Treated Wastewater to Be Recycled

Treated Wastewater to Be Recovered Experts note that large quantities of wastewater passing through treatment facilities are discharged into water sources, and say that treating water according to its intended use and reusing it as needed is technologically feasible. With the notification issued by the Ministry of Environment, Urbanization and Climate Change and published in the Official Gazette on 25 October 2022, titled "Notification on Amendments to the Technical Procedures Notification for Wastewater Treatment Plants," criteria for the use of treated wastewater have been redefined. In statements made by the ministry regarding the notification, it was announced that the target is to increase the reuse rate of treated wastewater as an alternative water source to 5 percent in 2023 and 15 percent in 2030. According to Turkish Statistical Institute (TÜİK) 2020 Water and Wastewater Statistics, Turkey has a total of 1,068 municipal wastewater treatment plants. While 4.4 billion cubic meters of water are treated at these plants, 98.4 percent of this volume is discharged into receiving environments such as rivers, seas, lakes and dams, with only 1.6 percent being reused in industry or agricultural irrigation.  

"Water must definitely be recovered"

Prof. Dr. Azize Ayol, Faculty Member at the Department of Environmental Technologies, Division of Environmental Engineering, Faculty of Engineering at Dokuz Eylül University, made comments on the reuse of urban wastewater and stated that it is possible to use water for different purposes after treatment. Emphasizing that the effective use of water resources is very critical at a time when the world is experiencing crises in water, energy and food, Ayol continued as follows: "Seventy percent of clean water obtained from water sources across Turkey is used in agricultural irrigation areas. It is possible to use a significant portion of treated wastewater for agricultural irrigation purposes. In particular, its use as cooling and process water in terms of water supply to industry; use in park and garden irrigation, general city cleaning; 'grey water,' which is urban, relatively cleaner water that can be separated and reused in reservoirs; and also the use of treated water as fire water is possible." Reminding that a large portion of treated water is discharged into receiving environments, Ayol said, "We know that significant amounts of treated water go to seas and rivers. This volume of water must definitely be recovered. We no longer have the luxury. Within the framework of the 'Green Deal,' regarding climate crisis issues, and more importantly, in terms of protecting a healthy environment and a healthy ecosystem, the reuse of well-treated water is essential. Turkey is currently among water-stressed countries, water appears sufficient now, but water pressure will increase in the coming years, we will reach the level of water-poor countries." she said.   Explaining that advanced biological treatment systems in Turkey's major cities have the capability to enable the use of wastewater as cooling water in industry, Ayol stated that advanced technologies are required for environmental use such as in parks and gardens, with membrane technologies being foremost among these.   Prof. Dr. Güçlü İnsel, Faculty Member at the Department of Environmental Engineering, Faculty of Civil Engineering at Istanbul Technical University (İTÜ), noted that recovery of wastewater after treatment according to need is technologically feasible, while stating "This will be very necessary within the next 30 years because we are approaching the threshold of becoming a water-poor country."

Drawing attention to the fact that transporting treated water to another location requires significant cost and that therefore it is important to position wastewater treatment plants close to industrial zones, İnsel continued as follows:

"When wastewater treatment plants are built, in some cities this was not planned this way, making it difficult to do later. In Kocaeli, because industry is within the city, after 90 percent of wastewater is treated as good quality water, it is supplied to industry." he explained.  

"Nitrogen and phosphorus can be used in agriculture"

Noting that when biological treatment is applied to wastewater, only organic matter in the water is removed, and in advanced biological treatment, nitrogen and phosphorus are also removed in addition to organic matter, İnsel said: "When you remove nitrogen and phosphorus and discharge into the sea, the damage it will cause to the environment is minimal. There are discharge standards set by the Ministry of Environment, Urbanization and Climate Change. When we want to use water through recovery, treatment levels can vary according to need. If you are going to use it in irrigation and agriculture, you need nitrogen and phosphorus for fertilization. For this reason, you want a certain amount of nitrogen and phosphorus to remain in the water. This way you both fertilize and irrigate. This must be done in a manner that will not pollute water sources and in a controlled way. Wastewater treatment is entirely a planning matter. You can equip the treatment plant with the technology you want. Treatment should be according to need."  

Touching on rainwater recovery, İnsel continued his remarks as follows:

"If one unit of water comes to the treatment plant, when rainwater enters the process, it increases to 4-5 times. It is also difficult to treat this at the treatment plant. If you want to recover rainwater, lines must be separated, meaning sewer systems need to be changed. Additionally, if you take rainwater and subject it directly to use, then you miss certain things. When rainfall starts or when it runs off surfaces, certain pollutants from the atmosphere mix with this water. Rainwater must be re-analyzed. Depending on the conditions of that region, it may require additional treatment." he assessed. Noting that separations must be done very well to control waters, İnsel stated, "These must be integrated into the city plan, these infrastructure facilities need to be positioned near industry. Urban transformation is not a situation concerning only the surface of the city. You do not transform the city merely by building buildings, infrastructure remains underground. Urban transformation must bring these infrastructure facilities, recovery and properly integrated systems to the fore."   Source