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Rücker C, Winkelmann M, Kümmerer K. Are Si-C bonds formed in the environment and/or in technical microbiological systems? ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2023; 30:91492-91500. [PMID: 37486465 PMCID: PMC10439844 DOI: 10.1007/s11356-023-28528-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Accepted: 06/27/2023] [Indexed: 07/25/2023]
Abstract
Organosiloxanes are industrially produced worldwide in millions of tons per annum and are widely used by industry, professionals, and consumers. Some of these compounds are PBT (persistent, biaccumulative and toxic) or vPvB (very persistent and very bioaccumulative). If organosiloxanes react at all in the environment, Si-O bonds are hydrolyzed or Si-C bonds are oxidatively cleaved, to result finally in silica and carbon dioxide. In strong contrast and very unexpectedly, recently formation of new Si-CH3 bonds from siloxanes and methane by the action of microorganisms under mild ambient conditions was proposed (in landfills or digesters) and even reported (in a biotrickling filter, 30 °C). This is very surprising in view of the harsh conditions required in industrial Si-CH3 synthesis. Here, we scrutinized the pertinent papers, with the result that evidence put forward for Si-C bond formation from siloxanes and methane in technical microbiological systems is invalid, suggesting such reactions will not occur in the environment where they are even less favored by conditions. The claim of such reactions followed from erroneous calculations and misinterpretation of experimental results. We propose an alternative explanation of the experimental observations, i.e., the putative observation of such reactions was presumably due to confusion of two compounds, hexamethyldisiloxane and dimethylsilanediol, that elute at similar retention times from standard GC columns.
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Affiliation(s)
- Christoph Rücker
- Institute for Sustainable Chemistry, Leuphana University Lüneburg, Universitätsallee 1, 21335, Lüneburg, Germany.
| | - Magnus Winkelmann
- Institute for Sustainable Chemistry, Leuphana University Lüneburg, Universitätsallee 1, 21335, Lüneburg, Germany
| | - Klaus Kümmerer
- Institute for Sustainable Chemistry, Leuphana University Lüneburg, Universitätsallee 1, 21335, Lüneburg, Germany
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Rücker C, Grabitz E, Kümmerer K. Are Si-C bonds cleaved by microorganisms? A critical review on biodegradation of methylsiloxanes. CHEMOSPHERE 2023; 321:137858. [PMID: 36642148 DOI: 10.1016/j.chemosphere.2023.137858] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2022] [Revised: 12/22/2022] [Accepted: 01/11/2023] [Indexed: 06/17/2023]
Abstract
Methylsiloxanes, compounds that contain H3C-Si-O subunits in their molecular structure, are emerging ubiquitous pollutants now detected in many environmental compartments. These compounds and generally Si-C bonds do not occur in living nature, but are industrially produced worldwide in millions of tons per annum and are widely used, resulting in their release to the environment. It is an open question whether or to what extent microorganisms are able to decompose these compounds. The presence of methylsiloxanes in many biogases adds to the economic relevance of this question. We here review and critically discuss, for the first time, the evidence obtained for and against degradation of methylsiloxanes by microorganisms, and in particular for microbial cleavage of Si-CH3 bonds. As a result, no convincing demonstration of Si-C cleavage by native environmental microorganisms has been found.
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Affiliation(s)
- Christoph Rücker
- Institute for Sustainable Chemistry, Leuphana University Lüneburg, Universitätsallee 1, D-21335, Lüneburg, Germany.
| | - Elisa Grabitz
- Institute for Sustainable Chemistry, Leuphana University Lüneburg, Universitätsallee 1, D-21335, Lüneburg, Germany
| | - Klaus Kümmerer
- Institute for Sustainable Chemistry, Leuphana University Lüneburg, Universitätsallee 1, D-21335, Lüneburg, Germany
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Lenis A, Ramírez M, González-Cortés JJ, Ooms K, Pinnekamp J. Implementation of a Pilot-Scale Biotrickling Filtration Process for Biogas Desulfurization under Anoxic Conditions Using Agricultural Digestate as Trickling Liquid. Bioengineering (Basel) 2023; 10:160. [PMID: 36829654 PMCID: PMC9951925 DOI: 10.3390/bioengineering10020160] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2022] [Revised: 01/15/2023] [Accepted: 01/21/2023] [Indexed: 01/26/2023] Open
Abstract
A pilot-scale biotrickling filter (BTF) was operated in counter-current flow mode under anoxic conditions, using diluted agricultural digestate as inoculum and as the recirculation medium for the nutrient source. The process was tested on-site at an agricultural fermentation plant, where real biogas was used. The pilot plant was therefore exposed to real process-related fluctuations. The purpose of this research was to attest the validity of the filtration process for use at an industrial-scale by operating the pilot plant under realistic conditions. Neither the use of agricultural digestate as trickling liquid and nor a BTF of this scale have previously been reported in the literature. The pilot plant was operated for 149 days. The highest inlet load was 8.5 gS-H2Sm-3h-1 with a corresponding removal efficiency of 99.2%. The pH remained between 7.5 and 4.6 without any regulation throughout the complete experimental phase. The analysis of the microbial community showed that both anaerobic and anoxic bacteria can adapt to the fluctuating operating conditions and coexist simultaneously, thus contributing to the robustness of the process. The operation of an anoxic BTF with agricultural digestate as the trickling liquid proved to be viable for industrial-scale use.
