N2 - The Henaya Irrigated Perimeter (HIP) is an agricultural area irrigated by treated wastewater (TWW) of Ain El Hout treatment plant. Various analyses have shown that i) this water has low concentration of heavy metals and toxic elements, ii) the average values of the physicochemical parameters for 136 samples are satisfactory (29.2 mg O2∙dm–3 for chemical oxygen demands – COD, 13.14 mg O2∙dm–3 for biological oxygen demands – BOD, 14.2 mg∙dm–3 of suspended matter – SM, 1.82 mg∙dm–3 of N-NO3, 7.7 for pH and 927.74 μS∙cm–1 for electric conductivity – EC). Thirdly, it contains a high number of bacteria and nematodes (7200 CFU∙(100 dm3)–1 for faecal coliforms and 30 eggs∙dm–3 for intestinal Nematodes) which makes it dangerous for groundwater contamination. The objective in this work is to characterize the TWW and evaluate the impact of it use for irrigation on the quality of Hennaya groundwater. Before this, one has to prove that there is an amount of TWW that feeds the water table to show that there is a risk of pollution. We then estimated the aquifer minimum recharge value by TWW using the Thormthwaite meth-od. The estimation has given 92 mm which is an important quantity. The results of the groundwater microbiological anal-yses reveal no sign of contamination. The cause is the efficiency of the degradation of pollutants of the Vadose zone. The soil purifying power Md of the HIP was evaluated by the Rehse method and gave values ranging from 2.1 to 12.7 which indicated a complete purification. L1 - http://www.czasopisma.pan.pl/Content/114801/PDF-MASTER/Bemmousat%20et%20al%20500.pdf L2 - http://www.czasopisma.pan.pl/Content/114801 PY - 2019 EP - 27 KW - groundwater KW - irrigation KW - pollution KW - treated wastewater A1 - Bemmoussat, Abdelkader A1 - Adjim, Mohammed A1 - Bensaoula, Fouzia PB - Polish Academy of Sciences; Institute of Technology and Life Sciences - National Research Institute VL - No 43 DA - 2019.12.05 T1 - Irrigation with treated wastewaters and the protection of Hennaya groundwater – Tlemcen, Algeria SP - 19 UR - http://www.czasopisma.pan.pl/dlibra/publication/edition/114801 T2 - Journal of Water and Land Development