Isfahan Tapping Into Greywater
EghtesadOnline: To reduce demand for fresh water in Isfahan Province, an agreement was signed by the provincial Water Company and the provincial Engineering Council to build infrastructure for greywater treatment systems in urban and suburban dwellings, head of the company said Tuesday.
"Isfahan University, Isfahan City Center, a large commercial and entertainment complex, have been equipped with greywater reuse system and plans are underway to develop the system across the city," Hashem Amini was quoted as saying by the Energy Ministry's news portal.
Aside from the benefit of saving the rapidly declining water resources (and money for consumers), reusing greywater keeps it out of the sewerage reducing the likelihood of it polluting local water bodies, Financial Tribune quoted him as saying.
"These systems can treat large volumes of water and play a role in water conservation in urban housing development and manufacturing units, schools, universities, and commercial buildings."
Greywater is defined as any domestic wastewater produced, excluding sewage. The main difference between greywater and sewage (blackwater) is the organic loading. Sewage has a much larger organic loading compared to greywater. Greywater is captured from household sources like sinks, hand-basins, showers, etc.
With proper treatment, greywater can be put to good use. Uses range from toilet flushing to watering plants. Treated greywater can be used to irrigate both food and non-food production. Nutrients in greywater (phosphorus and nitrogen) are an excellent food source for plants.
Amini went on to say that greywater accounts for 60% of urban sewage, a large proportion of which can be recycled.
Economic experts and environmentalists argue strongly against using high quality and costly potable water for purposes that do not require such high quality water, like irrigation.
“By reusing greywater, demand for costly potable water declines.”
It costs the government 25,000 rials (25 cents) to produce one cubic meter of water, whereas consumers pay 40% of the cost (10,000 rilas or 10 cents), which partly explains why people take the precious resource for granted.
According to the official, daily average water use of Isfahan residents is 150 liters per person, but because the region is fighting (a losing battle) against drought, consumption level should be reduced to 100 liters, he stressed.
Referring to the experience of other countries, he said Japan treats at least 345,000 cubic meters of greywater a year, of which 230,000 cubic meters is used for urban green spaces.
The reuse of greywater is being increasingly practiced in a many countries, namely the United States, Australia, Cyprus, the UK, Germany and Jordan.
According to Morteza Ebrahimi, CEO of Isfahan Oil Refining Company, greywater produced in Shahin-Shahr, a county in the province, will be treated and piped to the refinery soon.
"The refinery's share of water from Zayandehroud Dam was 10 million cubic meters per annum in 1978," he said, adding that that has now declined to 400,000 cubic meters.
The company refines 375,000 barrels of crude oil per day and this level cannot be sustained unless refining units get sufficient water.