Water Recycling Scheme Summaries Environmental Sciences

Add: 21-11-2017, 19:06   /   Views: 115

Water reuse refers to making beneficial use of diverse sources such as reclaimed water or treated water rather than fresh drinking water supply for specific purposes such as irrigation, industrial or environmental uses (Water recycling in AU, 2004).

Direct potable reuse refers to the water which is conveyed directly from treatment plant to the water supply system is highly treated and suitable for drinking water use (Water recycling in AU, 2004).

Indirect potable reuse refers to the water which is diluted with natural surface water or groundwater body after discharged from STP is further used as drinking water resources (Water recycling in AU, 2004).

Non potable use

Non potable recycled water which does not meet drinking water standards is used as a substitute for potable water in non drinking applications such as landscape irrigation, industrial uses, agricultural uses and household toilet flushing and gardening (QLD government website).

Greywater and Blackwater

Greywater is the wastewater generated in households except from the toilets.

It can be used treated or untreated depends on the purpose.

Blackwater is all of the components of domestic sewage (Wikipedia, 2010).

Water reuse in Australia

Since the scarcity of fresh water but the high water demand in Australia, exploring alternative water resources is becoming an urgent issue.

Desalination and water recycling are alternative resources.

According to Clean Ocean Foundation website, the recycling water is better than desalinated water in terms of infrastructure cost, treatment energy cost, CO2 equivalent gas emission and the ocean outfall discharge (Clean Ocean Foundation, 2009).

In addition, some recent studies using LCA model evaluate the energy consumption and environmental impact on water reuse from tertiary treatment plant to industrial uses and indicate the life cycle benefit from decreasing secondary discharge to natural streams and saving an equivalent volume of tap water (Zhang and Wang, 2009).

It was reported that over 500 Australian STPs recycled some or all of their effluent (Radcliffe, 2005).

In 2001-2, about 9.1% of effluents from STPs in Australia were reused (Water Recycling in AU, 2004).

These effluents incorporated with rainwater and stormwater are recycled for different end uses such as irrigation or industry uses etc.

Hundreds of water reuse schemes have been established in Australia, but they varied according to different conditions of different states.

Generally, water recycling was greater in the rural and regional areas than in the capital cities, and greater in inland cities than coastal cities (Radcliffe, 2005).

South Australia has the highest water reuse rate, accounting for 15.1%, where the water reuse schemes have been well carried out in regional and rural area for irrigation uses on farm and Golf Courses.

In areas such as Mannum and Murray Bridge, 100% reuse has been achieved (SoE SA, 2003).

Queensland has the second highest water reuse rate, accounting for 11.2%, where the majority reused water is used for golf course irrigation.

In Western Australia, groundwater use accounts for a large amount, nearly occupying 17%.

However, 39% of the resources of the Perth basin were already at or near the sustainability limit (Camkin, 2002).

Recycled water can be a substitute of groundwater and can recharge to groundwater in some cases.

In 2001-2, 10% effluents were reused with the most frequent use and high reuse rate occurred in Golf Course, town ovals and woodlot irrigation.

Tasmania's water recycling schemes are particularly applied to agricultural irrigation with the benefit of reducing cost than upgrading STPs when the effluent are discharged to estuarine, inland and bay waters and the advantage of reducing nutrient load to natural water bodies.

In NSW, the reused water is mostly used for Golf Courses and farms.

There are limited effluent reuse data of ACT, the recorded one was the effluent treated by activated sludge with 6% reuse rate was used for vineyards and Golf Courses.

In Victoria, the recycled water is mainly used for irrigation purposes such as pasture, forestry, grazing and agriculture, which accounts for 77%.

In Melbourne and other towns, the recycling is seen as use on landscape and recreational areas.

In Northern Territory, the main effluent reuse data are related to Darwin, Katherine and Alice Spring where oxidation pond treatment technology is mainly exerted, the treated water was supplied to Golf Course, Sport Ovals and Tree farm.

The end uses of reused water can be divided into five major categories.

