The project aims at developing an integrated system of water and nutrients reclamation from secondary effluents at the Wrocław “Janówek” Wastewater Treatment Plant (WOŚ), in accordance with the assumptions of the circular economy. The project includes the recycling of secondary effluents with the simultaneous production of purified water and the recovery of valuable nutrients (organic compounds and magnesium) in the form of concentrated retentates from individual membrane unit operations.
The project proposes:
- a new approach of secondary effluent (SE) management to recover the valuable components of wastewater for a variety of purposes, beginning with the water itself and followed by nutrients. Water is reclaimed in an integrated 3-stage pilot-scale membrane process (micro/ultrafiltration, nanofiltration and reverse osmosis). This technology allows the production of water for several types of applications. These uses include (a) industrial processes as a cooling medium, (b) urban non-potable applications (e.g., irrigation with reclaimed water and microelements), (c) potable water supplies, and (d) groundwater remediation.
- an approach to identify, monitor, and remove micropollutants from secondary effluent using pressure-driven membrane processes.
- a new strategy of membrane regeneration after secondary effluent separation, combining the nitric acid III/V-based chemical cleaning and backflushing with the simultaneous reusing of acidic waste-washings streams as nutrient-rich fertilizers. Different membrane contamination mitigation strategies, like backflushing and acid-alkaline, alkaline-acid, and alkaline-enzyme-acid chemical-based cleaning have been investigated, considering their cost-effectiveness and sustainability. The results from the pilot-scale CIP process suggest that the free nitrous acid (FNA) is as efficient as nitric acid in removing irreversible fouling and leads to an almost 100% recovery of permeate flux after an entire acid-alkaline cleaning cycle.
- a new hybrid SE management technology for the simultaneous production of (a) purified water, and (b) Mg(II)/Ca(II)-rich concentrates for the precipitation of various phosphate salts. The Mg(II)/Ca(II)-rich concentrate opens the door for struvite and brushite formation by adapting the problematic by-products such as retentates from water reclamation and anaerobic digestion liquor (ADL). The recycling and management of the produced by-streams may close the water loop in WWTP in mind of zero waste conception. The reclaimed water could meet the cooling water standards and the by-product can be recycled to produce valuable calcium (brushite) or magnesium (struvite) phosphate salts which could be beneficially reused in the agriculture sector.