With the completion of the second phase of Zanjan Wastewater Treatment Plant in October, it will cover 410,000 people in the northwestern city, the head of provincial water company said.
“The construction of the second phase, which employs the so-called SBR [sequential batch reactor] technology, started in 2019 and has registered 80% progress,” IRNA also quoted Alireza Jozqasemi as saying.
The plant now has a capacity of treating 40,000 cubic meters of wastewater per day. When the second phase comes on stream, total recycling capacity will reach 75,000 cubic meters a day, he added.
SBR is a type of activated sludge process for the treatment of wastewater. The treated effluent can be suitable for discharge to surface waters or possibly for use on land.
The process treats a wide range of influent volumes whereas the conventional system is based upon a fixed flow rate.
“The first phase that became operational in 2018 cost $3 million and $10 million have so far been spent on the second phase by the private sector,” he said.
Close to 400 kilometers of pipelines have been laid across Zanjan to link households to the plant.
The project aims to prevent the contamination of surface and ground water, as the recycled water is used by industries and farmers.
Located 300 km northwest of Tehran, Zanjan has very low precipitation. Deep water wells are creating serious problems for the region and the risk is that it may soon be unable to supply sufficient water to farmers.
According to local officials, some wells are 400 meters deep, while the average depth of water is between 50 to 60 meters in other countries.
There are more than 220 sewage treatment plants in Iran’s arid and semi-arid regions. About 20 million hectares of farmlands use treated wastewater. Total sewage treatment capacity has reached 11 million cubic meters per day.
Dire Consequences
If wastewater is not treated properly, it can have dire consequences on the environment and human health.
One cubic meter of polluted water contaminates 40 cubic meters of clean water, thus collecting wastewater is key to conserving the declining water resources and protecting the environment as is the case in most parts of the world.
Over 7.5 billion cubic meters of usable water are produced annually in Iran, of which 4.3 bcm are wasted. Less than 25% of wastewater are recycled.
Over 63,000 km of wastewater pipelines have been laid and 295 cities are connected to the national network.
Official reports say 48% of the urban population now are connected to the wastewater network and the figure for rural areas is barely 1%.
Wastewater use has increased globally mainly due to growing populations and rapid urbanization and industrialization. The scarcity of pure water in areas, including refineries, manufacturing plants and power plants, is driving the expansion of wastewater treatment.
According to the UN World Water Development Report, on average, high-income countries treat about 70% of the municipal and industrial wastewater they generate. That ratio drops to 38% in upper middle-income countries and to 28% in lower middle-income countries. In low-income countries, only 8% undergo treatment of any kind.
Wastewater treatment plants are expensive to set up and maintain. This is one of the major obstacles hampering the expansion of wastewater treatment systems and is a major challenge in poor countries and for small businesses that are normally saddled with funding constraints.