Type of UseSub categorieslandscape irrigation

Fire protection

Irrigation of parks, schoolyards, residential landscaping

Irrigation of cemeteries,

highway landscaping

Irrigation of nurseries

Landscape impoundment

Household uses

Toilet &Urinal flushing

Garden irrigation

Clothes washing

Agricultural irrigation

Pasture for milking animals

Fodder and Fibre Crops

Orchards

Vineyards

Non food bearing trees

Food crops eaten after processing

Food crops eaten raw

Commercial and industrial uses

Cooling &air conditioning with cooling towers

Structural fire-fighting

Commercial Car Washes

Commercial laundries

Artificial snow making

Soil Compaction, concrete mixing

Environmental and other uses

Recreational pools with body contact (swimming)

Wildlife habitat-wetland

Aquaculture

Groundwater Recharge

Seawater intrusion barrier

Replenishment of potable aquifers

(Source from Table 5, Water Recycling in AU, 2004)

Case studies of water reuse scheme in Australia

Landscape Irrigation

A successful example in NSW is the disinfected effluent from St Mary's STP used in Dunheved Golf Club.

The club consumes 310 KL/day irrigation water on average and this recycled water has a great value during drought.

In ACT, the reclaimed water from Fyshwick STP has been used for over 10 years on the playing fields at the Duntroon Military College.

After upgrading, it will supply irrigation water for 40 Ha of public parks and sporting fields in Reid, Campbell and Australian National University.

In Victoria, the Craigieburn STP from Yarra Valley Water retail company in Melbourne supplies around 10% of its effluent to the Craigieburn Sporting Club.

In QLD, at Springfield, the 1.2 GL/yr recycled water from Ipswich Water's Carole Park STP is being supplied for the irrigation of public open spaces including road verges and median strips on the Springfield Parkway and to Bob Gibbs Park as well as grasses areas and gardens at Woodfield College.

In rural SA, the Port Augusta City Council established a sewer mining plant to produce raw sewage to Class B recycled water for irrigating surrounding parks and ovals.

In Northern Territory, the Darwin Golf Course STP (450 ML/year) serves the Marrara Sports Complex and Darwin Golf Club.

The Marrara Sports utilises the effluent direct from the golf course pond.

A similar case happened in the Pine Creek Waste Stabilisation Ponds which produce 8 ML/year recycled water for sports oval and rail corridor.

At Alice Springs, 580 ML/year effluent was used to irrigate open spaces, sports ovals and a tree lot.

In WA, the recycled water from Halls Head STP can be an alternative source to groundwater for irrigation of parks, gardens and ovals in the Peel Harvey region where 122 ML is recovered from the aquifer.

Meanwhile, it is also concluded that the treated wastewater had negligible health or environmental risks.

Household uses

In NSW, a residential third pipe scheme has been installed from the Rouse Hill STP which can treat 4.4 ML/day of recycled water with ozonation and micro-filtration processes.

It serves 12000 homes for their garden, lawn and toilet flushing uses.

The Olympic Park STP serves Olympic Park as well as Newington suburb for toilet flushing and washing clothes with 100% reuse rate involving processes like micro-filtration and reverse-osmosis.

There are some onsite recycling projects as well which often collect rainfall and stormwater on the roof and through their self-containing treatment processes and then use for toilet flushing, clothes washing and garden watering.

Examples are Michael Mobbs' House, Melbourne Domain Gardens, Queensland Agnes Water, Healthy Home at Gold Coast and New Haven Village and Mawson Lakes at South Australia.

Another successful example is Gold Coast Water Future, which has dual reticulation for gardens and toilets and rainwater tank water used for bathroom, laundry and hot water.

Recycling greywater and collecting stormwater are also seen as a highly efficient and potential scheme.

Indented Head on the Bellarine Peninsula in Greater Geelong area of Victoria is being a pilot demonstration of long term water reuse method related to this.

Agricultural Irrigation

Agricultural uses are big contributors to recycled water consumption in Australia.

In NSW, the Picton STP operated by Sydney Water supplies 135 Ha areas with a demand of 0.8 to 4 ML/d of recycled water for growing lucerne and ryegrass/clover and woodlot.

Overall, 97% of the nitrogen and phosphorous is recycled.

Similarly, the Gerringong-Gerroa sewage reuse scheme with tertiary treatment near Kiama is developed for pasture production in a 120 Ha dairy farm.

Another typical example is the NSW Barwon Region where many of towns are highly recycling treated effluent for irrigation, for example, there are 100% water reuse for irrigation of cotton in Gunnedah, 100% reuse for pasture and fodder irrigation in Manilla.

Another recent new scheme named as Shoalhaven Water's Reclaimed Water Management Scheme has convert dryland to dairy farm without charge to local dairy farmers, leading to a major boost in production and efficiency and minimising the need to use ocean outfall.

