Degradation of toluene by a mixed population of archetypal aerobes, microaerophiles, and denitrifiers: Laboratory sand column experiment and multispecies biofilm model formulation

<p>Efforts to remove excess nitrate in the groundwater typically involves expensive ion-exchange membranes or slow reacting bio-reactors. Nano-sized zero valent iron (nZVI) has been used successfully to reduce nitrate into ammonia in various sites in USA and Europe. However, nZVI has a number of major setbacks associated with it, namely the tendency to agglomerate due to magnetic properties, and the possible toxicity due to the nano-sized material. To circumvent these two setbacks, nZVI could be adsorbed onto solid support. In this research, geothermal sediment microsilicate 600 (Misi) was utilised as a support. Initial results suggested that Misi has potential as a support for nZVI, however modifications were required to improve the adsorbance of nZVI onto Misi surface. Calcination, activation, acid wash and iron oxyhydroxide coating were used as surface modifications for Misi. It was found that the two most important modifications for nZVI adsorption was calcination at either 400 or 600 °C and acid washing in 5.6 M HCl. Equipped with this knowledge, other silica and silicates were also used to adsorb nZVI. For pure silica surfaces, 3-APTES and 3-TPTMS ligands and pore enlarging methods of calcination of porogen and salt wash were also used. nZVI was not able to be fully adsorbed on pure silica surfaces. Four other silicates were examined: Rice husk ash, Western Australia silica fume, Mt Piper fly ash, and precipitated aluminium silicate. Of these, only Western Australia silica fume and precipitated aluminium silicate showed potential as nZVI support. Based on the SEM-EDS XRD data of all the silica and silicates, it could be tentatively concluded that nZVI requires an aluminium silicate surface for successful adsorption. Aluminium silicate surfaces typically has an exchangeable cation present, and this cation might play a part in nZVI adsorption. The nZVI/Misi surface was then utilised to reduce nitrate. It was discovered that even though activation and FeOOH did not play a part in nZVI adsorption onto Misi surface, these two steps were important in reduction of nitrate, as the presence of activation and FeOOH increase the reduction of nitrate significantly within 60 minutes. The Misi-supported nZVI were also shown to be more stable in dispersion, and less agglomerated as shown in a sand column experiment.</p>

Download Full-text

A multispecies biofilm model

Biotechnology and Bioengineering ◽

10.1002/bit.260280304 ◽

1986 ◽

Vol 28 (3) ◽

pp. 314-328 ◽

Cited By ~ 379

Author(s):

O. Wanner ◽

W. Gujer

Keyword(s):

Biofilm Model ◽

Multispecies Biofilm

Download Full-text

Effect of Periodontal Pathogens on the Metatranscriptome of a Healthy Multispecies Biofilm Model

Journal of Bacteriology ◽

10.1128/jb.06328-11 ◽

2012 ◽

Vol 194 (8) ◽

pp. 2082-2095 ◽

Cited By ~ 60

Author(s):

J. Frias-Lopez ◽

A. Duran-Pinedo

Keyword(s):

Periodontal Pathogens ◽

Biofilm Model ◽

Multispecies Biofilm

Download Full-text

Spatial distribution and physiological state of bacteria in a sand column experiment during the biodegradation of toluene

Water Research ◽

10.1016/j.watres.2007.02.018 ◽

2007 ◽

Vol 41 (10) ◽

pp. 2089-2100 ◽

Cited By ~ 8

Author(s):

Hyun-su Kim ◽

Peter R. Jaffé

Keyword(s):

Spatial Distribution ◽

Physiological State ◽

Column Experiment ◽

Sand Column

Download Full-text

Methods to Improve nZVI Adsorbance on Silicates Surface for Nitrate Reduction

10.26686/wgtn.17067692 ◽

2021 ◽

Author(s):

◽

Handayani Fraser

Keyword(s):

