Hydraulic load rates effect on the performance of Horizontal Multi-Soil-Layering to treat domestic wastewater in rural areas of Morocco

The objective of the present study was to investigate an environmental and economically sustainable technic to treat domestic wastewater in rural areas of Morocco. To do this , a pilot-scale treatment system, horizontal multi-soil-layering (H-MSL) measuring 0,5 m × 0,3 m × 0,55 m (L ×W× H), was designed, constructed and operated to treat domestic wastewater, using natural substrate. A feeding tank (100L) was used to store prescreened wastewater from the inlet of the household wastewater using submersible pump. Three hydraulic loading rates (HLRs) were tested: 0.25, 0.35 and 0.50 m/day. This pilot-scale treatment was exposed to the environmental conditions and it does not include any pretreatment. Several water quality parameters including BOD5, COD, TSS, NH4 +, NO3 - and PO4^ 3- were monitored. The ANOVA test showed a significant difference between the means of these parameters at (p 0.05) for the influent and the effluent, except ammonium. Moreover, it showed a difference between the values of organic mattersat0.25m/d and 0.5m/d. However, it did not show any significant differences between each type of nutrients for all HLRs tested. The main treatment performance results showed the following average removal rates: BOD5 (66±13 %), COD (68±12 %) and TSS (75±14%), NH4 +(29.2±14.1%) and PO4^ 3- (45.2±27.3%). The quality of the treated wastewaters was under to Moroccan Reject Limit Value (RLV).