In Victoria, South East Water supplies agricultural areas from its Pakenham STP.

35 GL/year recycled water from the Western STP is being used for new intensive horticultural and agribusiness using a 38 km pipeline to the Balliang district to replace the current board acre dryland agriculture.

There are also some examples which indicate the advantage of the supply of reclaimed water to a number of users rather than one user, for instance, Tatura STP operated by Goulburn Valley Water has been upgraded supplied water for an adjoining farm area of 126 Ha as well as four neighbouring irrigation farmers, which minimizes the risk and allows long term environmentally sustainable reuse.

In Queensland, the South East Queensland Water Project delivers a high standard recycled water to irrigate Darling Downs and surrounding areas.

In regional areas, local agricultural industries in Wide Bay Water have considerable interest in and demand for recycled water.

They have been successfully applied recycled water in sugar cane farm which became the highest producing property in the district, and their aim was to achieve 100% recycling by 2007.

Another example is the Maryborough Effluent Reuse Scheme which irrigates sugar cane crops with effluent from Maryborough's Aubinville STP.

This scheme can reduce large amount of nitrogen and phosphorous entering into Mary River system and the STP can provide enough nutrients to the cane farm.

It also saves costs on treatment plant upgrades.

In South Australia, Virginia Scheme which is the largest formal recycling scheme has generally been successful in Virginia triangle horticultural area with 24 GL/year, meanwhile, the injection of 10 GL/annum water into aquifer is on trial which needs further community acceptance and approval.

Another innovative scheme has been developed by Willunga Basin Water Company to take Class B/C water to support viticulture industry.

In rural SA, the Septic Tank Effluent Disposal Scheme has been successfully applied which serves around 130,000 South Australians by STED networks treated over 18 ML of effluent for agriculture and irrigation uses.

In Tasmania, there were about 50 water recycling schemes in 2001-2002, most of which were applied to agricultural land.

New agricultural enterprises can be assisted by water recycling in future.

Commercial and Industrial uses

In NSW, there is an industrial recycled water use example at Australian Steel Mills, Port Kembla.

The Wollongong STP is to produce 20 ML/day tertiary treated water which contain less than 15 mg/L chlorine and 50 mg/L TDS for supply to Bluescope Steel.

Another successful example is Dora Creek STP operated by Hunter Water Corporation in Newcastle which provides 5 ML of recycled water per day for Pacific Power's Eraring Power Station.

This scheme saves $100000 over the annual operating costs and $1M over purchasing potable water.

In Queensland, the Wetalla STP in Toowoomba provides 1 GL/year effluent through an 80 km pipe to the Millmerran powerhouse for cooling, meanwhile, this plant is also developing a new 16 ML/day plant to produce further recycled water for coal washing, horticulture and agriculture etc.

In Gladstone, all of the wastewater is recycled as secondary effluent to industries such as NRG Power Station and Queensland Alumina, which can mitigate water strain during the drought.

There are some stormwater reuse schemes in SA such as the development of Parafield Wetlands for supply of recycled stormwater to GH Michell wool scouring factory with significant environmental and flood mitigation benefits as well.

Similar schemes are carried out by the City of Playford at Elizabeth and the Stebonheath flow control wetland project by Munno Para Council in industrial processes and amenity.

In WA, the first major water reuse scheme is the Kwinana Water Recycling Project which will produce 5 GL/year of water below 50 mg/L TDS for industrial use.

Environmental and other uses

The Lower Molonglo Water Quality Control Centre (LMWQCC) which is the main wastewater treatment facility for Canberra treats 90 ML of effluent daily and discharges parts of water to the Molonglo River and hence to the Murrumbidgee River, thus provides reused water for downstream users.

In Queensland, Caboolture Scheme is developed to improve the quality of the Caboolture River and Moreton Bay and to provide Council with a valuable source of high quality water suitable for potable type applications however the water is only used for non-potable reuse for turf farming, industrial non-potable use and irrigation of public areas rather than potable reuse because of the public rejection.

In rural SA, nearly 32% of effluents are reused.

The effluent from Adelaide Hills STP which discharges to creeks could be regarded as indirect potable supplies to downstream.

Groundwater recharge

Since groundwater usage contributes a lot to water consumption in WA at present, the recycled water used for groundwater recharge can be a promising project in the future.

However, before carrying out this kind of scheme, more detailed work have to be done such as public consultation and aquifer properties.

