Identification of mineral deposition at Akurana distribution line of Greater Kandy Water Treatment Plant
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Date
2013
Journal Title
Journal ISSN
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Publisher
Uva Wellassa University of Sri Lanka
Abstract
A water distribution network cannot be considered an inert system but a reactor interacting with
the interior aqueous environment. One of the main consequences of such interaction is the
formation of unwanted deposits. The main sources of deposits in water distribution systems are
particulate matter transported by water, microbial activity and physicochemical reactions both at
the water pipe wall interface and within the water bulk (Chawla et al, 2012).
Greater Kandy water treatment plant is situated at Katugastota in the Central province of Sri
Lanka Mahaweli river water taken as raw water is treated and distributed to the Northern part of
Central province. This plant has four transmission lines to distribute water. Those lines are
Asgiriya (A1),Gohagoda (A2), Kahawatte (A3), and Yatiyawala (A4). A3 transmission line
transmits water to Kahawatte and it distributes water to Akurana area. The reddish brown color
deposition can be observed, when flushing of the ductile iron pipes at pumping main of the
Akurana distribution line at Greater Kandy Water Treatment Plant. Natural river water
containing dissolved ions such as Ca, Mg, Al, and Si etc which can form stable mineral phases.
Those minerals can be deposited in distribution lines when they meet the favorable conditions to
form possible mineral phases. In this research, we will try to identify possible mineral phases
are formed by using VMINTEQ software.
Materials and methods
Water samples analysis was related to identification of causing factors of mineral deposition at
raw water and treated water. Samples were collected from plant, Akurana reservoir and Akurana
distribution lines. In plant samples were collected from raw water from intake, distribution
chamber, after flocculation tank, after sedimentation, filter inlet, filter outlet, and Sump. Two
distribution samples were collected from near the Akurana reservoir and at Akurana town.
pH, turbidity , electrical conductivity and colour were measured. Nitrate, nitrite, fluoride,
Iron
concentration of water was rechecked by using AAS (Atomic Absorption Spectrophotometer).
Powder fillers were used to measure ions by using UV spectrophotometer. Ferro Ver, SulfarVer
4, Nitro Ver 3, Nitro Ver 5, PhospoVer were used as powder fillers to measure iron, sulfate,
nitrite, nitrate and phosphate respectively. Different colours were given according to element
contained in samples. Ammonia was measured by adding mineral stabilizer, polyvinyl Alcohol
and Nesslar reagent, using spectrophotometer. Fluoride was also measured by adding SPANS
using spectrophotometer. Chloride was measured by using digital titration method. Hardness
and
Alkalinity were measured by using titration method. Then deposited sample was collected from
a tap which carrying sump water, was centrifuged and dried. It was analyzed using X-ray
diffraction method (XRD) at Chemistry laboratory of Peradeniya University. Visual MINTEQ
software was used to analyze water quality data and possible mineral phases that form deposits.
Description
Keywords
Mineral Sciences, Mineral, Science and Technology, Water Chemistry, Waste Water Treatment