Decentralised multimedia development by the content experts

This paper describes the possibility to develop interactive educational material by the content expert (teacher). It is suggested to develop small modules of flexible material that can be easily changed similar to traditional lecture presentations. The features of such material include: • Learning by problem solving and application of knowledge (constructing knowledge). • Easy internet on-line implementation of software pieces via Shockwave technology. At the same time CD-Rom versions of the same programs can be marketed. • Integrated assessment by progress tracking and uploading via the web. • Feel of ownership (avoiding the ìnot invented here syndromeî) of the program by the teacher. • Possible exchangeability of small modules between different courses. • Built in recording of student comments for improving and debugging program for the next year • Facilitated input by students (over a year by year updating). • Teachers develop expertise in using the modern and effective teaching tools. • Teachers can put into practice much more effectively than before the educational principles learned from staff development sessions such as (self paced learning, problem based learning, deep learning, constructive learning). • Student feedback (questionnaire) indicated that > 85% of students found the program modules were more effective and more ìfunî learning than traditional method

Distribution of methanogenic potential in fractions of turf grass used as inoculum for the start-up of thermophilic anaerobic digestion

This study aims to investigate thermophilic methanogens in turf used as an inoculum. Results showed that Methanoculleus sp. regarded as hydrogenotrophic and Methanosarcina sp. regarded as acetoclastic methanogens were present in turf tested. However, active acetoclastic methanogens were present in turf soil only. The current study showed that thermophilic methanogens were present in various turf grass species: Stenotaphrum secundatum, Cynodon dactylon, and Zoysia japonica. Severe treatments of grass leaves under oxic conditions, including blending, drying and pulverizing did not affect the thermophilic hydrogenotrophic methanogenic activity of the grass. A dried and pulverized grass extract could be generated that can serve as a readily storable methanogenic inoculum for thermophilic anaerobic digestion. The methanogens could also be physically extracted into an aqueous suspension, suitable as an inoculum. The possible contribution of the presence of methanogens on grass plants to global greenhouse emissions is briefly discussed

New insights into the supression of plant pathogenic fungus (Phytophthora cinnamomi) by compost leachates

Use of compost as a soil conditioner and low-grade fertiliser is gaining popularity worldwide (Epstein, 1997). Compost not only adds plant nutrients to the soil, but also improves physical properties of soil such as buffering capacity, cation exchange capacity and water holding capacity. In addition to these benefits, compost can also suppress plant diseases caused by Phytophthora cinnamomi (Hoitink et al., 1977), Pythium aphanidermatum (Mandelbaum and Hadar, 1990), Rhizoctonia solani and Sclerotium rolfoii (Gorodecki and Hadar, 1990). Irwin et al., (1995) reported that the diseases caused by P. cinnamomi are directly responsible for considerable economic losses in many horticultural, ornamental and forestry industries throughout Australia. Phytophthora spp. continue to be the focus of attention of many researchers due to the diversity of P. cinnamomi-host interactions and their potential economic impact on a wide range of industries. The practise of using methyl bromide and other chemicals for disinfection of soil is widespread (Trill as et al., 2002). However, the use of methyl bromide and other chemicals is phased out in the USA and Europe. The suppression of soil-borne plant fungus by composts produced from tree barks (Spencer et al., 1982) and municipal solid wastes is well documented (Trill as et al., 2002). Composts that suppress plant disease have been extensively described and are used in greenhouse production systems (Lazarovitis et aI, 2001). However, most studies have focused on compo sting different types of materials and their effect on fungal pathogens inhibition rather than compo sting conditions that may produce suppressive composts. An objective of this study was to investigate the role of moisture, aeration and compost maturity in enhancing the inhibition effect of compost on the plant pathogen P. cinnamomi. A further objective was to generate an increased understanding of the mechanism of growth inhibition

Bio-Electrochemical Sensor for Fast Analysis of Assimilable Organic Carbon in Seawater

A Microbial Fuel Cell (MFC) based biosensor for the determination of Assimilable Organic Carbon (AOC) inseawater was developed by establishing an anodophilic marine biofilm on the surface of an electrode poised at +250mV (vs Ag/AgCl) rather than the traditionally used potentials of about -300 mV. A linear correlation (R2>0.99)between electrochemical signals (peak current) and acetate concentration ranging 10 to 55 μM was achieved.Usingthe positive anodic potential enabled the rapid establishment of the electrochemically active anodophilic biomasswithin a period of less than 8 days, a higher sensitivity (0.017 mA/μM acetate added) and a lower detection limit (2.5μM acetate, 0.16 mg O2/L of Biological Oxygen Demand (BOD)) compared to the negative anodic potential. Further,it was shown that this bio-electrochemical AOC sensor could tolerate the presence of low concentrations ofdissolved oxygen. The established potentiostat controlled MFC biosensor could be used for the purpose of onlinewater quality monitoring for seawater desalination plants prone to biofouling of RO membranes

Energy efficient COD and N-removal from high-strength wastewater by a passively aerated GAO dominated biofilm

Conventional aerobic treatment of high-strength wastewater is not economical due to excessively high energy requirement for compressed air supply. The use of passive aeration avoids the use of compressed air and enables energy efficient oxygen supply directly from the air. This study evaluates a passively aerated simultaneous nitrification and denitrification performing biofilm to treat concentrated wastewater. The biofilm reactor was operated >5-months under alternating anaerobic/aerobic conditions. For 4-times concentrated wastewater, >80% COD (2307 mgL-1h-1) and >60% N (60 mgL-1h-1) was removed at a hydraulic retention time (HRT) of 7h. A double application in the same reactor enabled > 95% COD and 85% N-removal, at an overall HRT of 14h which is substantially shorter than what traditional activated sludge-based systems would require for the treatment of such concentrated feeds. Microbial community analysis showed Candidatus competibacter (27%) and nitrifying bacteria (Nitrosomonas, and Nitrospira) as key microbes involved in COD and N-removal, respectively

