共查询到20条相似文献,搜索用时 15 毫秒
1.
Research on Chemical Intermediates - Research on biosorption and biodegradation of bisphenol A (BPA) in the environment is crucial for pollutant remediation. In this study, the specific biosorption... 相似文献
2.
Takeshi Furuta Shuichi Ikefuji Koujirou Tokunaga Tze Loon Neoh Hidefumi Yoshii 《Journal of inclusion phenomena and macrocyclic chemistry》2007,57(1-4):21-27
Recently, air and ground water pollution and contamination of soil by toluene have been drawing increasing attention and became
an urgently important problem in environmental pollution. Hence, the development of highly sophisticated removal techniques
of toluene is required for the global environmental preservation. Since toluene is a highly volatile material, it is difficult
to treat it by usual activated sludge water treatment. In this study, in order to prevent volatilization of toluene, randomly
methylated β-cyclodextrin (RM-β-CD) was used to complex with toluene and by reason of that, facilitates the biodegradation
of toluene by activated sludge. The enhanced effect of RM-β-CD for the biodegradation of toluene by activated sludge was studied
in batch systems. The addition of RM-β-CD dominantly promoted proliferation of activated sludge. This implied that the addition
of RM-β-CD prevented toluene from evaporating during treatment, and as a result, toluene was effectively decomposed by the
activated sludge. 相似文献
3.
Hisaaki Yagi Fumi Ninomiya Masahiro Funabashi Masao Kunioka 《Polymer Degradation and Stability》2009,94(9):1397-1404
The anaerobic biodegradation tests of polycaprolactone (PCL) and poly(lactic acid) (PLA) powders were done at thermophilic temperature (55 °C) under aquatic conditions (total solid concentrations of the used sludge were 1.73% (undiluted sludge) and 0.86% (diluted sludge)) using a newly developed evaluation system. With this system, the evolved biogas is collected in a gas sampling bag at atmospheric pressure. This method is more convenient than using a pressure transducer or inverted graduated cylinder submerged in water. The biodegradation of PCL powder (10 g, 125–250 μm) in the diluted sludge stopped in about 47 days when the biodegradability reached 92%. The biodegradability of PLA powder (10 g, 125–250 μm) in undiluted sludge was 91% at about 75 days. The biodegradability of PLA powder (10 g, 125–250 μm) in diluted sludge was 79% at about 100 days. The biodegradability of PLA powder (5 g, 125–250 μm) in diluted sludge was 80% at about 85 days. It was found that the PCL and PLA powders were quite degraded using the new evaluation method. In addition, the smaller particle size PCL powder was biodegraded faster. 相似文献
4.
《The Chemical Engineering Journal》1991,45(3):173
The competition between floc-forming and non-settling filamentous populations has been analysed for an activated sludge process incorporating a plug-fl 相似文献
5.
Chua Hong Tan Kok N. Cheung Montgomery W. L. 《Applied biochemistry and biotechnology》1996,57(1):851-856
Applied Biochemistry and Biotechnology - Bulking and foaming in activated sludge have been associated with filamentous overgrowth. FilamentousNocardia amarae and nonfilamentousPseudomonas... 相似文献
6.
The creation of anoxic granulated biomass has been monitored in a laboratory USB (Upflow Sludge Blanket) reactor with the
volume of 3.6 L. The objective of this research was to verify the possibilities of post-denitrification of residual NO3-N concentrations in treated wastewater (denitrification of 10-20 mg L−1 NO3-N) and to determine the maximum hydraulic and mass loading of the granulated biomass reactor. G-phase from biodiesel production
and methanol were both tested as external organic denitrification substrates. The ratio of the organic substrate COD to NO3-N was 6. Only methanol was proven as a suitable organic substrate for this kind of reactor. However, the biomass adaptation
to the substrate took over a week. The cultivation of anoxic granulated biomass was reached at hydraulic loading of over 0.35
m h−1. The size of granules was smaller when compared with results found and described in literary reports (granules up to 1 mm);
however, settling properties were excellent and denitrification was deemed suitable for the USB reactor. Sludge volume indexes
of granules ranged from 35-50 mL g−1 and settling rates reached 11 m h−1. Maximum hydraulic and mass loadings in the USB reactor were 0.95 m3 m−2 h−1 and 6.6 kg m−3 d−1. At higher loading levels, a wash-out of the biomass occurred.
Presented at the 35th International Conference of the Slovak Society of Chemical Engineering, Tatranské Matliare, 26–30 May
2008. 相似文献
7.
