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[en] Full text: The City of Mount Gambier upgraded its boiler in September after analysis showed that biomass was still the optimal energy option. The Mount Gambier Aquatic Centre was built by the local city council in the 1980s as an outdoor pool facility for the public. The complex has three pools — an Olympic-sized, toddler and a learner pool — for a total volume of 1.38ML (including balance tanks). The large pool is heated to 27-28°C, the smaller one 30-32°C. From the very beginning, the pool water was heated by a biomass boiler, and via two heat exchangers whose combined capacity is 520 kW. The original biomass boiler ran on fresh sawdust from a local timber mill. After thirty years of dedicated service the original boiler had become unreliable and difficult to operate. Replacement options were investigated and included a straight gas boiler, a combined solar hot water and gas option, and biomass boilers. The boiler only produces heat, not electricity. All options were subjected to a triple bottom line assessment, which included potential capital costs, operating costs, community and environmental benefits and costs. The project was also assessed using a tool developed by Mount Gambier City Council that considers the holistic benefits — the CHAT Tool, which stands for Comprehensive Holistic Assessment Tool. “Basically it is a survey that covers environmental, social, economic and governance factors,” the council's environmental sustainability officer, Aaron Izzard told WME. In relation to environmental considerations, the kinds of questions explored by the CHAT Tool included: Sustainable use of resources — objective is to reduce council's dependence on non-renewable resources; Greenhouse emissions — objective is to reduce council's contribution of GHG into the atmosphere; Air quality — objective is to improve local air quality. The conclusion of these analyses was that while a biomass boiler would have a higher capital cost than a straight gas boiler, the running costs would be cheaper. This would result in significantly lower costs over a 10-year period. Biomass also has a superior environmental profile. The new Binder 650kW boiler, supplied by Living Energy, runs on dry woodchip, with the ideal moisture content being 20-30%. The long-term source of wood chip is pine sourced from local forestry activities. Council has considered using untreated urban timber waste collected at its transfer station and may conduct a trial in the future. Even if the trial is successful this would only supplement the main source of feedstock. The Binder boiler has automatic ash removal, which significantly reduces the maintenance cost on the previous system, which had to have ash manually removed three times a week on average. The ash is taken to a composter just north of Mount Gambier; mixed with other feedstock and turned into compost. The biomass boiler saves approximately 58 tonnes of greenhouse emissions per year. Due to the efficiency of the boiler, and the low moisture content of the wood chip, no smoke is produced, and only negligible particulates. “The trees that the biomass is sourced from are regrown and so the fuel source is essentially carbon neutral, as opposed to gas, which is a fossil fuel source,” said Izzard. “The biomass boiler is very efficient, up to 90%. It is more cost effective to run and has less environmental impact than coal-fired electricity.” The main disadvantage with this kind of biomass system is that it requires more human input than a straight gas system. With the latter, the fuel is piped in and the system runs mostly automatically, needing little human input. With a biomass system, the trees need to be harvested and chipped (which, in most situations will be occurring regardless, wood chips are simply purchased that were going to be made anyway), the chip needs to be stored (unless they can be made on demand, but for smaller systems this is unlikely to be cost effective), and it needs to be delivered to the site. “Even with these costs factored in, it is still cheaper to run than a gas system and it is supporting local jobs,”said Izzard.
