Water Journal March 1987

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water FEDERAL PRESIDENT M. Dureau , Kent Instruments P/L P.O. Box 333, Caringbah 2229 5252811.ISS N 0310-0367Official Journal AUSTRALIAN WATER AND WASTEWATER…
water FEDERAL PRESIDENT M. Dureau , Kent Instruments P/L P.O. Box 333, Caringbah 2229 5252811.ISS N 0310-0367Official Journal AUSTRALIAN WATER AND WASTEWATER ASSOCIATIONVol. 14, No. 1, March 1987FEDERAL SECRETARY G. Dooley, Box A232 P.O. Sydney Sth ., 2001.FEDERAL TREAS URER J . D. Molloy , C/- M.M.B.W. 625 Lt . Collin s St., Melbourne, 3000.BRANCH SECRETARIES Canberra , A.C .T. M. Sharpin , Willing & Part. ,P.O. Box 170, (062) 815 811Curtin , A.C.T. 2605.New South Wales M. Hannon, P.W.D. Sewerage Branch, 74 Phillip St. , Sydney, 2000. (02) 228 4488CONTENTS Viewpoint .............. ...... . .... ............... .... ...... .5Association News, Views and Comments ....... ......... ........ .6IA WPRC News .............................................. .9Index-Water Volume 13, 1986 . ............................ . ... .10Studies of the Trophic Status of the Brisbane River Estuary -A. J. Moss . . .... . ..... . ........................ '. ...... .11Mixing in Anaerobic Sludge Digesters -C. K. Hertle and M. L. Lever . . .... ........................ .16Water Management in Open Cut Coal Mining-A Case Study - T. C. French .............. ... . ............... . ........ .22People and Contracts ................ . .. . .................... .25Experience with Manganese in Queensland Water Supplies -E.T. Loos . . ... ...... ... . ........................ ..... .28Phosphorus Precipitation with Pickle Liquor at Glenfield WPCP -I. Lim and T. Nguyen ................................... .33Victoria J . Park, Water Training Centre, P.O. Box 409, Werribee, 3030. (74 1 5844)Queensland D. Mackay, P.O. Box 412, West End 4101 . (07) 844 3766)tSouth Australia A. Glatz, State Water Laboratories, E. & W.S. Private Mail Bag , Salisbury , 5108 . (08) 259 0243Western Australia Dr B. Kavanagh , Water Auth . of W.A. , P.O. Bo x 100, Leederville 6007 (09) 420 2452Tasmania G. Nolan , G.P.O . Box 78A, Hobart 7001 (002) 44 0600Northern Territory M. Burg ess, P.O. Box 37283 Wlnn el lie, N.T. 5789. (089) 39 7885EDITORIAL & SUBSCRIPTION CORRESPONDENCE G. R. Gollin, 7 Mossman Dr., Eaglemont 3084 03 459 4346COVER PICTURE The cover photo shows the new water treatment plant on the West bank of the Brisbane River at Mount Crosby. The first stage with a capacity of 250 ML/d was opened by the Lord Mayor, Alderman Sallyanne Atkinson on the 29th October, 1986. The treatment plant wh ich utilises the Dissolved Air Flotation process is the largest application of this process in Australia and was designed and constructed by the Brisbane City Council. Picture and front cover donated by the Brisbane City Council. The statements made or opinion s expressed in 'Water' do not necessarily reflect the views of the Australian Water and Wastewater Association, its Council or committees.WATER March, /98 7ASSOC/A TION • projects • use of new communications media • activities in developing countries • any other activity or initiative relevant to IA WPRC's international role in water pollution control. The ANC Executive will be preparing a submission and members of ANC (and A WW A) are invited to send suggestions to the Secretariat in Sydney .FUTURE PLANNING ANC Following the meeting with A WW A Exec. in March, the ANC will be formulating proposals for the future activities of the ANC. As the timetable for ·Biennial Conferences of IA WPRC is determined well in advance, it is unlikely that Australia would be approved as the venue until about the year 2000. Conference activities in the interim are therefore likely to be on the lines of the forthcoming co-sponsored Brisbane Conference or joining with regional ANCs in holding a regional conference. There are, however, other opportunities for members to participate in international activities as indicated by the list to be considered at Munich . Some Australian members are already involved with Task groups and Specialised Groups. The Executive would welcome any suggestions for ANC activities, bearing in mind that they need to be international or cooperative with national organisations such as A WW A.