p-Nitrophenol Biodegradation by Aerobic Microbial Granules

Mixed microbial consortia in the form of aerobic microbial granules (AMG) capable of xenobiotic degradation can be developed from activated sludge or by adaptation of microbial granules pre-grown on labile carbon sources. Both of these approaches were investigated for the cultivation of AMG capable of p-nitrophenol (PNP) biodegradation. Attempts to cultivate AMG from activated sludge using PNP as the sole carbon source were not successful due to poor microbial growth and washout of the inoculated activated sludge. As part of the second approach, parallel sequencing batch reactors (SBRs) were inoculated with pre-grown AMG and operated by feeding both acetate and PNP together (RA), PNP alone (RB) or acetate alone (RC). Acetate/PNP mineralization and nitrification were monitored in the three SBRs. PNP biodegradation was quickly established in both RA and RB. PNP removal rates were found to be 47 and 55?mg g VSS^?1 h^?1 in RA and RB, respectively. PNP biodegradation during the SBR cycle consisted of distinct lag, exponential and deceleration phases. However, with higher concentrations of PNP (>50?mg l^?1), disintegration of granules was observed in RA and RB. When PNP was the sole carbon source, it inhibited the development of aerobic granules from activated sludge and caused disintegration of pre-cultivated aerobic granules. When PNP was the co-substrate along with acetate, the structural and functional integrity (including nitrification) of the granular sludge was maintained. This report highlights the importance of a labile co-substrate for maintaining the physical and functional integrity of granular sludge, when used for toxic waste degradation.     

不同饥饿时间下稳态好氧颗粒污泥系统的特性和动力学分析

较长的饥饿时间是好氧颗粒污泥驯化形成的关键条件. 但在稳态颗粒污泥系统中, 饥饿时间长短对颗粒污泥的影响还不清楚. 因此本实验采用四个序批式反应器(SBR), 分别在好氧饥饿时间为1、2、3和4 h(R1~R4)条件下运行, 研究了饥饿时间对稳态好氧颗粒污泥系统的运行和特性等方面的影响. 结果表明: 对于稳态的好氧颗粒污泥系统, 较长饥饿时间已不是保持污泥颗粒化的关键因素, 系统在饥饿时间缩短后依然会保持污泥颗粒化和稳定运行效果. 四种饥饿时间条件下反应器中COD去除效果没有表现出明显差异, COD平均去除率都几乎为98%以上. 但在不同饥饿时间条件下, 好氧颗粒污泥的性质有很大差别. 在 35天实验运行中, 与较长饥饿时间相比, 饥饿时间的缩短会使污泥中胞外聚合物含量降 低, 但PN/PS值会提高约6%左右, 好氧颗粒直径增大. 同时, 当饥饿时间大于2 h会使颗粒污泥中丝状菌过度生长, SVI30值升高约1.5倍, 并且导致颗粒的物理性质降低. 但是, 动力学分析指出R1~R4的有机污染物降解速率在0.25~0.29 h^-1之间, 较短饥饿时间的系统虽具有较高的qmax值, 可是并不明显. 并且R1~R4系统的饱和常数(K)和产率系数(Y)分别在5.39~8.45 mg/L和 0.391~0.746 kgMLVSS/kgCOD, 较短饥饿时间的系统会具有较高的COD出水浓度和剩余污泥产率. 综上, 好氧颗粒污泥驯化成功后, 稳态的颗粒污泥系统不再需要在较长饥饿时间条件下运行, 可以适当缩短反应时间, 这不仅仅可以节约运行成本, 降低不必要的能源消耗, 还可以使系统具有较高的稳定性能.     

