Soluble manganese (Mn) in potable water supplies disinfected with strong oxidants such as free chlorine causes dirty black water, which in turn causes staining and damage to consumer-clothing, linen, goods etc. Tests performed at different sites using PACl and Alum, produced results that indicated PACl provided better Mn removal than Alum where 95% removal was achieved compared to 0%. In water with low levels of Mn, the management of Mn can be an option by using weaker oxidising disinfectants such as chloramines, which can be used in place of more radical oxidants such as free chlorine.

-Close

Plant optimisation is a continuous process and is one of the most important parts of running water treatment plants. Installing a ‘high tech’ and wise complete package treatment plant with touch screens and flow paced pumps will not ensure operating success. The Springhurst treatment plant commissioned in 1999 has been a very difficult plant to operate. Alterations to the inlet pipe work, calibration system and pipe work into the clarifier were undertaken, along with investigations into raw water quality and reservoir management options. Problems such as precipitating iron and floc formation have been improved by process changes. Since alterations, operator time put into the plant has been dramatically reduced and chemical usage significantly lowered. Dose rates previous to the changes were in the order of 80 – 220mg/L Aluminium Sulphate, now reduced to 40 – 65mg/L. Average turbidity of treated water has been reduced from 0.2 – 4 NTU to 0.1 – 0.2 NTU.

-Close

Ballarat North Wastewater Treatment Plant is one of the few Victorian plants remaining that discharge secondary class effluent to inland waters. With recent changes to the existing EPA discharge licence, Ammonia and Total Nitrogen limits have been set such that the traditional biological trickling filters struggle to achieve. To this end Central Highlands Water has been investigating a number of options to achieve compliance. It was decided to design and build a small pilot plant using an activated sludge process in the Modified Ludzack-Ettinger configuration, which has subsequently produced encouraging results. Having a high proportion of trade waste in the influent, CHW then decided to duplicate the pilot plant and test the process on a single industrial source, which has high ammonia concentrations. The pilot systems have successfully met ammonia removal efficiencies in excess of 95% and concentrations of less than 1.0 mg/L.

-Close

A recent survey of the Victorian water authorities found that Geographic Information Systems (GIS) are well-established across 17 of the 23 organisations. However, a generational shift from use of the GIS by a small number of backroom specialists to corporate-wide deployment is underway. In 2002, 40% of water authorities have, or are in the process of, implementing GIS that will enable everyone from front-desk staff, engineers and managers to access the latest details and locations for assets, complaints and customers.

The paper provides an insight into the common benefits, disappointments and issues faced by each of Victoria’s metropolitan, urban and rural water authorities in using GIS, based on a recent industry-wide survey. The paper also explores the typical approach to implementing a corporate GIS.

-Close

Maintaining microbiological compliance in the township of Willow Grove has been a challenge that has recently been overcome by Gippsland Water. This paper details the transition from simple hypochlorite dosing to the use of chloramination. Operational difficulties that were experienced with chloramination dosing equipment and chemical solution strengths, and the steps taken to overcome these problems are described. The use of chloramination at Willow Grove Water Treatment Plant is now relatively trouble free, and is producing consistent disinfectant residuals that ensure microbiological compliance is achieved.

-Close

Modifications to the Moe Waste Water Treatment Plant (WWTP) are discussed. The installation of an influent sewage distribution manifold system prevented ammonia (NH4) breakthrough into the final effluent, and improved phosphorus (P) removal. An additional selector balanced organic and hydraulic loading to individual cells and simplified the operation of the plant.

-Close

South East Water Limited is a state-owned company providing water and sewerage services to 1.3 million customers in the south east region of Melbourne. One of the key management issues for South East Water was the control of blockages and spills due to build-up of fats and grease in the sewer system. In 1995 it was estimated that approximately 30% of sewer blockages were caused by fats and grease, and that 80% of these fats came from commercial businesses (that is, restaurants, fast food outlets, etc.).

In order to reduce sewer blockages, South East Water implemented a three phase Greasy Waste Program in late 1995. The first phase involved putting all commercial premises on Trade Waste Consents. Over 4,100 such consents were issued. The second phase was to ensure all commercial customers had an appropriately sized grease interceptor. Over 1,650 new grease interceptors were installed. The third and final phase was to ensure that all grease interceptors were pumped out regularly. South East Water developed and implemented its Wastelog system in consultation with the Victorian Waste Management Association to monitor and enforce pump-outs.

By 2001, the Greasy Waste Program had contributed to a 50% reduction in sewer blockages caused by fats.

-Close

Operators of large-scale ultraviolet (UV) disinfection systems are becoming aware of the total utilisation cost of their assets and are beginning to focus on the total life-cycle costs (LCC) of the asset over ownership horizons of up to 20 years, as the primary tool to making procurement decisions.

Life cycle costs (LCC) are defined as the sum of all costs incurred during the lifetime of utilisation of the asset. Many of these are not obvious and do need to be understood at the time of procurement, otherwise the end user risks procuring an asset at a discount to pay for it over its lifetime.

-Close

Flocculation and clarification at the Airey’s Inlet Water Treatment Plant is achieved via an upflow sludge blanket clarifier. Raw water characteristics and the mode of plant operation made it difficult to achieve acceptable sediment removal through the clarifier. High solids loadings on downstream filters resulted.

