Malcolm Clark

Effects of carp, gambusia, and Australian bass on water quality in a subtropical freshwater reservoir

Publisher: Informa UK Limited

Date: 09-2012

DOI: 10.1080/07438141.2012.702337

Grain size normalization: A case for post extraction normalization and inclusion of selective extraction procedures

Publisher: Wiley

Date: 05-2011

DOI: 10.4319/LOM.2011.9.215

Radium and strontium binding by a modified bauxite refinery residue – isotope exchange studies of pH-dependence, reversibility and ageing

Publisher: Geological Society of London

Date: 24-07-2020

DOI: 10.1144/GEOCHEM2019-025

Diversity of microbial communities in an attached-growth system using Bauxsol™ pellets for wastewater treatment

Publisher: Elsevier BV

Date: 09-2012

DOI: 10.1016/J.SCITOTENV.2012.06.079

Abstract: Columns of Bauxsol™ pellets were used in a field experiment as biomass support particle for wastewater microbial communities. The attached microbial community structure was analysed using denaturing gradient gel electrophoresis (DGGE), targeting the 16S rDNA gene's V3 region. DGGE profiles showed that the type and composition of support particles used (i.e. Bauxsol™ pellets or gravel) had a significant impact on the attached bacterial communities (64% dissimilarity). In addition, ecological indices revealed a more heterogeneous bacterial community structure on the Bauxsol™ pellets. TOC/TN ratios post-experiment (6.5-9.3) suggested a good level of biological activity (i.e. active biofilm) in the Bauxsol™ columns. Moreover, Bauxsol™ pellets were mostly made of inorganic carbon, suggesting insoluble carbonate biomineralisation. Polymerase chain reaction (PCR) lification of specific marker genes (i.e. bacterial and archaeal amoA genes, nosZ gene, and hzo gene) were used to identify the presence of attached bacterial communities associated with nitrogen transformation. The results along with geochemical data (i.e. up to 50% nitrogen removal) revealed co-existence of ammonia-oxidising bacteria, denitrifiers, and anammox organisms. This study conclusively demonstrates that microbial communities are well-adapted to Bauxsol™ pellets and bacterial communities involved in the nitrogen cycle are present.

Effects of pH, competing ions and aging on arsenic(V) sorption and isotopic exchange in contaminated soils

Publisher: Elsevier BV

Date: 06-2019

DOI: 10.1016/J.APGEOCHEM.2019.04.016

Effects of fish and macrophytes on phytoplankton and zooplankton community structure in a subtropical freshwater reservoir

Publisher: Elsevier BV

Date: 2017

DOI: 10.1016/J.LIMNO.2016.09.009

Arsenic(V) sorption kinetics in long-term arsenic pesticide contaminated soils

Publisher: Elsevier BV

Date: 12-2019

DOI: 10.1016/J.APGEOCHEM.2019.104444

Nutrient and trace-metal removal by bauxsol pellets in wastewater treatment

Publisher: American Chemical Society (ACS)

Date: 03-06-2011

DOI: 10.1021/ES200934Y

Abstract: In this study, Bauxsol pellets packed in PVC columns were used to remove nutrients and trace-metals from municipal wastewater during a 6 months field trial. Bauxsol pellet columns showed a high phosphate removal rate via precipitation of PO(4)(3-) with Ca(2+) and Mg(2+) ions: at 90% in the 1st month at 80% from the second to fifth months and at 60% in the sixth month. Pellet bound total phosphorus and Colwell phosphorus were 7.3 g/kg and 2 g/kg and are about 20 times the concentrations found in most fertile soils. Trace-metals in effluents were bound, probably irreversibly under the columns' environmental conditions, to the Bauxsol minerals that have high surface area to volume ratios and high charge to mass ratios. Experimental results showed a complex nitrogen cycle operating within the Bauxsol pellet columns including anoxic nitrification, denitrification, and anammox processes. Although a transient pH spike, associated with the release of unreacted CaO from the cement binder used in the pellets, was observed, this may be readily corrected through post-treatment pH adjustment. Hence, the geochemistry of Bauxsol pellets can effectively remove and bind nutrients and trace-metals during wastewater treatment, and further research may show that saturated spent pellets can be used as fertilizer.