Groundwater recharge schemes can also be applied to other states and areas where water table is deep or groundwater usage is being exceeded its sustainability limit.

Current water reuse developments in Australia

Water sensitive urban design (WSUD) and integrated water cycle management (IWCM) are innovative ways of managing water supply, sewage and drainage systems with the integration of urban planning and development, local catchment considerations and water resources (Water Recycling in AU, 2004).

Anderson has conducted a study which indicated the potential to reduce the ecological footprint of water, sewage and drainage system by more than 25% when bringing together these concepts and associated evaluation methods (Anderson, 2003).

However, another study focused on water integration and sustainable process index (SPI) indicated that the maximum water reuse scenario has the highest footprint compared with no water reuse scenario and minimum SPI scenario because of the SPI contributed by the installation and operation of pumps.

The minimum SPI scenario takes advantage of reusing into processes which do not require pumps and there's no reuse in some treatment processes which can reduce the footprint of pipe installation (Ku Pineda, 2005).

Therefore, integrated and optimal management becomes urgent.

According to the guideline, WSUD and IWCM should form the basis of future water resource planning and management in Australia.

In June 2004, all of the Australian States and Territories except WA and Tasmania signed the 108 clauses of the Intergovernmental Agreement on the National Water Initiative with the Australian Government (Intergovernmental Agreement on the National Water Initiative, 2004).

The parties agreed to the establishment of a National Water Commission (NWC) to assist with the effective implementation of the agreement.

The actions included the evaluation of WSUD, review the institutional and regulatory models for achieving IWCM and develop national health and environmental guidelines (Radcliffe, 2005).

In Sydney, WSUD is being taken into account with new guidelines.

A recent example is the Water Conservation Strategy of Albury Water with the idea of harvesting and reusing storm water, rainwater tanks for garden watering, reuse of domestic water at site scale, at the same time, beneficial using of recycled water from local sewage treatment facilities, and returning reclaimed water for City then saling of reclaimed water to downstream irrigators at local scale (McGregor 2003b).

Besides, Sydney Olympic Park is also a leading demonstration of sustainable and integrated urban water management.

This scheme has incorporated collection and treatment of sewage and stormwater and supply of recycled water for non potable uses and has served 20,000 people.

It has the benefits of saving drinking water, no discharge of sewage effluent to waterways and ocean and controlling stormwater pollution thus it demonstrates that the large scale integrated urban water recycling schemes are feasible, reliable and beneficial for the community and the environment (Recycling Water for Our Cities, 2003).

Fig Tree Place Development is also an innovative WSUD in Newcastle in which rainwater tanks and cleansed stormwater have been incorporated into an integrated water management system for an urban redevelopment project.

The scheme includes gather all runoff from paved area, recharge cleansed stormwater to groundwater, supply 50% of the in house needs for hot water and toilet flushing and provide surplus water for irrigation and bus washing at adjacent area.

A Greenfield study at Healthwood in QLD demonstrated an integrated urban water management system that using rainwater, stormwater and reuse water for non potable purposes lead to 77% in the import of potable mains water, 25% reduction in the export of sewage and 27% in stormwater.

It would be likely to be a more sustainable development than conventional water supply infrastructure.

In SA, a mining town named Roxby Downs also presents an integrated water cycle management incorporating groundwater, desalination, storm water and sewage effluent recycling.

This program saved the community $200,000 annually over the purchase of potable water (Kroemer 2003).

In Perth, WSUD is espoused with the management of stormwater that effective stormwater reuse occurred via the Coastal Plain groundwater system (McFarlane 2003).

The Western Australian State Water Strategy aims to achieve 20% reuse of treated wastewater by 2012.

The objectives include the water reuse in industries, golf course, horticulture, possible indirect potable reuse and establishing a western salt water barrier.

In future water reuse plans, public consultation and community education are very important since there were some cases of unimplemented water reuse schemes due to the public objections.

New technologies

New technologies have also been applied.

In NSW, the BASIX which is an online assessment tool to make sure new homes meet the sustainable performance indices including water use efficiency, rainwater and stormwater harvesting.

And a small scale compact automated multiple water reuse unit based on micro-filtration and reverse osmosis developed by CRC was suitable for use on site and has potential for use in high-rise buildings (Garman and Borton, 2003).

In ACT, a newly developed compact wastewater treatment unmanned technology has been designed to treat municipal and industrial wastewater containing biodegradable organic pollution.