Characterization of a Newly Isolated Biphenyl-Degrading Bacterium, <Emphasis Type="Italic">Dyella ginsengisoli</Emphasis> LA-4

A novel biphenyl-degrading bacterium, Dyella ginsengisoli LA-4 was isolated from activated sludge. This isolate could utilize biphenyl as sole source of carbon and energy. The resting cells of strain LA-4 could utilize 100 mg/L biphenyl within 20 h, and they were able to degrade 500 mg/L biphenyl within 40 h. The surfactant, Tween 80, could accelerate the biodegradation process. The increase of NaCl concentration inhibited the biphenyl degradation. No biphenyl degradation was detected when the NaCl concentration exceeds 10%. The effects of metal ions on biphenyl degradation were investigated. The results indicated that metal ions such as Cu²⁺, Mn²⁺, and Co²⁺ could completely inhibit the biodegradation of biphenyl, but Mg²⁺, Ca²⁺, and Zn²⁺ had no effects on the degradation of biphenyl. The removal rate was about 64% and 37% in the presence of Fe³⁺ and Ni²⁺, respectively. This study suggested that strain LA-4 could be widely used for bioremediation of soil and wastewater contaminated by biphenyl, NaCl, and metal ions.     

The Utilization of Post-chlorinated Municipal Domestic Wastewater for Biomass and Lipid Production by <Emphasis Type="Italic">Chlorella</Emphasis> spp. Under Batch Conditions

South Africa has a rich microalgal biodiversity which has the potential to be used for renewable bio-fuel production in the region. Bioprospecting for oleaginous microalgae in KwaZulu Natal Province, South Africa, resulted in the establishment of a microalgal culture collection system for alternative energy research in the country. A potential hyper-lipid-producing Chlorella spp. strain was isolated, purified, and cultured in supplemented post-chlorinated wastewater for biomass and lipid production at the laboratory scale under batch mode. The microalgal strain was cultivated in different strengths of BG-11 media supplemented with wastewater from a local municipal domestic wastewater treatment plant. The Chlorella spp. was grown using ambient dissolved carbon dioxide in shake flasks under photosynthetically active radiation (±120 μmolm⁻²s⁻¹). Microalgal biomass and lipid productivity were monitored at 24-h intervals in the batch mode. The microalgal biomass was analyzed by direct light microscopy and indirectly by spectrophotometry at 600 nm, and the lipids were extracted and quantified. The growth rate of the Chlorella spp. was enhanced in post-chlorinated wastewater supplemented with 5 mM NaNO₃ with maximal biomass productivity. A dramatic increase in lipid yield was achieved with the post-chlorinated wastewater supplemented with 25 mM NaNO₃. Low dosages of free chlorine were found to enhance microalgal growth. These findings serve as a basis for further scale-up trials using municipal wastewater as a medium for microalgal biomass and lipid production.     

Enhanced Production of <Emphasis Type="SmallCaps">l</Emphasis>-Arginine by Expression of <Emphasis Type="Italic">Vitreoscilla</Emphasis> Hemoglobin Using a Novel Expression System in <Emphasis Type="Italic">Corynebacterium crenatum</Emphasis>

Corynebacterium crenatum SYPA 5-5 is an aerobic and industrial l-arginine producer. It was proved that the Corynebacterium glutamicum/Escherichia coli shuttle vector pJC1 could be extended in C. crenatum efficiently when using the chloramphenicol acetyltransferase gene (cat) as a reporter under the control of promoter tac. The expression system was applied to over-express the gene vgb coding Vitreoscilla hemoglobin (VHb) to further increase the dissolved oxygen in C. crenatum. As a result, the recombinant C. crenatum containing the pJC-tac-vgb plasmid expressed VHb at a level of 3.4 nmol g⁻¹, and the oxygen uptake rates reached 0.25 mg A₅₆₂⁻¹ h⁻¹ which enhanced 38.8% compared to the wild-type strain. Thus, the final l-arginine concentration of the batch fermentation reached a high level of 35.9 g L⁻¹, and the biomass was largely increased to 6.45 g L⁻¹, which were 17.3% and 10.5% higher than those obtained by the wild-type strain, respectively. To our knowledge, this is the first report that the efficient expression system was constructed to introduce vgb gene increasing the oxygen and energy supply for l-arginine production in C. crenatum, which supplies a good strategy for the improvement of amino acid products.     

