Ecological Engineering 91 (2016) 294–301 Contents lists available at ScienceDirect Ecological Engineering journal homepage: www.elsevier.com/locate/ecoleng Domestic wastewater disinfection by combined treatment using multi-soil-layering system and sand filters (MSL–SF): A laboratory pilot study Lahbib Latrach a,b , Naaila Ouazzani a,b , Tsugiyuki Masunaga c , Abdessamad Hejjaj a , Khadija Bouhoum b , Mustapha Mahi d , Laila Mandi a,b,∗ a National Center for Research and Study on Water and Energy (CNEREE), Cadi Ayyad University, P.O. Box 511, 40000 Marrakech, Morocco b Laboratory of Hydrobiology, Ecotoxicology and Sanitation (LHEA, URAC 33), Faculty of Sciences Semlalia, Marrakech, Morocco c Faculty of Life and Environmental Science, Shimane University, Matsue 690-8504, Japan d International Institute for Water and Sanitation, National Office for Electricity and Potable Water (IEA-ONEE), Rabat, Morocco a r t i c l e i n f o Article history: Received 12 August 2015 Received in revised form 27 January 2016 Accepted 27 February 2016 Keywords: Fecal indicators Multi-soil-layering system Nutrients Organic matter Parasites Sand filter Wastewater treatment a b s t r a c t This study aims to present the removal of bacterial indicators of fecal contamination and parasites in a combined treatment using a multi-soil-layering system with sand filters (MSL–SF). This experiment was carried out in a laboratory scale. The MSL pilot (height 65 cm, width 36 cm, depth 30 cm) was composed of soil mixture layers (SML) and gravel layers that are arranged in a brick-layer like pattern. The soil mixture layers are composed of local sandy soil mixed with sawdust, metal iron and charcoal at the ratio of 70, 10, 10 and 10%, respectively, on a dry weight basis. The applied hydraulic loading rate (HLR) was 200 L m −2 day −1 . The experimental sand filter included three parallel similar sand columns (inside diameter 12.5 cm, height 120 cm). Each column was filled with 80 cm of fine sand and 10 cm of gravel in the top and the bottom of the filter. Three sand columns HLRs (100, 200 and 400 L m −2 day −1 ) were compared. The obtained results indicated that the conceptual model based on the combination of the MSL method and sand filter (MSL–SF) showed very high efficiency in organic matter, nutrients, bacteria and the reduction of parasites. The high performances were noted in the low HLR. The main removal percentage of SS, BOD5, COD, TN and TP were respectively 99.73, 97.78, 98.40, 92.93 and 96.21% for the HLR-100. In addition, the Log 10 removal for total coliforms, fecal coliforms and fecal streptococci were 4.46, 4.47 and 4.13 Log unit respectively. MSL-SF is capable of removing 100% of helminthes eggs. The MSL system is an efficient method, especially for organic matter and nutrients (N, P) removal. Sand filters have experimentally been proved to be useful for fecal indicators and the removal of parasites. Good operational stability and high contaminants removal efficiency of the combined systems were observed. Therefore, the combination of the MSL system and sand filter offer a good alternative option for agricultural wastewater reuse. © 2016 Elsevier B.V. All rights reserved. 1. Introduction Wastewater collection and disposal are still one of the most public health and environmental problems in Moroccan rural areas. Most of these areas lack wastewater collection systems and rarely have wastewater treatment plants. Indeed, the irrigation water supply constitutes a major limiting factor for agricultural production in the arid region. Recently the Moroccan government ∗ Corresponding author at: National Center for Research and Study on Water and Energy, Cadi Ayyad University, P.O. Box 511, 40000 Marrakech, Morocco. Tel./Fax: +212 524434813. E-mail addresses: mandi@uca.ma, mandi laila@yahoo.fr (L. Mandi). has implemented an integrated national sanitation master plan in rural areas, with special attention to wastewater treatment and reuse (PNAR, 2013). In this context, irrigation practices can offer significant opportunity for water reuse in Morocco: about 85% of the total available water supply is used in irrigation (Roe et al., 2005). In Morocco, a strict microbiological limit is used to regulate treated wastewater reuse in irrigation (0 helminthes eggs/L and 3 Log10 of fecal coliforms/100 mL) (Moroccan regulation guide- lines, 2007). Consequently, a very high degree of disinfection is necessary to achieve these criteria levels. The use of efficient and natural techniques represents a simple and low-cost solution to decentralized rural domestic wastewater treatment for reuse appli- cation in developing countries. http://dx.doi.org/10.1016/j.ecoleng.2016.02.036 0925-8574/© 2016 Elsevier B.V. All rights reserved.