Bioremediation of contaminated urban river sediment with methanol stimulation: Metabolic processes accompanied with microbial community changes.

The intense pollution of urban river sediments with rapid urbanization has attracted considerable attention. Complex contaminated sediments urgently need to be remediated to conserve the ecological functions of impacted rivers. This study investigated the effect of using methanol as a co-substrate on the stimulation of the indigenous microbial consortium to enhance the bioremediation of petroleum hydrocarbons (PHs) and polycyclic aromatic hydrocarbons (PAHs) in an urban river sediment. After 65 days of treatment, the PAHs degradation efficiencies in the sediment adding methanol were 4.87%-40.3% higher than the control. The removal rate constant of C31 was 0.0749 d-1 with 100 mM of supplied methanol, while the corresponding rate was 0.0399 d-1 in the control. Four-ring PAHs were effectively removed at a degradation efficiency of 65%-69.8%, increased by 43.3% compared with the control. Sulfate reduction and methanogenesis activity were detected, and methane-producing archaea (such as Methanomethylovorans, with a relative abundance of 25.87%-58.53%) and the sulfate-reducing bacteria (SRB, such as Desulfobulbus and Desulfobacca) were enriched. In addition, the chemolithoautotrophic sulfur-oxidizing bacteria (SOB, such as Sulfuricurvum, with a relative abundance of 34%-39.2%) were predominant after the depletion of total organic carbon (TOC), and markedly positively correlated with the PHs and PAHs degradation efficiencies (P < 0.01). The SRB and SOB populations participated in the sulfur cycle, which was associated with PHs and PAHs degradation. Other potential functional bacteria (such as Dechloromonas) were also obviously enriched and significantly positively correlated with the TOC concentration after methanol injection (P < 0.001). This study provides a new insight into the succession of the indigenous microbial community with methanol as a co-substrate for the enhanced bioremediation of complexly contaminated urban river sediments.

Effects of sludge lysate for Cr(VI) bioreduction and analysis of bioaugmentation mechanism of sludge humic acid.

This study evaluated the effects of sludge lysate (SL) on the anaerobic bioreduction of Cr(VI) and the role of sludge humic acid (SHA) during this process. The results showed that supplement of SL significantly enhanced the efficiency of Cr(VI) bioreduction by 29.61%, in 12 h compared with that of the control without SL. Moreover, SHA exhibited promoting effects on bioreduction of Cr(VI), and the promotion increased with increasing SHA concentrations from 100 to 300 mg/L. In the presence of 300 mg/L SHA, Cr(VI) (98.21 mg/L) was completely reduced after 24 h with a removal rate increased by 34.3% compared with that of the control without SHA. Further investigation on the bioaugmentation mechanism of SHA by studying the nature of SHA and the reaction mechanism between SHA and Cr(VI) revealed that SHA exhibited a strong adsorption ability, which could adsorb and combine with Cr(VI). The adsorption capacity of Cr(VI) by SHA was calculated as 34.4 mg/g with 0.2 g of SHA and 10 mg/L of Cr(VI). It could also act as redox mediators to accelerate the electron transfer between microorganisms and Cr(VI) to promote reduction of Cr(VI). Furthermore, the effects of SL on the microbial community compositions of the anaerobic Cr(VI) bioreduction system were studied. Brachymonas was the primary bacteria at the genus level. The abundance of electroactive bacteria, such as Acinetobacter, Pseudomonas, and Arcobacter, increased in the SL-amended system. These findings expand the versatility of SL and justify wider use of residual activated sludge, which might contribute to the treatment of heavy metal-contaminated wastewater.

Enhancing Electricity Generation Using a Laccase-Based Microbial Fuel Cell with Yeast Galactomyces reessii on the Cathode.