Silica Fume ◽

Western Australia ◽

Column Experiment ◽

Exchangeable Cation ◽

Sand Column ◽

Silica Surfaces ◽

Pure Silica ◽

Acid Washing ◽

Silicate Surface ◽

Aluminium Silicate

<p>Efforts to remove excess nitrate in the groundwater typically involves expensive ion-exchange membranes or slow reacting bio-reactors. Nano-sized zero valent iron (nZVI) has been used successfully to reduce nitrate into ammonia in various sites in USA and Europe. However, nZVI has a number of major setbacks associated with it, namely the tendency to agglomerate due to magnetic properties, and the possible toxicity due to the nano-sized material. To circumvent these two setbacks, nZVI could be adsorbed onto solid support. In this research, geothermal sediment microsilicate 600 (Misi) was utilised as a support. Initial results suggested that Misi has potential as a support for nZVI, however modifications were required to improve the adsorbance of nZVI onto Misi surface. Calcination, activation, acid wash and iron oxyhydroxide coating were used as surface modifications for Misi. It was found that the two most important modifications for nZVI adsorption was calcination at either 400 or 600 °C and acid washing in 5.6 M HCl. Equipped with this knowledge, other silica and silicates were also used to adsorb nZVI. For pure silica surfaces, 3-APTES and 3-TPTMS ligands and pore enlarging methods of calcination of porogen and salt wash were also used. nZVI was not able to be fully adsorbed on pure silica surfaces. Four other silicates were examined: Rice husk ash, Western Australia silica fume, Mt Piper fly ash, and precipitated aluminium silicate. Of these, only Western Australia silica fume and precipitated aluminium silicate showed potential as nZVI support. Based on the SEM-EDS XRD data of all the silica and silicates, it could be tentatively concluded that nZVI requires an aluminium silicate surface for successful adsorption. Aluminium silicate surfaces typically has an exchangeable cation present, and this cation might play a part in nZVI adsorption. The nZVI/Misi surface was then utilised to reduce nitrate. It was discovered that even though activation and FeOOH did not play a part in nZVI adsorption onto Misi surface, these two steps were important in reduction of nitrate, as the presence of activation and FeOOH increase the reduction of nitrate significantly within 60 minutes. The Misi-supported nZVI were also shown to be more stable in dispersion, and less agglomerated as shown in a sand column experiment.</p>

Download Full-text

All together now: experimental multispecies biofilm model systems

Environmental Microbiology ◽

10.1111/1462-2920.13594 ◽

2017 ◽

Vol 19 (1) ◽

pp. 42-53 ◽

Cited By ~ 33

Author(s):

Chuan Hao Tan ◽

Kai Wei Kelvin Lee ◽

Mette Burmølle ◽

Staffan Kjelleberg ◽

Scott A. Rice

Keyword(s):

Model Systems ◽

Biofilm Model ◽

Multispecies Biofilm

Download Full-text

Heavy metals removal from landfill leachate by coagulation/flocculation process combined with continuous adsorption using eggshell waste materials

Water Science & Technology ◽

10.2166/wst.2021.493 ◽

2021 ◽

Author(s):

A. Q. Jaradat ◽

Dua'a B. Telfah ◽

Rabah Ismail

Keyword(s):

Heavy Metals ◽

Landfill Leachate ◽

Agricultural Waste ◽

Column Experiment ◽

Waste Materials ◽

Optimum Dose ◽

Sand Column ◽

Heavy Metals Removal ◽

Metals Removal ◽

Eggshell Waste

Abstract The use of agricultural waste materials to remove heavy metals from wastewater is attractive due to its simplicity and economic efficiency. In this study, the applicability of calcined eggshell waste materials (CES) for heavy metals removal from real wastewater were examined via transport column experiment preceded by coagulation/flocculation process.A column packed with granular activated carbon (GAC) is operated in parallel to CES column to evaluate the adsorptive attributes of CES. The findings are assessed from another set of column experiment consisting of sand followed by CES column to evaluate the effect of particulate matter on CES performance toward heavy metals removal. In coagulation experiment, alum addition at an optimum dose (3.0 g/L) reduced the total suspended solids (TSS) by 80%, whereas the Fe, Pb, Zn, Cu, Ni, and Cr were reduced by 80, 77, 76, 73, 56, and 49% respectively. Under the current applied hydrodynamic conditions, using sand column before CES column improved the removal efficiencies of Fe, Pb, Cu, Zn, Ni, and Cr from 50–92%, 55–93%, 60–87%, 53–76%, 45–65%, and 41–60% respectively. The whole results illustrate that CES can be competitive to GAC for heavy metals removal from landfill leachate, mainly if applied after PM removal by sand filtration.

Download Full-text