[en] Full text: Many mining and industrial processes generate wastewater that contains a variety of contaminants, such as metals and metalloids. These must be removed to ensure the wastewater is suitable for reuse or safe discharge to the environment. However, mining wastewater treatment processes have traditionally been difficult due to the large range of different contaminants present, requiring a number of complex steps. In current processes, the mining industry generally adds lime to the wastewater to purify it. While often effective, the key issue with this method has been the volume of sludge that forms and the subsequent problems with dealing with this sludge - either to extract the contained water, which often requires additional treatment, or to find enough space for long-term disposal. This complex practice could end soon thanks to a new treatment solution that utilises hydrotalcites. Developed by CSIRO, the treatment overcomes the complexities of lime-based methods and offers a simpler and more water smart process. The CSIRO team found that hydrotalcites, which are layered minerals consisting of aluminium- and magnesium- rich layers, can simultaneously remove a variety of contaminants in wastewater in a single step. Scientists noticed that hydrotalcites begin to form when aluminium and magnesium are present at an ideal ratio and under conditions during neutralisation of acidic waters. As hydrotalcites form, the contaminants become trapped and are easily removed from the wastewater as a solid. Mining wastewater often contains substantial magnesium and aluminium concentrations. This means that we can create hydrotalcites utilising common contaminants that are already present in the wastewater, by simply adjusting their concentrations and adding alkaline compounds to rapidly increase pH. Initial applications have focussed on treating wastewater generated from the mining and extraction of uranium. A range of contaminants including uranium, rare earth elements, transition metals, metalloids and anions such as arsenate have been effectively removed from wastewater. This process purifies the wastewater from mines in a faster, more effective way that does not require large amounts of infrastructure or difficult chemistry to achieve it. The advantages don't stop there. The hydrotalcites themselves are easily removed using centrifugation, leaving behind a much cleaner sludge and a lot less of it. Initial results have shown the treatment produces around 80 to 90% less sludge than that of lime-based treatments — so it does not present the same scale of handling and final disposal problems. The hydrotalcite-treated water can be recycled back into the plant to lower the total cost of water used in the mining operations, ultimately helping to reduce water consumption as there will be less water drawn from the environment such as from the groundwater near to the mine. This would be particularly valuable for mining operations in arid regions with limited water supply such as in Australia and Chile. Around the world the minerals industry is keen to find more efficient ways to treat their wastewaters and reduce their environmental footprint. With the inherent technical advantages and added benefits of using hydrotalcites, there's a high likelihood of the mining industry adopting this technology on a global scale. The steps to making this a reality have already been made, with commercialisation of the technology underway via Australian company Virtual Curtain. There is also the potential use the treatment to reprocess and recover valuable commodities and produce 'ore- grade' material out of the contaminants. The material can be fed back into the recovery process to recover a greater proportion of the contained metals. This is a very real example of extracting 'wealth from waste', opening up the possibility of partially offsetting wastewater treatment costs for the mining industry.
[en] The City of Sydney may have hit the statewide resource recovery target of 66% two years early, but it is not resting on its laurels. Instead, it wants to do more with the remaining 34% of non-recyclable waste that is being sent to landfill. Its Advanced Waste Treatment Master Plan explores how the waste-derived gas can be injected itito the gas grid to fuel local energy generation or transport networks, killing two birds with one stone - meeting the city's energy needs and diverting waste from landfill. The plan seems sound. After all, landfill costs have increased 300% in the past decade and landfill levies are projected to exceed $400 a tonne by 2030. In addition, four landfills sites operating near the city will close within the next few years
[en] Full text: The project at Biodiesel Producers Limited in Victoria involved remediation of a wastewater treatment process containing a large covered anaerobic lagoon, an aerobic sequencing batch reactor (SBR) and a series of downstream open ponds. The pond downstream of the SBR was heavily loaded with a thick hard grease cap. The CAL was believed to have a metre-plus grease cap and the SBR had developed a thick foam cap that prevented aeration and mixing. Environmental Biotech was called in to assist with bioremediation using its Grease Eradication System bacteria cultures, with the aim of reducing the fats, oil and grease in the CAL discharge to less than 150 milligrams per litre, eliminating the stable fat foam in the SBR to allow the denitrification sequencing program to be reinstated and to clean up the hard fat layer from the surfaces of the comany's open ponds. The inflow to the CAL was designed for a flow of 210kL per day with a loading of 6900mg/L biochemical oxygen demand and FOG of 425mg/L. The actual load, as measured by Environmental Biotech, was 100kL with 20,000mg/L BOD and 1800mg/L (180kg) FOG. The CAL had been in use for more than two years, generating methane but assumed to be working well in the breakdown of chemical oxygen demand and FOG. In December 2009 the quality of the effluent began to decrease, overloading the SBR with FOG. It caused the formation of dense foam on aeration and mixing. The foam would not break down despite a variety of methods being employed and would overflow from the walls of the SBR. “Due to the foaming issue the SBR became a large holding tank for the fat and because of the reduced mixing, the solids were settling on the bottom of the tank,” Environmental Biotech project manager and franshisee Craig Barr said. “We were brought in to start work inApril 2010 and initially we slug dosed the CAL with 400 litres of GES bacteria in addition to a constant metered dosing rate of 400 litres per