The fungi associated with termites secrete enzymes such as laccase (multi-copper oxidase) that can degrade extracellular wood matrix. Laccase uses molecular oxygen as an electron acceptor to catalyze the degradation of organic compounds. Owing to its ability to transfer electrons from the cathodic electrode to molecular oxygen, laccase has the potential to be a biocatalyst on the surface of the cathodic electrode of a microbial fuel cell (MFC). In this study, a two-chamber MFC using the laccase-producing fungus Galactomyces reessii was investigated. The fungus cultured on coconut coir was placed in the cathode chamber, while an anaerobic microbial community was maintained in the anode chamber fed by industrial rubber wastewater and supplemented by sulfate and a pH buffer. The laccase-based biocathode MFC (lbMFC) produced the maximum open circuit voltage of 250 mV, output voltage of 145 mV (with a 1,000 Ω resistor), power density of 59 mW/m2, and current density of 278 mA/m2, and a 70% increase in half-cell potential. This study demonstrated the capability of laccase-producing yeast Galactomyces reessii as a biocatalyst on the cathode of the two-chamber lbMFC.

Establishing anaerobic hydrocarbon-degrading enrichment cultures of microorganisms under strictly anoxic conditions.

Traditionally, the description of microorganisms starts with their isolation from an environmental sample. Many environmentally relevant anaerobic microorganisms grow very slowly, and often they rely on syntrophic interactions with other microorganisms. This impedes their isolation and characterization by classic microbiological techniques. We developed and applied an approach for the successive enrichment of syntrophic hydrocarbon-degrading microorganisms from environmental samples. We collected samples from microbial mat-covered hydrothermally heated hydrocarbon-rich sediments of the Guaymas Basin and mixed them with synthetic mineral medium to obtain sediment slurries. Supplementation with defined substrates (i.e., methane or butane), incubation at specific temperatures, and a regular maintenance procedure that included the measurement of metabolic products and stepwise dilutions enabled us to establish highly active, virtually sediment-free enrichment cultures of actively hydrocarbon-degrading communities in a 6-months to several-years' effort. Using methane as sole electron donor shifted the originally highly diverse microbial communities toward defined mixed cultures dominated by syntrophic consortia consisting of anaerobic methane-oxidizing archaea (ANME) and different sulfate-reducing bacteria. Cultivation with butane at 50 °C yielded consortia of archaea belonging to Candidatus Syntrophoarchaeum and Candidatus Desulfofervidus auxilii partner bacteria. This protocol also describes sampling for further molecular characterization of enrichment cultures by fluorescence in situ hybridization (FISH), and transcriptomics and metabolite analyses, which can provide insights into the functioning of hydrocarbon metabolism in archaea and resolve important mechanisms that enable electron transfer to their sulfate-reducing partner bacteria.

Aerobic and anaerobic biosynthesis of nano-selenium for remediation of mercury contaminated soil.

Selenium (Se) nanoparticles are often synthesized by anaerobes. However, anaerobic bacteria cannot be directly applied for bioremediation of contaminated top soil which is generally aerobic. In this study, a selenite-reducing bacterium, Citrobacter freundii Y9, demonstrated high selenite reducing power and produced elemental nano-selenium nanoparticles (nano-Se0) under both aerobic and anaerobic conditions. The biogenic nano-Se0 converted 45.8-57.1% and 39.1-48.6% of elemental mercury (Hg0) in the contaminated soil to insoluble mercuric selenide (HgSe) under anaerobic and aerobic conditions, respectively. Addition of sodium dodecyl sulfonate enhanced Hg0 remediation, probably owing to the release of intracellular nano-Se0 from the bacterial cells for Hg fixation. The reaction product after remediation was identified as non-reactive HgSe that was formed by amalgamation of nano-Se0 and Hg0. Biosynthesis of nano-Se0 both aerobically and anaerobically therefore provides a versatile and cost-effective remediation approach for Hg0-contaminated surface and subsurface soils, where the redox potential often changes dramatically.

Taxonomical and functional microbial community dynamics in an Anammox-ASBR system under different Fe (III) supplementation.