Culture of Microalgae <Emphasis Type="Italic">Chlamydomonas reinhardtii</Emphasis> in Wastewater for Biomass Feedstock Production

The objective of this research was to develop large-scale technologies to produce oil-rich algal biomass from wastewater. The experiments were conducted using Erlenmeyer flasks and biocoil photobioreactor. Chlamydomonas reinhardtii was grown in artificial media and wastewaters taken from three different stages of the treatment process, namely, influent, effluent, and centrate. Each of wastewaters contained different levels of nutrients. The specific growth rate of C. reinhardtii in different cultures was monitored over a period of 10 days. The biomass yield of microalgae and associated nitrogen and phosphorous removal were evaluated. Effects of CO₂ and pH on the growth were also studied. The level of nutrients greatly influenced algae growth. High levels of nutrients seem to inhibit algae growth in the beginning, but provided sustained growth to a high degree. The studies have shown that the optimal pH for C. reinhardtii is in the range of 7.5. An injection of air and a moderate amount of CO₂ promoted algae growth. However, too much CO₂ inhibited algae growth due to a significant decrease in pH. The experimental results showed that algal dry biomass yield reached a maximum of 2.0 g L⁻¹ day⁻¹ in the biocoil. The oil content of microalgae of C. reinhardtii was 25.25% (w/w) in dry biomass weight. In the biocoil, 55.8 mg nitrogen and 17.4 mg phosphorus per liter per day were effectively removed from the centrate wastewater. Ferric chloride was found to be an effective flocculent that helps the algae settle for easy harvest and separation from the culture media.     

First Evidence of Aerobic Biodegradation of BTEX Compounds by Pure Cultures of <Emphasis Type="Italic">Marinobacter</Emphasis>

Marinobacter vinifirmus was shown to degrade toluene as sole carbon and energy source under aerobiosis and at NaCl concentrations in the range 30–150 g/L. Maximum toluene consumption rate, total CO₂, and biomass productions were measured in the presence of 60 g/L of NaCl. Under these conditions, 90% of the carbon from toluene was recovered as CO₂ and biomass. Maximum specific toluene consumption rate was about 0.12 mgC toluene mgC biomass⁻¹ h⁻¹ at NaCl concentrations between 30 and 60 g/L. It decreased to 0.03 mgC toluene mgC biomass⁻¹ h⁻¹ at 150 g/L. Besides toluene, M. vinifirmus degraded benzene, ethylbenzene, and p-xylene. Benzene and toluene were utilized to a lesser extent by another Marinobacter sp., Marinobacter hydrocarbonoclasticus.     

Response of aerobic sludge to AHL-mediated QS: Granulation,simultaneous nitrogen and phosphorus removal performance

The effects of different species and concentrations’ signal molecules on aerobic activated sludge system were investigated through batch experiments. Results showed that the fastest NH₄⁺-N oxidization rate and the most extracellular polymeric substances (EPS) secretion were obtained by adding 5 nmol/L N-hexanoyl-l-homoserine lactone (C₆-HSL) into the aerobic activated sludge. Further study investigated the correlation among N-acyl-homoserine lactones-mediated quorum sensing (AHLs-mediated QS), nutrient removal performances and microbial communities with the long-term addition of 5 nmol/L C₆-HSL. It was found that C₆-HSL-manipulation could enhance the stability and optimize the decontamination performance of aerobic granular sludge (AGS) system. Microbial compositions considerably shifted with long-term C₆-HSL-manipulation. Exogenous C₆-HSL-manipulation inhibited quorum quenching-related (QQ-related) activities and enhanced QS-related activities during the stable period. The proposed C₆-HSL-manipulation might be a potential technology to inhibit the growth of harmful bacteria in AGS, which could provide a theoretical foundation for the realization of more stable biological wastewater treatments.     