In this study, activated sludge bacteria from a conventional wastewater treatment process were induced to accumulate polyhydroxyalkanoates
(PHAs) under different carbon-nitrogen (C:N) ratios. As the C:N ratio increased from 20 to 140, specific polymer yield increased
to a maximum of 0.38 g of polymer/g of dry cell mass while specific growth yield decreased. The highest overall polymer production
yield of 0.11 g of polymer/g of carbonaceous substrate consumed was achieved using a C:N ratio of 100. Moreover, the composition
of polymer accumulated was dependent on the valeric acid content in the feed. Copolymer poly (3-hydroxybutyrate-co-3-hydroxyvalerate)
[P(3HB-co-3HV)] was produced in the presence of valeric acid. The 3-hydroxyvalerate (3HV) mole fraction in the copolymer was
linearly related tovaleric content in the feed, which reached a maximum of 54% when valeric acid was used as sole carbon source.
When the 3HV U in the polymer increased from 0–54 mol%, the melting temperature decreased from 178° to 99°C. Thus, the composition,
and hence the mechanical properties, of the copolymer produced from activated sludge can be controlled by adjusting the mole
fraction of valeric acid in the feed medium. 相似文献
8.
Hisaaki Yagi 《Polymer Degradation and Stability》2010,95(8):1349-1355
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. 相似文献
9.
《Journal of membrane science》1999,157(1):73-84
This paper investigates the reversibility of membrane fouling by activated sludge in a membrane bioreactor equipped with a 0.1 μm pore ceramic membrane. The membrane was submitted to a series of tests in which the permeate flux, the transmembrane pressure (TMP) or the circulation velocity were successively varied in cycles by step increments or decreases. When the permeate flux is set below the critical flux, the TMP remains stable and fouling is reversible. On the contrary, when the critical flux is exceeded, the TMP increases and does not stabilize, as in dead-end filtration. The fouling formed is partly irreversible when the flux is lowered again. When the TMP is first increased up to 400 kPa and then decreased back at constant velocity, no hysteresis is found on the flux–TMP graph, showing that fouling is reversible in this case. Velocity cycles were performed by first lowering the velocity from 5 to 1 m/s and raising it again to 5 m/s. In this case again, the fouling induced by reducing the velocity was found to be reversible. However, when the same pressure and velocity cycle tests were performed with activated sludge collected in the aeration tank of a classical wastewater treatment plant, fouling was found to be partly irreversible, showing that the cake formed in the absence of shearing is much more cohesive. In the final part of the paper, we tested a hydrodynamic method of fouling control consisting in alternating short periods of filtration (1–4 s) and short periods of washing (1 or 2 s) at low TMP and high velocity. This method yielded to a 20% permeate flux increase with a 10% reduction in hydraulic energy consumption for classical plant activated sludge. 相似文献
10.
Polyhydroxyalkanoates (PHAs) have been recognized as good candidates for biodegradable plastics, but their high price compared
with conventional plastics has limited their use. In this study, actiated sludge microorgan isms from a conventional wastewater
treatment process were induced, bycontrol-lingthe carbon: nitrogen (C:N) ratioin the reacorliquor, toaccumulate PHAs. In addition,
an intermittent nitrogen feeding program was established to optimize the volumetric PHA productivity in a wastewater treatment
process. The optimal overall polymer production yield of 0.111 g of polymer/g of carbonaceous substrate consumed was achieved
under a C:N ratio of 96:1 by feeding nitrogen in the reactor liquor onceevery four cycles. At the same time, the amount of
excess sludge generated from the wastewater treatment process was reduced by22.9%. 相似文献
11.
Michał Kowalski Katarzyna Kowalska Jarosław Wiszniowski Jolanta Turek-Szytow 《Chemical Papers》2018,72(11):2699-2706
The ability to measure and control the composition of activated sludge is an important issue, aiming at evaluating the effectiveness of changes occurring in the sludge, what determines its usefulness to treat wastewater. In this research, diffuse reflectance infrared Fourier transform (FTIR–DRIFT) technique was used, which relies on measuring the reflectance of the powdered substance’s surface layer and capturing spectra in range of infrared wave. First, spectra correlation table of the substances mostly occurring in wastewater was developed to assess the main components of the tested samples of activated sludge. The simplest compounds containing functional groups characteristic for particular chemical classes were chosen: peptides (peptone and albumin), fats (glycerin and fatty acids), carbohydrates (glucose and sucrose), nitrogen compounds (NaNO3 and NH4SO4), sulfur compounds (Na2SO4 and Na2S2O3), silicate, etc. The spectra of those substances were captured and characteristic absorption bands for respective bonds in the function groups were assigned. Second, samples of activated sludge from lab-scale membrane bioreactors (MBRs), which purifies petroleum wastewater, were taken. Samples were properly prepared (lyophilization and homogenization) and their spectra were captured. During spectra analysis, previously developed correlation table was used. In obtained spectra of activated sludge, absorption bonds characteristic for amides, peptides, carbohydrates, fats, and aliphatic was identified. The spectra profile of the sludge sample from MBR feed with petroleum wastewater was slightly different from the control MBR sample’s spectra. Intensity of bands in the area characteristic for aliphatic compounds and phenols was clearly higher. This study proves the usefulness of FT-IR technique to observe changes in the chemical composition of activated sludge. 相似文献
12.