In the present study, we explored the metabolic versatility of anaerobic ammonium oxidation (anammox) bacteria in a variety of Fe (III) concentrations. Specifically, we investigated the impacts of Fe (III) on anammox growth rates, on nitrogen removal performance, and on microbial community dynamics. The results from our short-term experiments revealed that Fe (III) concentrations (0.04-0.10 mM) significantly promote the specific anammox growth rate from 0.1343 to 0.1709 d-1. In the long-term experiments, the Anammox-anaerobic sequencing batch reactor (ASBR) was operated over 120 days and achieved maximum NH4+-N, NO2--N, and TN efficiencies of 90.98 ± 0.35, 93.78 ± 0.29, and 83.66 ± 0.46 %, respectively. Pearson's correlation coefficients between anammox-(narG + napA), anammox-nrfA, and anammox-FeRB all exceeded r = 0.820 (p < 0.05), confirming an interaction and ecological association among the nitrogen and iron-cycling-related microbial communities. Illumina MiSeq sequencing indicated that Chloroflexi (34.39-39.31 %) was the most abundant phylum in an Anammox-ASBR system, followed by Planctomycetes (30.73-35.31 %), Proteobacteria (15.40-18.61 %), and Chlorobi (4.78-6.58 %). Furthermore, we found that higher Fe (III) supplementation (>0.06 mM) could result in the community succession of anammox species, in which Candidatus Brocadia and Candidatus Kuenenia were the dominant anammox bacteria species. Combined analyses indicated that the coupling of anammox, dissimilatory nitrogen reduction to ammonium, and iron reduction accounted for nitrogen loss in the Anammox-ASBR system. Overall, the knowledge gained in this study provides novel insights into the microbial community dynamics and metabolic potential of anammox bacteria under Fe (III) supplementation.

A quasi-universal medium to break the aerobic/anaerobic bacterial culture dichotomy in clinical microbiology.

In the mid-19th century, the dichotomy between aerobic and anaerobic bacteria was introduced. Nevertheless, the aerobic growth of strictly anaerobic bacterial species such as Ruminococcus gnavus and Fusobacterium necrophorum, in a culture medium containing antioxidants, was recently demonstrated. We tested aerobically the culture of 623 bacterial strains from 276 bacterial species including 82 strictly anaerobic, 154 facultative anaerobic, 31 aerobic and nine microaerophilic bacterial species as well as ten fungi. The basic culture medium was based on Schaedler agar supplemented with 1 g/L ascorbic acid and 0.1 g/L glutathione (R-medium). We successively optimized this media, adding 0.4 g/L uric acid, using separate autoclaving of the component, or adding haemin 0.1 g/L or α-ketoglutarate 2 g/L. In the basic medium, 237 bacterial species and ten fungal species grew but with no growth of 36 bacterial species, including 22 strict anaerobes. Adding uric acid allowed the growth of 14 further species including eight strict anaerobes, while separate autoclaving allowed the growth of all tested bacterial strains. To extend its potential use for fastidious bacteria, we added haemin for Haemophilus influenzae, Haemophilus parainfluenzae and Eikenella corrodens and α-ketoglutarate for Legionella pneumophila. This medium allowed the growth of all tested strains with the exception of Mycobacterium tuberculosis and Mycobacterium bovis. Testing primoculture and more fastidious species will constitute the main work to be done, but R-medium coupled with a rapid identification method (matrix-assisted laser desorption/ionization time-of-flight mass spectrometry) will facilitate the anaerobic culture in clinical microbiology laboratories.

Low pH anaerobic digestion of waste activated sludge for enhanced phosphorous release.

This paper assesses anaerobic digestion of waste activated sludge (WAS) at low pH to enhance phosphorous solubility. Batch biochemical methane potential tests were conducted at a pH range of 5 to 7.2 in two separate sets (two different WAS samples collected from municipal WWTP). Low pH (<5.7) caused a significant (p = 0.004) decrease in methane potential (B0) up to 33% and 3.6 times increase in phosphorus release compared to neutral pH (7-7.7), but with no major change in methane production rate coefficient (khyd). The loss in methane yield was mainly due to decrease in hydrolytic capability rather than inhibition of methanogenesis with volatile fatty acids being <300 mgCOD L(-1) and soluble COD <1300 mgCOD L(-1) even at low pH. While pH did not influence the acetoclastic community (Methanosaeta dominated), it was the primary driver for the remaining community (p = 0.004), and caused a loss of diversity and shift to Clostridia.