•NEWSPlanning for this Conference on Water Quality and Management for Recreation and Tourism is the responsibility of a local committee representative of A WW A and IA WPRC, which reports to the A WW A Council, the ANC and IA WPRC London as well as the Queensland Branch Committee on its progress. The venue will be Griffith University at which low cost accommodation will be available. Up market accommodation will also be available in the city. There will be a mix of 'scientific' and 'management' papers and workshops . Arrangements for keynote speakers (including overseas specialists) have been made and a brochure calling for offers of papers and interest in attending has been widely disseminated . It is hoped to limit the registration fee to around $300 but still have a conference to international standards.New Journal A quarterly journal 'Water Quality International' will commence in 1987. Articles concerning new projects, new processes, innovations, etc are invited from the Australian Water Quality area. Australian manufacturers marketing overseas may take advertising space in the Journal. Members receive a lOOJo discount. Consultants wishing to practice internationally may be listed in the Journal•COMMENTfor an annual fee, again with lOOJo discount for members. Enquiries regarding the Journal should be addressed to the Journal correspondent (Leon Henry) or to the Secretariat.Proposals for New Specialist Groups The following proposals are being considered by IA WPRC: Acid Rain, Agroindu s tries, Compu ter Technology, Estuarine and Coastal Pollution, Flocculation and Filtration, Industrial Water and Effluent Management, Marine Disposal, Macrophytes in Water Pollution Control, Wastewater Reclamation.Existing Specialist Groups Health Related Water Microbiology, Instrumentation and Automation, Phosphate Removal, Urban Storm-Water Drainage, Systems Analysis, River basin Management, Large Wastewater Treatment Plants, Tastes and Odours , Anaerobic Digestion, Monitoring and Control of Contaminants .Activated Sludge Model A 76 page report by the Task Force on Mathematical Modelling for Design and Operation of Biological Wastewater Treatment is available for perusal from the Secretariat.L. HENRYWATER VOL. 13, 1986No. 1 - MARCH Australia's Overseas Aid Programme . .. ..... . . R. F. Goldfinch Water Supply for the Singida Region, Snowy Mountains Tanzania ... . .. . ... ..... ... . .. . .. Engineering Corporation Water Engineering in Asia - Problems and Solutions ..... . .... .. .. .. . .... . ... .... . . F. R. Bishop Overseas Projects Corporation of Victoria 'Water' - Index, Volume 12, 1985 Combined Sewer Implementation D. C . Hanrahan and Project - Shanghai .. . . . . .. . . . . . . . ... ... . .... M. F . Oddie Flow Measurement and Analysis in the Chang Jiang . .. ..... . .. . ..... .. .. . .. . . .. . .. ... . . . T . Beer Wastewater Disposal in Three Regional R.H. Edwards Cities in Thailand .......... ..... . .. .. .... and M. J. Hazell Village Water Supplies in Burma .. .. . ..... . ... H.F. Eggington Historical Malacca - Sewerage and Urban Drainage Strategies J. H . Crockett, T . J. Fricke, for the Future . .. ....... . .. . . . J. B. Murray and R. H. Smith No. 2 - JUNE Science and Technology in the Victorian Water Industry ..... . .... ... .. .. ... .. W. M . Drew The Olympic Dam Mining Project P. Nadebaum and - Water Management .... .. .... .. ... ... . ...... T. Amiconi Australia's Hydraulic Infrastructure A.G. Longstaff and - Planning for Renewal . .. . . . . ... . .. . .. .. . .. . F . B. Barnes Staged Oxidation of Sulphides in Wastewater Using Mechanical G. Williams and Aerators ..... . .. . ......... ........ . ... .. : ... . R. G . Shaw WATER March, 1987VIEWSCo-sponsored Conference Brisbane, July 10-15INDEX10•No. 3 - SEPTEMBER Augmentation of the West Pilbara Water Supply-The Harding R. J. Wark, G. C. Meink Dam Project .. .· . . . . . . . ..... . ....... . .. .. . and C . R. Tenby Industrial Waste Disposal in Victoria - The M.M.B.W. Proposal Cape Peron Environmental P. N . Chalmer and Monitoring . ..... . .. . ... . ....... .... ..... L. W. Edmonds Swampy Odour in the J.E . Wajon, B. V. Kavanagh, Drinking Water of R. I. Kagi, R. S. Rosich, Perth, Western Australia . . .. . . .. R. Alexander and B. J. Fleay Water Hammer A lleviation -A Y. H. Ng and Western Australian Case Study . . .. . .......... .. . A. J. GaleNo. 4 - DECEMBER Protecting Alice Springs S. Hancock, T. Fricke, Water Supply .... . . .. J . Crocket, R. Freyling and A . Bowden Water for Leisure . ... . .. . ..... . .. .. ..... . ... . .. J. Lawrence Rum Jungle Rehabilitation Department of Project - Update . . . . .. ........ .. . .. . . .. Mines and Energy Water Resources of the Northern Territory - Management at the Cross-roads ...... H. Watson A WW A - Preliminary Stategic Plan, 1987 to 1991 Water and Sewerage Administration in The Northern Territory - A WWA Submission to the N .T . GovernmentSTUDIES OF THE TROPHIC STATUS OF THE BRISBANE RIVER ESTUARY A. J. Moss ABSTRACT The Brisbane River estuary passes through the centre of the Brisbane urban area and receives a large number of polluting discharges . Concern over the effects of planned increases in these discharges prompted an intensive water quality study of the estuary in 1983-1985. This paper presents results relevant to the estuary's trophic status together with comparative data from unpolluted Queensland estuaries. The main finding was that although much of the Brisbane estuary is highly nutrient enriched, due to adverse physical conditions, principally high turbidity, few if any significant eutrophication effects are apparent. Possible consequences of increased nutrient loading are discussed.INTRODUCTION The Brisbane River estuary passes through the middle of