Feasibility of an Aquaponic System Composed of a Living Wall Coupled With an Ornamental Pond With Fish in Real-Life Conditions

Green and blue infrastructures are often combined to create pleasant urban landscapes and provide new ecosystems in the built environment. New techniques for building integrated vegetation systems, such as vertical greening, are becoming common. In this work, we evaluate a case study of a combined aquaponic system composed of a living wall (LW) coupled to an ornamental pond with fish. The system allows the metabolic waste of fish and the unconsumed feed to be converted by a bacterial population into mineral nutrients that are used by the plants in the LW. For this purpose, the pond water was recirculated through a 7.2 m² LW planted with 11 different ornamental plant species. The objectives of the study were (1) assessing the performance of LW vegetation irrigated with water from a pond and (2) monitoring the pond water quality with the LW used as a biofilter. The evolution of vegetation growth was monitored for 1 year by image analysis, and the concentration of some nutrients in the water was determined pre- and post-coupling. Vegetation cover increased from 30% to almost 100% after 1 year. Iron, magnesium, and nitrogen content increased in the LW plants after coupling with the pond. Electrical conductivity increased slightly with time, keeping below 500 µS cm⁻¹. Nitrates, nitrites, and phosphates in the water were significantly reduced after the pond was coupled with the LW. Overall, the combination of both systems proved to be successful, optimizing the use of water and fertilizers with a circular economy focus.