Assessment of crude glycerol for Enhanced Biological Phosphorus Removal: Stability and role of long chain fatty acids.

Enhanced Biological Phosphorus Removal (EBPR) of urban wastewaters is usually limited by the available carbon source required by Polyphosphate Accumulating Organisms (PAO). External carbon sources as volatile fatty acids (VFA) or other pure organic compounds have been tested at lab scale demonstrating its ability to enhance PAO activity, but the application of this strategy at full-scale WWTPs is not cost-effective. The utilization of industrial by-products with some of these organic compounds provides lower cost, but it has the possible drawback of having inhibitory or toxic compounds to PAO. This study is focused on the utilization of crude glycerol, the industrial by-product generated in the biodiesel production, as a possible carbon source to enhance EBPR in carbon-limited urban wastewaters. Crude glycerol has non-negligible content of other organic compounds as methanol, salts, VFA and long chain fatty acids (LCFA). VFA and methanol have been demonstrated to enhance PAO activity, but there is no previous study about the effect of LCFA on PAO. This work presents the operation of an EBPR SBR system using crude glycerol as sole carbon source, studying also its long-term stability. The effect of LCFA is evaluated at short and long-term operation, demonstrating for the first time EBPR activity with LCFA as sole carbon source and its long-term failure due to the increased hydrophobicity of the sludge.

Long-term effect of low concentration Cr(VI) on P removal in granule-based enhanced biological phosphorus removal (EBPR) system.

In light of the fact that most wastewater in China contained both industrial and domestic wastewater, a 52-d systematical investigation was conducted on the long-term effect of low concentration Cr(VI) (0.3-0.8 mg L(-1)) on P removal performance of granule-based EBPR system in this study. The mechanisms were likewise discussed. Results showed that high Cr(VI) concentration (⩾0.5 mg L(-1)) could significantly inhibit P removal, while this phenomenon was not found when Cr(VI) concentration was less than (or equal to) 0.4 mg L(-1). Most of the granules was disintegrated and filamentous bacteria overgrew inducing sludge bulking occurred at 0.7 mg L(-1) Cr(VI). During the exposure test, the abundance of poly-phosphate-accumulating organisms (PAOs) significantly decreased while the populations of glycogen accumulating organisms (GAOs) and other bacteria increased. Both production and degradation of poly-ß-hydroxyakanoates (PHAs) were apparently inhibited. An improved polysaccharide/protein (PS/PN) ratio was observed with the increasing Cr(VI) concentration, implying excessive polysaccharide was secreted by microorganisms to support its resistance to the toxicity of Cr(VI). Besides, good linear regression between PS/PN ratio and the granule size (R(2)=-0.86, p<0.01) was obtained, indicating that high PS/PN was adverse to granule stability. Correlation analysis indicated that the accumulation of granules intracellular Cr was directly responsible for the observed inhibitory effect on P removal process. The long-term Cr(VI) treatment had irreversible effects on granule-based EBPR system as it could not revive after a 16-d recovery process.

Flux analysis of the human proximal colon using anaerobic digestion model 1.

The colon can be regarded as an anaerobic digestive compartment within the gastro intestinal tract (GIT). An in silico model simulating the fluxes in the human proximal colon was developed on basis of the anaerobic digestion model 1 (ADM1), which is traditionally used to model waste conversion to biogas. Model calibration was conducted using data from in vitro fermentation of the proximal colon (TIM-2), and, amongst others, supplemented with the bio kinetics of prebiotic galactooligosaccharides (GOS) fermentation. The impact of water and solutes absorption by the host was also included. Hydrolysis constants of carbohydrates and proteins were estimated based on total short chain fatty acids (SCFA) and ammonia production in vitro. Model validation was established using an independent dataset of a different in vitro model: an in vitro three-stage continuous culture system. The in silico model was shown to provide quantitative insight in the microbial community structure in terms of functional groups, and the substrate and product fluxes between these groups as well as the host, as a function of the substrate composition, pH and the solids residence time (SRT). The model confirms the experimental observation that methanogens are washed out at low pH or low SRT-values. The in silico model is proposed as useful tool in the design of experimental setups for in vitro experiments by giving insight in fermentation processes in the proximal human colon.