This technology can be sized for 1500 to 30,000 people.

The trial on urban Canberra has been approved to be successful.

In QLD, the Model for Effluent Disposal by Land Irrigation (MEDLI) has been developed to facilitate the development of appropriately sized infrastructure for recycled water use for irrigation.

Several new treatment and disinfection technologies are offering significant benefits which can minimize the health risk while maximize the cost effectiveness.

Microfiltration and reverse osmosis are increasing being used as tertiary treatment processes which are suitable for office and apartment buildings installation.

Membrane bioreactors are substitutes for sedimentation and filtration processes of secondary treatment.

They can be installed in small capacity industrial plants with a significant reduction in total cost compared to traditional oxidation ditch or activated sludge processes.

Membrane bioreactors have already been applied in city of Key Colony beach in Florida (Pierre, 2009).

In addition, UV and ozonation are effective disinfection methods that do not create disinfection by products compared with chlorination.

Constructing wetlands and harvesting stormwater are also good technologies which can mitigate the storm and provide a low cost alternative to tertiary biological nutrient removal plants.

New waste stream separation technologies such as low flush toilets, dry composting toilets with urine separation allow the collection of 50-85% of the major plant nutrients currently present in sewage and reduce the odour and leachate issues (Ashbolt, 2004).

Moreover, the existing sewer system will handle only greywater, 50% of which will be used as a local water source with treatment to drinking water standard allowing direct reuse in the existing distribution system (Recycling Water for Our Cities, 2003).

Furthermore, other advanced monitoring technologies on warning of treatment system failures or efficient garden watering schedules can also be exerted in the future.

Future plans

In NSW, according to the 2006 Metropolitan Water Plan by NSW Government, large recycling schemes are planned and recycling water will provides 12% of greater Sydney's water needs (nearly 70 billion litres per year) by 2015 (NSW Government website).

It also noted that over the next 5 years, Sydney Water expected to save additional 8 GL through several business and residential recycled water projects.

In Victoria, the Government has published the white paper-Securing our Water Future Together which stated a comprehensive integrated water strategy for Victoria.

This report stated the future challenges of climate change and water shortage circumstances in the next 15 years and recognised a more sustainable way that urban water supplies should comprise all available water resources including recycled water, stormwater, rainwater and greywater.

It also stated the government's planning projects, investment and water pricing in the long term.

Eight committed recycling projects in Melbourne are outlined and a further six projects are listed as under investigation along with several rural irrigation proposals (Radcliffe, 2005).

In QLD, the EPA Queensland issued the document entitled Queensland Water Recycling Guidelines in 2005.

It stated the recycled water management plans considering integrated economic, social, environmental and health issues.

Meanwhile, the Brisbane City Council has issued a water smart strategy which established a water policy and regulatory framework for city plan.

And from the statement of strategic outcomes, by 2012, Brisbane will be recognised as Australia's most water smart city where the drinking water consumption will be slashed up to 60% by delivering alternative resources such as stormwater harvesting, wastewater recycling and seawater desalination.

Due to its sub-tropic climate, stormwater harvesting is promising and beneficial and importantly, the target is 100% of all recycled water to be used sustainably at the same time (Radcliffe, 2005).

In SA, the Government is planing for a large scale expansion in recycling of storm and wastewater with the goal to recycle 45 per cent of urban wastewater for use in agriculture, industry and parklands and double the amount of Adelaide stormwater harvested each year to 20 billion litres by 2013 (Theage website).

It is estimated that wastewater reuse can reach to 30,000 ML per annum by 2025 (Radcliffe, 2005).

The detailed water strategy for Adelaide from 2005 to 2105 can be found in a document entitled Water Proofing Adelaide.

The detailed benefits from water recycling and integrated water cycle management were also mentioned.

In WA, More than 70% of Perth's water is sourced from groundwater sources (Blair, 2004).

State Water Strategy set a target of achieving 20% water recycling by 2012 (Radcliffe, 2005).

Due to large consumption of groundwater, there is a potential for use of the aquifers to reduce costs.

A recognised major benefit of using aquifers in a water recycling scheme is that they are a cheap way of storing large volumes of water.

Aquifers could also be used to transport water to customers, and this could replace a costly reticulation scheme (Blair, 2004).

However, whether the scheme is viable or not still depends on customers' attitudes to water recycling and their willingness to pay costs.