In October 2001 tube settlers were installed to optimise clarifier performance. The result was a significant improvement in clarifier performance and, in turn, treated water quality. Theoretical calculations of tube settler performance correlate well to the actual performance of the clarifier.

-Close

From the establishment of the Warrnambool Waste Water Plant in 1996 the of reuse and reduction of the biosolids produced has been an ongoing problem. At the start of the plants operation a successful composting process was conducted at the Warrnambool municipal tip site but the closure of the tip for rehabilitation forced the authority to seek another suitable site to carry out this process. A bid for a new site to the north of the township of Koroit was thwarted by strong public opposition and did not go ahead.

An agreement was reached with Melbourne Water to store the biosolids in a lagoon at the Werribee site from 1998. The high cost of transport along with the knowledge that this was only a temporary arrangement has seen the authority move into the field of biosolid reuse and reduction trials.

-Close

Consideration of best practice in trade waste management is timely, given the challenges that the water industry and its customers face in managing the triple bottom line so we can maximise sustainability of both our environment and business.

City West Water (CWW) is one of Australia’s largest providers of trade waste disposal services. These services, and the associated trade waste programs we operate, are critical to managing the risks associated with trade waste, as well as facilitating the uptake of cleaner production and waste minimisation across industrial and commercial sectors. Providers of trade waste services have direct contact with a large number of waste generators. This is a unique platform for risk management and facilitation of cleaner production and waste minimisation. Consequently, trade waste services and programs are critical to the outworking of Government policies and commitments in relation to cleaner production, waste minimisation and sustainability, as well as to meeting the community’s expectations in relation to waste management. However, it is not these issues alone which should drive consideration of trade waste management. We must consider these issues alongside the viability of economic development and employment and look for solutions that maximise the beneficial outcomes across all three dimensions of the triple bottom line.

This paper takes a look at the current trade waste management environment, along with the existing legislative and policy frameworks. It then suggests what best practice trade waste management should entail. It examines key issues and drivers, elements of an effective strategy, roles and responsibilities, resource requirements, challenges/obstacles and solutions, and performance measurement and how it should be communicated.

-Close

Over the last 3-5 years there has been a growing awareness of the opportunity for wastewater reuse as part of our total response to water management. There are now many examples, particularly in rural and regional areas, of reuse of partially treated wastewater on golf courses, parks and for some agricultural purposes.

These responses have to a large extent been the easy ones. Typically what is required is an agreement between the user, for example the golf course committee, and the water authority. This governs the way in which the wastewater will be used and managed, provides indemnities to the water authority and in other ways creates a legal and commercial relationship between the parties.

The precise scope of the indemnities in such relationships is unclear given the provisions of the Trade Practices Act and court rulings regarding the ‘fitness for purpose’ relating to the sale of goods. However, it appears that the sale of wastewater which is acknowledged to be unfit for drinking and suitable for use only under certain conditions as set out in the contract for sale would generally provide a sufficient defence to any action. It is where the water quality goes outside the specifications that difficulties may arise.

So, given that the easy projects have largely been completed, the question becomes: where to now with reuse in order to better use the resource and to reduce potable water consumption.

-Close

Bemm River is a small coastal community located in East Gippsland. High numbers of algae have been consistently experienced in the Bemm River Storage Basin over a number of years. These occurrences resulted in taste and odour complaints as well as interfering with the effectiveness of the disinfection process. In 2000 East Gippsland Water initiated an innovative proactive response to the algae problems in Bemm River. Of the three growth limiting factors of algae – nitrogen, phosphorus and light – it was decided that light would be the easiest parameter to control. This control was achieved via the construction of a 95% UV blockout shadecloth structure covering the entire surface of the storage basin. Monitoring to date has shown an apparent decrease in algae numbers on a seasonal basis.

-Close

Griffith Sewage Treatment Plant is a trickling filter System with a 75,000 EP capacity. It consists of an inlet-balance tank, sedimentation tanks, anaerobic digesters, super high rate trickling filters, humus tanks and, before the modifications outlined in this paper, a 15mm raked bar-screen on the inlet – balance tank.

-Close

Although the predominant approach to sewage sludge management in Victoria has historically involved a progressively increasing stockpile, there is wide recognition that this is not a sustainable management option. Not only is ongoing stockpiling contrary to statutory policy obligations for maximising biosolids reuse, the practice is simply a deferment of the management costs. The stockpile areas will ultimately need rehabilitation upon plant closure. There is also an ever-increasing amount of information that demonstrates the significant improvements in land productivity that can result from biosolids applications. The constituents of biosolids such as nutrients (nitrogen and phosphorous), micronutrients and trace metals, organic matter and moisture have been shown to result in significant increases in crop yields, particularly in the more weathered soils widely found in Australian agriculture.

-Close

The aim of this paper is to outline some simple spreadsheet tools that can be used to monitor storage volumes and the soil water balance. These will:

• Enable accurate irrigation scheduling (so that plants are irrigated according to demand).
• Provide a record of irrigation, weather data, storage inflows and storage levels.
• Check actual performance against “design”.
• Provide projections of winter storage levels and therefore planning can occur to ensure an empty storage prior to winter.
• Determine levels of seepage from the storage.
• Check the accuracy of meter readings.

  -Close