Howard Lowndes -- Computer Administrator ================================================================ DEVELOPMENT OF A MULTI-FACETED WASTEWATER MANAGEMENT SCHEME FOR A REGIONAL CITY IN AUSTRALIA Daryl McGregor, Manager Design Services Albury City Council Albury City Council, 553 Kiewa Street Albury, New South Wales, Australia
The Water Reclamation Project involves :- construction in stages, of a new activated sludge treatment facility (8 ML/d initially; 30 ML/d ultimately), incorporating biological/chemical nutrient removal, provision for sand filtration and UV disinfection. reuse of reclaimed water via re-established wetlands and irrigation of 375 hectares of riverine and commercial woodlots and 6 hectares of local recreation areas.
The total scheme cost is estimated at A$35 million for Stage 1 and A$57.5 million for the ultimate development.
Complementary initiatives include:- expansion of user pays water rates to reflect the true cost of the resource. maintenance of stringent trade waste policies to minimise discharge of heavy metals and other toxic compounds to the sewerage system. ongoing sewer rehabilitation programmes to minimise stormwater ingress. construction of urban stormwater runoff sedimentation basins, retarding basins and water quality control ponds. encouraging the use of dual flush toilets and low flow shower nozzles in all new buildings. improved phosphorus removal facilities and implementation of a community based phosphorus awareness and reduction campaign.
KEYWORDS:- wastewater, treatment, beneficial re-use, reclaimed water, phosphorus removal, nutrients, wetlands, woodlots, biological nutrient removal, stormwater.
The total discharge from ALL Australian rivers is about the same as that for the St Lawrence (Canada) and about half of that for the Amazon. In the Murray Darling Basin, where Albury is located, the total discharge is about 10% of the Danube.
Continent Rainfall (millimetres) Runoff (millimetres) Runoff as a Percentage of rainfall South America 1350 480 36 Africa 710 180 25 North America 660 250 38 Asia 640 200 31 Europe 610 230 38 Australia 420 50 12 TABLE 1: AVERAGE RAINFALL AND RUNOFF OF THE CONTINENTS SOURCE: Water and the Natural Resources Water Resources Commission, Australia
AREA 1,058,800 square kilometres or 106 million hectares Equivalent to 14% of total area of Australia RIVERS 3 Main Groups Darling River and Tributaries Murrumbidgee River and Tributaries The Murray River and Tributaries FARMING Basin contains 42% of all Australian Farms Includes: - = Australia's crop land - = our sheep population - = our orchards - < our cattle - > our irrigated crops and pastures POPULATION 1.8 million people The Basin is obviously important to Australia's on-going welfare, wealth and prosperity. TABLE 2: THE MURRAY DARLING BASIN: A FEW FACTS SOURCE: Murray Darling Basin Commission
Only recently, and largely as a result of a disastrous blue-green algae outbreak along 1,000 kilometres of the Darling River in 1991-'92, have we begun to realise how precious our water really is and how vulnerable we are to a lack of supply.
Currently, Albury City Council is proceeding with a strategy to develop the most sophisticated, integrated wastewater treatment and water reclamation project in inland Australia. A range of urban housekeeping strategies are also being implemented under an all embracing philosophy of "Co-operating for a Cleaner River".
The aspects of the strategy which will be developed in this paper include:- nutrient control philosophies, including development of a biological process for phosphorus removal. the City's overall wastewater management strategy. employment of complementary initiatives, including measures for source minimisation, particularly of phosphorus. stormwater management objectives and initiatives. future developments.
However, this solution, as a universal panacea, has not been fully evaluated in a number of aspects, including:- consideration of the real value of reclaimed water as a resource. potential for detrimental impacts of land disposal schemes, including overland discharges, uncontrolled discharges to groundwaters, potential impacts associated with elevating water tables etc. potential for long term irreversible environmental damage. difficulties in monitoring and controlling such schemes.
Since 1919, Albury has discharged its treated water to the Murray River. The City entered the arena of biological nutrient removal in 1987 with the conversion of an existing intermittent cycle extended aeration activated sludge plant to a continuously aerated, three stage BNR process. Over the eight years of operation this plant has averaged 76% removal of total phosphorus and 64% total nitrogen removal.