Interlinkages of recent research outcomes for the treatment of organic wastes

Recent research into conversion of organic wastes at Murdoch University is reviewed to highlight interlinkages, insights gained and potential future research. Central to the research underpinning the success of the one vessel sequential aerobic (to bring temperature to thermopilic)-anaerobic (to extract methane)-aerobic (to produce compost) thermophilic process is utilising the concept of electron transfer, which links aerobic and anaerobic phases through electrons as a common currency. This concept is consistent with our ability to produce electricity from the process liquor using a microbial fuel cell. Management of the liquor has been found to be critical as it is a carrier of micro-organisms that perform all the biological processes in the reactor and assist with start up. Start up has also been facilitated by the presence of grass clippings in MSW. Linkages to nitrogen removal, unusual properties of liquor, grass clippings and possible pre-treatment of cellulose wastes using fungus are highlighted

Bio-cementation of sandy soil using microbially induced carbonate precipitation for marine environments

This study proposes and describes a novel approach for cementing sandy soils in marine environments by modifying the promising technique of microbially induced carbonate precipitation (MICP). In contrast to the usual MICP technique described in the literature, the method proposed herein relies on the calcium ions dissolved in seawater as the sole source of calcium for calcite formation. This proposed method involves flushing high-salinity-tolerant, urease-active bacteria followed by a mixture of urea and seawater through a porous sandy soil, leading to bacterial carbonate release from the urease reaction and precipitation of insoluble and semi-soluble carbonate salts including calcium carbonate and magnesium carbonate trihydrate. This precipitation method resulted in a physical stabilisation of sand that reached an unconfined compressive strength of up to 300 kPa, which is about two-fold higher (with same amount of crystals produced) than that of the MICP treatment in which highly concentrated calcium and urea solutions are used. Permeability was retained at about 30% for all MICP-treated samples, suggesting good drainage ability. This new exploration of MICP technology provides a high potential for using bio-cementation in marine environments, for applications such as mitigation of submarine sediment liquefaction and prevention of beach sand erosion and cliffs scouring

Organic carbon removal from wastewater by a PHA storing biofilm using direct atmospheric air contact as oxygen supply

The principal reason for the high energy costs for biological wastewater treatment is the poor transfer efficiency of oxygen to the bulk water phase. The current paper describes a biofilm reactor in which oxygen transfer to the bulk solution is avoided by alternating anaerobic submersed (2. h) and drained (1. h) operation of the biofilm. During the submersed phase the biofilm enriched for glycogen accumulating organism (GAO) stored the organic carbon (acetate) as poly-hydroxy-alkanoate (PHA). After draining the reactor, this carbon stored as PHA was biologically oxidised, using oxygen directly from the atmosphere. The 12. Cmmol/L (384. mg/L BOD) of acetate was completely removed during long term automated operation of the reactor for 9. months with a cycle length of 3.3. h. As the process specifically removes dissolved organic carbon but not N or P it could possibly be coupled with novel processes such as Anammox or nutrient recovery

New method for characterizing electron mediators in microbial systems using a thin-layer twin-working electrode cell

Microbial biofilms are significant ecosystems where the existence of redox gradients drive electron transfer often via soluble electron mediators. This study describes the use of two interfacing working electrodes (WEs) to simulate redox gradients within close proximity (250 µm) for the detection and quantification of electron mediators. By using a common counter and reference electrode, the potentials of the two WEs were independently controlled to maintain a suitable “voltage window”, which enabled simultaneous oxidation and reduction of electron mediators as evidenced by the concurrent anodic and cathodic currents, respectively. To validate the method, the electrochemical properties of different mediators (hexacyanoferrate, HCF, riboflavin, RF) were characterized by stepwise shifting the “voltage window” (ranging between 25 and 200 mV) within a range of potentials after steady equilibrium current of both WEs was established. The resulting differences in electrical currents between the two WEs were recorded across a defined potential spectrum (between −1 V and +0.5 V vs. Ag/AgCl). Results indicated that the technique enabled identification (by the distinct peak locations at the potential scale) and quantification (by the peak of current) of the mediators for individual species as well as in an aqueous mixture. It enabled a precise determination of mid-potentials of the externally added mediators (HCF, RF) and mediators produced by pyocyanin-producing Pseudomonas aeruginosa (WACC 91) culture. The twin working electrode described is particularly suitable for studying mediator-dependent microbial electron transfer processes or simulating redox gradients as they exist in microbial biofilms

Stabilisation of wool scouring sludge by composting

Wool scouring sludge is the solid waste product of anaerobic treatment of wool scouring effluent. It has a high wool grease content (13- 16% of the dry weight, 45 -55% of the organic matter), resulting in a low melting point (approx.45°C). The low melting point, the putty-like physical properties and the odourous, unstable nature of the sludge makes it unsuitable for land application in its raw state. Composting of the sludge was investigated to ascertain its suitability as a treatment method for stabilising wool scouring sludge and improving its suitability as a soil amendment. Composting was carried out in a computer controlled, laboratory scale, forced aeration, incubator system. Wool scouring sludge was rapidly compostable, reaching 47.1°C in 3 days. The temperature did not exceed 47.1°C. The mesophilicIthermophilic phase of the com posting process required 21 days. Composting reduced the grease content of the waste by 37%, with the result that the composted waste could not be melted. The compost resulted in greater plant yields of radish and wheat than the original sludge