Biological removal of iron content from water sources using iron-oxidizing bacteria: a review

Background and Aim: Iron-oxidizing bacteria (IOB) are harmless, chemotrophic organisms that use oxygen to dissolve iron in wastewater contaminated with heavy metals. They thrive in water with iron concentrations as low as 0.1 mg/L, offering a cost-effective, eco-friendly solution for water treatment. In Uttarakhand, widespread iron contamination continues to limit access to safe drinking water despite efforts to address the issue. This study aimed to explore the use of bioremediation and microbial consortia to reduce and eliminate iron contamination in drinking water sources. Methods: The study employed a biosorption process, where the iron-oxidizing bacteria and microbial consortia were immobilized on a solid carrier (coarser sand) to facilitate contact with the contaminated water. The bacteria and consortia adsorbed iron ions from the water onto the surface of the carrier material through various mechanisms, including ion exchange, chelation, and surface complexation. The biosorption experiments were conducted in a batch mode, where the contaminated water was mixed with the carrier material containing the microbial consortium. The mixture was agitated under controlled conditions to promote iron removal. Results: The study assessed the iron removal efficiency of various carriers (gravel, sand, coarse sand, bentonite, and lignite) and iron-oxidizing bacteria (IOB-1 to IOB-6) from 100 water samples collected in Uttarakhand. The key findings are: Carrier Performance: Coarse sand consistently demonstrated the highest iron removal efficiency among all carriers, with an average removal rate of 84.67% ± 0.02%. Microbial Isolate Performance: Among the IOB strains, IOB-1 exhibited the best iron removal efficiency, achieving an average of 46.67% ± 0.08%. Microbial Consortium: The microbial consortium formed using IOB-1 in combination with coarse sand achieved the highest overall iron removal efficiency of 89.33% ± 0.05. These results underscore the effectiveness of bioremediation techniques, particularly using microbial consortia, for addressing iron contamination in water resources. Discussion: The present study demonstrates the efficacy of bioremediation techniques, specifically utilizing iron-oxidizing bacteria and microbial consortia, in addressing iron contamination in water resources. The results indicate that the selected carriers, particularly coarse sand, and the microbial isolate IOB-1 exhibited significant potential for iron removal. Conclusion: The combination of iron-oxidizing bacteria and suitable carriers offers a promising approach for water treatment in regions affected by iron pollution. The microbial consortia entrapped in coarse sand demonstrated superior performance compared to individual strains, suggesting the synergistic effects of microbial interactions.

Sampling techniques with centimeter-scale spatial resolution were applied to investigate biogeochemical processes controlling groundwater arsenic fate across the groundwater-surface water interface at a site characterized by fine sediments (40% sand, 46% silt, 14% clay). Freeze-core sediment collection gave more detailed and depth-accurate arsenic and iron contaminant and microbial distributions than could be obtained with the use of a hand auger. Selective chemical extractions indicated that greater than 90% of the arsenic was strongly sorbed to very amorphous iron oxyhydroxides. These solids accounted for more than 80% of the total iron in the sediments. Microbial enrichments indicated that iron-oxidizing bacteria (IOB) were up to 1% of the total bacterial abundance, whereas iron-reducing bacteria (IRB) were about two orders of magnitude less abundant than IOB. The abundance of IRB mirrored the IOB depth profile. Push-point pore-water sampling captured large amounts of sediment fines, even with controlled (20 ml/min) water withdrawal, thereby necessitating filtration before water quality analysis. Bead columns containing glass media enabled short-term (29 d) characterization of pore water-to-sediment transfer of arsenic and iron. Bead columns indicated quantitative capture of groundwater arsenic and iron during 2003, suggesting that freeze-core inventories corresponded to 2 to 20 years of accumulation, depending on location.

