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1.
Phenol inhibition of biological nutrient removal in a four-step sequencing batch reactor 总被引:3,自引:0,他引:3
Nutrient removal from synthetic wastewater was investigated using a four-step sequencing batch reactor (SBR) at different phenol (C6H5OH) concentrations in order to determine the inhibition effects of phenol on biological nutrient removal. The nutrient removal process consisted of anaerobic, oxic, anoxic, and oxic phases with hydraulic residence times (HRT) of 1 h/3 h/1 h/1 h and a settling phase of 3/4 h. Solids retention time (SRT) was kept constant at 10 days in all experiments. Initial phenol concentrations were varied between 0 and 600 mg l−1 at seven different levels. The effects of phenol on COD, NH4-N, and PO4-P removals and effluent nutrient levels were investigated. Phenol was almost completely degraded up to 400 mg l−1 phenol concentration resulting in almost negligible inhibition effects on COD, NH4-N, and PO4-P removals. Nutrient removals were adversely affected by phenol at concentrations above 400 mg l−1. Above 95% COD, 90% NH4-N and 65% PO4-P removal was obtained for phenol concentrations below 400 mg l−1. The sludge volume index (SVI) was almost constant around 45 ml g−1 for phenol concentrations below 400 mg l−1 but increased to 90 ml g−1 at a phenol level of 600 mg l−1. 相似文献
2.
Treatment of aged (500 day, 4 °C stored) chlortetracycline (CTC; 0, 20, 40, 80 mg/L CTC)-amended swine manure using two cycle, 22 day stage anaerobic sequencing batch reactors (SBR) was assessed. Eighty milligrams per liter CTC treatment inhibited SBR treatment efficiencies, although total gas production was enhanced compared to the no-CTC treatment. The 20 and 40 mg/L CTC treatments resulted in either slight or no differences to SBR treatment efficiencies and microbial diversities compared to the no-CTC treatment, and were generally similar to no-CTC treatments upon completion of the first 22 day SBR cycle. All CTC treatments enhanced SBR gas generation, however CH4 yields were lowest for the 80 mg/L CTC treatment (0.111 L CH4/g tCOD) upon completion of the second SBR react cycle. After a 22 day acclimation period, the 80 mg/L CTC treatment inhibited methanogenesis due to acetate accumulation, and decreased microbial diversity and CH4 yield compared to the no-CTC treatment. 相似文献
3.
A mathematical model is developed to describe the growth of multiple microbial species such as heterotrophs and autotrophs
in activated sludge system. Performance of a lab-scale sequencing batch reactor involving storage process is used to evaluate
the model. Results show that the model is appropriate for predicting the fate of major model components, i.e., chemical oxygen
demand, storage polymers (X
STO), volatile suspended solid (VSS), ammonia, and oxygen uptake rate (OUR). The influence of sludge retention time (SRT) on
reactor performance is analyzed by model simulation. The biomass components require different time periods from one to four
times of SRT to reach steady state. At an SRT of 20 days, the active bacteria (autotrophs and heterotrophs) constitute about
57% of the VSS; the remaining biomass is not active. The model established demonstrates its capacity of simulating the reactor
performance and getting insight in autotrophic and heterotrophic growth in complex activated sludge systems. 相似文献
4.
In this study, a series of tests were conducted in a 6 L anaerobic sequencing batch reactor (ASBR) to investigate the effect of pH, hydraulic retention time (HRT) and organic loading rate on biohydrogen production at 28 °C. Sucrose was used as the main substrate to mimic carbohydrate-rich wastewater and inoculum was prepared from anaerobic digested sludge without pretreatment. The reactor was operated initially with nitrogen sparging to form anaerobic condition. Results showed that methanogens were effectively suppressed. The optimum pH value would vary depending on the HRT. Maximum hydrogen production rate and yield of 3.04 L H2/L reactor d and 2.16 mol H2/mol hexose respectively were achieved at pH 4.5, HRT 30 h, and OLR 11.0 kg/m3 d. Two relationships involving the propionic acid/acetic acid ratio and ethanol/acetic acid ratio were derived from the analysis of the metabolites of fermentation. Ethanol/acetic acid ratio of 1.25 was found to be a threshold value for higher hydrogen production. 相似文献
5.
Biodegradation and kinetics of aerobic granules under high organic loading rates in sequencing batch reactor 总被引:1,自引:0,他引:1
Biodegradation, kinetics, and microbial diversity of aerobic granules were investigated under a high range of organic loading
rate 6.0 to 12.0 kg chemical oxygen demand (COD) m−3 day−1 in a sequencing batch reactor. The selection and enriching of different bacterial species under different organic loading
rates had an important effect on the characteristics and performance of the mature aerobic granules and caused the difference
on granular biodegradation and kinetic behaviors. Good granular characteristics and performance were presented at steady state
under various organic loading rates. Larger and denser aerobic granules were developed and stabilized at relatively higher
organic loading rates with decreased bioactivity in terms of specific oxygen utilization rate and specific growth rate (μ
overall) or solid retention time. The decrease of bioactivity was helpful to maintain granule stability under high organic loading
rates and improve reactor operation. The corresponding biokinetic coefficients of endogenous decay rate (k
d), observed yield (Y
obs), and theoretical yield (Y) were measured and calculated in this study. As the increase of organic loading rate, a decreased net sludge production (Y
obs) is associated with an increased solid retention time, while k
d and Y changed insignificantly and can be regarded as constants under different organic loading rates. 相似文献
6.
