Release of formaldehyde during the biofiltration of methanol vapors in a peat biofilter inoculated with Pichia pastoris GS115

BACKGROUND: Methanol can be effectively removed from air by biofiltration (Shareefdeen et al., 1993; Babbitt et al., 2009 [1,2]). However, formaldehyde is one of the first metabolic intermediates in the consumption of methanol in methylotrophic microorganisms (Negruta et al., 2010 [3]), and it can be released out of the cell constituting a secondary emission. RESULTS: The total removal of methanol was achieved up to input loads of 263 g m−3 h−1 and the maximum elimination capacity of the system was obtained at an empty bed residence times of 90 s and reached 330 g m−3 h−1 at an input methanol load of 414 g m−3 h−1 and 80% of removal efficiency. Formaldehyde was detected inside the biofilter when the input methanol load was above 212 g m−3 h−1 . Biomass in the filter bed was able to degrade the formaldehyde generated, but with the increase of the methanol input load, the unconsumed formaldehyde was released outside the biofilter. The maximum concentration registered at the output of the system was 3.98 g m−3 when the methanol load was 672 g m−3 h−1 in an empty bed residence times of 60 s. CONCLUSIONS: Formaldehyde is produced inside a biofilter when methanol is treated in a biofiltration system inoculated with Pichia pastoris. Biomass present in the reactor is capable of degrading the formaldehyde generated as the concentration of methanol decreases. However, high methanol loads can lead to the generation and release of formaldehyde into the environment.

Characterization of a novel heterotrophic nitrifying and aerobically denitrifying bacterium, Halomonas sp. Z8, as a potential bioagent for wastewater treatment

Aim: The aim of the present study was to identify and characterize the functions of key microbes mediating nitrification.Methodology: After sampling the biofilm from a submerged biofilter in a marine aquaculture system, selective media were used to isolate microbial strains involved in nitrification. Isolates were identified using physiological and biochemical assays and sequencing of 16S rRNA gene. Nitrogen removal under different conditions was characterized. Nitrogen removal pathway was characterized by a 15N tracer experiment. Representation of key microbes in the biolfim was characterized by metagenomics analysis. Results: Single-factor tests showed that Halomonas sp. strain Z8 exhibited good heterotrophic nitrification and aerobic denitrification abilities, with maximum NH4+-N, NO2--N and No3--N removal rates of 2.37, 1.28 and 1.7 mg N l-1 hr-1, respectively. The 15N isotope tracer experiment confirmed the aerobic nitrogen removal pathway of strain Z8. Average NO3-removal efficiencies were all above 80% in an aerated moving bed bioreactor inoculated with strain Z8 and employed to treat synthetic marine aquaculture wastewater. Metagenomic microbial community analysis revealed that Halomonas sp. Z8 was one of the dominant taxa at genus level, suggesting a vital role in removing nitrate from bioreactor

Release of formaldehyde during the biofiltration of methanol vapors in a peat biofilter inoculated with Pichia pastoris GS115

Background: Methanol can be effectively removed from air by biofiltration. However, formaldehyde is one of the first metabolic intermediates in the consumption of methanol in methylotrophic microorganisms, and it can be released out of the cell constituting a secondary emission. Results: The total removal of methanol was achieved up to input loads of 263 g m−3 h−1 and the maximum elimination capacity of the system was obtained at an empty bed residence times of 90 s and reached 330 g m− 3 h−1 at an input methanol load of 414 g m−3 h−1 and 80% of removal efficiency. Formaldehyde was detected inside the biofilter when the input methanol load was above 212 g m−3 h−1 . Biomass in the filter bed was able to degrade the formaldehyde generated, but with the increase of the methanol input load, the unconsumed formaldehyde was released outside the biofilter. The maximum concentration registered at the output of the system was 3.98 g m−3 when the methanol load was 672 g m−3 h−1 in an empty bed residence times of 60 s. Conclusions: Formaldehyde is produced inside a biofilter when methanol is treated in a biofiltration system inoculated with Pichia pastoris. Biomass present in the reactor is capable of degrading the formaldehyde generated as the concentration of methanol decreases. However, high methanol loads can lead to the generation and release of formaldehyde into the environment