The accumulation of bacterial biofilms and consequent clogging of screens, pipes, and heat exchanger equipment is problematic for water supply systems contaminated with iron bacteria and other slime forming bacteria.Despite the ubiquitous threat posed by iron bacteria contamination in groundwater sources, limited research has focused on physical treatments to address this issue.We sought to investigate the effectiveness of ultraviolet (UV) irradiation on inactivating iron bacteria and slime forming bacteria in a fish hatchery supply water known to have issues with bacterial biofilms.Biological activity reaction tests (BART) were used to analyze the presence or absence of iron related and slime forming bacteria in raw well water at UV dosages of 0 mJ/cm 2 , 15 mJ/cm 2 , 30 mJ/cm 2 , 45 mJ/cm 2 and 60 mJ/cm 2 .Results suggest that UV treatment decreases iron bacteria survival, with the highest percent of non-reactive BART TM test vials resulting from 45 mJ/cm 2 and 60 mJ/cm 2 UV exposure; however, data regarding UV inactivation of slime forming bacteria were inconclusive.These initial 'proof of concept' findings can be used to design pilot UV water treatment systems for fish hatcheries known to have iron bacteria problems.Pilot treatment system testing can then provide the necessary results to ensure that UV treatment is effective against site-specific iron bacteria populations before full-scale treatment systems are implemented.

Characteristics of corrosion sales and biofilm in aged pipe distribution systems with switching water source

Microbial influenced corrosion (MIC) has been implicated in many corrosion related challenges in the well service industry in the past. Recently, the industry is observing an influx of MIC related equipment damage. The recurrence of MIC is coincidental with the switch to unconventional water sources. As fresh water for fracturing operations and well interventions becomes less available, operators are forced to use alternative water sources such as recycled flowback water, produced water, recycled frac water, and even 'grey water' from wastewater treatment plants. Regardless of the water source for a particular well treatment operation, the same water-hauling equipment and tanks are used for successive hydraulic fracturing operations. This 'communal' use of water hauling and temporary water storage equipment is an ideal situation for bacteria to move from one water repository to another. Even if the water source used to supply water for oilfield operations is free from harmful bacteria, it may become contaminated - in transport or temporary storage vessels - before it is pumped downhole. This paper will highlight a recent discovery of MIC in coil tubing that has been used for milling frac plugs in the Eagle Ford Shale play in Texas. In this case, MIC had significantly decreased the life span of the affected coil tubing strings. Metallurgical analysis was conducted to determine if the corrosion was the result of sulfur-reducing bacteria (SRB) or anaerobic acid producing bacteria (APB) - two specific types of several microbes that can lead to MIC. Bend fatigue testing was conducted on MIC-affected coil tubing samples, which showed a significantly reduced coil fatigue life when compared to non-affected coil tubing. This paper will explore the potential source(s) of the bacteria, the impact to the equipment that was exposed to the bacteria, as well as what is being done to mitigate the problem. Introduction Representing the largest portion of the Earth's overall biomass, bacteria are ubiquitous on the planet's surface. They have been recovered from subterranean rock to depths in excess of 13,000 ft (4,000 m) (Moser, 2006). Microbial species have been shown to survive temperatures in excess of 120°C (Breeder, 1994) and pressures in excess of 130 MPa (Jun, 2011). Thriving bacteria can exist in either a free floating (planktonic) or static (sessile) state wherein they are attached to a solid surface of nearly any sort. In this attached or sessile state, the bacteria commonly coexist with other microbes such as other bacterial, archaeal or fungal species. These microbial communites create their own protective environment made of biopolymers of virtually all types. These sessile communities are commonly refered to as a biofilm, which is the state the overwhelming majority of microbes exist in (Costerton, 2007). Microbial-influenced corrosion, also known as biological corrosion, bacterial corrosion, bio-corrosion, biofouling, biotic corrosion, microbiologically-influenced corrosion, or MIC is a type of corrosioncaused, promoted or accelerated bymicroorganisms. MIC has been shown to greatly accelerate corrosion relative to the rates that occur abiotically and is thought to contribute roughly 20% to the overall cost of corrosion (Little, 2007). MIC in anaerobic conditions is most often associated with sulfate-reducing bacteria (SRB) that produce sulfide species (H2S and/or FeS) as part of their metabolic process, which can contribute to sulfide stress cracking (SCC) in addition to MIC (Cheng, 2013). In addition to SRB, thiosulfate-reducing bacteria (TRB), nitrate-reducing bacteria (NRB), sulfite-producing bacteria (SuRB), acid-producing bacteria (APB), methanogens- and exopolymeric substances (EPS)-producing baceteria, and iron-oxidizing bacteria (IOB) have also been implicated in MIC (Little, 2007).