Influent and effluent analysis results for the plant are summarised in Table 3 below.
Sept '87 to Oct '88 Nov '88 to Jul '91 From Aug '91 Parameter Average No. of Samples Average No. of Samples Average No. of Samples INFLUENT Flow 11 ML/d - 13.5 ML/d - 14.2 ML/d - COD 472 65 578 122 486 95 SS 247 46 244 128 260 63 pH 7.2 units 51 6.7 units 128 7.3 64 TKN 39 16 38 24 41 21 NH3-N 29 52 26 121 26 60 Ortho-P 6.2 65 6.5 125 - - Total-P 9.4 28 9.4 67 8.4 40 EFFLUENT COD 38.2 73 55 58 - - SS 11.4 45 15.1 133 18.1 104 TKN 8.2 20 16.1 52 18 4 NH3-N 6.1 99 11.7 129 12.1 105 NO3-N 1.1 74 0.3 109 0.25 14 Ortho-P 2.7 97 1.2 137 - - Total-P 3.3 33 1.7 66 2.1 105 1. All units in mg/L unless shown otherwise 2. All samples are 24 hour composites
The selected option, shown schematically in Figure 1, involves:- construction in stages of a new activated sludge treatment plant (8 ML/d initially; 30 ML/d ultimately) incorporating biological and chemical removal of nutrients with provision for addition of sand filtration if subsequently found necessary. (Initial aim of 1 mg/L effluent phosphorus concentration, reducing to 0.5 mg/L never to be exceeded; 0.3 mg/L as a 90 percentile). retention of the existing Activated Sludge Plant (12 ML/d) augmented by chemical nutrient removal, again with provision for addition of sand filtration if found necessary. development of woodlot irrigation for summer utilisation of reclaimed water (involving 375 hectares of land). development of irrigation schemes for local recreation areas (involving 6 hectares of land). construction, initially, of 35 hectares of wetlands to serve as enhanced treatment modules providing a suitable aquatic system and environment for the re-establishment of wetland plant species and providing habitat for water based colonies. The Estimated Capital Cost to implement Stage 1 of the Strategy is $35.22 million with Annual Costs (in year 2000) of $3.29 million. The ultimate scheme development (involving construction of a further two stages in 2010 and 2019) will cost approximately $57.5 million (based on 1993 prices).
[By way of comparison, the option involving best available technology for high standard wastewater treatment, with continued discharge of the reclaimed water to the Murray River would have a Stage 1 Capital Cost of $28.14 million (Annual Cost $2.91 million) and an ultimate cost of $48.6 million.]
4.2 Objectives of Scheme
The objectives of the Water Reclamation and Reuse Project are to:- provide wastewater management facilities capable of securing the future growth and economic development of Albury well into the next century. provide an improvement in Murray River water quality that will not be eroded as the population grows. replace essential infrastructure that has reached the end of its service life. ultimately relocate all sewage treatment facilities to a site where adequate buffer zones can be maintained with no risk of urban encroachment. contribute to the conservation and enhancement of the environment of the Murray River floodplain by re establishing and providing the resources to actively manage riverine wetlands and floodplain forests. enable the recurrent operating costs of the project to be offset to some extent by sustainable production of timber and associated products.
The new plant at Nursery Valley will incorporate advanced sewage treatment technology including biological and chemical nutrient removal and ultra-violet disinfection; resulting in a much higher standard of treatment than is currently provided. The EPA licensed discharge point will be at the outlet from the plant and prior to any reuse. The water quality standard required at the licensed discharge point will be such that no deleterious impact will be caused even if discharged to environmentally sensitive waters. Council believes that this is the responsible level of pre-treatment for any land or water based reuse of reclaimed water.