The pH-dependence and reversibility of uranium and thorium binding on a modified bauxite refinery residue using isotopic exchange techniques

Publisher: Elsevier BV

Date: 04-2011

DOI: 10.1016/J.JCIS.2011.01.068

Abstract: The pH-dependence and reversibility of uranium and thorium binding onto a modified bauxite refinery residue (MBRR) were studied in laboratory uptake/leaching experiments. Natural (238)U and (232)Th isotopes were contacted with MBRR in an 8day loading period (equilibrium pH≈8.5) then leached in pH-dependent experiments, where the pH was decreased from 8 to 3 over several hours following addition of exchange isotopes (232)U and (229)Th. Relative concentrations of the thorium isotope pair ((232)Th and (229)Th) indicate that Th is very strongly bound to MBRR, and although at pH 3, some de-sorption is observed (232)Th (≈3%) and (229)Th (≈2.5%), released thorium is partially re-adsorbed during an overnight equilibration. During the initial equilibration, approximately 50% of the (238)U was adsorbed, and a U adsorption maximum occurs between pH 5 and pH 6, where <0.5% of the U remains in solution. However, at a pH between 5 and 3, some 60% of the bound U releases, hence the pH range of maximum U retention on the MBRR is relatively narrow. When equilibrated overnight, the MBRR releases additional U, suggesting a kinetically controlled de-sorption linked to mineral dissolution. Plots of U isotope exchange between (232)U and (238)U are linear, and suggest that U adsorption is mostly reversible. Data for adsorption in mixed systems of U and Th suggest that Th and U compete for similar binding sites.

The effect of copper and temperature on juveniles of the eurybathic brittle star Amphipholis squamata – Exploring responses related to motility and the water vascular system

Publisher: Elsevier BV

Date: 04-2015

DOI: 10.1016/J.CHEMOSPHERE.2014.10.063

Abstract: The limited availability of test organisms that represent tropical and deeper water environments is a significant concern when assessing the risk of contaminants in these environments. Amphipholis squamata (Delle Chiaje 1828) is a widely distributed brittle star with many phylogenetic clades reported from different latitudes, and it also occurs from the intertidal zone to a depth of ∼1300 m. In the present study, the effect of copper on four behavioural responses and mortality of A. squamata were quantified at four different temperatures including 25, 20, 15 and 10°C. At 25°C the four behavioural responses and mortality were relatively sensitive to copper, with 96 h EC50 values of 25 (confidence interval 18-44), 24 (7-26), 32 (24-41), 29 (9-41) μg L(-1) for the measured ability to turn from the oral surface up to oral surface down, curling behaviour, tube foot movement, and tube foot retraction respectively. The average 96-h LC50 value for copper at 25°C was 46 μg L(-1). Some endpoints investigated showed significant effects of reduced temperature compared to the optimal temperature. These effects were enhanced with increasing copper concentrations and significant differences in copper toxicity between temperature treatments were most notable when measuring the ability to turn from the oral surface up to oral surface down where the EC50 changed from 25 (18 to 44) to 6 (-18 to 14) μg L(-1) with a reduction of temperature from 25 to 15°C. The results showed that A. squamata is relatively sensitive to copper and that further investigation into the effects of other stressors on these endpoints is warranted.

Aiptasia pulchella: a tropical cnidarian representative for laboratory ecotoxicological research