Variable Volume Fed-Batch Fermentation for Nisin Production by <Emphasis Type="Italic">Lactococcus lactis</Emphasis> subsp<Emphasis Type="Italic">. lactis W28</Emphasis>

A feeding technology that was suitable for improving the nisin production by Lactococcus lactis subsp. lactis W28 was established. The effects of initial sucrose concentration (ISC) in the fermentation broth, feeding time, and feeding rate on the fermentation were studied. It was observed that a fed-batch culture (ISC = 10 g l⁻¹) with 100 ml sucrose solution (190 g l⁻¹) being evenly fed (9–10 ml h⁻¹) into the fermenter after 3-h fermentation gave the best performance in terms of biomass and nisin yield. Under these conditions, the total biomass and the total nisin yield were approximately 23% and 51% higher than those in batch fermentation, respectively. When the sucrose concentration was controlled at 5–10 g l⁻¹ in variable volume intermittent fed-batch fermentation (VVIF) with ISC = 10 g l⁻¹, the total biomass and the total nisin yield were 29% and 60% above those in batch fermentation, respectively. The VVIF proved to be effective to eliminate the substrate inhibition by maintaining sucrose at appropriate levels. It is also easy to be scaled up, since various parameters involved in industrial production were taken into account.     

Bioplastic biodegradation activity of anaerobic sludge prepared by preincubation at 55 °C for new anaerobic biodegradation test

The new method to evaluate the anaerobic biodegradability of bioplastics, such as polycaprolactone (PCL) and poly (lactic acid) (PLA), under aquatic (slurry) conditions at 55 °C is applying. For this method, we prepared the sludge at 55 °C from the sludge at 37 °C by the method in which the sludge from the real tank operating at around 37 °C using cow manure and vegetable waste as the feed stock was preincubated at 55 °C. It was unknown at which stage the sludge during preincubation has the optimized anaerobic biodegradation activity of plastics. Four different stage sludges during preincubation (the sludge at 7 days after the start of preincubation at 55 °C, at 12 days, at 18 days, and at 40 days) were compared by the anaerobic biodegradation activity of PLA. The preincubated sludge at around 18 days (a gradual decrease in biogas evolution and a methane ratio over 60%) showed the highest biodegradation activity of PLA. In addition, the bacterial population in each sludge was analyzed by the denaturing gradient gel electrophoresis (DGGE) analysis of the amplified 16S rRNA gene fragments, however, the newly grown bacteria bands at 55 °C were not clearly detected.     

Preparation and biodistribution of [<Superscript>131</Superscript>I]linezolid in animal model infection and inflammation

Linezolid is the first of new class of antibiotics, the oxazolidinones, and exhibits activity against many gram-positive organisms, including vancomycin-resistant Enterococcus faecium, methicillin-resistant Staphylococcus aureus, and penicillin-resistant Streptococcus pneumoniae. Aim of the study: Linezolid was to label with I-131 and potential of the radiolabeled antibiotic was to investigate in inflamed rats with S. aureus (S. aureus) and sterile inflamed rats with turpentine oil. Linezolid was labeled with I-131 by iodogen method. Biodistribution of [¹³¹I]linezolid was carried out in bacterial inflamed and sterile inflamed rats. Radiolabeling yield of [¹³¹I]linezolid was determined as 85 ± 1% at pH 2. After injecting of [¹³¹I]linezolid into bacterial inflamed and sterile inflamed rats, radiolabeled linezolid was rapidly removed from the circulation via the kidneys. Binding of [¹³¹I]linezolid to bacterial inflamed muscle (T/NT = 77.48 at 30 min) was five times higher than binding to sterile inflamed muscle (T/NT = 14.87 at 30 min) of rats. [¹³¹I]linezolid showed good localization in bacterial inflamed tissue. It was demonstrated that [¹³¹I]linezolid can be used to detect S. aureus inflammation in rats.     