fortnight with the inflow.” The SBR was initially dosed with 200 litres of GES bacteria in addition to a constant metered dosing rate of 400 litres of aerated bacteria per fortnight. Two 1000 litre UBC storage drums were fitted with 300 watt aquarium heaters to keep the bacteria at a temperature between 22C and 25C. “Mixing and aeration of the SBR was carried out as much as possible using the two 30K watt surface mounted aspiring aerators and two 11kW submersible venture aerators,” Barr explained. “This mixing was extremely limited due to rapid formation of foam which quickly covered the pontoons on which the mixing motors are mounted.” After 12 weeks large drops were observed in all measured chemical parameters in the effluent from both the CAL and SBR. FOG from the CAL had dropped to below 150mg/L to achieve one of the initial primary goals. The thick mica like foam in the SBR had all been removed and replaced with coarse, large bubble soft foam that easily collapsed and the associated odour had become earthy and inoffensive. The CAL discharge averaged a COD drop of 82%, total suspended solids drop of 81%, FOG drop of 93% and volatile fatty acids drop of 42%. The SBR discharge averaged a COD drop of 66% and total suspended solids (TSS) fell 66%. Later results from the period January- March 2011 showed the CAL discharge had completely stabilised. “The COD is averaging a 94 per cent reduction with FOG dropping below laboratory detection limit levels of 40mg/L, a TSS reduction of 90 per cent and VFAs averaging 96 per cent reduction,” Barr said. “The SBR discharge has also stabilised, with COD reduction of 94 per cent and BOD averaging 106mg/L, with TSS averaging 444mg/L representing a 92 per cent reduction. The second pond is now completely clear of any floating fats.” Once the foam was remediated the SBR could be returned to its correct usage, allowing for the batch sequencing for denitrification to occur. The bacteria have also broken down the solids formation on the bottom of the SBR further reducing the FOG. Not only were the initial aims of the project exceeded but the GES bacteria was progressively reduced and it has now been suspended.
[en] Full text: Using biomimicry, an Australian cleantech innovation making inroads intoChinas's industrial sector offers multiple benefits to miners and processors in Australia. Stephen Shelley, the executive chairman of Creative Water Technology (CWT), was on hand at a recent trade show to explain how his Melbourne company has developed world-class techniques in zero liquid discharge and fractional crystallization of minerals to apply to a wide range of water treatment and recycling applications. “Most existing technologies operate with high energy distillation, filters or biological processing. CWT's appliance uses a low temperature, thermal distillation process known as adiabatic recovery to desalinate, dewater and/or recycle highly saline and highly contaminated waste water,” said Shelley. The technology has been specifically designed to handle the high levels of contaminant that alternative technologies struggle to process, with proven water quality results for feed water samples with TDS levels over 300,000ppm converted to clean water with less than 20ppm. Comparatively, reverse osmosis struggles to process contaminant levels over 70,000ppm effectively. “CWT is able to reclaim up to 97% clean usable water and up to 100% of the contaminants contained in the feed water,” said Shelley, adding that soluble and insoluble contaminants are separately extracted and dried for sale or re-use. In industrial applications CWT has successfully processed feed water with contaminant levels over 650,000 mg/1- without the use of chemicals. “The technology would be suitable for companies in oil exploration and production, mining, smelting, biofuels, textiles and the agricultural and food production sectors,” said Shelley. When compared to a conventional desalination plant, the CWT system is able to capture the value in the brine that most plants discard, not only from the salt but the additional water it contains. “If you recover those two commodities... then you've recovered more than the desalination plant produced in the first place,” said Shelley, adding you also mitigate the environmental impacts. “I think because a lot of technologies focus on collecting clean water they actually do that... We didn't concentrate on that, we wanted to stop the wastage, which meant there wasn't a percentage level at which we were happy.” CWT currently has the following volume models available: 20, 55, 120, 260, 400, 600, 800, 1200 and 2400m"3 per day of output water. The total energy requirements can be below 3OkWh per cubic metre, in favourable conditions. This includes the electricity use of the compressor, the pumps and the fans. The standard equipment does not require steam, but if the site has significant free or low cost steam available, it can be used to further reduce the electricity use by 50-75%. “There's a real commercial benefit in combining this with any kind of existing reverse osmosis installation, or even with RO systems that are planned and still on the drawing board,” said Shelley. He believes it offers the opportunity for government or semi-government facilities to 'look outside the square' and investigate how they could use this technology to obtain increased revenue from their waste streams. “The other thing that this creates is the opportunity to decentralise water infrastructure,” said Shelley. “You could put significant water infrastructure anywhere when you don't have to a run a pipe to the ocean to get rid of the brine. What that means is you can tap into low quality water sources. ” Such water sources could be saltwater removed from the bottom of an oil well or the water that's contained in an aquifer. “You can tap into these water sources and produce very large quantities of water sufficient for regional water facilities,” said Shelley, adding that you don't have to source the water from the ocean or hope for more rain. While it has been a 'long haul' getting the product to market, CWT is now moving 'between half a million and a million Australian dollars worth of product per calendar month' in the Chinese market. Ironically, CWT technology is licensed by a German manufacturer who is marketed it in the mining sector in Western Australia and appears to be having more success than Shelley to date. “It is sometimes hard to believe that a guy working in his garage can come up with something worthwhile. If it doesn't have a big international brand name stuck on the side of it, it's not taken seriously,” he said.