Publisher: Wiley

Date: 11-09-2012

DOI: 10.1002/ETC.1993

Abstract: An urgent need exists to identify suitable tropical marine species for use in the development of sensitive and reliable test methods for routine laboratory ecotoxicological testing. Corals are a group of organisms not represented in routine ecotoxicology due to inherent difficulties in laboratory husbandry, and sea anemones from the same phylum (cnidaria) may be useful proxies. Aiptasia pulchella is a tropical symbiotic sea anemone with a wide geographic range. It is well suited to laboratory conditions and has been used extensively in research. However, its suitability as a toxicity test species has not been investigated. Assessment of juvenile recruitment in laboratory and semi-outdoor conditions showed higher production in semi-outdoor conditions however, laboratory rearing produced enough recruits to run routine toxicity tests. In investigations of the sensitivity of A. pulchella to contaminants, acute tests were conducted on 1- to 2-mm juveniles using copper. Lethal concentration, 50% (LC50) values at 96 h estimated from tests using five and 10 replicates ranged from 30 to 83 and 60 to 90 µg/L, respectively, and a 28-d LC50 of 26 µg/L was estimated. During the present study, sublethal endpoints were investigated chronic assessment of inhibited asexual reproduction looks promising (12-d effective concentration, 50% [EC50] 15 µg/L) and should be assessed further. Aiptasia pulchella is a species worthy of investigation as a cnidarian representative, and will be an invaluable contribution to tropical marine ecotoxicologists.

An investigation into the behaviour of concrete containing seawater-neutralised bauxite refinery residues in silage effluent

Publisher: Elsevier BV

Date: 08-2010

DOI: 10.1016/J.BIOSYSTEMSENG.2010.05.007

Reversibility of uranium and thorium binding on a modified bauxite refinery residue: The effects of aging temperature

Publisher: Elsevier BV

Date: 02-2015

DOI: 10.1016/J.APGEOCHEM.2014.12.011

Phosphate removal from aqueous solutions using neutralised bauxite refinery residues (Bauxsol^TM)

Publisher: CSIRO Publishing

Date: 2006

DOI: 10.1071/EN05038

Abstract: Environmental Context.Eutrophication of freshwater and marine ecosystems is a global problem, which is frequently linked to high phosphorus concentrations. The present study investigated the use of Bauxsol™, a modified bauxite refinery residue, to remove dissolved phosphate from water, and has shown that it can be used as a cost-effective adsorbent for treating phosphate-contaminated waters. The results provide water and environmental managers with a new technique for decreasing the phosphate loads in water and wastewater. Environmental benefits include improved water quality, minimisation of excessive plant growth, including potentially toxic blue green algae, and the utilisation of an industrial residue for environmental remediation. Abstract.Phosphate (PO43–) removal by Bauxsol™, a neutralised bauxite refinery residue, was investigated as a function of time, pH, ionic strength, adsorbent dosage, competing ions, and initial phosphate concentration. The results of adsorption and desorption studies indicate that adsorption of PO43– by Bauxsol™ is based on a ligand-exchange mechanism, although the low reversibility pH-independent desorption observed in acid-treated Bauxsol™ indicates a dominance of chemisorption. It was shown that PO43– adsorption onto both Bauxsol™ and acid-treated Bauxsol™ followed a Langmuir isotherm model, with adsorption capacities of 0.21 and 0.48 mmol g−1 at pH 9.0 and 5.2 respectively. Adsorption of PO43– by Bauxsol™ increased with decreasing pH, with maximum adsorption efficiencies obtained at pH 5.2 ± 0.1 (the lowest pH investigated), higher Bauxsol™ to initial phosphate concentration ratios, and increased time. Studies of the effects of competing ions on the adsorption of PO43– by Bauxsol™ indicated that adsorption decreased in the presence of HCO3− ions, whereas SO42–and Cl− ions had little effect, and Ca2+ and Mg2+ ions increased adsorption. These findings suggest that Bauxsol™ could be used as an efficient low-cost adsorbent for treating phosphate-contaminated waters.

Diurnal variations in the chemistry of geothermal fluids after discharge, Champagne Pool, Waiotapu, New Zealand

Publisher: Elsevier BV

Date: 02-2004

DOI: 10.1016/J.CHEMGEO.2003.10.004

Toxicity estimates for diuron and atrazine for the tropical marine cnidarian Exaiptasia pallida and in- hospite Symbiodinium spp. using PAM chlorophyll- a fluorometry

