Evaluation of Effectiveness of Domestic Wastewater Treatment by Infiltration Through Sand and Pozzolana in PVC Columns

The purpose of this work was to test the efficiency of the treatment of wastewater by infiltration under laboratory conditions, to remove bacterial and organic load and to convert it to available nutrient for crop plants. In order to achieve this objective, polyvinyl chloride (PVC) columns of 133 cm of height were used. The columns were filled with sand and/or pozzolana and loaded with municipal wastewaters. Various parameters were measured at the inlet and outlet of these columns: chemical oxygen demand (COD), biochemical oxygen demand (BOD), ammonium (NH4+), nitrate (NO3 -), Total Kjeldahl Nitrogen (TKN), total phosphorus (pt), pH and Escherichia coli (E. coli). With an average charge in chemical oxygen demand (COD) of 601.5 mg/L O2 at the input, A better reduction by sand (S) followed by mixing sand-pozzolana (SP) and finally by pozzolana (P) were observed. Good bacterial removal was also achieved with S. Indeed, after 49 days of experiment, the output effluent treated by S showed only 2.4×104 CFU/100 mL of Escherichia coli, against 108 CFU/100 mL in the output effluent treated by P. Moreover the almost total conversions of the nitrogen to nitrate makes the water treated by sand filter suitable for irrigation, because it is rich in nutrients and enables the conservation of conventional water stocks thereby protecting human life and environmental quality.