4.3 Proposed Beneficial Re-uses of Reclaimed Water
As outlined above, the water reclaimed by the treatment plant(s) will be utilised for local beneficial reuse. The reuses proposed are:- the rehabilitation and expansion of degraded riverine wetlands on the floodplain, ultimately 80 ha in area. the establishment of 86 ha of irrigated commercial woodlots at Nursery Valley. the establishment of 26 ha of irrigated commercial woodlots in West Albury around the existing Kremur Street Treatment Works. the progressive establishment of an irrigated River Red Gum floodplain forest adjacent to and complementing the wetlands. Ultimately 263 ha in area. irrigation of 6 ha of playing fields in West Albury.
Additional benefits that will flow from the implementation of the project will include:- the re establishment of riparian zones along all the streams, drainage lines and water bodies within the project area. the establishment of wildlife corridors linking Nursery Valley and the Nail Can Hill area to the River. extensive non-harvestable screen plantings around the publicly accessible boundaries of the woodlot areas. re-vegetation of a significant proportion of Nursery Valley that has been previously cleared and has a high erosion risk potential. the establishment and progressive development of a wetlands amenities park providing access to wetlands, boardwalks, bird hides and interpretative trails. the ultimate incorporation of the wetlands, suitable re-vegetation areas and the floodplain forests into the Albury-Wodonga Regional Parklands.
In order to deliver the Design and Documentation of the Project (with a budget of A$2.4 million), Council has entered into a joint venture arrangement with the NSW Public Works Department with the author designated as the Project Manager.
4.4 Wetlands Proposal
The primary objectives in developing the wetlands proposal are:- to provide a beneficial reuse of the reclaimed water by establishing an ecological resource for the region with development primarily for conservation purposes whilst affording educational and controlled recreational opportunities. to maximise water purification by utilising the natural abilities of wetlands to filter pollutants. to provide a measure of system backup as a buffer against unforeseen treatment plant operational difficulties. to enable monitoring and assessment of the treatment effectiveness (and efficiency) of wetlands, particularly with respect to receipt of highly treated reclaimed water. The operational objective of the wetlands will be to manage the hydrological regime of the system to emulate the pattern which would have occurred in the past, prior to river regulation; that is winter-spring flooding followed by a gradual lowering of the water over the summer-autumn. The lowering of the wetlands will be achieved by using the water for irrigation of woodlots and recreation areas.
4.5 Irrigated Woodlots Proposal
The aim of the woodlot/recreation area irrigation schemes is to not only maximise the beneficial reuse of the reclaimed water, but also to minimise, in total load terms, the ultimate discharge of nutrients to the river. Therefore, it is proposed to direct water from the wetlands for summer irrigation of approximately 6 hectares of recreation areas and up to 375 hectares of opportunity woodlots. Irrigation with highly treated effluent/reclaimed water will, to a large extent, address concerns about phosphorus accumulations in the soil profile of irrigation areas. Based on Stage 1 design flows of 20 ML/d (ADWF) approximately 40% of the reclaimed water can be effectively utilised on the areas identified based on balancing peak monthly, irrigation season, water supply demand with average dry weather flow.
5.0 COMPLEMENTARY STRATEGIES
Council is also implementing a range of complementary actions as part of its commitment to an on-going urban pollution reduction strategy. Actions to be continued or implemented include:- to continue stringent trade waste policies to ensure minimal heavy metals and other toxic compounds are accepted into the sewerage system. to continue sewer rehabilitation programmes to minimise stormwater ingress. to continue construction of urban stormwater runoff sedimentation basins, retarding basins and water quality control ponds. to encourage the use of dual flush toilets and low flow shower nozzles in all new buildings. operation of alum dosing facilities on the activated sludge section of the existing Sewage Treatment Plant to further improve phosphorus removal. (Implemented in 1994) the development of a community awareness programme aimed at reducing the discharge of phosphorus from all sources in the urban environment, with particular emphasis on encouraging the use of phosphorus free detergents.
6.0 THE PHOSPHORUS AWARENESS AND REDUCTION CAMPAIGN
6.1 General
A major initiative has been the development of a Phosphorus Awareness and Reduction Campaign. The campaign was launched in 1993 with the joint aims of increasing community awareness about the sources and impacts of phosphates and the measures that can be taken at a local level to reduce the amount of phosphorus in the urban environment.