Chemolithoautotrophic iron-oxidizing bacteria play an essential role in the global iron cycle. Thus far, the majority of marine iron-oxidizing bacteria have been identified as Zetaproteobacteria, a novel class within the phylum Proteobacteria. Marine iron-oxidizing microbial communities have been found associated with volcanically active seamounts, crustal spreading centers, and coastal waters. However, little is known about the presence and diversity of iron-oxidizing communities at hydrothermal systems along the slow crustal spreading center of the Mid-Atlantic Ridge. From October to November 2012, samples were collected from rust-colored mats at three well-known hydrothermal vent systems on the Mid-Atlantic Ridge (Rainbow, Trans-Atlantic Geotraverse, and Snake Pit) using the ROV Jason II. The goal of these efforts was to determine if iron-oxidizing Zetaproteobacteria were present at sites proximal to black smoker vent fields. Small, diffuse flow venting areas with high iron(II) concentrations and rust-colored microbial mats were observed at all three sites proximal to black smoker chimneys. A novel, syringe-based precision sampler was used to collect discrete microbial iron mat samples at the three sites. The presence of Zetaproteobacteria was confirmed using a combination of 16S rRNA pyrosequencing and single-cell sorting, while light micros-copy revealed a variety of iron-oxyhydroxide structures, indicating that active iron-oxidizing communities exist along the Mid-Atlantic Ridge. Sequencing analysis suggests that these iron mats contain cosmopolitan representatives of Zetaproteobacteria, but also exhibit diversity that may be uncommon at other iron-rich marine sites studied to date. A meta-analysis of publically available data encompassing a variety of aquatic habitats indicates that Zetaproteobacteria are rare if an iron source is not readily available. This work adds to the growing understanding of Zetaproteobacteria ecology and suggests that this organism is likely locally restricted to iron-rich marine environments but may exhibit wide-scale geographic distribution, further underscoring the importance of Zetaproteobacteria in global iron cycling.

Characteristics of biostability of drinking water in aged pipes after water source switching: ATP evaluation, biofilms niches and microbial community transition.

Effect of sulfate on the transformation of corrosion scale composition and bacterial community in cast iron water distribution pipes

To assess the microbiological status of a biofiltration system used to treat borehole water, filter matrix samples were analyzed after staining for the presence of active biofilms using confocal laser scanning microscopy (CLSM). CLSM revealed the presence of biofilms on the filter matrix with actively metabolizing microbial cells present. Thereafter, heterotrophs, manganese oxidizing bacteria (MOB) and iron oxidizing bacteria (IOB) present in the biofilms were quantified. For heterotrophs a count of 2.9×10 7 cfu/g was established using R2A agar while counts for presumptive MOB and IOB were established as 2.4×10 7 cfu/g and 3.1×10 7 cfu/g respectively. In addition, a clone library was established using DNA extracted from a pooled filter matrix sample to assess the diversity of bacteria present within the biofilter matrix. A total of 100 randomly selected clones were separated into 14 unique operational taxonomic unit (OTU's) based upon restriction patterns of amplified partial 16S rRNA genes. Overall, 38% of the clones were assigned to the phylum Proteobacteria, 13% to the phylum Actinobacteria, 24% to the phylum Firmicutes, 21% to the phylum Nitrospirae and 4% to the phylum Verrucomicrobia.

