LOWER RUVU TREATMENT PLANT
Water Treatment Plant (WTP)
The design capacity of the Mtoni WTP is estimated to be about 9,000 m3/d. Mtoni WTP which comprises the following:
– Intake on Kizinga River: Minimum flow recorded 0.036 m3/s in November 1971, maximum flow 2.9 m3/s in April 1968, design and operating capacity from 13,000 to 22,000 m3/d.
– Raw water pumping main: Cast iron DN 375 mm, 1 km long, capacity
0.12 – 0.16 m3/s.
– Grit removal: Sand trap not covered.
– Raw water pumping station: 4 compartment well sump, 4 x 4 x 5.4 m deep each, total volume 300 m3, inlet pipe DN 375 mm,
– Chemical Building: Chemicals dosed into flocculation chamber.
– Clarifiers: 6 units, vertical up-flow floc blanket type, dimensions 7.5 x 7.5 x 7.5 m depth each, total capacity 0.10 – 0.15 m3/s.
– Filters: 3 rapid gravity sand filters, each unit comprising 2 bays of dimensions
5.5 x 2.5 m.
– Disinfection: Post chlorination gas or hypochlorite injected via 35 – 50 mm diameter pipes.
– Clear water tanks: 2 compartment reinforced concrete rectangular tank, dimensions 54 x 38 x 4.5 m height, capacity 9,100 m3.
– Clear water pumping station: 2 single stage pumps of discharge 38 L/s each and head 35 m, 2 pumps of discharge 90 L/s and head 37 m and 2 multistage horizontal pumps of discharge 32 L/s and head 37 m.
Mtoni Transmission System
Mtoni transmission system is considered the oldest system commissioned in 1951 feeding southern and eastern part of Changombe, Kurasini, Mtoni, Tandika, Kigamboni and Mbagala. Mtoni transmission system comprises the following:
– A cast iron transmission main of length 1 km and DN 375 mm conveying raw water from the intake to the Mtoni plant, the main is in good condition. Hazen-Williams (H-W) friction coefficient (C-value) is assessed to be 100.
– Two transmission mains conveying treated water from the Mtoni plant directly to the distribution system, diameters varying from DN 150 – 375 mm. Pipe materials were CI, DI and PVC. The transmission mains have many off-takes along their route. C-value ranges from 90 to 100. The mains are in a satisfactory condition.
A tank of capacity 500 m3 at Mbagala, is connected to the treated water main in order to serve Mbagala area.