Publisher: Elsevier BV

Date: 06-2017

DOI: 10.1016/J.JPHOTOBIOL.2017.05.006

Abstract: Effective ecotoxicological risk assessments for herbicides in tropical marine environments are restricted by a lack of toxicity data, sensitive test methods and endpoints for relevant species, and this requires rectification. The symbiotic sea anemone Exaiptasia pallida is a suitable test species, representing the phylum Cnidaria and allowing for assessments of toxicological responses of both the animal host and in-hospite Symbiodinium spp. Pulse litude modulated (PAM) chlorophyll-a fluorometry is recognised as a valuable ecotoxicological tool, and here newly-developed test methods are presented using PAM fluorometry to measure herbicide effects on photosynthetic efficiency of in-hospite Symbiodinium spp. Additionally, measurements on healthy laboratory-reared E. pallida provide baseline data demonstrating the normal effective quantum yield (EQY) and the maximum electron transport rate (ETR

Effects of seawater-neutralised bauxite refinery residue on properties of concrete

Publisher: Elsevier BV

Date: 07-2011

DOI: 10.1016/J.CEMCONCOMP.2011.03.010

Arsenic bio-accessibility and bioaccumulation in aged pesticide contaminated soils: A multiline investigation to understand environmental risk

Publisher: Elsevier BV

Date: 03-2017

DOI: 10.1016/J.SCITOTENV.2017.01.009

Abstract: Bio-accessibility and bioavailability of arsenic (As) in historically As-contaminated soils (cattle tick pesticide), and pristine soils were assessed using 3 different approaches. These approaches included human bio-accessibility using an extraction test replicating gastric conditions (in vitro physiologically-based extraction test) an operationally defined bioaccessibility extraction test - 1.0M HCl extraction and a live organism bioaccumulation test using earthworms. A sequential extraction procedure revealed the soil As-pool that controls bio-accessibility and bioaccumulation of As. Findings show that As is strongly bound to historically contaminated soil with a lower degree of As bio-accessibility (<15%) and bioaccumulation (<9%) compared with freshly contaminated soil. Key to these lower degrees of bio-accessibility and bioaccumulation is the greater fraction of As associated with crystalline Fe/Al oxy-hydroxide and residual phases. The high bio-accessibility and bioaccumulation of freshly sorbed As in pristine soils were from the exchangeable and specifically sorbed As fractions. Arsenic bioaccumulation in earthworms correlates strongly with both the human bio-accessible, and the operationally defined bioavailable fractions. Hence, results suggest that indirect As bioavailability measures, such as accumulation by earthworm, can be used as complementary lines of evidence to reinforce site-wide trends in the bio-accessibility using in vitro physiologically-based extractions and/or operationally defined extraction test. Such detailed knowledge is useful for successful reclamation and management of the As contaminated soils.

Treatment of an Iron-rich ARD Using Waste Carbonate Rock: Bench-Scale Reactor Test Results

Publisher: Springer Science and Business Media LLC

Date: 10-07-2009

DOI: 10.1007/S10230-009-0080-X

Toxicity of raw and neutralized bauxite refinery residue liquors to the freshwater cladoceran Ceriodaphnia dubia and the marine amphipod Paracalliope australis

Publisher: Wiley

Date: 14-10-2011

DOI: 10.1002/ETC.692

Abstract: The extraction of alumina from bauxite produces a highly toxic residue, termed bauxite refinery residue (BRR) or red mud. The toxicity of this material is due to chemical and biological effects of high pH, alkalinity, electrical conductivity (EC), and Na(+) and Al(3+) concentrations. Several neutralization techniques may allow BRR to be used for environmental remediation. The present study investigated standardized 48-h acute toxicity tests with a freshwater cladoceran, Ceriodaphnia dubia, and a marine hipod, Paracalliope australis, against raw supernatant BRR liquor (RL) versus liquors neutralized with acid (ANL), CO(2) (CNL), seawater (SNL), and a hybrid method (HNL). Based on 48-h LC50 values, the toxicity of the liquors to C. dubia increased in the following order HNL ≤ SNL< ANL ≤ CNL < RL, with comparable responses from P. australis. The high toxicity of RL likely is due to high pH (≈ 12), alkalinity, and Al concentration. Toxicity of CNL likely is due to high EC and alkalinity. Sulfate and Na(+) concentrations are considered sources of toxicity in ANL. Seawater-neutralized liquor and HNL were considerably less toxic to both test species. These data provide evidence of the acute lethal toxicity of raw supernatant liquor from BRR and four neutralized supernatant liquors to the freshwater cladoceran C. dubia and the marine hipod P. australis, providing valuable baselines for further ecotoxicological investigations of BRR materials in aquatic environments.

