Integrated Treatment for Drinking Water, Dominica

Background

Dominica is an island in the Caribbean Sea that was granted independence by the United Kingdom on December 3rd 1978 after many years as a British colony. The island comprises black volcanic sandy coastal strip, rain forest and mountains rising to a height of over 1,400 meters. The island’s area is about 750 km2 with population of 70,000. One of the island’s main sources of income is tourism; cruise ships visits the island and the demand for tourists’ services is high. However the island suffers from lack of high quality drinking water for both the local population and the cruise ships visiting the island

Challenge

The Dominica project treats river water which is collected into piping and transferred downstream to sedimentation ponds. The accumulated water is then transferred to distribution reservoirs located in the various neighborhoods of Roseau, the capitol of Dominica. The water treatment system is designed to handle a flow of 380m3/h at gravitational pressure of 6atm. The system is installed downstream of the collection piping and produces water at potable quality water that is discharged to a reservoir and then transferred to the city’s neighborhoods by a distribution system.

Solution

Amiad designed and supplied an integrated water filtration system which combines three main stages of filtration and treatment, providing at continues 22 hours operation cycle a flow rate of 380 (m3/h) daily: 1. The first stage of filtration, designed to remove large suspended solids from the raw water, consists of SAF 6000 series automatic screen filters battery with 80 micron filtration degree stainless steel screens. 2. The second filtration stage comprises a battery of fifteen Amiad’s 60” granular filter units, installed in 3 rows of 5 filters each with 60cm bed height, and 25M/h high Velocity filtration.The granular filters filtration media is Anthracite and they are capable of removing 40% of the TSS load. 3. The main treatment stage consists of three AMF² 370K thread filters of 2 micron filtration degree.

Results

TSS Raw Water (Max): 40 PPM Target: <2 PPM Result: ,<1 PPM

NTU: Raw Water (Max): 10-20 Target: 1-5 NTU Result: <0.45 NTU