2. Materials and methods
2.1. Description of the study site and the treatment system
The Moshi Municipality wastewater treatment system which is located in the Northern part of Tanzania within the Kilimanjaro region is managed by the Moshi Urban Water and Sewerage Authority (MUWSA). The treatment system receives domestic sewage from sewered area with coverage of 46% of the municipality which is the highest in Tanzania. It also receives some of sewage from the areas with no sewerage network via the septic pump trucks.
The treatment system consists of a waste stabilization pond (WSP) and a constructed wetland (CW) system connected to it. The WSP has a design capacity of 4500 m3/d and consists of an anaerobic pond, two facultative ponds and six maturation ponds. The facultative ponds are arranged in parallel while the maturation ponds are connected in series (Fig. 1). The CW has a capacity of 200 m3/day and it receives effluent from the WSP at the maturation pond 2 and runs parallel to the remaining four maturation ponds (Fig. 1). The CW treats the partially treated waste water so the effluent from it gets treated by both the treatment systems (WSP-CW) while major portion of the wastewater gets treated through the WSP only. The final effluent is discharged to the irrigation channel via a fish pond located on the downstream.