Activated carbon/MOFs composite: AC/NH2-MIL-101(Cr), synthesis and application in high performance adsorption of p-nitrophenol

P-nitrophenol (PNP), a hazardous phenolic material, should be eliminated from water in order to prevent damage to the marine ecosystem, animals as well as humans. Although adsorption seems to become the most widely used strategy, an effective and strong-capacity adsorbent to minimize PNP under the approved concentration is essential to discovering. In this study, a class of porous adsorbents composite was developed for the PNP removal from water. AC-NH₂-MIL-101(Cr) has chosen to boost the removal of PNP from water owing to extremely porous and stable in water. The fabricated composite has 2049 m².g⁻¹ large surface area and 0.93 cm³.g⁻¹ pore volume. The adsorption kinetics and isotherms were investigated. AC-NH₂-MIL-101(Cr) was found to exhibit an adsorption capacity of ~ 18.3 mg g⁻¹. The mechanism for this strong adsorption performance was suggested and related to affinity NO₂ groups of PNP and the unsaturated chromium site of AC-NH₂-MIL-101(Cr), the coulombic interaction via the hydrogen bond between the PNP and AC-NH₂-MIL-101(Cr) and π-π stacking interaction. AC-NH₂-MIL-101(Cr) composite also displayed exceptional stability and reusability after a successive PNP removal processes. This study provides new insight into developing and synthesizing extremely effective nanoporous material for organic contaminants disinfection from waste water based on MOFs.     

Cultivating <Emphasis Type="BoldItalic">Chlorella</Emphasis> sp. in a Pilot-Scale Photobioreactor Using Centrate Wastewater for Microalgae Biomass Production and Wastewater Nutrient Removal

This study is concerned with a novel mass microalgae production system which, for the first time, uses “centrate”, a concentrated wastewater stream, to produce microalgal biomass for energy production. Centrate contains a high level of nutrients that support algal growth. The objective of this study was to investigate the growth characteristics of a locally isolated microalgae strain Chlorella sp. in centrate and its ability to remove nutrients from centrate. A pilot-scale photobioreactor (PBR) was constructed at a local wastewater treatment plant. The system was tested under different harvesting rates and exogenous CO₂ levels with the local strain of Chlorella sp. Under low light conditions (25 μmol·m^-2s^-1) the system can produce 34.6 and 17.7 g·m^-2day^-1 biomass in terms of total suspended solids and volatile suspended solids, respectively. At a one fourth harvesting rate, reduction of chemical oxygen demand, total Kjeldahl nitrogen, and soluble total phosphorus were 70%, 61%, and 61%, respectively. The addition of CO₂ to the system did not exhibit a positive effect on biomass productivity or nutrient removal in centrate which is an organic carbon rich medium. The unique PBR system is highly scalable and provides a great opportunity for biomass production coupled with wastewater treatment.     

A Direct OnFlow Assay to Monitor the Activity of Purine Nucleoside Phosphorylase from Mycobacterium tuberculosis

Purine nucleoside phosphorylase (PNP) catalyzes the phosphorolysis of N-ribosidic bonds of purine nucleosides and deoxynucleosides to the corresponding purine bases and (deoxy)ribosyl-1-phosphate. PNP plays a central role in purine recycling and salvage pathway and has been considered an attractive chemotherapeutic target for several diseases. In this work, PNP from Mycobacterium tuberculosis (MtPNP) was covalently immobilized into fused-silica capillaries. The activity of the produced immobilized enzyme reactor (MtPNP-IMER) was monitored onflow in a multidimensional liquid chromatography system containing the MtPNP-IMER in the first dimension. A C18 analytical column inserted in the second dimension furnished the rapid chromatographic separation of the substrate (inosine) and product (hypoxanthine) from the MtPNP catalyzed reaction, allowing monitoring MtPNP-IMER activity through the direct quantification of hypoxanthine formed. Kinetic studies showed that the K_M values (59.19 μmol L^?1) for substrates using the immobilized enzyme were consistent with those reported for the free enzyme in solution (40 μmol L^?1). To validate the use of the proposed methodology for screening purposes, a fourth-generation immucillin derivative (DI4G), known as a PNP inhibitor, was used as a standard inhibitor. The studies revealed that the immobilized enzyme retained the ability to recognize enzyme inhibitors and the onflow assay allowed the characterization of the inhibitor by determining the IC₅₀ (29.85?±?1.02 nmol L^?1), inhibition mechanism and constant (K_i?=?34.8?±?0.2 nmol L^?1). The results revealed that the immobilized MtPNP retained its catalytic activity (up to 60%) and the ability to recognize ligands with high stability for up to 10 days. The proposed model has as advantages the automation and the possibility of reusing the same amount of enzyme in several assays.