F. E. Moura S. Prasad V. D. Leite Crislene R. S. Morais A. J. M. Barros A. G. Souza 《Journal of Thermal Analysis and Calorimetry》2007,87(3):679-683
The present
study describes the aerobic biodegradation process of a mixture of sanitary
sewage sludge and lubricating oil. TG/DTG curves confirmed that the applied
aerobic biological treatment decreased the organic material content and caused
significant modifications in the thermal behavior of the studied substrates
after the functioning period. 相似文献
13.
The analysis of volatile siloxanes in waste activated sludge 总被引:1,自引:0,他引:1
The increasing presence of siloxanes in waste activated sludge (WAS) considerably hampers the energy use of the biogas obtained during the anaerobic digestion of the sludge when concentrations exceed critical limits. To prevent the occurrence of unacceptable operating conditions, it is hence necessary to have a reliable analysis method for determining the siloxane content of the sludge. This paper describes and validates such a method, consisting of the extraction of the siloxanes using n-hexane and a subsequent analysis of the extract using GC-FID. The validation procedure confirms the excellent recovery and repeatability of the proposed method. 相似文献
14.
Park Don-Hee Witt Andrew R. Tanner Robert D. Roth John A. 《Applied biochemistry and biotechnology》1995,51(1):339-346
Previously collected data describing aerated synthetic waste water, treated in a continuous stirred-tank reactor, are analyzed to understand better the dynamic response to step changes in the dilution rate,D. Comparing a change inD between steady states leads to hysteresis trajectories on both the graph of specific growth rate, μ, vs limiting substrate level (S) and the graph of (S) vs the cell level (X). Qualitative differences between the three different monitored cases will be compared to simulations of simple models at various dilution level changes in order to gain understanding of the dynamics of the process.
相似文献15.
This work estimated the porosities of activated sludge flocs, cationic polyelectrolyte flocculated, based on free-settling tests, buoyant weight measurements, and confocal laser scanning microscope (CLSM) tests. The extent of advective flow was estimated based on bubble-tracking test. The former two measurements suggested a close-to-unity porosity, that is, an extremely void floc interior. Meanwhile, the latter two tests recommended a dense floc interior with a porosity less than 64%. A discrepancy exists between the porosities estimated by various tests. A floc model was proposed based on the understanding that a vast amount of bound water in the floc was regarded as void in buoyant weight measurement, but was impermeable for advective flow. The distribution rather than the mean value of the porosity controls the advective flow. There existed no simple correlation between the porosities measured by different tests. 相似文献
16.
The sorption of Cu(II) and Cd(II) from synthetic solution by powdered activated carbon (PAC), biomass, rice husk (RH) and activated rice husk (ARH) were investigate under batch conditions. After activated by concentrated nitric acid for 15 hours at 60-65 degrees C, the adsorption capacity for RH was increased. The adsorbents arranged in the increasing order of adsorption capacities to the Langmuir Q degree parameter were biomass > PAC > ARH > RH. The addition of adsorbents in base mix solution had increased the specific oxygen uptake rate (SOUR) activated sludge microorganisms with and without the presence of metals. The increased of SOUR were due to the ability of PAC and RH in reducing the inhibitory effect of metals on microorganisms and provide a reaction site between activated sludge microorganisms and substrates. 相似文献
17.
Twelve aerobic bacteria from activated sludge were isolated and identified. These included both Gram-positive (e.g., Bacillus) and Gram-negative (e.g., Pseudomonas) bacteria. The biosorption capacity of these strains for three different heavy metals (copper, nickel, and lead) was determined
at pH 5.0 and initial metal concentration of 100 mg/L. Among these 12 isolates, Pseudomonas pseudoalcaligenes was selected for further investigation owing to its high metal biosorption capacity. The lead and copper biosorption of this
strain followed the Langmuir isotherm model quite well with maximum biosorption capacity (q
max) reaching 271.7mg of Pb2+/g of dry cell and 46.8 mg of Cu2+/g of dry cell at pH 5.0. Study of the effect of pH on lead and copper removal indicated that the metal biosorption increased
with increasing pH from 2.0 to 7.0. A mutual inhibitory effect was observed in the lead-copper system because the presence
of either ion affected the sorption capacity of the other. Unequal inhibitions were observed in all the nickel binary systems.