Biofiltration of trimethylamine in biotrickling filter inoculated with Aminobacter aminovorans

Background: Trimethylamine (TMA) is the main responsible for the odor associated with rotting fish and other annoying odors generated in many industrial activities. Biofiltration has proved to be efficient for treating odorous gaseous emissions. The main objective of this work was to determine the removal capacity of TMA of a biotrickling filter inoculated with Aminobacter aminovorans and to evaluate the effect of H2S on its performance. Results: The maximumspecific growth rate ofA. aminovorans in a liquid culture was 0.15 h -1 , witha TMAto biomass yield of 0.10 (g g -1) and a specific consumption rate of 0.062 g·g-1·h-1 . The initial specific consumption rate of TMA was highly influenced by the presence of H2S in liquid culture at concentrations of 20 and 69 ppm in heading space oftheflasks.ABTF inoculatedwithA. aminovorans showedremoval efficiencieshigher than98%ina range ofloading rate of 0.2 to 8 g·m-3·h-1 at empty bed residence time (EBRT) of 85 and 180 s. No effect on the elimination capacity and efficiency was detected when H2S was added at 20 and 50 ppm to the inlet gaseous emission, though the fraction of A. aminovorans measured by qPCR in the biofilm decreased. Conclusions:Abiotrickling filter inoculated with A. aminovorans can remove efficiently the TMA in a gaseous stream. The elimination capacity of TMA can be negatively affected by H2S, but its effect is not notorious when it is forming part of a biofilm, due to its high specific consumption rate of TMA.

Characterization of a hyperthermophilic sulphur-oxidizing biofilm produced by archaea isolated from a hot spring

Background: Sulphur-oxidizing microorganisms are widely used in the biofiltration of total reduced sulphur compounds (odorous and neurotoxic) produced by industries such as the cellulose and petrochemical industries, which include high-temperature process steps. Some hyperthermophilic microorganisms have the capability to oxidize these compounds at high temperatures (N60°C), and archaea of this group, for example, Sulfolobus metallicus, are commonly used in biofiltration technology. Results: In this study, a hyperthermophilic sulphur-oxidizing strain of archaea was isolated from a hot spring (Chillán, Chile) and designated as M1. It was identified as archaea of the genus Sulfolobus (99% homology with S. solfataricus 16S rDNA). Biofilms of this culture grown on polyethylene rings showed an elemental sulphur oxidation rate of 95.15 ± 15.39 mg S l-1 d-1, higher than the rate exhibited by the biofilm of the sulphur-oxidizing archaea S. metallicus (56.8 ± 10.91 mg l-1 d-1). Conclusions: The results suggest that the culture M1 is useful for the biofiltration of total reduced sulphur gases at high temperatures and for other biotechnological applications.

Utilização de carvão ativado biológico para o tratamento de água para consumo humano / Use of biological activated carbon for drinking water treatment

RESUMO: Este artigo de revisão aborda o uso do carvão ativado biológico no tratamento das águas para consumo humano. O tratamento biológico tem aplicação na redução da instabilidade da água potável causada por matéria orgânica biodegradável e compostos inorgânicos reduzidos presentes em baixas concentrações. A instabilidade tem efeitos prejudiciais à qualidade da água potável, tais como o crescimento de bactérias e a formação de biofilmes na rede de distribuição. O artigo discute as causas e consequências da instabilidade, as medidas de avaliação da matéria orgânica, os mecanismos de formação e controle de biofilmes no carvão ativado granular e as técnicas de avaliação microbiológica e da biodiversidade nos biofilmes. Além disso, analisa-se também a integração do carvão ativado biológico com outros processos usados no tratamento de água para consumo humano.

