Valorisation of biowaste for the production of high-quality irrigation water: A sustainable approach in hydroponic wheat cultivation

Abstract

Faced with the increasing scarcity of water and the challenges of organic waste management, this study proposes an innovative method for valorizing biowaste to produce high-quality irrigation water by combining thermal drying and biofiltration. Three types of biowaste, including potato peels, orange peels, and coffee grounds, were treated using devices with or without biofilters, incorporating ashes derived from Hermetia illucens L. or Cupressus atlantica G. Each thermal cycle operated at 55 °C for 24 h and treated 100 g of fresh biowaste, yielding on average 60 ml of condensed water per cycle. Physicochemical, microbiological, and agronomic analyses revealed that the device without a biofilter produced water rich in biodegradable nutrients (BOD₅: 1103 mg/l), promoting an average germination rate of 93.22 % and optimal vegetative growth of wheat in hydroponic systems. In contrast, devices equipped with biofilters effectively reduced organic load (COD: 461.66 mg/l for Cupressus atlantica and 70.44 mg/l for Hermetia illucens L.) while eliminating microbial contaminants, with no detectable traces of heavy metals. The Cupressus atlantica G..-based biofilter achieved a high germination rate (94.55 %) due to the controlled release of mineral salts, whereas the Hermetia illucens L.-based biofilter resulted in a germination rate of 85.10 %, highlighting the critical balance between nutrient availability and contaminant reduction. These findings demonstrate the potential of this technology to produce environmentally friendly water suitable for sustainable irrigation and circular resource management. This approach offers a promising solution to address the dual challenges of water scarcity and biowaste valorization.