Constructed wetland as a low cost and sustainable solution for wastewater treatment adapted to rural settlements: the Chorfech wastewater treatment pilot plant

摘要

The paper presents the detailed design and some preliminary results obtained from a study regardingna wastewater treatment pilot plant (WWTPP), serving as a multistage constructed wetland (CW)nlocated at the rural settlement of ‘Chorfech 24’ (Tunisia). The WWTPP implemented at Chorfech 24 isnmainly designed as a demonstration of sustainable water management solutions (low-costnwastewater treatment), in order to prove the efficiency of these solutions working under realnTunisian conditions and ultimately allow the further spreading of the demonstrated techniques. Thenpilot activity also aims to help gain experience with the implemented techniques and to improventhem when necessary to be recommended for wide application in rural settlements in Tunisia andnsimilar situations worldwide. The selected WWTPP at Chorfech 24 (rural settlement of 50 housesncounting 350 inhabitants) consists of one Imhoff tank for pre-treatment, and three stages in series: asnfirst stage a horizontal subsurface flow CW system, as second stage a subsurface vertical flow CWnsystem, and a third horizontal flow CW. The sludge of the Imhoff tank is treated in a sludgencomposting bed. The performances of the different components as well as the whole treatmentnsystem were presented based on 3 months monitoring. The results shown in this paper are related toncarbon, nitrogen and phosphorus removal as well as to reduction of micro-organisms. The meannoverall removal rates of the Chorfech WWTPP during the monitored period have been, respectively,nequal to 97% for total suspended solids and biochemical oxygen demand (BOD5), 95% for chemicalnoxygen demand, 71% for total nitrogen and 82% for P-PO4. The removal of E. coli by the wholensystem is 2.5 log units.