ABSTRACT: This review article portrays the use of biological activated carbon for drinking water treatment. Biological treatment has applications in the reduction of drinking water instability caused by the presence of low levels of biodegradable organic matter and reduced inorganic compounds. Instability causes deterioration in the quality of drinking water, such as bacterial growth and biofilm formation in the water distribution system. The article discusses the causes and consequences of instability, the measures used for organic matter evaluation, the formation and control mechanisms of biofilms in granular activated carbon and the techniques used for microbiological and biodiversity assessment of biofilms. In addition, it analyzes the integration of biological activated carbon with other processes used for drinking water treatment.

Biofiltration of a styrene/acetone vapor mixture in two reactor types under conditions of styrene overloading

This aim of study was to compare the performance of a biofilter (BF) and trickle bed reactor (TBR) under increased styrene loading with a constant acetone load, 2 gc/m3/h. At styrene loading rates up to 30 gc/m3/h, the BF showed higher styrene removal than TBR. However, the BF efficiency started to drop beyond this threshold loading and could never reach steady state, whereas the TBR continued to yield a 50% styrene removal. The acetone removal remained constant (93-98%) in both the reactors at any styrene loading. Once the overloading was lifted, the BF recovered within 26 min, whereas the TBR efficiency bounced back only to 95%, gradually returning to complete removal only in 10 h.

Bio-filtration capacity, oxygen consumption and ammonium excretion of Dosinia ponderosa and Chione gnidia (Veneroida: Veneridae) from areas impacted and non-impacted by shrimp aquaculture effluents / Bio-filtración, consumo de oxígeno y excreción amoniacal de Dosinia ponderosa y Chione gnidia (veneroida: veneridae), en áreas impactadas y no impactadas por efluentes de granjas camaroneras

Mollusks are some of the most important, abundant and diverse organisms inhabiting not only aquatic ecosystems, but also terrestrial environments. Recently, they have been used for bioremediation of aquaculture effluents; nevertheless, for that purpose it is necessary to analyze the capacity of a particular species. In this context, an experimental investigation was developed to evaluate the performance of two bivalves C. gnidia and D. ponderosa, collected from areas with or without shrimp aquaculture effluents. For this, the filtration capacity (as clearance rate) as well as the oxygen consumption and ammonia excretion rates were measured following standard methods. The clearance rate was significantly higher for D. ponderosa from impacted areas, when com- pared to C. gnidia, from both areas. Contrarily, the oxygen consumption was greater for C. gnidia from impacted areas compared to D. ponderosa from both areas. The same tendency was observed for the ammonia excretion with the highest rates observed for C. gnidia from impacted areas, whereas no differences were observed among D. ponderosa from both areas. The results suggest that both species developed different strategies to thrive and survive under the impacted conditions; D. ponderosa improved its filtration efficiency, while C. gnidia modified its oxygen consumption and ammonia excretion. We concluded that both species, and particularly D. ponderosa, can be used for bioremediation purposes.

Los moluscos son algunos de los organismos más importantes, abundantes y diversos que habitan no solo ecosistemas acuáticos sino también terrestres. Recientemente ellos han sido utilizados para la biorremediación de efluentes acuícolas; para este propósito, es necesario conocer la capacidad de especies particulares que funcionan como biorremediadores. En este contexto, se evaluó la eficiencia de filtración (medida como tasa de clarificación), así como las tasas de consumo de oxígeno y excreción amoniacal en los bivalvos D. pon- derosa y C. gnidia recolectados en áreas impactadas y no impactadas por efluentes de granjas camaroneras. La tasa de clarificación fue mayor para D. ponderosa procedente de áreas impactadas, comparada con la de C. fluctifraga en las dos áreas de recolecta. Contrariamente, la tasa de consumo de oxígeno fue superior en C. gnidia en las áreas impactadas al compararla con organismos de áreas no impactadas y con D. ponderosa de las dos áreas de recolecta. La tasa de excreción amoniacal siguió una tendencia similar con valores más altos para C. gnidia en áreas impactadas, mientras que no se observaron diferencias para D. ponderosa entre las áreas de recolecta. Los resultados sugieren que ambas especies desarrollan diferentes estrategias para adaptarse y sobrevivir bajo condiciones de impacto; D. ponderosa mejora su eficiencia de filtración y C. gnidia modifica su consumo de oxígeno y excreción amoniacal. Se concluye que ambas especies, pero sobre todo D. ponderosa pueden ser utilizadas con propósitos de biorremediación.

