Optimizing Chlorine Dosing for Water Distribution Reservoirs Presented By : Sharon Lesa

Industrial Supervisors : Mr. Mark Jennings & Mr. Ivan Wady Academic Supervisor : Prof Yuan Chen BACKGROUND

ADWG NSW Health

• Free chlorine aesthetic • Drinking water supplied limits range from 0.2mg/L to ALL retic areas must to 5.0 mg/L. contain > 0.2 mg/L of free chlorine.

Sharon Lesa Shoalhaven Water The University of 2 Shoalhaven Water Network

• NSW Health requires 100% compliance from SW regarding free chlorine content of the supplied drinking water. • Compliance requirement not met due to low residual detection (< 0.2 mg/L) from almost all retic areas.

Disinfection Strategy

• SW’s refined disinfection strategy led to significant improvements. • Involved the use of satellite chlorinators (chlorine gas), in conjunction with tablet dosing.

Sharon Lesa Shoalhaven Water The University of Sydney 3 120

100

80 • SW’s free chlorine 60 compliance has improved over the years. Northern 40 Shoalhaven • BUT not to the point that

Compliance Compliance (%) Southern 20 Shoalhaven SW wants. Kangaroo 0 Valley • Improved Compliance - Project Incentive.

Month

Sharon Lesa Shoalhaven Water The University of Sydney 4 PROJECT SCOPE

Temperature Optimal Dosing Mechanical Economic Controlled Arrangement Mixers Evaluations Chlorination (Inlet vs Outlet) Feasibility

Sharon Lesa Shoalhaven Water The University of Sydney 5 TEMPERATURE CONTROLLED CHLORINATION • Summer Temperatures : 200C, 220C, 250C, 300C. Decay • Winter Temperatures : 100C , 150C. Profiling

• Northern Shoalhaven (in part). EPANET • 5 Reservoirs. Modelling • 12 Study Areas.

• Field Measurements vs Model Estimates. Model • Sensitivity Analysis. Validation

Sharon Lesa Shoalhaven Water The University of Sydney 6 Chlorine Decay Profiling

Monthly Average Temperatures of Town Decay Curves for 1.0 mg/L Water Reservoir at Bamarang WTP 1.20 30.0 1.00 25.0 22 Degrees 0.80 25 Degrees 20.0 10 Degrees 15 Degrees 0.60 15.0 20 Degrees Expon. (22 Degrees)

10.0 0.40 Expon. (25 Degrees)

Free Chlorine (mg/L) Chlorine Free Temperature(0C) Expon. (10 Degrees) 5.0 0.20 Expon. (15 Degrees) Expon. (20 Degrees) 0.0 0.00 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 0 50 100 150 200 Month Time (h)

Sharon Lesa Shoalhaven Water The University of Sydney 7 Chlorine Decay Models Validation SUMMER CONDITIONS

• Decay Constants (200C, 220C, 250C). • Demands (Dec-Feb).

Sharon Lesa Shoalhaven Water The University of Sydney 8 WINTER CONDITIONS

• Decay Constants (100C, 150C). • Demands (Jun-Aug).

Sharon Lesa Shoalhaven Water The University of Sydney 9 Real Systems Application • WTPs and reservoirs chlorine aims now tailored in accordance to temperature changes.

WTP Winter Summer (May – October) (Oct – May) Bamarang 1.3 + 0.2/-0.1 1.7 + 0.2/-0.1 Old Aims Milton 1.0 + 0.2/-0.1 1.3 + 0.2/-0.1

WTP Summer Autumn Autumn/Winter Winter Spring Spring (Dec – Feb) (Mar – Apr) (May – Jun) (Jul – Aug) (Sep) (Oct – Nov) Bamarang 2.0 ± 0.1 1.9 ± 0.2 1.8 ± 0.2 1.5 ± 0.2 1.8 ± 0.2 1.9 ± 0.1 New Aims Milton 1.7 ± 0.1 1.6 ± 0.2 1.5 ± 0.2 1.3 ± 0.1 1.5 ± 0.2 1.6 ± 0.3

Sharon Lesa Shoalhaven Water The University of Sydney 10 INLET VS OUTLET DOSING

Contaminant • Preliminary tracer study in EPANET. Removal • Operational and health perspective.