Seasonal variation of the chemical composition and antimicrobial and cytotoxic activities of the essential oils from Inga laurina (Sw.) Willd.

The seasonal chemical composition of essential oils from Inga laurina was determined by GC/MS. In the stem bark's essential oil extracted during the dry season, the presence of terpenoids (30.05%) stood out, and phytol (9.76%) was the major compound identified. For the stem bark oil obtained during the rainy season, in addition to terpenoids (26.63%), a large amount of fatty acids (46.84%) were identified, in particular palmitic acid (25.40%). Regarding the leaves' essential oil obtained in the dry season, esters (42.35%) were the main components. The main ester present was (Z)-hex-3-enyl benzoate (10.15%) and the major compound of this oil was (Z)-hex-3-en-1-ol (14.23%). Terpenoids (33.84%), long-chain alkanes (27.04%) and fatty acids (21.72%) were the main components of the essential oil from leaves in the rainy season. Phytol (33.21%), nonacosane (21.95%) and palmitic acid (15.20%) were the major compounds identified. The antimicrobial activity against aerobic and anaerobic oral bacteria was evaluated by the microdilution broth method and cytotoxic activity was carried out with Vero cells. The essential oils from the rainy season showed a better inhibition of the bacterial growth with Minimal Inhibitory Concentrations (MIC) values of 25 or 50 µg·mL⁻¹ for aerobic bacteria, and high selectivity against bacteria was observed. The large amount of fatty acids in rainy season oils may be related to the better inhibitory effects observed.

Dynamics of intracellular polymers in enhanced biological phosphorus removal processes under different organic carbon concentrations.

Enhanced biological phosphorus removal (EBPR) may deteriorate or fail during low organic carbon loading periods. Polyphosphate accumulating organisms (PAOs) in EBPR were acclimated under both high and low organic carbon conditions, and then dynamics of polymers in typical cycles, anaerobic conditions with excess organic carbons, and endogenous respiration conditions were examined. After long-term acclimation, it was found that organic loading rates did not affect the yield of PAOs and the applied low organic carbon concentrations were advantageous for the enrichment of PAOs. A low influent organic carbon concentration induced a high production of extracellular carbohydrate. During both anaerobic and aerobic endogenous respirations, when glycogen decreased to around 80 ± 10 mg C per gram of volatile suspended solids, PAOs began to utilize polyphosphate significantly. Regressed by the first-order reaction model, glycogen possessed the highest degradation rate and then was followed by polyphosphate, while biomass decay had the lowest degradation rate.

Study of the antimicrobial efficacy of chlorhexidine in dental unit water: evaluation of microbial contamination in the dental office / Estudo da capacidade antimicrobiana da clorexidina na água do equipamento odontológico: avaliação de contaminação microbiana em ambiente odontológico

Objective: The aim of this study to count anaerobic bacteria before and after the use of dental equipment and to study the influence of chlorhexidine on the dental unit reservoir water. Methods: Sterile swabs were used to collect bacterial samples from the cuspidor, lights, syringes, low-and high speed handpieces and dental chairs (arms and backrest) before and after the placement of barriers. Blood agar plates were placed on the patient's and dentist's forehead and by the patient's nose and shoulder and exposed to aerosoils without (group 1) and with 0,5% (group 2) and 1,0% (group 3) chlorhexidine generated by the high speed handpiece. Ten aerosol samples were collected for each group. A sample of 1mL of the dental unit reservoir water was collected before and after the use of the high speed handpiece. The anaerobic bacterial counts were compared by the Wilcoxon and Kruskal-Wallis tests. Results: The contamination of the high speed handpiece (p=0,0431) and cuspidor (p=0,0117) increased significantly after use. Contamination in the dental unit reservoir water also increased significantly after use of the high speed handpiece. The most contaminated area was the patient's nose. Conclusion: The addition of 0,5% and 1,0% chlorhexidine in the dental office sifnificantly.