the Brisbane urban area and, together with its tributaries, receives a large number of polluting discharges. Up to 1983, the Water Quality Council, the State Government body responsible for maintaining water quality in Queensland waters, had carried out low frequency monitoring of the estuary. Results showed that while existing dissolved oxygen levels were generally satisfactory, much of the estuary was significantly nutrient enriched. Little was known of the effects of these high nutrient levels but no serious eutrophication problems were apparent. At that time the Water Quality Council was faced with the requirement of setting effl uent quality standards for two large planned treated sewage discharges to the Brisbane estuary and for this reason further studies were initiated. These included an 18 month intensive water quality study and some computer modelling of the fate of effluents . The main aims of these studies were: • to predict the effect of the additional BOD loads; • to examine the current trophic status/ behaviour of the estuary; and • to predict the effect of increased nutrient loads. This paper is concerned mainly with the second aim consideration of the estuary's trophic status - but includes some discussion of the possible effects of increased nutrient loading.DESCRIPTION OF AREA The Brisbane estuary (Figure 1) extends a distance of 84 km from its confluence with Moreton Bay to its tidal limit. It has one major tributary, the Bremer, which enters 73 km upstream . In its lower reaches the est uary is 300-400 m wide with mid channel depths up to 12 m. In the up per estuary, widths decrease to 100-150 m but depths up to 12 m persist as far upstream as 70 km, decreasing thereafter. For much of its length the estuary is characterised by large tidal flows and high turbidity. The lower estuary passes through the Brisbane urban area while further upstream it enters a less densely populated semi-rural zo ne. With the recent completion of the large Wivenhoe Dam, natural inflows from its major upstream catchment (55% of the total) are now severely restricted. Inflows from its other upstream catchments, the Bremer River (16% of the total) and Lockyer CreekAndrew Moss, B.Sc.(Hons), M.Sc. is senior biologist with the Water Quality Section of the Queensland Department of Local Government. He joined the Department in 1974 and since then has been involved in a wide variety of water quality in vestigations.A. J. Moss(18% of the total) are less restric;ted but as both contain areas of intensive agriculture these inflows may be highly turbid. The lower estuary is subject to continuous dredging for navigation purposes while in the mid and upper estuary there is extensive sand and gravel extraction .MONITORING Intensive water quality monitoring of the estuary was carried out between October 1983 and March 1985. Dissolved oxygen, salinity, pH, temperature (depth profiles) and nutrients (surface samples for organic N, NO3-N, NH 3-N, filterable reactive P[FRP] and total P) were measured monthly, while surface chlorophyll and Secchi depth were measured twice monthly. A total of 27 sites covering the entire estuary at approximately 315 km intervals were sampled on each run. Net samples for phytoplankton were collected monthly at 10 sites. To ensure uniformity, sampling was always carried out at high tide. Sites and other features in the estuary are located in terms of distaflce (km) from the estuary mouth.ANN UAL NUTR I EN T LO AD= 100 000 Kg / Yr NorP 0(0~N"MORETONluggage Pt0STPFigure 1. Location map including major point source nutrient inputs. WATER March, 1987IIRESULTS AND DISCUSSION --Location of f res hwa t e,/salfwafer inter face - - - Secchi depth <: 0·2m • loca tion of turbidity maximum >< Location of secondary turbidity maximumHydrodynamic and Salinity Regime The nature of estuarine hydrodynamic and salinity regimes were strongly influenced by the characteristics of their freshwater inflows. In southern Queensland, climatic conditions give rise to streamflows that are typically episodic, long low flow periods are interspersed with occasional large storm flows. Low flow periods of 2-3 months are not unusual. Thus for much of the time, southern Queensland estuaries fall into Bowdens' (1980) category 3, that is, estuaries in which the ratio of daily inflow volume to tidal prism is less than 1:100. Such estuaries states Bowden, are characterised by a vertically well mixed water column and absence of a salt wedge. The Brisbane estuary clearly falls within this category. Inflows are usually very small in relation to the size of the estuary and salinity monitoring results indicate the water column is vertically well mixed throughout except immediately following storm inflows . Because freshwater inflows are so relatively small, water movement in the Brisbane estuary is dominated by tidal effects and these provide the only significant mechanism for effluent dispersion. Mean tidal range at the mouth is 1.5 m and there are considerable tidal flows in much of the