Tehran wastewater network will be completed by 2023, managing director of Tehran Water and Wastewater Company said at the weekend.
“So far 65% of the sewage network is complete,” Mohammad Reza Bakhtiari said, noting that construction of wastewater treatment plants is also underway, ISNA reported.
When the new infrastructure is up and running, it will help add 250 million cubic meters of (recycled) water to Tehran's water reserves per annum, and decrease the water stress in the capital city, he said.
“Currently, the volume of Tehran water reserves stands at 1.06 billion cubic meters, 70% of which comes from surface water and 30% groundwater,” Bakhtiari added.
Precipitation in Tehran was 256 millimeters in the last water year (Sept 2017-Sept 2018) -- a 21% decline compared to the year before. Per capita water consumption in Iran is over and above the world average.
Given years of dwindling rainfall and rising consumption, authorities and independent experts have called for greater attention to collecting, treating and recycling water. According to reports, the agriculture sector alone consumes more than 90% of the scarce water resources due to outdated farming practices and equipment.
Expansion of wastewater network has been a priority in the sprawling capital in the recent decades, but lack of funds plus rapid expansion of urban areas has slowed down the process.
>Wastewater Hazard
If wastewater is not properly treated it can have dire consequences on the environment and human health. Other than contaminating drinking water, it can cause harm to marine and wildlife habitats, oxygen depletion and restrictions on recreational water use as well as on fish harvesting.
Primary treatment of wastewater removes about 60 percent of suspended solids. This treatment also involves aerating (stirring up) the wastewater, to put oxygen back in.
Secondary (biological) treatment removes the dissolved organic matter that escapes primary treatment. This is achieved by microbes consuming the organic matter as food, and converting it to carbon dioxide, water, and energy for their own growth and reproduction.
Tertiary treatment can remove more than 99% of all the impurities from sewage, producing “an effluent of almost drinking-water quality.”
> Water Supply Project
TWWC is the main contractor of a major water supply project in Tehran, dubbed as Tehran Water Ring that seeks to provide residents with clean water and improve the quality of potable water in all the urban districts in the capital.
Work on the project started in 2015 and will include 180km of pipeline connecting seven water treatment facilities and ensure stable water quality in the ever-expanding capital. After the project is complete, if any water treatment plants stop working other plants will replace it.
Bakhtiari said, “the project has made 65% progress and is planned to be launched by 2021”.
According to officials, Tehran Water Ring will save about 750 mcm of water per annum, 400 mcm of which will be injected into the underground water tables, 300 mcm will be allocated to farming and the rest for watering green spaces.