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 173658, “Microbial-Influenced-Corrosion-Related Coiled-Tubing Failures and Equipment Damage,” by Scott Sherman, SPE, Duane Brownlee, SPE, and Sarkis Kakadjian, SPE, Trican Well Service, prepared for the 2014 SPE Coiled Tubing and Well Intervention Conference and Exhibition, The Woodlands, Texas, USA, 24–25 March. The paper has not been peer reviewed. Microbial-influenced corrosion (MIC) has been implicated in few corrosion-related challenges in the well-service industry in the past. Recently, however, the industry is observing an increase of MIC-related equipment damage. This upsurge of MIC coincides with a switch to unconventional water sources, including recycled water. This paper is an overview of premature coiled-tubing and other-well-servicing-equipment failures and pumping-equipment damage related to MIC. Introduction Recycled fracturing water has been found to contain high levels of bacteria, typically on the order of 106–109 colony-forming units (CFU) per mL. The bacteria can originate from essentially anywhere in the water-handling system: the water source, transportation, storage, pumps, or downhole. Tanks and pits used for storage of flowback water are ideal habitats for bacteria; typically, these are sessile environments; the water temperature is commonly 15–35°C; and organic compounds found in the water such as oil carryover, surfactants, or polymers can be ideal carbon and energy sources for many microbial species. Higher-than-normal bacteria populations and clear evidence of MIC have been identified from flowback water in the Eagle Ford, Marcellus, Haynesville, and Horne River shale plays. MIC Microbes do not have a significant impact on general metal corrosion. MIC, on the other hand, is localized. This is because microbes tend to locate themselves in out-of-the-way locations such as cracks and pits or under scale or other deposits, presumably because these places are less affected by the flow of passing fluids. Once one or more species have attached themselves to a surface, many more species follow suit. It is through this process that a biofilm is built. MIC occurs where the biofilm and the metal come into contact. Probably the most notorious and widely studied of the microbes implicit in MIC are sulfate-reducing bacteria (SRB) and acid-producing bacteria, although iron-oxidizing bacteria, sulfate-reducing archaea, thiosulfate- reducing bacteria, nitrate-reducing bacteria, and methanogenic archaea are also known to be involved.

The monitoring of iron in water sources has been and will be of immense importance because modern applications require accurate and reliable results of quantification of low levels of iron in water being used in specialized fields. Although iron in drinking water supplies is found to exist in four forms, Fe(II), Fe(III), iron bacteria, and organic iron, no single method is capable of nano-level analysis of all these forms of iron. Hence, various advanced and hyphenated techniques are being used for the determination of iron species in drinking water sources that give precise and reliable results and reduce human effort. The present article reviews the new generation of equipment and a variety of modified and hyphenated instrumental techniques for iron analysis. Additionally, this review describes detection limits of widely used hyphenated techniques for quantitative analysis of four forms of iron in water down to ultratrace levels.

The patronage of water of questionable qualities in the study area due to the failure of the Anambra State Water Corporation to provide potable water supply in Awka and environs prompted this research work. Various water sources patronized in the study area were collected and subjected to physical, chemical and microbial analysis to determine their pollution/contamination status. The work revealed that the surface and borehole/well Water sources are microbiologically polluted. Ca+2 and Mg+2 levels in water samples were high, this results to hard water. Fe+2 concentrations in the water samples ranged from 1.20-5.00 mg/l. 100% of samples exceeded the MPL of 0.3mg/l, low pH favours oxidation of ferrous iron to ferric iron, giving an objectionable reddish-brown colour to the water. Iron also promotes the growth of “iron bacteria”. Aggressive public awareness of the pollution status, routine check of the water quality and increased sanitary conditions in the study area in order to ameliorate this problem were recommended.Keywords: Patronage, Contamination, Aggressive, Water Quality

