GROUP PRESENTATIONPROCESS: WATER TREATMENT

Group 11:Deventry Daniel LeeRaymond ChuRafidah Bte Haziami AfdzalillahFadilah Binti Rusdianshah

1.0 Introduction

2.0 Process Flow

3.0 Problems Regarding Bulk Solid

4.0 Solution for Problem 3.1

Overview

1.0 What is water treatment?

Process where the raw water undergo purification to make sure that the supplied water are safe.

Raw water Potable drinking water

• Groundwater• Upland lakes and reservoir• River

In Malaysia, 99% of raw water sources are obtained from riversand 1% obtained from groundwater.

(Source : WHO)

In Sabah, Telibong II Water Treatment Plant operated by YudaWater Sdn Bhd supplied drinking water to several locationaround Kota Kinabalu with maximum capacity of 96 MLD (millionlitres per day)

Usual raw water source

Aeration Mixing Flocculation

ClarificationFiltrationClear water tank

Post-lime & post-chlorine

PolymerPre-alum

Pre-chlorine & pre-lime

2.0 Process Flow

Objective :- to provide oxygen for the oxidation of dissolved iron and manganese

- increase the dissolved oxygen content in water

Volume : 320.4 m3 (18 x 8.9 x 2) m3

Retention time : 1.38 mins

2.1 Aeration

Objective : to obtain rapid and uniform dispersion of a chemical throughout the mass of water

Volume : 45 m3 (3 x 3 x 5) m3

Retention time : 45.7 sec

2.2 Mixing Chamber

Objective : to provide an increase in the number of contacts between coagulated particles suspended

Volume : 262.65 m3 ( 8.5 x 7.5 x 4.12) m3

Retention time : 13.35 min

2.3 Flocculator

Objective : to settle down the flocs

Volume : 561.12 m3 (20 x 6 x 4.676) m3

Retention time : 28.51 min

2.4 Clarifier

Objective : to separates impurities suspended in the settled water by filtering through a bed filter media.

Volume : 150.28 m3 2(3.3 x 9 x 2.53) m3

Retention time : 15.37 min

2.5 Filtration

• Pre lime – coagulation pH conditioning• Post –lime – final pH correction• Pre-chlorine – biological control• Post- chlorine – disinfection purpose• Pre- alum – to coagulate impurities• Polymer - coagulant aid

lime- calcium hydroxide slurry (5%w/w)chlorine- 10%w/w solutionalum- aluminium hydroxide slurry (15%w/w)polymer(polyelectrolyte) - polyDADMAC (10-50%w/w)

2.6 Dosing

• Problems mainly occur in clarifier, where sedimentation of flocs take place.

• Examples of bulk solid in water treatment process– settled flocs– lime powder– alum powder– polyDADMAC powder

3.0 Problems Regarding Bulk Solid

• settling of flocs requires a slow, non turbulent flow, and large space • settling efficiency is never 100%, requires filter on the next stage• slower flow rate, larger space, frequent filter backwash = more cost

& lesser profitSolution should target: higher flow rate, lower area and depth of clarifier, higher settling efficiency.

3.1 Incomplete settling of flocs

Sedimentation of flocs causes alum sludge buildup. • at 1/3 of clarifier height, incoming flocculated water knocks

sludge back into suspension• suspended flocs will stress filters, causing head loss and low

flow rate.Solution :4 parallel clarifiers running simultaneously1 clarifier can be desludged at any one timeWashing done via mechanical scrapers

3.2 Alum sludge buildup

• alum comes in powder form • if alum powder is dosed directly to the stream, agglomeration

might occur, causing size enlargement of the alum powder.• lumps of alum = inefficient for flocculation

Solution :Alum is dosed in slurry form and mixed• high shear mixing at alum slurry preparation plant• flash mixing at chemical dosing point

3.3 Dosing of alum

Recap : Incomplete Settling of Flocs

Target : achieve maximum achievable flow rate, minimize effective clarifier volume, increase overall settling efficiency

Solution : installation of lamellar tube settler and baffles

4.0 Solution to Problem 3.1

4.1 Lamellar tube settler

Conventional clarifier design3 dimensional representation of lamellar tube settler

Lamellar tube settler used by Yuda Water Sdn. Bhd.

4.2 How does it work?

Lamellar Principle

Resultant forces on a floc particle

• Clarifier can operate at 2 to 4 times the normal rate of clarifiers without tube settlers (0.246 m3/s)

• Cut alum dosage by up to half while maintaining a lower influent turbidity

• Less filter backwashing of filters• Tube settlers allows smaller volume of clarifier, flocs are

forced to settle in the tubes.(20 m x 6 m x 4.676 m )

4.3 Results