Unlock the Potential of Wastewater Reuse in Arid Regions

Sewage treatment plants play a significant role in urban expansion. In the coming years, effluent will become an essential source of water for municipal use. Population growth, increasing living standards in developing countries and migration into cities all contribute to water stress throughout the world. Reclaimed wastewater is the key to unlocking the potential for more non-potable water sources for urban, industrial and groundwater recharge needs.

Challenges & Opportunities

Wastewater reuse is an intelligent, responsible solution for many countries, including those in the Middle East and North Africa, to manage water scarcity challenges. Reuse systems make municipal wastewater a resource available to several industries. The right treatment process can match the exact effluent quality required for the selected application. While wastewater treatment technology is available, the reuse of effluent water is not a simple process. Different reuse technologies can have fewer environmental benefits than others depending on life-cycle factors. These technologies also must prove their economic advantage compared with traditional water use. Despite these challenges, the effluent from reclaimed wastewater provides significant advantages for several industries. In many cases, the wastewater contaminants can be properly recycled into fertilizers for agricultural use. This reduces the need to disperse more chemicals for crops. Direct reuse of wastewater requires a more stringent removal process of emergent contaminants. Those contaminants are pharmaceuticals and endocrine substances that are naturally released after consumption. Oxidation processes are required to remove these contaminants beyond standard tertiary treatment. The challenge for reuse solution suppliers is to ensure that the offered product reaches the target treatment level without over-performing.

Research & Development

Hammarby Sjöstadsverk is the center for Sweden's leading research and development activities in the field of wastewater purification. Since 2008, all research at the plant is performed by a consortium consisting of IVL (Swedish Environmental Research Institute) and KTH (Royal Institute of Technology). Sjöstadsverk facilitates a long-term cooperation between researchers, municipal water and wastewater treatment plants, and industry. A major reuse technology supplier began a project at the Hammarby facility to showcase different solutions for economical wastewater recovery. Biological, filtration and disinfection systems were all tested to reach a target effluent quality while saving time and resources. High efficiency motors, advanced control processes and optimized ultraviolet lamps were among the technologies included during the tests. The project had three major goals. First, the processes and systems had to be optimized for the targeted non-potable reused applications worldwide. Second, the system had to achieve the best possible reduction of emergent micropollutants. Third, the treatment processes must reduce life-cycle costs while attaining the highest possible standards of sustainability.

System Background

Raw wastewater feeds a treatment line under an adjustable proportional flow to the wastewater flow coming into the main wastewater treatment plant. The secondary treatment handling nutrient reduction and reclamation is a unique sequential batch reactor with continuous inflow. The batch reactor integrates mixer, pump, and monitoring devices and diffusers. An intelligent control system monitors the process and offers preventive maintenance based on communication between the equipment and the controller. For tertiary treatment, a gravity sand filter offers high reduction of fine particles and phosphorus. Pressurized and submerged ultrafiltration treatments were added for their high treatment performance on reduced footprint compared with conventional media filtration. The disk filter is also tested as a treatment with strong potential in reaching good effluent quality at reduced investment and operating costs. Ozone and UV treatment eliminate emergent micropollutants and microbial pathogens. More than 25 online sensors and three IQ sensor networks directly connect the system to the server for data acquisition.

Preliminary Results

Eight treatment lines were tested at the Hammarby platform for more than two years. Two to three treatment lines were selected for reaching the targeted effluent quality. The optimal line was defined for reaching treatment requirements without over-performing. For example, in a groundwater recharge application, the full elimination of micropollutants was attained while keeping the same filtration.