ObjetivoO objetivo deste estudo foi quantificar as bactérias anaeróbicas, antes e após o uso deequipamentos odontológicos e estudar a influência da clorexidina na água doreservatório.MétodosOs seguintes itens foram avaliados: cuspideira, luzes, seringas, baixa e alta rotação,braço da cadeira e do encosto com coleções realizadas antes e após a colocação debarreiras. A contaminação microbiana causada pelos aerossóis de alta rotação tambémfoi avaliada: Grupo 1 (controle): (100%) de água no reservatório; Grupo 2: água noreservatório contendo 0,5% de clorexidina, Grupo 3: água no reservatório contendo1,0% de clorexidina. Dez amostras de aerossol foram recolhidos a partir de cadagrupo: placas de ágar-sangue foram colocadas na testa do paciente e do dentista e nonariz e ombro do paciente. Amostra de 1mL a partir do conteúdo da água no reservatóriofoi medida antes e após a utilização de alta rotação. Comparações entre bactériasanaeróbias foram feitas com o uso de Wilcoxon e Kruskal-Wallis teste estatístico.ResultadosVerificou-se um aumento significativo na contaminação antes e após o procedimentoutilizando alta rotação (p=0,0431) e na cuspideira (p=0,0117). Foi possível observarum aumento significativo de contaminação microbiana na água do reservatório, apósa sua utilização. O nariz do paciente era a área mais afetada.ConclusãoA adição de 0,5% e 1,0% de clorexidina no reservatório representa uma reduçãosignificativa de contaminação microbiana gerado no ambiente de um consultório odontológico.

Start-up, steady state performance and kinetic evaluation of a thermophilic integrated anaerobic-aerobic bioreactor (IAAB).

Thermophilic treatment of palm oil mill effluent (POME) was studied in a novel integrated anaerobic-aerobic bioreactor (IAAB). The IAAB was subjected to a program of steady-state operation over a range of organic loading rate (OLR)s, up to 30 g COD/L day in order to evaluate its treatment capacity. The thermophilic IAAB achieved high chemical oxygen demand (COD), biochemical oxygen demand (BOD) and total suspended solids (TSS) removal efficiencies of more than 99% for OLR up to 18.5 g COD/L day. High methane yield of 0.32 LCH(4) (STP)/g COD(removed) with compliance of the final treated effluent to the discharge limit were achieved. This is higher than that of the mesophilic system due to the higher maximum specific growth rate (µ(max)) of the thermophilic microorganisms. Besides, coupling the model of Grau second order model (anaerobic system) with the model of Monod (aerobic system) will completely define the IAAB system.

Microbiological analysis of a prospective, randomized, double-blind trial comparing moxifloxacin and clindamycin in the treatment of odontogenic infiltrates and abscesses.

The objective of this study was to identify the oral pathogens found in odontogenic infections, to determine their susceptibilities to amoxicillin-clavulanic acid (AMC), clindamycin (CLI), doxycycline (DOX), levofloxacin (LVX), moxifloxacin (MXF), and penicillin (PEN), and to search for associations between specific pathogens and types of infection. Swabs from patients enrolled in a randomized, double-blind phase II trial comparing MXF with CLI for the treatment of odontogenic abscesses or inflammatory infiltrates were cultured on media for aerobes and anaerobes. All bacterial isolates were identified at the species level. Overall, 205 isolates were cultured from 71 patients: 77 viridans group streptococci, 56 Prevotella spp., 19 Neisseria spp., 17 Streptococcus anginosus group isolates and hemolytic streptococci, 15 other anaerobes, and 21 other bacteria. Ninety-eight percent of pathogens were susceptible to MXF, 96% to AMC, 85% to LVX, 67% to PEN, 60% to CLI, and 50% to DOX. S. anginosus group and hemolytic streptococci were found significantly more frequently (P = 0.04) in patients with abscesses (12/95) than in patients with infiltrates (5/110). In four patients with infiltrates who failed to respond to CLI therapy, three isolates of the Streptococcus mitis group and four Neisseria spp. resistant to CLI were found. In this study, S. anginosus group and hemolytic streptococci were clearly associated with odontogenic abscesses. Our analysis suggests that viridans group streptococci and Neisseria spp. play a decisive role in the etiology of odontogenic infiltrates. The high in vitro activity of MXF against odontogenic bacteria corresponds well to its clinical results in the treatment of odontogenic abscesses and infiltrates.