Biofiltration of volatile organic compounds of Brazilian gasoline

Gasoline vapors pollute the atmosphere and can be harmful to human and animal health. Tons of particles of this pollutant are expelled to the atmosphere, generating great economic losses to the industries and serious damage to the environment. Biofiltration is an option of simple technology with low costs that can be used for the gasoline vapor treatment. The present study was carried out in two biofilter systems of laboratorial scale. The biofilter system 1 was operated with a total volume of 2.72 L (four columns) and the biofilter 2 with 2.04 L (three columns) of total volume. Both of them were operated in sequence, with airflow of 450 mL entering each one. Results obtained were as follows for the removal efficiency (RE) of different gasoline vapor concentrations in the air: 1.3 g.m-3 during 35 days, RE of 100%; 3 g.m-3 during 52 days, RE of 90%; 4.5 g.m-3 during 48 days, RE of 70-80% and 8g.m-3 during 28 days, RE of 70%.

Rainbow trout (Oncorhynchus mykiss) fry initiation in closed water recirculation systems / Iniciación de alevinos de trucha arcoíris (Oncorhynchus mykiss) en sistemas cerrados de recirculación de agua / Iniciação de alevinos de truta arco-íris (Oncorhynchus mykiss) em sistemas fechados de recirculação de água

Background: rainbow trout is widely accepted for human consumption worldwide, however, its culture requires large quantities of high quality water. Objective: the aim of this study was to evaluate growth and survival of rainbow trout fry cultured in closed water recirculation systems (CRS). Methods: three sequential experiments were conducted, each with three CRS consisting of a fish tank, a gravel bio-filter, a water pump and aeration pumps. Fifty rainbow trout fry were placed in each system and fed with 45% protein pellets. Physicochemical and fish growth parameters were measured for each system at days 1, 15, and 30. Results: water parameters were maintained within normal values for the species in all the experiments. Observed fish growth was similar or greater than previously reported. Survival was lower, mainly due to the presence of Ich in some of the cultures. Although total biomass increase was small due to the low stocking density, condition factor and food conversion were within reported values. Conclusion: this study demonstrates that simple recirculation systems with a very small amount of water can be used for rainbow trout initiation.

Antecedentes: la trucha es una especie de consumo de amplia aceptación a nivel mundial. Sin embargo, su cultivo requiere de la utilización de grandes cantidades de agua de muy buena calidad. Objetivo: el principal objetivo de este trabajo fue el de evaluar el crecimiento y supervivencia de alevinos de trucha arcoíris cultivados en sistemas cerrados de recirculación de agua (CRS). Métodos: se llevaron a cabo tres experimentos secuenciales, cada uno de ellos con tres CRS que estaban compuestos de un tanque de peces, un biofiltro en grava, una bomba de agua y bombas de aireación. En cada sistema se sembraron 50 alevinos de trucha arcoíris que se alimentaron con concentrado al 45% de proteína. Los días 1, 15 y 30 de cultivo se tomaron parámetros fisicoquímicos del agua y parámetros de crecimiento de los peces para cada sistema. Resultados: en general, en todos los experimentos se mantuvieron parámetros del agua dentro de los reportados para la especie. El crecimiento fue similar o mayor a lo observado en otros trabajos. La supervivencia fue menor, debido principalmente a un brote de Ich en algunos cultivos. El incremento en biomasa total fue bajo ya que la densidad de siembra fue baja; el factor de condición y la conversión alimenticia fueron similares a valores ya descritos. Conclusión: de acuerdo con los resultados obtenidos en este trabajo, los sistemas de recirculación simples pueden ser utilizados para la iniciación de trucha arcoíris, con un nivel de utilización de agua muy bajo.

