Water reuse potential for irrigation in Brazilian hydrographic regions

The present paper carried out an evaluation of the reuse potential of the Wastewater Treatment Plants (WWTPs) effluents for irrigation in the 12 Brazilian Hydrographic Regions (BHRs). For this purpose, initially, the WWTPs were categorized and the effluent flow rate was estimated. Category 1 represents secondary effluent with an efficiency of organic matter removal greater than 80%; Category 2 represents effluent that underwent some disinfection step; and effluents that perform less than the other categories were called ‘Uncategorized’. After that, the irrigation water demands for each BHRs were compiled, and finally, the production of water for reutilization was compared with the demand for irrigation. Thus, it was observed that all the sewage flow rates generated in Brazil classified in Categories 1 and 2 represent 9% of the total irrigation water demand in the country (1,078.71 m3/s) and it stands out that only 7% of the flows treated in Brazil undergo a tertiary treatment step.