From a treatment point of view the aim is to minimise the amount of phosphorus in the raw sewage (emanating from detergents) with the aims of:- minimising the cost of chemical addition to achieve required effluent phosphorus levels. providing a better balance between influent COD, Ammonia, TKN and total-P such that the biological removal processes are optimised.
The campaign has involved the preparation of a promotional video, regular Newsletters, a campaign poster, static displays, a schools programme, a guest speaker programme to community groups and service clubs and a direct mail brochure to every household in Albury-Wodonga. Television and other media commercials have been an important aspect of this intensive on-going campaign.
The program developed in Albury has now been adopted as a model for similar campaigns across New South Wales and ultimately it is hoped that a national campaign will ensue.
6.2 Campaign Monitoring
Two methodologies were adopted to measure and monitor the programme's performance:- i) Laboratory Analyses and the "Phos-Watch" Graph Phosphorus inputs to the Albury Sewage Treatment Works were measured on a daily basis and compared with pre-campaign levels. The results were graphed as weekly averages and published (weekly) in the local press and included in the weather forecast on local television. The levels were also included in local radio news bulletins. A copy of the "Phos-Watch" graph from October 1993 to June 1995 is reproduced in Figure 2. The graph indicates that the campaign has been very successful. From a pre-campaign level of 150 kgs of phosphorus per day, the level dropped to a low of 108 kg/day, but stabilised at around 120 kg/day. This represents a 20-28% reduction in the amount of phosphorus emanating from laundry detergents.
Laboratory analyses of all known detergents were also carried out by Council's Laboratory Staff and this information was reproduced in a leaflet which was sent to every residence in Albury-Wodonga in March last year. These detergent lists have now also been used (to provide consumer information) by a number of other organisations throughout Australia.
ii) Market Research
A Melbourne based research company, Boston Partners, was engaged to carry out questionnaire surveys and measure the success of the campaign. Three rounds of market research were carried out; in November 1993, May 1994 and November 1994. The results of this research are reproduced below:-
Nov. '93 May. '94 Nov. '94 Awareness of link Between Phosphorus and blue green algae less than 10% 96% 94% Changed Detergent Brands as result of Campaign - 21% 31% Doing Something different as result of Campaign - - 50% Using phosphorus free laundry Powders - 25% 28% Using low phosphorus (less than 5%) Powders - 41% 49% Using high (greater than 5%) content Powders - 36% 30% Wash Cars on lawn - 45% 52% Care in Fertiliser Use - 10% 14% Preventing Run-off of Manure - 10% 14% Preventing organic matter from entering drains - 17% 22% Av. number of washing loads per week - 6.3 5.4
On Eight Mile Creek, the Albury-Wodonga Development Corporation has in the past, built a number of retarding basins. Council in partnership with the Corporation has recently completed a major pollution control project at the discharge end of the Creek. The works will enable the first flush of major storms to be diverted to an existing wetlands on the flood plain of the Murray River. It is anticipated that this facility will significantly decrease the amount of nutrients, particularly phosphorus, in discharges to the river. The nutrient load in the drainage discharge will be absorbed and utilised by the wetlands.
South Albury drainage to Mudges Canal is directed to a large sedimentation basin, Brown's Lagoon. This lagoon is currently being expanded in volume with development of another basin just down stream. Brown's Lagoon is extremely efficient in collecting sediment in the stormwater and hence significantly reduces the nutrient load on the River. Trash and other gross pollutants are prevented from reaching the River at the Levee Bank Pump Facility.
A further wetlands facility is planned for Mungabareena Reserve to treat stormwater from another major drain, the Lavington Outfall.
The elements of this future strategy, planned for implementation in stages from 1998, include:- development of new, high technology treatment facilities incorporating combined biological/chemical removal of nutrients with provision for the addition of sand filtration, if subsequently required. development of woodlot irrigation areas on the floodplain of the Murray River. development of irrigation schemes for recreation areas. utilisation of wetlands for final polishing and to establish an ecological resource for the region. commitment to a range of complementary, wastewater management issues including urban stormwater treatment and source minimisation of pollutants, particularly phosphorus.