7.
The aim of this study was to examine nitrogen removal from slaughterhouse wastewater in a laboratory-scale sequencing batch
reactor (SBR) operated at low dissolved oxygen (DO) levels under two aeration strategies: intermittent aeration (IA) and continuous
aeration (CA). Under the IA strategy, during the aeration periods, the maximum DO was controlled at 10% saturation; under
the CA strategy, in the first hour of the react phase, the DO was maintained at 10% saturation, and then it was kept at 2–3%
saturation in the remaining react phase. Total nitrogen removals of up to 95 and 91% were achieved under the IA and CA aeration
strategies, respectively. It is proposed that in situ measurement of oxygen utilization rates can be used to control the operation
of SBRs for nitrogen removal. 相似文献
8.
A sequencing batch reactor (SBR) was used to remove phosphate in biological wastewater treatment as an alternative to the activated sludge process, in order to improve the low removal efficiency of phosphate and the operational instability. After a cycle of 2 h anaerobic and 4 h aerobic conditions, phosphate removal was optimized. The removal efficiencies of 5 and 50 mg phosphate l–1 by Staphylococcus auricularis under repeated anaerobic and aerobic conditions were above 90%. These results showed that a long adaptation time, one of the major problems in biological phosphate removal process, was overcome by SBR. 相似文献
9.
A nutrient-removal sequencing batch reactor operated with short anaerobic/aerobic cycles was subjected to different operating
conditions, namely, cycle length, feeding pattern and feed composition. The changes in microbial population, as well as the
contribution of microbial groups to the total nutrient removal, were estimated using the kinetic parameters obtained in this
study. Denitrifying polyphosphate-accumulating organisms (DPAOs) were detected in the system, representing a fraction of 23%
of phosphorus-accumulating organisms (PAOs). The results suggest that DPAOs and non-DPAOs are different microorganisms. The
presence of nitrate in the feed stimulated DPAOs to predominate over non-DPAOs. Feeding the reactor with a mixture of organic
substrates also stimulated DPAOs. Glycogen-accumulating organisms (GAOs) were likely to be present in the system and their
development over PAOs was apparently favoured by increasing the aeration time and feeding during the aerobic phase. In contrast,
the presence of propanoate in the feed apparently favoured PAOs over GAOs. 相似文献
10.
A. Kuprijanov S. Gnoth R. Simutis A. Lübbert 《Applied microbiology and biotechnology》2009,82(2):221-229
Design and experimental validation of advanced pO2 controllers for fermentation processes operated in the fed-batch mode are described. In most situations, the presented controllers
are able to keep the pO2 in fermentations for recombinant protein productions exactly on the desired value. The controllers are based on the gain-scheduling
approach to parameter-adaptive proportional-integral controllers. In order to cope with the most often appearing distortions,
the basic gain-scheduling feedback controller was complemented with a feedforward control component. This feedforward/feedback
controller significantly improved pO2 control. By means of numerical simulations, the controller behavior was tested and its parameters were determined. Validation
runs were performed with three Escherichia coli strains producing different recombinant proteins. It is finally shown that the new controller leads to significant improvements
in the signal-to-noise ratio of other key process variables and, thus, to a higher process quality. 相似文献
11.
One of the key challenges in stem cell bioprocessing is the large-scale cultivation of stem cells in order to meet the demanding meaningful cell numbers needed for biomedical applications, especially for clinical settings. Mouse embryonic stem cells [1], used as a model system herein, were cultivated on microcarriers in a fully controlled stirred tank reactor (STR) [2]. The impact of varying the concentration of dissolved oxygen (at 5%, 10%, 20% and 30% DO) and operating under a continuous perfusion mode on cell growth and pluripotency maintenance was investigated. In addition, in order to further optimize the feeding strategy of the STR operating under continuous perfusion toward maximal cell production, the influence of different medium residences times (12 h, 24 h, 32 h, 48 h and 96 h) was evaluated. Overall, the maximal cell concentration of 7.9–9.2 × 106 cells/mL were attained after 11 days, with no passaging required, under a DO of 10–20% in the continuous perfused bioreactor with cell retention and medium residences times of 32–48 h. Importantly, mESC expanded under these conditions, retained the expression of pluripotency markers (Oct4, Nanog and Ssea-1), as well as their differentiation potential into cells of the three embryonic germ layers.The STR-based cultivation platform optimized herein represents a major contribution toward the development of large-volume production systems of differentiated cell derivatives for a wide range of biomedical applications. 相似文献
12.