     

Modified <Emphasis Type="Italic">Rhizopus arrhizus</Emphasis> biomass for sorption of <Superscript>241</Superscript>Am and other radionuclides

The improvement and the refinement of non-viable Rhizopus arrhizus biomass were investigated via immobilization. Immobilization was carried out by using sodium alginate/CaCl₂ solution and formaldehyde/HCl cross-linking with dead Rhizopus arrhizus biomass and were used for the sorption of radionuclides from low level effluent wastes. The sodium alginate/CaCl₂ immobilized biomass (ratio 1:2) showed about 86% sorption for ²⁴¹Am activity but due to its soft nature and tendency to undergo distortion in shape, is unsuitable for practical applications. The biomass cross-linked with 15% formaldehyde/0.1 M HCl solution has a relatively high mechanical strength and rigidity. It was showing a sorption of >99% for ²⁴¹Am activity and has the sorption capacity of ~65 mg/g for americium and uranium. Hence, it can be utilized for the removal of radionuclides from radioactive waste effluents.     

Aerobic and anaerobic microbial degradation of poly-beta-hydroxybutyrate produced by Azotobacter chroococcum

Food industry wastewater served as a carbon source for the synthesis of poly-β-hydroxybutyrate (PHB) by Azotobacter chroococcum. The content of polymer in bacterial cells grown on the raw materials reached 75%. PHB films were degraded under aerobic, microaerobic, and anaerobic conditions in the presence and absence of nitrate by microbial populations of soil, sludges from anaerobic and nitrifying/denitrifying reactors, and sediment from a sludge deposit site. Changes in molecular mass, crystallinity, and mechanical properties of PHB were studied. Anaerobic degradation was accompanied by acetate formation, which was the main intermediate utilized by denitrifying bacteria or methanogenic archaea. On a decrease in temperature from 20 to 5° C in the presence of nitrate, the rate of PHB degradation was 7.3 times lower. Under anaerobic conditions and in the absence of nitrate, no PHB degradation was observed, even at 11°C. The enrichment cultures of denitrifying bacteria obtained from soil and anaerobic sludge degraded PHB films for a short time (3–7 d). The dominant species in the enrichment culture from soil were Pseudomonas fluorescens and Pseudomonas stutzeri. The rate of PHB degradation by the enrichment cultures depended on the polymer molecular weight, which reduced with time during biodegradation.     

Effects of Light Intensity on the Growth and Lipid Accumulation of Microalga <Emphasis Type="Italic">Scenedesmus</Emphasis> sp. 11-1 Under Nitrogen Limitation

Scenedesmus spp. have been reported as potential microalgal species used for the lipid production. This study investigated the effects of light intensity (at three levels: 50, 250, and 400 μmol photons m⁻² s⁻¹) on the growth and lipid production of Scenedesmus sp. 11-1 under N-limited condition. Carotenoid to chlorophyll ratio was higher when algae 11-1 grew under 250 and 400 μmol photons m⁻² s⁻¹ than that under 50 μmol photons m⁻² s⁻¹, while protein contents was lower. Highest biomass yield (3.88 g L⁻¹), lipid content (41.1 %), and neutral lipid content (32.9 %) were achieved when algae 11-1 grew at 400 μmol photons m⁻² s⁻¹. Lipid production was slight lower at 250 μmol photons m⁻² s⁻¹ level compared to 400 μmol photons m⁻² s⁻¹. The major fatty acids in the neutral lipid of 11-1 were oleic acid (43–52 %), palmitic acid (24–27 %), and linoleic acid (7–11 %). In addition, polyunsaturated fatty acids had a positive correlation with total lipid production, and monounsaturated fatty acids had a negative one.     

