Tertiary-level treated wastewater can help Qatar's sustainable agriculture goals, says QF scientist

A Qatar-based scientist has advocated the use of wastewater treated to the tertiary level for agricultural irrigation to help realise some of the goals of the country in sustainability. “If treated to the tertiary level – which is the final stage of the multi-stage wastewater cleaning process which removes organic and inorganic compounds, bacteria, viruses, and parasites – treated wastewater can safely be used for agricultural irrigation,” said Dr Sa’d Abdel-Halim Shannak, a scientist at Qatar Environment and Energy Research Institute, part of Qatar Foundation’s Hamad Bin Khalifa University (HBKU).“Treated wastewater is currently being used in Qatar but is limited to non-agricultural use such as irrigation of green belts, artificial recharge of groundwater aquifers and growing animal fodder. However, there remains a large quantity of treated wastewater - up to 40% - which at certain times of the year is either discharged to lagoons or injected to the deep aquifers,” explained Dr Shannak in an article published by Qatar Foundation recently.According to the scientist, Qatar plans to achieve 70% self-sufficiency in the production of certain vegetables by 2023 but the water resource remains a major concern to sustainably continue its journey.“Maximising use of treated wastewater and pricing reform,” are two key action points advocated by Dr Shannak. Qatar’s lone source of natural water – groundwater - is overused and its extraction rate is four times its replenishment rate, and its biggest consumer is the agricultural sector at 91% . According to the scientist, the only source of water the country has in surplus is recycled water or treated wastewater, which "is a source that will continue to be available for as long as there is human life,” he said.Dr Shannak, however, does not support the use of desalinated seawater for agricultural purposes. He remarked: “Seawater is highly saline, and the cost of desalinating it, both in terms of energy and financial, is very high. Because of the low salinity of wastewater treatment, it’s considerably less energy-intensive to treat, and therefore costs less too.”The approximate energy required to produce one cubic metre of water through desalination is reported to be 1.5-7 kWh/m3, whereas for wastewater treatment it is only 0.62-0.87 kWh/m3. In terms of financial costs, the cost of desalination reported ranges between $0.52-1.30/m3, whereas the estimated cost of wastewater treatment is reported to be $0.29/m3.“It just makes sense, both financially as well as energy-wise, and is a very viable way to extend the life of our rather limited existing groundwater supply stock,” highlighted, Dr Shannak.Several countries are already using treated wastewater for agriculture. However, there are some barriers to adopting this seemingly logical and much-needed solution.Dr Shannak explained: “The problem with recycled water is purely psychological. Truth is, several of the fruits that we buy here today are grown in Europe where treated waste water is already being used for agriculture, so we are already consuming it, albeit unknowingly.”Commenting on the religious aspect of it, Dr Abdulazeem Abozaid, professor, College of Islamic Studies at HBKU, said: “If it passes the relevant quality checks and is deemed fit for consumption then there is absolutely no issue in using it. In Islam, the source of water is irrelevant. In fact, according to Sharia, if the water is tasteless, colourless, and odourless then it can even be used for ablution.”“Innovation is what we need through and through, not just by using new technologies, but also by accepting unconventional but viable sources of water and adopting responsible behaviour when it comes to water consumption,” added Dr Shannak.