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Affiliation(s)
- Alejandra Lenis
- Research Institute for Water Management and Climate Future, RWTH Aachen University, (FiW) e. V., Kackertstraße 15-17, D-52056 Aachen, Germany
| | - Martín Ramírez
- Department of Chemical Engineering and Food Technology, Cadiz University, 11510 Puerto Real, Spain
| | | | - Kristoffer Ooms
- Research Institute for Water Management and Climate Future, RWTH Aachen University, (FiW) e. V., Kackertstraße 15-17, D-52056 Aachen, Germany
| | - Johannes Pinnekamp
- Research Institute for Water Management and Climate Future, RWTH Aachen University, (FiW) e. V., Kackertstraße 15-17, D-52056 Aachen, Germany
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Jia T, Zhang L, Li X, Zhao Q, Peng Y, Sui J, Wang C. Characteristics of biotrickling filter system for hydrogen sulfide removal with seasonal temperature variations: A strategy for low temperature conditions. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 857:159617. [PMID: 36273568 DOI: 10.1016/j.scitotenv.2022.159617] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2022] [Revised: 10/17/2022] [Accepted: 10/17/2022] [Indexed: 06/16/2023]
Abstract
The impact of temperature on the biological removal of hydrogen sulfide (H2S) from air is critical to its effective application in cold regions or seasons. This study investigated the effect of seasonal temperature variations (7-30 °C) on the H2S removal performance of a biotrickling filter system, with an effective H2S elimination capacity of 98.1 g/m3/h (removal efficiency = 83.1 %) achieved at temperatures of 10-12 °C. Biofilm growth was found to be accelerated by increased secretion of extracellular polymeric substances, enhanced biofilm adhesion capacity and relatively high levels of elemental sulfur accumulation, which help to retain heat within the filter bed under cold conditions. High-throughput sequencing showed that the psychrotolerant sulfur-oxidizing bacterium (SOB) Metallibacterium was gradually enriched (54.8 %) at temperatures below 15 °C. The major pathways of sulfur metabolism under low temperature conditions were determined based on the detection of enzymes related to sulfur metabolism. Finally, a strategy to enrich Metallibacterium was proposed to promote the application of biodesulfurization under low temperature conditions.
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Affiliation(s)
- Tipei Jia
- National Engineering Laboratory for Advanced Municipal Wastewater Treatment and Reuse Technology, Engineering Research Center of Beijing, Beijing University of Technology, Beijing 100124, PR China
| | - Liang Zhang
- National Engineering Laboratory for Advanced Municipal Wastewater Treatment and Reuse Technology, Engineering Research Center of Beijing, Beijing University of Technology, Beijing 100124, PR China
| | - Xiyao Li
- National Engineering Laboratory for Advanced Municipal Wastewater Treatment and Reuse Technology, Engineering Research Center of Beijing, Beijing University of Technology, Beijing 100124, PR China
| | - Qi Zhao
- National Engineering Laboratory for Advanced Municipal Wastewater Treatment and Reuse Technology, Engineering Research Center of Beijing, Beijing University of Technology, Beijing 100124, PR China
| | - Yongzhen Peng
- National Engineering Laboratory for Advanced Municipal Wastewater Treatment and Reuse Technology, Engineering Research Center of Beijing, Beijing University of Technology, Beijing 100124, PR China.
