abbasali Mesrzadeh was also quoted as saying by ISNA.
Although a long time has passed since the launch of the project’s executive operations, it has registered less than 30% progress and investors, including Bank Mellat, need to speed up the process, he added.
“The longer this project is postponed, the more the suburban areas around the capital will subside.”
The earth sinks in some plains of Tehran Province by about 0.5 millimeter each day, and conditions are more critical in Shahriar and Varamin counties in southwest and south Tehran, he added.
An annual 31 centimeters of land subsidence is reported in Tehran Province because over 3 billion cubic meters of water are extracted from underground sources in the capital.
The main causes of overuse are the aquifer-system compaction, drainage of organic soils, mining, gas and oil extraction plus earthquakes.
However, the main reason of land subsidence in Iran is injudicious groundwater extraction that has been causing serious concern among conservationists, environmental experts and academia.
Mesrzadeh noted that although reversing land subsidence is impossible, slowing its progress is doable if the government and the public were to cooperate.
Tehran’s South Wastewater Treatment Plant is the biggest of its kind in the country. The two new units are needed, as the population density of southern areas is increasing.
Underground Resources
According to the official, as long as the new units are not operational, about 30% of tap water in the region should be supplied from underground resources that have lower quality compared to dam water.
Six wastewater treatment plants are up and running in Tehran Province, producing 450,000 cubic meters of processed sewage a day, of which 30% are supplied to industries and the rest goes to waste as there are no buyers for the valuable commodity.
The output, which complies with environmental standards, is piped largely to southern Tehran for farming and industrial use, and is also suitable for watering green spaces.
The treatment plant is intended to cover a population of 4.2 million people.
Currently, six units with an input capacity of 675,000 cubic meters per day are operational, covering a population of 3.35 million people.
The output of the treatment plant is used mainly for irrigating farms and the resulting sludge (as compost) is used as fertilizer.
The treated wastewater is transferred to the irrigation network of the Varamin Plain, 40 km southeast of the capital, and is used to irrigate about 90,000 hectares.
Tehran’s wastewater treatment plants are located in Shahrak-e Gharb, Shahrak-e Mahallati, Ekbatan Town, Zargandeh, Qeytariyeh and Sahebqaraniyeh districts, Malard (50 kilometers southwest of Tehran), Safadasht (on the province’s southwestern flank) and Eslamshahr (a working district in the southwest).
Economic Benefits
Wastewater treatment has long become a matter of compulsion, not convenience.
In addition to environmental and health benefits, treated wastewater has economic benefits through its reuse in different sectors. Its byproducts, such as nutrients and biogas, can be used for farming and energy generation.
Unlike some countries, recycled wastewater is not used for drinking purposes in Iran, as it is against Islamic tenets.
“Wastewater reuse has been universally recognized as a pragmatic solution to the water crisis. However, it is regrettable that municipalities, industries and farmers in Iran’s dry and arid regions, including Tehran, Hormozgan and South Khorasan, insist on extracting water from depleting ground tables instead of tapping into unconventional sources that is not only available but can easily meet their need,” Mesrzadeh said.
“A paradigm shift is a must for creating and supporting an [efficient] economic system, in which wastewater is considered a precious resource rather than a liability.”
Tehran is zoned into 22 municipal districts, of which only districts 1 and 2 meet a limited portion of their needs from reclaimed wastewater.