Low temperature biological phosphorus removal and partial nitrification in a pilot sequencing batch reactor system.

Partial nitrification and biological phosphorus removal appear to hold promise of a cost-effective and sustainable biological nutrient removal process. Pilot sequencing batch reactors (SBRs) were operated under anaerobic/aerobic configuration for 8 months. It was found that biological phosphorus removal can be achieved in an SBR system, along with the partial nitrification process. Sufficient volatile fatty acids supply was the key for enhanced biological phosphorus removal. This experiment demonstrated that partial nitrification can be achieved even at low temperature with high dissolved oxygen (>3 mg/L) concentration. Shorter solid retention time (SRT) for nitrite oxidizing bacteria (NOB) than for ammonia oxidizing bacteria due to the nitrite substrate limitation at the beginning of the aeration cycle was the reason that caused NOB wash-out. Controlling SRT should be the strategy for an SBR operated in cold climate to achieve partial nitrification. It was also found that the aerobic phosphorus accumulating organisms' P-uptake was more sensitive to nitrite inhibition than the process of anaerobic P-release.

Anaerobic degradation of palm oil mill effluent (POME).

The biodegradation characteristics of palm oil mill effluent (POME) and the related microbial community were studied in both actual sequential anaerobic ponds in Malaysia and enrichment cultures. The significant degradation of the POME was observed in the second pond, in which the temperature was 35-37 °C. In this pond, biodegradation of major long chain fatty acids (LCFA), such as palmitic acid (C16:0) and oleic acid (C18:1), was also confirmed. The enrichment culture experiment was conducted with different feeding substrates, i.e. POME, C16:0 and C18:1, at 35 °C. Good recovery of methane indicated biodegradation of feeds in the POME and C16:0 enrichments. The methane production rate of the C18:1 enrichment was slower than other substrates and inhibition of methanogenesis was frequently observed. Denaturing gradient gel electrophoresis (DGGE) analyses indicated the existence of LCFA-degrading bacteria, such as the genus Syntrophus and Syntorophomonas, in all enrichment cultures operated at 35 °C. Anaerobic degradation of the POME under mesophilic conditions was stably processed as compared with thermophilic conditions.

[Producing of molecular hydrogen by association of sporulating microorganisms].

Technologically promising microbe association, consisting of aerobic and anaerobic sporulating bacteria has been isolated. The association synthesizes molecular hydrogen during fermentation of potato and starch. The association was isolated from soil, pasteurized on the boiling water bath. The association destroys potato during 5-7 days with a decrease of mass up to 17.4 times and synthesizes gas consisting of 60% of H2.

Updating a model of pulp and paper wastewater treatment in a partial-mix aerated stabilization basin system.

A relatively simple set of calculations was presented in 1994 to evaluate the effectiveness of each ASB cell as reactor, clarifier, and digester. The steady-state model, which incorporated estimates of solids settling and benthal feedback of BOD5 and nutrients, has been a reasonable diagnostic tool for municipal and industrial applications. Results have aided in understanding normal system function, the nature of chronic inefficiencies of individual systems, and appropriate modifications to meet changes in discharge requirements. For applications in the pulp and paper industry, several changes have been incorporated recently. Nitrogen limitation is not needed in modeling pulp and paper ASB reactions. Slowly biodegradable material is modeled as a contributor to soluble BOD5, and this contribution becomes a significant factor in the latter segments of an ASB. Phosphorus availability is modeled as a stoichiometric control of soluble BOD5 uptake. Anoxic microorganisms are assumed to be responsible for a portion of the soluble BOD5 consumption in the first ASB aeration zone. Finally, the long-term nutrient capture in ASBs is modeled as 3% for nitrogen and 28% for phosphorus.