| | - Jun Sui
- Guangdong Shouhui Lantian Engineering and Technology Co. Ltd., Guangzhou 510075, PR China
| | - Chuanxin Wang
- Guangdong Shouhui Lantian Engineering and Technology Co. Ltd., Guangzhou 510075, PR China
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Jia T, Zhang L, Sun S, Zhao Q, Peng Y. Adding organics to enrich mixotrophic sulfur-oxidizing bacteria under extremely acidic conditions-A novel strategy to enhance hydrogen sulfide removal. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 854:158768. [PMID: 36108867 DOI: 10.1016/j.scitotenv.2022.158768] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Revised: 08/29/2022] [Accepted: 09/10/2022] [Indexed: 06/15/2023]
Abstract
Biotreatment of high load hydrogen sulfide (H2S) can lead to rapid acidification of a bioreactor, which greatly challenges the application of bio-desulfurization technology. In this study, the bio-desulfurization performance was improved by enriching acidophilic mixotrophic sulfur-oxidizing bacteria (SOB) by adding organics under extremely acidic conditions (pH < 1.0). A biotrickling filter (BTF) for the removal of H2S was established and operated under pH < 1.0 for 420 days. In the autotrophic period, the maximum H2S elimination capacity (ECmax-H2S) was 135.8 g/m3/h with biofilm mass remaining within 11.1 g/L-BTF. The autotrophic SOB bacterium Acidithiobacillus was dominant (62.1 %). When glucose was added to the BTF system, ECmax-H2S increased by 272 % to 464.3 g/m3/h as biofilm mass increased to 22.3 g/L-BTF. The acidophilic mixotrophic SOB bacteria Mycobacterium (78.4 %) and Alicyclobacillus (20.7 %) were enriched while Acidithiobacillus was gradually eliminated (<0.1 %). Furthermore, the major sulfur metabolism pathways were identified to explore the desulfurization mechanism under extremely acidic conditions. To maintain optimal desulfurization performance and avoid biofilm overgrowth in the BTF system, biofilm mass should be maintained within 20-22 g/L-BTF. This can be achieved by adding 1.0 g/L-BTF glucose every 20 days under a load rate of H2S in 50-90 g/m3/h and a trickling liquid velocity of 1.8 m/h. Extremely acidic conditions eliminated non-aciduric microorganisms so that the addition of organics can increase the abundance of acidophilic mixotrophic SOB (>99 %), thus offering a novel strategy for enhancing H2S removal.
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Affiliation(s)
- Tipei Jia
- National Engineering Laboratory for Advanced Municipal Wastewater Treatment and Reuse Technology, Engineering Research Center of Beijing, Beijing University of Technology, Beijing 100124, China
| | - Liang Zhang
- National Engineering Laboratory for Advanced Municipal Wastewater Treatment and Reuse Technology, Engineering Research Center of Beijing, Beijing University of Technology, Beijing 100124, China
| | - Shihao Sun
- National Engineering Laboratory for Advanced Municipal Wastewater Treatment and Reuse Technology, Engineering Research Center of Beijing, Beijing University of Technology, Beijing 100124, China
| | - Qi Zhao
- National Engineering Laboratory for Advanced Municipal Wastewater Treatment and Reuse Technology, Engineering Research Center of Beijing, Beijing University of Technology, Beijing 100124, China
| | - Yongzhen Peng
- National Engineering Laboratory for Advanced Municipal Wastewater Treatment and Reuse Technology, Engineering Research Center of Beijing, Beijing University of Technology, Beijing 100124, China.
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Das J, Lens PNL. Resilience of hollow fibre membrane bioreactors for treating H 2S under steady state and transient conditions. CHEMOSPHERE 2022; 307:136142. [PMID: 36028125 DOI: 10.1016/j.chemosphere.2022.136142] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Revised: 07/15/2022] [Accepted: 08/17/2022] [Indexed: 06/15/2023]
Abstract
H2S removal performance by hollow fibre membrane bioreactors (HFMBs) was investigated for 271 days at ambient (20 ± 2 °C) temperature employing an inlet H2S concentrations up to 3600 ppmv and empty bed residence time (EBRT) of 187, 92 and 62 s. Different operating conditions including pH control (with or without), famine period, shock loads (4-72 h) and different biomass types (presence or absence of suspended biomass) were investigated. The H2S flux and mass-transfer coefficient were significantly higher for the biotic HFMBs (R1 and R2) compared to the abiotic control (R3) at all employed EBRTs. Significant differences in H2S removal efficiency (RE) and elimination capacity (EC) were noted for different inlet H2S concentrations, EBRTs, pH and biomass type. The HFMB achieved >99% RE at steady-state for biotic operation with an EC of 33.8, 30.0 and 30.9 g m-3 h-1 at an EBRT of 187, 92 and 62 s, respectively. Sulfate (92-93%) was the main sulfur species in the H2S bioconversion process. The HFMB showed a good resilience to shock loads and showed quick recovery (<24 h) after withdrawal of the shock loads. The HFMB had a critical loading rate of H2S about 135 g m-3 h-1 under transient-state.
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Affiliation(s)
- Jewel Das
- National University of Ireland Galway, University Road, H91 TK33, Galway, Ireland; Bangladesh Council of Scientific and Industrial Research (BCSIR), BCSIR Laboratories Chattogram, Chattogram 4220, Bangladesh.
| | - Piet N L Lens
- National University of Ireland Galway, University Road, H91 TK33, Galway, Ireland
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