The distribution of heavy metals in an abandoned mining area; a case study of Strauss Pit, the Drake mining area, Australia: implications for the environmental management of mine sites

Publisher: Springer Science and Business Media LLC

Date: 23-03-2001

DOI: 10.1007/S002549900073

Resolving topography of an electron beam-sensitive oxalate-phosphate-amine metal–organic framework (OPA-MOF)

Publisher: Springer Science and Business Media LLC

Date: 15-10-2016

DOI: 10.1007/S10853-015-9478-Y

Elemental speciation and distribution in sediments of a eutrophied subtropical freshwater reservoir using postextraction normalisation

Publisher: Springer Science and Business Media LLC

Date: 28-06-2012

DOI: 10.1007/S11270-012-1220-7

Solid phases responsible for Mn II , Cr III , Co II , Ni, Cu II and Zn immobilization by a modified bauxite refinery residue (red mud) at pH 7.5

Publisher: Elsevier BV

Date: 2014

DOI: 10.1016/J.CEJ.2013.09.101

Development of a chronic, early life-stage sub-lethal toxicity test and recovery assessment for the tropical zooxanthellate sea anemone Aiptasia pulchella

Publisher: Elsevier BV

Date: 02-2014

DOI: 10.1016/J.ECOENV.2013.10.024

Abstract: There is an urgent need to identify additional tropical marine species and develop sensitive sub-lethal and chronic toxicity test methods for routine ecotoxicology. The tropical symbiotic sea anemone Aiptasia pulchella is a suitable species for use in ecotoxicology and here we have assessed the effects of trace metal exposures on the development of asexually produced A. pulchella pedal lacerates to a juvenile stage. Concentrations of 55 µg/L for cadmium, 262 µg/L for cobalt, 5 µg/L for copper, and 269 µg/L for zinc were estimated to inhibit normal development by 50 percent after 8-d exposures, and are among the most sensitive available toxicity estimates for marine organisms. This work illustrates the potential value of this species and sub-lethal toxicological endpoint for routine ecotoxicology in tropical marine environments.

Minimising alkalinity and pH spikes from portland cement-bound bauxsol (seawater-neutralized red mud) pellets for pH circum-neutral waters

Publisher: American Chemical Society (ACS)

Date: 18-02-2010

DOI: 10.1021/ES9032138

Abstract: Bauxsol reagents (powder, slurry, or pellet forms) are powerful tools in environmental remediation and water and sewage treatment However, when used in circum-neutral water treatments, cement-bound Bauxsol pellets produce a sustained pH and alkalinity spike due to the presence of unreacted CaO in the cement binder. This study developed a pellet treatment system to minimize the alkalinity H spike. The recipe for pelletization consisted of Bauxsol powder, ordinary Portland cement (OPC), hydrophilic fumed silica, aluminum powder, a viscosity modifier, and water. Several batches (including different ratios and sizes) were run using modified makeup waters (H(2)0 + CO(2) or NaHCO(3)) or curing brines (CO(2), NaHCO(3), or Mg/CaCl(2)). Alkalinity, pH stability, and slake durability tests were performed on pellets before and/or after curing. The best result for reducing the alkalinity H spike was obtained from a MgCl(2), CaCl(2) bath treatment using a Bauxsol:cement ratio of 2.8:1 (pH 8.28 alkalinity 75.1 mg/L) for a 100 g batch or 245:1 (pH 8.05 alkalinity 35.4 mg/L) for a 1 kg batch. Although brine curing does provide a control on pH/alkalinity release, the pellets may still contain unreacted CaO. Therefore, a freshwater rinse of pellets before treating circum-neutral waters is recommended as is the continued investigation of alternative pellet binders.

