We use a number of different processes and technologies to treat the water – this usually depends on the characteristics of the water to be treated.
The treatment processes are:
Coagulation/flocculation is a complex process where a controlled amount of chemical coagulant is added into the water to de-stabilise particles, allowing clumps to form (flocculation) and settle out of suspension. This occurs in a mixing tank prior to the filtration process. The particles are then easily removed during the sedimentation and filtration stage. The type of filtration process used to remove the particles depends on the weight of the particles formed.
The coagulation/flocculation process is utilised at water treatment plants at Avoca, White Swan, Lal Lal, Beaufort, Blackwood, Daylesford, Landsborough and Maryborough.
Chemicals used for coagulation/flocculation at the water treatment plants include: aluminium sulphate, aluminium chlorohydrate, poly electrolyte, polyaluminium chloride and ferric sulphate.
Where the raw water quality allows large heavy particles (floc) to be formed during the coagulation/flocculation process, the water is further treated by the sedimentation process. The floc forms a blanket which continues to trap more suspended particles. The particles sink to the bottom of the sedimentation tank and are drawn off to waste. The clear water which flows to the surface of the sedimentation tank is collected and then passed through sand filters. Any particles not removed in the sedimentation process are filtered out by the sand filter. The filters are washed regularly to remove the collected material to waste. Filtration of the water removes naturally occurring particulate material from the water prior to disinfection. The process improves the efficacy of disinfection; assists with clarity; reduces the risk of taste and odour; and ensures a consistent quality of supply.
This process is utilised at the Avoca and Maryborough water treatment plants.
Dissolved air flotation and filtration (DAFF)
Some waters contain coagulated matter which is lighter and will not easily sink. For these supplies dissolved air flotation and filtration is used. DAFF relies on the injection of microscopic air bubbles into the water stream, causing the flocculated particles to float to the surface of the filtration tank. The particles are drawn off the surface of the filtration tank and removed to waste. Clear water then passes down through filtering material in the bottom of the filtration tank, capturing any fine particles that were not removed by the air.
This process is utilised at the White Swan, Lal Lal, Beaufort, Blackwood and Daylesford water treatment plants.
Ultrafiltration is used to remove suspended solids and some colloidal matter from the source water. The water is pumped through a filter membrane trapping suspended solids in the process. The concentrate (material that does not pass through the membrane) is periodically removed to waste to prevent the blocking of the membrane filters.
The Lexton Water Treatment Plant utilises membrane ultrafiltration technology.
Water softening, or dealkalisation, is a process used to remove calcium and magnesium salts from the water to reduce the hardness and hence the ‘scaling’ effect of the water.
This process is utilised at the Clunes and Forest Hill water treatment plants.
Ozone pre-treatment is used specifically at the Clunes Water Treatment Plant to reduce the levels of iron and manganese that can be present in the groundwater source. The process involves oxidation of soluble iron and manganese from the water, and removal during the filtration process. The oxidising process also assists in minimising colour and odour causing sulphides.
Reverse osmosis is used to remove dissolved salts from the source water. Pre-treated water is pumped at high pressure through spiral wound membranes, trapping dissolved salts in the process. The concentrate (material that does not pass through the membrane) is periodically removed to waste. The water passing through the membranes is extremely pure and is blended to maintain an acceptable salt balance in the water.
The Avoca Water Treatment Plant utilises reverse osmosis membrane technology.
Electrodialysis is used to remove dissolved salts from the source water. Water is transferred to a treatment unit and an electrical DC voltage is applied, removing dissolved salts through special ion exchange membranes. The concentrate (material that passes through the membranes) is periodically removed to waste by reversing the charge or polarity across the membranes. This treatment process has the advantage of being robust, flexible and results in high product recoveries.
The Landsborough Water Treatment Plant utilises electrodialysis reversal membrane technology.
Lime/soda ash/sodium hydroxide
To assist the water treatment process and to ensure the pH level in filtered water is within a desirable target range, high quality lime, soda ash or sodium hydroxide is automatically added to the water in the treatment plant. Maintaining pH in the desired range optimises the efficacy of treatment and disinfection, minimises the risk of corrosion/scaling and improves taste.
This process is utilised at the Avoca, White Swan, Lal Lal, Beaufort, Blackwood, Clunes, Daylesford, Forest Hill, Landsborough and Maryborough water treatment plants.
Potassium permanganate can be added to the water supply as required to reduce iron and manganese levels. When present in higher concentrations, these metals can cause staining of laundry and plumbing fixtures and contribute to ‘dirty water’ events.
Potassium permanganate dosing capability is currently available at the Avoca, Beaufort, Blackwood, Daylesford, White Swan, Lal Lal and Maryborough water treatment plants.
Powdered activated carbon
Powdered activated carbon can be added to the water supply as required to remove compounds that contribute to taste and odour issues, usually associated with higher levels of certain algae in raw water.
Powdered activated carbon dosing capability is currently available at the Avoca, Beaufort, Blackwood, Daylesford, White Swan, Lal Lal and Maryborough water treatment plants.
Chlorine is widely used throughout the world to disinfect drinking water and control disease-causing organisms. The type of chlorine used at our plants is either chlorine gas or sodium hypochlorite.
Chlorination is utilised at the Beaufort, Clunes, Daylesford, Dean, Forest Hill, Landsborough, Learmonth, Lexton and Waubra water treatment plants.
Chloramination is used throughout the world as a means of disinfecting drinking water to control disease-causing organisms. Small amounts of chlorine gas and ammonia are added to the water to form chloramines, providing a relatively long lasting process to safely disinfect water.
Chloramination is utilised at the Avoca, White Swan, Lal Lal and Maryborough water treatment plants.
Ultra violet disinfection
Ultra-violet (UV) light is an effective means of disinfection; however, efficacy is only at the point of application, as UV treatment has no lasting residual. Effectiveness also relies on the water having low turbidity as particulates minimise the amount of UV light penetration, hence potentially shielding micro-organisms that could be present in the water.
UV disinfection is utilised at the Beaufort and Blackwood water treatment plants.
In accordance with the Victorian Department of Health and Human Services requirements, the Ballarat and district and Maryborough and district water supplies are fluoridated. All other systems are currently non-fluoridated. Any fluoride present in these non-fluoridated systems is due to naturally occurring sources.
Fluoridation occurs at the Lal Lal, White Swan and Maryborough water treatment plants.