Bacterial indicator organisms (e.g., coliforms, E. coli) and some chemical parameters (e.g., turbidity, ammonia) are basic monitoring tools used to measure both changes in drinking-water quality and the presence of hard-to-detect pathogenic bacteria, viruses and protozoa. Microscopically detectable free-living organisms, such as some groups of bacteria, fungi, nematodes, rotifers and protozoa, are usable as additional indicators of fecal or environmental contamination of drinking water as well as any changes in the drinking-water quality. Our aim in this paper is to summarize the results of microscopic examination of 913 drinking-water samples from different water sources in Hungary in 2004 and 2005 and to demonstrate how these results can be used to maintain safe and good-tasting drinking-water quality. A total of 277 drinking-water samples failed Hungarian microscopic water quality standards as a result of helminths (58%), protozoa (41%), iron bacteria (16%), sulfur bacteria (13%), fungi (11%), algae (5%) and multiple biological contaminants (34%). Based on these results, pipe washing or water storage tank cleaning was deemed necessary. In addition, a number of disinfection or filtration failures were found. Two detailed case studies show the usefulness of monitoring microscopic parameters to avoid disease outbreaks. To our knowledge this is the first paper discussing drinking-water microscopy based on Hungarian experience and practice, which could be useful and informative for other countries.

A novel iron-oxidizing chemolithoautotrophic bacterium, strain ET2T, was isolated from a deep-sea sediment in a hydrothermal field of the Bayonnaise knoll of the Izu-Ogasawara arc. Cells were bean-shaped, curved short rods. Growth was observed at a temperature range of 15-30°C (optimum 25°C, doubling time 24h) and a pH range of 5.8-7.0 (optimum pH 6.4) in the presence of NaCl at a range of 1.0-4.0% (optimum 2.75%). The isolate was a microaerophilic, strict chemolithoautotroph capable of growing using ferrous iron and molecular oxygen (O2) as the sole electron donor and acceptor, respectively; carbon dioxide as the sole carbon source; and either ammonium or nitrate as the sole nitrogen source. Phylogenetic analysis based on the 16S rRNA gene sequence indicated that the new isolate was related to the only previously isolated Mariprofundus species, M. ferrooxydans. Although relatively high 16S rRNA gene similarity (95%) was found between the new isolate and M. ferrooxydans, the isolate was distinct in terms of cellular fatty acid composition, genomic DNA G+C content and cell morphology. Furthermore, genomic comparison between ET2T and M. ferrooxydans PV-1 indicated that the genomic dissimilarity of these strains met the standard for species-level differentiation. On the basis of its physiological and molecular characteristics, strain ET2T (=KCTC 15556T=JCM 30585 T) represents a novel species of Mariprofundus, for which the name Mariprofundus micogutta is proposed. We also propose the subordinate taxa Mariprofundales ord. nov. and Zetaproteobacteria classis nov. in the phylum Proteobacteria.

Based on the balneotherapeutic applications of mineral spring water and particularly sulphurous water, the aim of our research was to study the physicochemical and microbiological parameters of some drainage waters of Siriu dam that showed a strong hydrogen sulphide odour. In addition, due to the corrosive effect of some groups of microorganisms, such as iron-oxidizing bacteria and sulphatereducing bacteria, the present paper also aimed to detect their presence in order to signal the need for some disinfection measures. According to physicochemical analysis, there has been found an external drain that is suitable for use in balneotherapy, presenting a balanced content of mineral elements such as sulphur, calcium, silicon, chlorine and potassium. However, due to the presence of potentially toxic phytoplankton microorganisms such as Microcystis sp. and Phormidium sp. it is necessary to disinfect this water source before using it for any purpose. On the other hand, the identification of both sulphate-reducing bacteria and iron-oxidizing bacteria in the drainage waters of Siriu dam should be considered as an alarm signal as they may lead to bio-corrosion and deterioration of metallic or concrete structures, affecting the integrity of the dam and hydropower constructions.