Comparison of several different neutralisations to a bauxite refinery residue: Potential effectiveness environmental ameliorants

Publisher: Elsevier BV

Date: 05-2015

DOI: 10.1016/J.APGEOCHEM.2015.01.015

Nutrient removal and microbial communities' development in a young unplanted constructed wetland using Bauxsol™ pellets to treat wastewater

Publisher: Elsevier BV

Date: 06-2014

DOI: 10.1016/J.SCITOTENV.2014.03.030

Abstract: Municipal wastewater was treated over a six month period in an unplanted constructed wetland with a lower soil layer and an upper Bauxsol™ pellet layer. The interactions between Bauxsol™ pellets, soil, effluent and microbial communities demonstrated a positive influence on contaminant removal. Bauxsol™ treated effluent showed >95% phosphate removal and ~26% nitrogen removal during the trial. Substantial quantities of nitrate, trace-metals and Colwell P were bound to the pellets, whereas only ammonium was bound to the soil. The structure of microbial communities analysed by denaturing gradient gel electrophoresis (DGGE) showed distinct bacterial communities attached to Bauxsol™ pellets and soil owing to differences in geochemistry and micro-environmental conditions. Polymerase chain reaction (PCR) lification of specific marker genes (i.e. bacterial and archaeal amoA genes, nosZ gene, and hzo gene) was used to evaluate the presence of microbial communities associated with nitrogen transformation. Data revealed the co-existence of aerobic ammonia-oxidising bacteria, anaerobic ammonia-oxidising bacteria (anammox) and denitrifiers attached to Bauxsol™ pellets and ammonia-oxidising bacteria and archaea attached to soil. This study successfully demonstrates that Bauxsol™ pellets are a suited alternative media for constructed wetland to treat wastewater effectively removing phosphate and serving as biomass support particles for bacterial communities associated with nitrogen-cycling.

Response Surface Optimisation of an Oxalate–Phosphate–Amine Metal–Organic Framework (OPA-MOF) of Iron and Urea

Publisher: Springer Science and Business Media LLC

Date: 21-04-2017

DOI: 10.1007/S10904-017-0547-3

Effects of Cd, Co, Cu, Ni and Zn on asexual reproduction and early development of the tropical sea anemone Aiptasia pulchella

Publisher: Springer Science and Business Media LLC

Date: 14-08-2014

DOI: 10.1007/S10646-014-1299-2

Abstract: Currently few studies present sub-lethal toxicity data for tropical marine species, and there are no routine toxicity tests using marine cnidarians. The symbiotic sea anemone Aiptasia pulchella has been identified as a useful species for ecotoxicological risk assessment, and would provide a tropical marine cnidarian representative. Chronic sub-lethal toxicity tests assessing the effects of 28-day trace metal exposure on asexual reproduction in A. pulchella were investigated, and concentration-dependant reductions in the number of offspring that were produced were evident for all metal exposures. Metal concentration estimates causing 50% reductions in the numbers of asexually-reproduced juveniles after 28-day exposures (28-day effect concentrations 50%: EC50s) were 14 µg/L for copper, 63 µg/L for zinc, 107 µg/L for cobalt, 145 µg/L for cadmium, and 369 µg/L for nickel. Slightly higher 28-day EC50s of 16 µg/L for copper, 192 µg/L for zinc, 172 µg/L for cobalt, 185 µg/L for cadmium, and 404 µg/L for nickel exposures and were estimated based on reductions in the total number of live developed and undeveloped offspring. These sensitive and chronic sub-lethal toxicity estimates help fill the knowledge gap related to metal effects on cnidarians over longer exposure periods, and this newly-developed bioassay may provide a much needed tool for ecotoxicological risk assessment relevant to tropical marine environments.