[en] Full text: First there was the Beer Battery, which aimed to generate electricity from brewery wastewater using a microbial fuel cell (MFC). Trials at Foster's Yatala brewery in Queensland in 2007 ran into challenges around the cost of electricity and duration of treatment, but they also revealed a new possibility. Komeel Rabaey, a University of Queensland specialist in microbial dynamics with a particular passion for bioelectrochemical systems, recognised the potential to extract sodium hydroxide - caustic soda - out of wastewater in a form suitable for reuse. In 2008 he converted such a system into a lab-scale caustic recovery plant, then upsized it to a one litre test reactor, which is again running at the Yatala brewery. The concept flips wastewater treatment on its head, seeing the discharge as a resource to be harvested rather than a cost and a contaminant load to be managed. “We typically aim to make a concentration of about four per cent caustic. That is what is easily achievable with the system and you will also note a lot of industries use caustic at four per cent,” said Dr Rabaey. “So you can use the wastewater from the plant to drive caustic production, with the extra advantage of removing enormous amounts of sodium.” Sodium hydroxide is a ubiquitous industrial compound used in pH regulation, as a cleaning agent in clean-in-place systems and variously in pulp and paper, textiles and food processing. Dr Rabaey wants to close the loop on caustic. Industries along the Murray-Darling basin, for example, truck in a lot of it from outside the area and then discharge it with their wastewater into the salt-sensitive river system. “If you use a bioelectrochemical system to recover the sodium hydroxide, you are not even importing the sodium into the area but recycling the sodium the whole time on-site,” he told WME. Get the technology right and he reckons a three-year payback on investment is readily achievable. A microbial fuel cell oxidises organics in the chosen medium (wastewater) and passes electrons freed up in the process around a circuit from the anode side to the cathode, generating electricity. The protons diffuse through the liquid and a membrane to the cathode, where they re-bond with the electrons and oxygen to create water, keeping the entire system neutral. Use wastewater as the medium though, and the high levels of sodium means that rather than the protons, sodium is preferentially transferred to the cathode, preventing the full reduction of oxygen to water. Instead, hydroxyl (OH) is created, which then bonds with the sodium to create sodium hydroxide (NaOH) in a continuous process. Unlike with the electricity generation trials, the theoretical capacity of the bioelectrochemical system to produce sodium hydroxide is compelling and cost-effective. “The process is pretty successful thus far. Per kilogram of organics we remove in an anode, we can think about 5kg of caustic soda on the cathode side,” said Dr Rabeay. “You need a very small number of electrons to make sodium hydroxide and the organic matter contains a lot of electrons, it is very electron-rich.” While recovery rates will vary case by case, depending on factors such as the water parameters and how companies drive their production processes, a model wastewater containing 3kg of organics and 2kg of sodium per m"3 could remove about 0.5kg of the organics, producing 2.5kg of sodium hydroxide and removing 1.44kg of sodium from the waste stream. For a pulp and paper plant, Dr Rabaey reckons 5-10 per cent of the typical organic load could provide all the site's sodium hydroxide demand. Most industries he's studied have more than enough wastewater organics to become self-sufficient in sodium hydroxide. In 2008, he co-founded Bilexys, a spin-off company from the University of Queensland aiming to commercialise the technology for recovery of caustic and, down the track, hydrogen peroxide. Early next year, Bilexys will be building a pilot plant containing several larger modules at a pulp and paper plant around Brisbane. The key tests are how well it scales up and operational controls to manage any build-up of calcium scale and solids in the reactor wastewater. All going well, Dr Rabaey hopes to go to market in 2012 with a technology that turns sodium hydroxide from a problem to a medium-term profit.