Antecedentes: a truta é uma espécie de ampla aceitação a nível mundial. No entanto, o seu cultivo requer a utilização de grandes quantidades de água de boa qualidade. Objetivo: avaliar o crescimento e a sobrevivência de alevinos de truta arco-íris cultivados em sistemas fechados de recirculação de água (CRS). Métodos: Foram realizados três experimentos sequenciais, cada um com três CRS. Os CRS estavam constituídos por um tanque com peixes, um biofiltro em cascalho, uma bomba de água e bombas de aeração. Em cada sistema foram cultivados 50 alevinos de truta arco-íris que se alimentaram com uma ração de 45% de proteína. Os dias de cultivo 1, 15 e 30 foram medidos os parâmetros físico-químicos da água e os parâmetros de crescimento dos peixes em cada sistema. Resultados: em todos os experimentos, os parâmetros da água estiveram dentro dos reportados para a espécie. O crescimento foi semelhante ou maior ao observado em outros estudos. A supervivência foi menor devido ao surto de Ich em alguns cultivos. O incremento em biomassa total foi baixo porque a densidade de alevinos também foi baixa. O fator de condição e a conversão alimentar foram semelhantes aos valores descritos para a espécie. Conclusão: de acordo com os resultados deste trabalho, os sistemas de recirculação simples podem ser usados para a iniciação da truta arco-íris com um menor consumo de água.

Modelling of the biofiltration of reduced sulphur compounds through biotrickling filters connected in series: effect of H2S

Background: The behaviour of two biotrickling filters connected in serie (BTF) inoculated with Acidithiobacillus thiooxidans and Thiobacillus thioparus, biodegrading hydrogen sulphide (H2S) and dimethyl sulphide (DMS) simultaneously were studied. A model which considers gas to liquid mass transfer and biooxidation in the biofilm attached to the support is developed. Additionally, a fixed bed biotrickling filter where the microorganism is immobilized in a biofilm which degrades a mixture of H2S and DMS is implemented. Validation of the model was carried out using experimental data obtained at different H2S and DMS loads. Results: The inhibitory effect caused by the presence of H2S on the DMS is observed, which is evidenced by the decrease of the DMS removal efficiency from 80 to 27 percent, due to the preference that T. thioparus has by simple metabolism. H2S is not affected by the DMS, with removal efficiencies of 95 to 97 percent, but it decreases at high concentrations of the compound, due to the inhibition of metabolism by high H2S input loads. The model which describes the BFT fits successfully with the experimental results and it has a high sensitivity to inhibition parameters. Conclusion: It is shown that the microorganism has a high affinity for H2S, producing substrate inhibition when the concentration is high. The H2S is able to inhibit the DMS biooxidation, whereas the DMS does not affect the H2S biooxidation.

Thiosulphate oxidation by Thiobacillus thioparus and Halothiobacillus neapolitanus strains isolated from the petrochemical industry

Sulphur Oxidizing Bacteria (SOB) is a group of microorganisms widely used for the biofiltration of Total Reduced Sulphur compounds (TRS). TRS are bad smelling compounds with neurotoxic activity which are produced by different industries (cellulose, petrochemical). Thiobacillus thioparus has the capability to oxidize organic TRS, and strains of this bacterium are commonly used for TRS biofiltration technology. In this study, two thiosulphate oxidizing strains were isolated from a petrochemical plant (ENAP BioBio, Chile). They were subjected to molecular analysis by real time PCR using specific primers for T. thioparus. rDNA16S were sequenced using universal primers and their corresponding thiosulphate activities were compared with the reference strain T. thioparus ATCC 10801 in batch standard conditions. Real time PCR and 16S rDNA sequencing showed that one of the isolated strains belonged to the Thiobacillus branch. This strain degrades thiosulphate with a similar activity profile to that shown by the ATCC 10801 strain, but with less growth, making it useful in biofiltration.

