Natural attenuation of Mn(II) was observed inside the metal refinery wastewater pipeline, accompanying dark brown-colored mineralization (mostly MnIVO2 with some MnIII2O3 and Fe2O3) on the inner pipe surface. The Mn-deposit hosted the bacterial community comprised of Hyphomicrobium sp. (22.1%), Magnetospirillum sp. (3.2%), Geobacter sp. (0.3%), Bacillus sp. (0.18%), Pseudomonas sp. (0.03%), and non-metal-metabolizing bacteria (74.2%). Culture enrichment of the Mn-deposit led to the isolation of a new heterotrophic Mn(II)-oxidizer Pseudomonas sp. SK3, with its closest relative Ps. resinovorans (with 98.4% 16S rRNA gene sequence identity), which was previously unknown as an Mn(II)-oxidizer. Oxidation of up to 100 mg/L Mn(II) was readily initiated and completed by isolate SK3, even in the presence of high contents of MgSO4 (a typical solute in metal refinery wastewaters). Additional Cu(II) facilitated Mn(II) oxidation by isolate SK3 (implying the involvement of multicopper oxidase enzyme), allowing a 2-fold greater Mn removal rate, compared to the well-studied Mn(II)-oxidizer Ps. putida MnB1. Poorly crystalline biogenic birnessite was formed by isolate SK3 via one-electron transfer oxidation, gradually raising the Mn AOS (average oxidation state) to 3.80 in 72 h. Together with its efficient in vitro Mn(II) oxidation behavior, a high Mn AOS level of 3.75 was observed with the pipeline Mn-deposit sample collected in situ. The overall results, including the microbial community structure analysis of the pipeline sample, suggest that the natural Mn(II) attenuation phenomenon was characterized by robust in situ activity of Mn(II) oxidizers (including strain SK3) for continuous generation of Mn(IV). This likely synergistically facilitated chemical Mn(II)/Mn(IV) synproportionation for effective Mn removal in the complex ecosystem established in this artificial pipeline structure. The potential utility of isolate SK3 is illustrated for further industrial application in metal refinery wastewater treatment processes.

The thermo-acidophilic archaeon, Sulfolobus tokodaii was utilized for the production of 20 Pd(0) bionanoparticles from acidic Pd(II) solution. Use of active cells was essential to form well-21 dispersed Pd(0) nanoparticles located on the cell surface. The particle size could be manipulated 22 by modifying the concentration of formate (as electron donor; e-donor) and by addition of 23 enzymatic inhibitor (Cu 2+ ) in the range of 14-63 nm mean size. Since robust Pd(II) reduction 24 progressed in pre-grown S. tokodaii cells even in the presence of up to 500 mM Cl -, it was possible 25 to conversely utilize the effect of Clto produce even finer and denser particles in the range of 8.7-26 15 nm mean size. This effect likely resulted from the increasing stability of anionic Pd(II)-chloride 27 complex at elevated Clconcentrations, eventually allowing involvement of greater number of 28 initial Pd(0) crystal nucleation sites (enzymatic sites). The catalytic activity (evaluated based on 29 Cr(VI) reduction reaction) of Pd(0) bionanoparticles of varying particle size formed under 30 different conditions were compared. The finest Pd(0) bionanoparticles obtained at 50 mM Cl -31 (mean 8.7 nm; median 5.6 nm) exhibited the greatest specific Cr(VI) reduction rate, with 4-times 32 higher catalytic activity compared to commercial Pd/C. The potential applicability of S. tokodaii 33 cells in the recovery of highly catalytic Pd(0) nanoparticles from actual acidic chloride leachate 34 was thus suggested. 35 36 Page 2 of 34 Extremophiles important industrial catalysts. To secure a stable world supply of PGMs and other precious metals, 40 recycling of secondary metal resources (e.g., spent catalysts and e-wastes) is considered 41 increasingly important. For Pd recycling from such secondary resources, strong leaching lixiviants 42 such as aqua regia, HCl, HNO 3 and H 2 SO 4 are used together with an oxidizing agent. To lower 43 environmental impacts, cleaner alternatives, such as using diluted HCl with H 2 O 2 , are also 44 investigated by different groups (e.g., Barakat et al. 2006). Since Pd catalysts today are mostly 45 used as nanoparticles due to their greater specific surface area with higher reactivity (De Corte et 46 al. 2012), developing recycling techniques of the metal in the nanoparticle form would be 47 beneficial. 48 Microbiological production of precious metal nanoparticles is gaining increasing attention 49 as a simple and clean technology which proceeds under ambient conditions without the use of 50 hazardous chemicals (Zhang et al. 2011). Upon utilization of microbial cells, reduction of aqueous 51 Pd(II) ions is triggered by enzymatic activity by an expense of externally added e-donor (or 52 intracellular electron carriers such as NADH accumulated during pre-growth; Okibe et al. 2017). 53 They are then deposited as solid Pd(0) nanoparticles at different cellular locations as a scaffold (on 54 the cell wall, within the periplasmic space and inside cytoplasm), depending on the microbial 55 species and conditions used (De...

For sustainable wastewater treatment, bioremediation technology was introduced. Due to its complexity, peoples being skeptical and start to refuse. This making the installation of such technology become more difficult. To prevent conflict between the company and the local, public acceptance is needed to be evaluated and improved. CSR activity was found to be a booster promoting a trust toward the company, it is expected to boost positive perception as well. This study surveyed the attitude toward bioremediation and CSR activity participation. Data analysis found that people believe that bioremediation is an environmental-friendly approach and is a long-term solution for wastewater treatment. Peoples with CSR activity experience tended to have higher positive perception score than non-experienced. The results illustrated that if the company giving accurate, adequate information and doing appropriate CSR activity, social's positive perception toward bioremediation could be improved.

No abstract

The necessity of arsenic (As) removal from metallurgical wastewaters is increasing. Despite its wide recognition as a natural oxidant, the utility of Mn oxide for scorodite production is mostly unknown. In acidic solutions containing both As(III) and Fe 2+ , simultaneous oxidation of the two progressed by MnO 2 and the resultant As(V) and Fe 3+ triggered the formation of crystalline scorodite (FeAsO 4 •2H 2 O). At 0.5% or 0.25% MnO 2 , 98% or 91% As was immobilized by day 8. The resultant scorodite was sufficiently stable according to the TCLP test, compared to the regulatory level in US and Chile (5 mg/L): 0.11 « 0.01 mg/L at 0.5% MnO 2 , 0.78 « 0.05 mg/L at 0.25% MnO 2 . For the oxidation of As(III) and Fe 2+ , 54% (at 0.5% MnO 2 ) or 14% (at 0.25% MnO 2 ) of initially added MnO 2 remained undissolved and the rest dissolved in the post As(III) treatment solution. For the Mn recycling purpose, the combination of Mn 2+ -oxidizing bacteria and biogenic birnessite (as homogeneous seed crystal) was used to recover up to 99% of dissolved Mn 2+ as biogenic birnessite ((Na, Ca)0.5(Mn IV , Mn III ) 2 O 4 •1.5H 2 O), which can be utilized for the oxidation treatment of more dilute As(III) solutions at neutral pH. Although further optimization is necessary, the overall finding in this study indicated that Mn oxide could be utilized as a recyclable oxidant source for different As(III) treatment systems.