[en] Full text: Some mining by-products that are currently stockpiled or disposed of could be put to use preventing nutrients from entering river systems, helping reduce the potential for algal blooms. A joint project between CSIRO and the Western Australia (WA) Department of Water investigated a range of spent materials from mining and industry to determine their ability to filter nutrients from natural waters or to treat wastewater. “The largely unexploited by-product materials we generate in Western Australia could be developed as 'designer' contaminant adsorbents,” said CSIRO project leader Dr Grant Douglas. The use of abundant, low-cost wastes generated from mineral processing, in particular, offers a potentially cost- effective and environmentally-friendly strategy for removing nutrients. “The productive use of the by-products also has the potential to reduce the environmental footprint of mining and mineral processing industries by lowering by-product stockpiles,” he said. But the key benefits are in water; not only improving the health of surface waters but, by facilitating reuse, also easing the competition for water resources in an increasingly climate constrained part of the country. Re-use of industrial by-products in WA is currently considered on a case-by-case basis rather than regulated according to established standards. The project aimed to inject some rigour by characterising for the first time the nutrient, trace element uptake and acid neutralising capacity of a range of low-cost by-products (see Fact File). It also underpinned the development of a draft protocol for screening similar by-products in the future. The comprehensive characterisation included identification and procurement, and basic characterisation of by-products included major and trace element geochemistry, mineralogy, radioactivity, geochemical modelling and leachate chemistry and toxicity. These inherent properties and suitability of by-products for potential environmental use were then classified. Of all by-products examined in laboratory tests, the most promising was neutralised used acid (NUA), a by-product from heavy mineral processing. It proved particularly effective in the removal of phosphorous, exhibiting more than 95 per cent PO_4-P and attenuation total phosphorous. It also possessed a substantial sorption capacity for dissolved organic carbon, reducing it by 40 per cent over 180 days, and dissolved organic nitrogen by 26 per cent. The next step was a four-year field trial conducted with the neutralised used acid, either alone or in combination with the steelmaking by-product and calcined magnesia. It was added to soil at a turf farm in the Swan Canning catchment and removed 97 per cent of phosphorus and 82 per cent of nitrogen from the shallow groundwaters. Adding the by-product also reduced water use and improved turf health. With about 400 hectares of turf farms currently under cultivation in the Swan Coastal Plain alone, use of this by-product as a soil amendment on turf farms would equate to the removal of about two tonnes of phosphorus and nitrogen from groundwater each year. “This is good news for the health of Perth's waterways as it could lead to a substantial reduction in the key nutrients that eventually contribute to algal blooms,” said Dr Douglas.A large pilot-scale field trial is currently underway in a. tributary of Ellen Brook as part of a joint CSIRO-Swan River Trust study. According to the CSIRO, the potential benefits of the novel research project could be realised anywhere in the world where similar by-product materials are produced and similar water management issues exist. The research is being delivered for the Water Foundation in Western Australia, which promotes water-related research and development in the state, in this case to challenge boundaries and investigate innovative ways of conserving water and maximising reuse of wastewater. Fact file: By-products not wastes. Neutralised used acid (NUA) - high phosphorous and nitrogen sorption. Steelmaking by-product - high capacity to neutralise acidity. Red mud and red sand from alumina refining - substantial capacity for sorption of metals and metalloids. plus adsorption of phosphorus. Fly ash from power plants - may help neutralise acid mine drainage. Groundwater treatment residues - good sorption of phosphorous. Calcined magnesia - chemical and operational advantages for the neutralisation of acidic wastes. Activated carbon - the by-product of processing mallee eucalypts can be used in water purification and sewage treatment. Zeolite - good sorption of organic molecules, radionuclides, metals and ammonium.
[en] Very few of the hard rock and coal mines that have been decommissioned since 1985 have successfully cancelled their mine lease and regained their bond. Poor management of mine waste during operation is one of the issues to affect this. Regulations now demand sustainable closure and containment plans, hydrological management of any storage or disposal site and a vegetative cover system for long term ecological recovery. Some vegetation covers used to rehabilitate and stabilise waste dumps and tailings in Australia are discussed.