Oxidation of volatile reduced sulphur compounds in biotrickling filter inoculated with Thiobacillus thioparus

Reduced volatile sulphur compounds generate an impact on the environment, because of the bad smell and its low odour threshold. Compared with the existing physicochemical technologies for their elimination, biotrickling filters are an economically and environmentally sustainable alternative. Usually mixed cultures of microorganisms are used for inoculating biotrickling filters, in this case a pure culture of Thiobacillus thioparus is used for generating a biofilm, allowing to measure its capacity for the oxidation of four volatile reduced sulphur compounds: hydrogen sulphide, dimethyl sulphide, methyl mercaptan and dimethyl disulphide, using a residence time of 0.033 hrs. The viable cells of the biofilm were quantified by epifluorescence microscopy, staining the cells with ethidium bromide and acridine orange, polymerase chain reaction analysis in real time was used for testing the predominance of T. thiopharus in the biofilm. The microorganism was able to adhere and grow on the surface of rings made of polyethylene, with a viable population of 7•10(7) cell•ring-1, a 74 percent of total cells. The real time PCR showed a persistence of the population of T. thioparus for more than 300 days of operation, without being displaced by other microbial species. The maximum elimination capacities for each compound were 34.4; 21.8; 30.8 and 25.6 gS•m-3•h-1 for H2S, dimethylsulphide, dimethyldisulphide and methyl mercaptan, respectively. We conclude that it is possible to implement a biotrickling filter with the bacteria T. thioparus, which can oxidize volatile reduced sulphur compounds efficiently.

Identification and characterization of bacteria isolated under selective pressure of volatile organic compounds.

Several bacterial strains tolerant to volatile organic compounds (VOCs) were isolated from the air emissions of a typical industrial wood painting plant. Four strains that grew vigorously on a mineral salt basal medium and VOC-saturated atmosphere were identified using BIOLOG and fatty acids analysis. A 16S rDNA sequence comparison was also performed on three of the four strains. Their phylogenetic positions were respectively: MC8M6 of the genus Arthrobacter, MCEP3 of the genus Microbacterium, MCEPFL2 of the genus Rhodococcus. The fourth strain, C14, was identified as Pseudomonas aeruginosa. All the four strains showed multiple carbon sources among toluene, butyl acetate, ethoxy propyl acetate, isobutyl alcohol, ethyl acetate, diaceton alcohol, methyl ethyl ketone, methyl isobutyl ketone. By identifying a particular strain, an evaluation of its risk group can be made by comparing it to each strain type within important world-wide culture collections. This is the first step required to implement correct procedures using the strains and in implementing the appropriate biosafety containment in large scale applications.

Styrene biofiltration in a trickle-bed reactor

The biological treatment of styrene waste gas in a trickle-bed filter (TBF) was investigated. The bioreactor consisted of a two-part glass cylinder (ID 150 mm) filled with 25 mm polypropylene Pall rings serving as packing material. The bed height was 1m. Although the laboratory temperature was maintained at 22 ºC, the water temperature in the trickle-bed filter was slightly lower (about 18 ºC).The main aim of our study was to observe the effect of empty-bed residence time (EBRT) on bioreactor performance at a constant pollutant concentration over an extended time period. The bioreactor was inoculated with a mixed microbial consortium isolated from a styrene-degrading biofilter that had been running for the previous two years. After three weeks of acclimation period, the bioreactor was loaded with styrene (100 mg.m-3). EBRT was in the range of 53 s to 13 s. A maximum elimination capacity (EC) of 11.3 gC.m-3.h-1 was reached at an organic loading (OL) rate of 18.6 gC.m-3.h-1.