estuary (peak mid estuary tidal velocity for an average tide is approximately 0.65 m/ s). Such flows can achieve significant dispersion of pollutants but their physical loss from the estuary can only occur through net water exchange at the mouth. Water Quality Council modelling studies indicate that such exchange is only significant in the lower 7 kms of the estuary. Loss of pollutants from further upstream can only occur via dispersive exchange with the lower estuary, a relatively much slower process. Thus, effluents entering the mid and upper reaches are likely to have long residence times and a significant degree of assimilation may occur in the estuary itself. The low rate of new downstream advection in the estuary is illustrated by the fairly even distribution of nutrient concentrations, Figure 3, around the location of the large Donaldson Road sewage treatment plant discharge (47 km) . Salinity during the study period is shown in Figure 2, expressed as the location of the saltwater/ freshwater interface. Salinity at the estuary mouth was always above 30 g/ L. Major freshwater inflows occurred during December 1983 and January, July and November 1984. Figure 2 indicates that while interface can shift fairly readily between 25 and 60 km, penetration of saltwater further upstream is relatively slow. TurbidityTurbidity in estuaries is a function of external particulate inputs and internal cycling and resuspension processes. A signficant fraction of catchment particulate input is trapped within estuaries and, depending on current velocities, a proportion of this trapped load is held in suspension, thus creating turbidity. As a result of estuarine hydrodynamic processes, maximum turbidity usually occurs close to the saltwater/ freshwater interface, regardless of its geographical location (Postma 1967; Morris et al 1982). Tubidity in Queensland estuaries exhibits both temporal and spatial variation. Highest turbidities occur immediately following storm inflows. During ensuing dry periods, saltwater intrusion moves the turbidity maximum upstream and overall levels decline due to dispersion and coagulation and settlement of particulates. Superimposed on this general pattern are considerable short term variations associated with the neap/spring tidal velocity cycle. For the Brisbane estuary, comprehensive turbidity data is not available. Instead, Secchi depth, strictly speaking a measure of light penetration, is used here as a relative measure of turbidity in order to illustrate the estuary' s turbidity behaviour. Figure 2 shows both location of the turbidity maximum (Secchi minimum) and extent of the s0.2 m Secchi zone for individual surveys . The turbidity maximum location is fairly consistent with the saltwater/ freshwater interface but Secchi depths :S0.2 m often extend well up and downstream of this and it is clear that an extensive mid-reach of the estuary is characteristically highly turbid . The wide extent of this zone is probably due mainly to high tidal velocities in this long estuary but the high absolute levels of turbidity may be a result of the large particulate load held in the estuary. There is historical evidence that in the 1920s/ 30s the estuary was much less turbid . At that time there was less land clearance and development within the catchment and particulate inputs and accumulated loads would have been less. 12WATER March, 1987-- -- --- --0 1983ND J ~8FM...... ......A.....MJ---1984JA's ~<.. ::,"'---0 ND J1985 F-M1020304050> 60• 70Brisba ne es t uary, dis tance from mouth (km/Figure 2. Salinity and Secchi depth data for individual surveys.It would be expected that turbidity levels would decrease during dry periods but evidence of this in Figure f is inconsistent. During some dry periods, notably December 1984/ January 1985, the :S 0.2 m Secchi zone is reduced but during others, it exhibits considerable variability and on some occasions a second downstream turbidity maximum is present. So;na of this observed variability may be associated with the neap/ spring cycle but the presence of secondary maxima suggests that other factors are operative. One possibility is that the extensive channel and sand and gravel dredging in the estuary is affecting its turbidity regime. Unfortunately to quantify this would require cessation of all dredging for several months. The turbidity regime of the Brisbane estuary is of interest because turbidity - fine inorganic particulates - is the principal factor affecting light penetration of the water column. The effect of turbidity on light penetration is measured here in terms of Secchi depth and mean Secchi values for the Brisbane estuary are given in Figure 3. Values are :S0.2 in the highly turbid mid estuary between 30 and 70 km. Values increase in the lower estuary but levels remain variable. The :S 0.2 zone sometimes extends as far downstream as 15 km while at other times, particularly during dry periods, Secchi values around 0.8 m occur in the 1
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