Monitoring & • Incorporation of alert limits in SCADA. Dosage Control • Better dosage adjustments.

• Amount of chlorine required (annually). Economic • Associated costs for each arrangement. Evaluations • Optimization for cost reduction.

Sharon Lesa Shoalhaven Water The University of Sydney 11 Contaminant Removal Preliminary Tracer Study • Simulated in EPANET. • Gives the time taken for contaminant to move from reservoir to consumer. Study Area Contaminant Travel Time Time taken to (h) reach first consumer is 1.0 • Inlet Dosing alarmingly short! Berry Less than 1.0 - Longer residence times is 5.0 advantageous to removal of contaminants with high C.ts. 3.0 Hyams Beach 7.0 • Outlet Dosing - Contact time between Cl and 27.0 2 water depends on pipe length. Vincentia 5.0 Old 3.0

Sharon Lesa Shoalhaven Water The University of Sydney 12 Monitoring and Dosage Control Outlet Dosed Reservoir Inlet Dosed Reservoir

Low-level alert limit

Outlet Dosage Inlet Dosage • Inconsistencies in analyser readings • Near fixed inlet flowrates allows for higher makes it impossible to incorporate low-level alarms setpoints in SCADA. higher low-level alarm setpoints in • Less fluctuation in analyser readings as

SCADA. amount of Cl2 added is fixed. • Fluctuation is due to diurnal variations.

Sharon Lesa Shoalhaven Water The University of Sydney 13 Economic Evaluation

$9,000.00

$8,000.00

$7,000.00

$6,000.00

$5,000.00 Outlet Dosing $4,000.00 Annual Cost Annual Inlet Dosing $3,000.00

$2,000.00

$1,000.00 Coonemia Vincentia West Shoalhaven Berry Ulladulla Heads Reservoir • Inlet dosing is marginally more expensive for larger reservoirs (> 10 ML) • Cost expenditure is relatively the same for smaller reservoirs 2.3 ML to 2.8 ML (e.g. Shoalhaven Heads and Berry)

Sharon Lesa Shoalhaven Water The University of Sydney 14 Optimization for Cost Reduction • Increasing the minimum operating levels OR inlet feed rates. • Reduces overall investment costs on chlorine. • Cost reduction is achieved via decreasing the chlorinator run-time. $9,000.00 $8,000.00 $7,000.00 $6,000.00 $5,000.00 $4,000.00 Outlet Dosage $3,000.00 Optimization $2,000.00 Current Operations Annual Cost Annual $1,000.00

Reservoir

Sharon Lesa Shoalhaven Water The University of Sydney 15 MECHANICAL MIXERS FEASIBILITY

• Mixed vs Unmixed reservoir configurations also simulated in EPANET. • End results showed that inlet flows are sufficient to induce enough column mixing.

Simulation Results (based on last 80 hrs)

Reservoir Average Residual Average Residual Mixed Unmixed • In-house mixer design concept (mg/L) (mg/L) however, has been Shoalhaven Heads 0.98 0.93 recommended to Coonemia 0.92 0.89 SW for future Vincentia 1.02 0.98 studies. Berry 0.97 0.89

Sharon Lesa Shoalhaven Water The University of Sydney 16 SUMMARY

Improved New Inlet Dosing Better Compliance Chlorine of Cl at Chlorine 2 for Residual selected Sampling Shoalhaven Aims reservoirs Locations Water

Sharon Lesa Shoalhaven Water The University of Sydney 17 Special Thanks : • Mr. Mark Jennings & Mr. Ivan Wady. • Mr. Robert Horner. • Mr. Matthew Kidd. • Mr. Ljupčo Lazarevski. • Shoalhaven Water Operations Team (Flinders Depot). • USYD School of Chemical and Biomolecular Engineering. THANK YOU