An innovative and simplified treatment scheme for wastewater reuse in energy crops irrigation

The aim of this study is to define new methodologies and new Waste Water Treatment Plant (WWTP) schemes for urban waste water reuse for the sustainable irrigation of energy crops. In the new proposed scheme, wastewater is sent to the WWTP characterized by simplified treatment schemes, able to remove pathogens and dangerous components for the environment, but releasing nutrients useful for the fertigation of energy crops. The more important advancement is that the proposed plant has a significant operational flexibility, guaranteed by the possibility of gradually changing the plant configuration passing from the configuration of the irrigation period to that of the period without irrigation. The proposed plant is also able to selectively remove only the harmful substances. The wastewater reclamation is obtained modifying a common activated sludge process with predenitrification. Numerical simulations have been performed by implementing the ASM1 model using SIMULINK in MATLAB code. For the sedimentation tank the model proposed by Takács has been used. The developed model allows us to run simulations in nonirrigated and irrigated periods, which are characterized by different plant configurations. The simulation results show that the effluent concentrations of the various substances (readily and slowly biodegradable organic matter, nitrites, nitrates and ammonia) are highly variable depending on the plant configuration. The advantage is that with the same system, by setting up a plant configuration rather than another, we can define the quality level of the effluents that may be more suitable for irrigation of the biomass or for protection of the receiving water.