Reuse of agro-food industry wastewater for fertirrigation: laboratory investigation on the role of soil as a natural filter

During the last years, problems in the availability of water increased due to climate change and irresponsible use of this resource. The depletion of water sources has become a major problem in the society since it may cause diseases, death, and reduction in agricultural production. This study aims to investigate an innovative approach for sustainable water resource management, namely Soil Aquifer Treatment (SAT), which is a specific case of Managed Aquifer Recharge (MAR) exploiting the possible reuse of wastewater for irrigation purposes. One of the industrial sectors that use the largest quantities of water in their production processes and therefore produces a great amount of wastewater is represented by the agro-food industry. In this thesis a lab-scale study was performed to assess the main processes occurring when wastewater originated in two food production plants when such water is put in contact with soil or sand, thus simulating its use for irrigation. Batch experiments with different duration and agitation conditions and column leaching tests were performed using representative wastewater of dairy industry and jam production industry collected from specific sites. The analyses included measurements of pH, Total Organic Carbon (TOC), Total Nitrogen (TN), Electrical Conductivity (EC), turbidity, Redox Potential (ORP) to assess the effectiveness of different types of substrates in the degradation of dissolved organic matter (DOM). Analyses provided insights into chemical changes during the treatment process, which need to be further investigated. The results highlighted that both batch tests and column leaching tests proved effective in decreasing the TOC present in the effluent over time. This study contributes to understanding the potential of MAR and SAT as tools for sustainable water resource management, providing a preliminary scientific basis for implementing these practices in specific environmental contexts.