Investigating lethal and sublethal effects of the trace metals cadmium, cobalt, lead, nickel and zinc on the anemone Aiptasia pulchella, a cnidarian representative for ecotoxicology in tropical marine

Publisher: CSIRO Publishing

Date: 2014

DOI: 10.1071/MF13195

Abstract: The zooxanthellate sea anemone Aiptasia pulchella is found throughout the tropical and subtropical oceans of the Indo-Pacific and is easily maintained in aquaria, posing potential suitability as a standard tropical marine test organism for use in ecotoxicology. To gain an understanding of the sensitivity of A. pulchella to trace metals, 96-h static-renewal toxicity tests were conducted. Values of 96-h LC50 between 946 and 1196 µg L–1 were estimated for cadmium, between 595 and 1146 µg L–1 for zinc, 8060 and 12 352 µg L–1 for lead and 2209 and 5751 µg L–1 for nickel. In addition, preliminary assessment of rapid tentacle retraction was made. Six-hour EC50 values of 355 and 979 µg L–1 for cadmium, between 384 and 493 µg L–1 for zinc, between 2340 and 2584 µg L–1 for nickel, and 2610 µg L–1 for lead, were estimated for ‘severe’ tentacle retraction. Cobalt concentrations up to 1547 µg L–1 caused extreme zooxanthellae loss, but no more than 10% mortality and no rapid ‘severe’ tentacle retraction. The present study has provided important baseline information, enabling comparison of the acute sensitivity of A. pulchella to trace metals with other marine invertebrates, and guiding the development of sublethal endpoints.

Carbon capture and the aluminium industry: Preliminary studies

Publisher: CSIRO Publishing

Date: 2006

DOI: 10.1071/EN06018

Abstract: Environmental Context. Carbon dioxide concentrations in the atmosphere are rising every year by 1.5–3.0 ppm and there is now a general acceptance that increased efforts must be made to reduce industrial sources of this greenhouse gas. Carbonation of red mud wastes produced by aluminium refineries has been carried out to study the capacity of these wastes to capture carbon dioxide. Removal is very rapid, with the added carbon dioxide recorded as a large increase in bicarbonate alkalinity. Although these results can only be considered preliminary, the experiments indicate that these wastes can potentially remove up to 15 million tonnes of carbon dioxide produced in Australia per annum. Furthermore, the carbonated waste can be used in other industrial processes to add further value to these waste materials. Abstract. Carbonation of raw red mud produced by aluminium refineries and a chemically and physically neutralized red mud (Bauxsol™) has been carried out to study the capacity of these wastes to capture carbon dioxide. After only 5 min of carbonation of raw red mud, total alkalinity dropped 85%. Hydroxide alkalinity was almost totally consumed, carbonate alkalinity dropped by 88%, and bicarbonate alkalinity increased to 728 mg L–1. After 24 min carbonation, the bicarbonate alkalinity reached its maximum value of 2377 mg L–1, and hydroxide and carbonate alkalinity were virtually absent. After 30 and 60 min carbonation, bicarbonate alkalinity started to decrease slightly as the pH of the slurry increased. After 5 min carbonation of Bauxsol™, total and bicarbonate alkalinity dropped 89% and 9%, respectively. After 20 min carbonation, bicarbonate alkalinity dropped another 11%, but after 30 min carbonation bicarbonate alkalinity increased 26% to levels found in the original Bauxsol material, and pH was stable. Based on these experiments, a calculation of the amount of carbon dioxide that could be removed annually at aluminium refineries in Australia is potentially 15 million tonnes, and suggests that further studies are necessary to maximize this carbon removal process. Furthermore, carbonation produces a product, which can potentially be used in other industrial and agricultural activities to remove toxic metals and nutrients.

Linkage Projects - Grant ID: LP0562012

Start Date: 11-2005

End Date: 12-2008

Amount: $400,000.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP110100519

Start Date: 2011

End Date: 12-2015

Amount: $380,000.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE100100013

Start Date: 07-2010

End Date: 06-2011

Amount: $170,000.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE0668495

Start Date: 05-2006

End Date: 08-2006

Amount: $274,000.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE140100007

Start Date: 2014

End Date: 12-2014

Amount: $330,000.00

Funder: Australian Research Council

Linkage Projects - Grant ID: LP0212037

Start Date: 2002

End Date: 06-2005

Amount: $225,000.00

Funder: Australian Research Council