Greywater Vertical Treatment and Possibility of Reuse in the Fields from Peri-Urban Area

Abstract

This study highlighted the potential for greywater reuse in irrigation of olive trees. An experimental field was set up in a household of Soukra, located northwest of Tunis City, to test the performance of vertical greywater treatment. Treated greywater (TGW) was used for the irrigation of two olive tree varieties (Chétoui and Picholine) during five years. The results show high performance of the treatment, as reflected by the good quality of TGW. The chemical and biological parameters of this TGW are under the threshold values of the Tunisian Norms of Treated Wastewaters for agriculture use (NT106.03). The BOD5 average decreased from 160.44 mg O2/L for UGW (Untreated greywater) to 15.32 mg O2/L for TGW. The COD average recorded a high reduction from 290.15 mg O2/L for UGW to 49.58 mg O2/L for TGW. The average removal rate was 90% for BOD5 and 83% for COD, proving the high performance of the treatment. The average increases in height, diameter, and olive production are significantly high for the two varieties of olive trees irrigated with treated greywater (ITGW), compared to those not irrigated and under natural conditions. In this regard, the present study has shown promising potentials for the reuse of TGW in agriculture.