The increasing order of affinity of the three metals toward P. pseudoalcaligenes was Ni<Cu<Pb. The metal biosorptive potential of these isolates, especially P. pseudoalcaligenes, may have possible applications in the removal and recovery of metals from industrial effluents. 相似文献
18.
Law Kin-Ho Leung Yun-Chung Lawford Hugh Chua Hong Lo Wai-Hung Yu Peter Hoifu 《Applied biochemistry and biotechnology》2001,91(1-9):515-524
Plastic wastes are considered to be severe environmental contaminants causing waste disposal problems. Widespread use of biodegradable
plastics is one of the solutions, but it is limited by high production cost. Biologic wastewater treatment generates large
quantities of biomass as activated sludge. Only a few reports focus on the potential of utilizing resident Bacillus species from activated sludge in polyhydroxbutyrate (PHB) production as well as the production of PHB from food wastes. They
have attractive properties such as short generation time, absence of endotoxins, and secretion of both amylases and proteinases
that can well utilize food wastes for nutrients, which can further reduce the cost of production of polyhydroxyalkanoates
(PHAs). Two PHA-producing strains, HF-1 and HF-2, were isolated from activated sludge. HF-1 outperfomed HF-2 in terms of growth
and PHB production in hydrolyzed soy and malt wastes. The isolated bacteria was characterized by DNA sequence alignment. Cell
extracts of HF-1 were also compared to Bacillus megaterium cell extracts on sodium dodecyl sulfate polyacrylamide gel electrophoresis. The biopolymers accumulated were analyzed by
gas chromatography, nuclear magnetic resonance, and Fourier transform infrared methods. 相似文献
19.
Muhammad Hanif Yoichi Atsuta Koichi Fujie Hiroyuki Daimon 《Journal of chromatography. A》2010,1217(43):6704-6708
Supercritical carbon dioxide (scCO2) extraction was applied for the determination of microbial phospholipid fatty acids (PLFA) in activated sludge. Quantification was performed by using gas chromatography–mass spectrometry (GC–MS). The highest extraction yields of PLFA, at a concentration of 7.28 nmol/mg-dry activated sludge, was obtained at a temperature of 80 °C, pressure of 25 MPa and 10% (v/v) methanol for a 15-min extraction time. ScCO2 extraction results obtained in these conditions were comparable with those obtained by liquid organic solvent extraction (LSE) based on diversity and equalibility indices. The repeatability test showed that the relative standard deviation values were less than 13%. The experimental results show that the scCO2 extraction saves time and uses much less organic solvent. In addition, scCO2 extraction is a promising and alternative method for the analysis of microbial community structure in environmental assessment using the PLFA profile. 相似文献
20.
Chua Hong Yu Peter H. F. Sin Shirley N. Tan Kok N. 《Applied biochemistry and biotechnology》2000,84(1-9):1127-1135
Foaming is a common operational problem in activated sludge processes that often adversely affects the quality of the treated
effluent. Overgrowth of the filamentous Nocardia spp. in the microbial ecosystem was previously identified as the cause of foaming. In the present study, the specific growth
rate of Nocardia amarae was found to be much higher than that of nonfilamentous bacteria under food:microorganism (F:M) ratios lower than 0.5 mg
of biological oxygen demand (BOD)/(mg of mixed liquor suspended solids [MLor]·d). This indicated that filamentous overgrowth
may occur in normal activated sludge processes that are continually operated under the usual F:M range of 0.2–0.6 mg of BOD/(mg
of MLSS·d). A novel two-component feast-fast operation (FFO) that capitalized on the sensitivity of filamentous bacteria to
F:M ratio was designed to prevent and control foaming problems. The F:M ratio in the “feasting” aeration unit was 0.8 mg of
BOD/(mg of MLSS·d) whereas that in the “fasting” aeration unit was 0.2 mg of BOD/(mg of MLSS·d). The FFO resulted in an overall
process F:M ratio that still remained within the normal range, while avoiding prolonged exposure of the activated sludge ecosystem
to an F:M ratio below 0.5 mg of BOD/(mg of MLSS·d). The FFO suppressed the over growth of filamentous bacteria without adversely
affecting the organic treatment efficiency of the modified process. 相似文献