Biodegradation studies of <Emphasis Type="Italic">N</Emphasis><Superscript>4</Superscript>-acetylsulfapyridine and <Emphasis Type="Italic">N</Emphasis><Superscript>4</Superscript>-acetylsulfamethazine in environmental water by applying mass spectrometry techniques

This work evaluates the biodegradation of N ⁴-acetylsulfapyridine (AcSPY) and N ⁴-acetylsulfamethazine (AcSMZ), metabolites of two of the most commonly used sulfonamides (SAs) in human and veterinary medicine, respectively. Aerobic transformation in effluent wastewater was simulated using aerated fixed-bed bioreactors. No visible changes in concentration were observed in the AcSMZ reactor after 90 days, whereas AcSPY was fully degraded after 32 days of experiment. It was also demonstrated that AcSPY transformed back to its parent compound sulfapyridine (SPY). The environmental presence of these two metabolites in wastewater effluent had been previously investigated and confirmed, together with three more SA acetylated metabolites and their corresponding parent compounds, in 18 different wastewater treatment plants in Hesse (Germany). Sulfamethoxazole (SMX) and SPY were the two SAs detected most frequently (90% and 89% of the samples, respectively) and in the highest concentrations (682 ng L⁻¹ for SMX and 532 ng L⁻¹ for SPY). To conclude, hazard quotients were calculated whenever toxicity data were available. None of the SAs studied posed an environmental risk.     

Comparison of anoxic granulation in USB reactors with various inocula

Anoxic granulation process with four different inocula was monitored in a laboratory post-denitrification up-flow sludge bed (USB) reactor. Wastewater containing 20 mg L⁻¹ NO₃-N and methanol as an organic carbon source was used. Gradual increase of mass volumetric loading (B _v) and hydraulic loading (γ) resulted in spontaneous granulation of anoxic biomass both from flocculant activated sludge and from anaerobic granulated sludge. With flocculant activated sludge as the inoculum, anoxic granules sedimentation properties and maximum loadings of the USB reactor depended on the sludge volume index (SVI) of the inoculum. B _v,max achieved in the USB reactor with flocculant inoculum from a municipal wastewater treatment plant (SVI = 208 mL g⁻¹) was only 4.2 kg of COD per m³ per day and 0.7 kg of NO₃-N per m³ per day. B _v,max using flocculant inoculum from an industrial wastewater treatment plant (SVI = 170 mL g⁻¹) was 8.1 kg of COD per m³ per day and 1.35 kg of NO₃-N per m³ per day. With anaerobic granulated inoculum (SVI range 8–11 mL g⁻¹), markedly higher loadings in the USB reactor and lower SVI values of anoxic granulated biomass were achieved. Values of B _v,max were in the range of 16.1–22.4 kg of COD per m³ per day and of 2.7–3.7 kg of NO₃-N per m³ per day (depending on the inoculum and the granulation procedure). It was proved that anaerobic granulated sludge is not just an inoculum, it is also a carrier for new denitrification biomass.     

The Ethanol Tolerance of <Emphasis Type="Italic">Pachysolen tannophilus</Emphasis> in Fermentation on Xylose

The influence of ethanol on fermentation by Pachysolen tannophilus was studied. When xylose utilization rate was 80%, ethanol concentration began to decline. Fermentation of P. tannophilus was affected by ethanol addition in the beginning of fermentation; average xylose consumption rate was 0.065 g·l⁻¹·h⁻¹, and maximum specific growth rate was 0.07 h⁻¹ at 28 g·l⁻¹ ethanol, comparing with the average xylose consumption rate of 0.38 g·l⁻¹·h⁻¹ and maximum specific growth rate of 0.14 h⁻¹ in fermentation with no ethanol addition; P. tannophilus stopped growth at 40 g·l⁻¹ ethanol. When the initial ethanol concentration was 30 g·l⁻¹, the addition of glucose in xylose media made the growth of P. tannophilus better, and the most favorable glucose concentration was 15 g·l⁻¹ with the highest biomass of 1.51 g·l⁻¹ as compared with that of 0.95 g·l⁻¹ in pure xylose media.