Effects of glucose and phenol on soluble microbial products (SMP) in sequencing batch reactor systems 总被引:2,自引:0,他引:2
Guangtuan Huang Gang Jin Jinghui Wu Yongdi Liu 《International biodeterioration & biodegradation》2008,62(2):104-108
Soluble microbial products (SMP) are ubiquitously present in the effluents of biological wastewater treatment systems. In sequencing batch reactor (SBR) systems, effects of influent concentration and temperature on the amount and the molecular weight (MW) distribution of SMP were investigated for the two substrates, glucose and phenol. The values of effluent SMP/S0 of phenol were higher than those of glucose at different influent concentrations and temperatures. It was found that the effluent SMP (Se) was linearly correlated to the influent total organic carbon (TOC) (S0) for both substrates. The slope and intercept of the equation were affected by the temperature. According to the analysis of the MW distribution, it was shown that there exists a bimodal pattern with the majority of SMP having a MW<1 kDa or >10 kDa. The low MW fraction (<1 kDa) amounts to 47.3–70.4% of the effluent SMP. The high MW fraction (>10 kDa) slightly fluctuates in the range of 21.2–32.8% of the effluent SMP. 相似文献
13.
Mauro de Paula Moreira Celso S. Yamakawa Victor Haber Perez Ranulfo Monte Alegre 《World journal of microbiology & biotechnology》2008,24(9):1937-1942
The effect of carbon source addition on the operation of a sequencing batch reactor in order to remove nitrogen and COD of
poultry wastewater was studied. The reactor was constructed with a glass tube having a volume of 7 l and a jacket for temperature
control. The reactor bottom consisted of a conical porous stone in order to promote liquor aeration and agitation. Initial
conditions and operation strategies were adjusted to improve the final effluent quality. According to the attained experimental
results, it was verified that nitrification and denitrification can occur simultaneously in aerated culture, contrary the
observation of some authors. 相似文献
14.
Krishna Rao DV Ramu CT Rao JV Narasu ML Bhujanga Rao AK 《Journal of industrial microbiology & biotechnology》2008,35(9):991-1000
The impact of different levels of agitation speed, carbondioxide and dissolved oxygen concentration on the key parameters and production of rhG-CSF in Escherichia coli BL21(DE3)PLysS were studied. Lower carbondioxide concentrations as well as higher agitation speeds and dissolved oxygen concentrations led to reduction in the acetate concentrations, and enhanced the cell growth, but inhibited plasmid stability and rhG-CSF expression. Similarly, higher carbondioxide concentrations and lower agitation speeds as well as dissolved oxygen concentrations led to enhanced acetate concentrations, but inhibited the cell growth and protein expression. To address the bottlenecks, a two-stage agitation control strategy (strategy-1) and two-stage dissolved oxygen control strategy (strategy-2) were employed to establish the physiological and metabolic conditions, so as to improve the expression of rhG-CSF. By adopting strategy-1 the yields were improved 1.4-fold over constant speed of 550 rpm, 1.1-fold over constant dissolved oxygen of 45%, respectively. Similarly, using strategy-2 the yields were improved 1.6-fold over constant speed of 550 rpm, 1.3-fold over constant dissolved oxygen of 45%, respectively. 相似文献
15.
P. A. Grecay K. L. Stierhoff 《Journal of experimental marine biology and ecology》2002,280(1-2):53-62
Hypoxia is common in freshwater, estuarine, and shallow or enclosed marine systems. Research on the sub-lethal effects of hypoxia on feeding and growth includes both field and laboratory studies. Extended regulation of dissolved oxygen (DO) is difficult to precisely control in the laboratory. Here we describe a device that is capable of simultaneously monitoring and controlling DO at multiple treatment levels, in replicate experimental tanks, for indefinite periods of time. Each treatment level may be static or fluctuate on a diel cycle. The device consists of a series of independent aquarium systems, each of which is monitored and adjusted by a computer program. A data file and chart of DO levels in each treatment level is recorded. A computer program that repeatedly measures and adjusts DO controls the device. Because this apparatus is software-controlled, the user has the flexibility of altering treatment parameters at any time without interrupting experiments. 相似文献
16.
The combination of anaerobic and aerobic periods in the operation cycle of a Sequencing Batch Reactor (SBR) was chosen to study biological color removal from simulated textile effluents containing reactive, sulfonated, monoazo and diazo dyes, respectively, Remazol Brilliant Violet 5R and Remazol Black B. 90% color removal was obtained for the violet dye in a 24-h cycle with a Sludge Retention Time (SRT) of 15 days and an aerated reaction phase of 10 h. For the black dye only 75% color removal was achieved with the same operational conditions and no improvement was observed with the increase of the SRT to 20 days. For the violet dye a reduction of the color removal values from 90 to 75% was observed with the increase of the aerated reaction phase from 10 to 12 h. However, this increase did not promote the aerobic biodegradation of the produced aromatic amines. Abiotic tests were performed with sterilized SBR samples and no color removal was observed in cell-free supernatants. However color removal values of 30 and 12% were observed in the presence of sterilized cells and supernatants with violet and black dye, respectively and could be attributed to the presence of active reducing principles in the sterilized samples. 相似文献
17.
Assessing contemporary anaerobic biotechnologies requires proofs on reliable performance in terms of renewable bioenergy recovery such as methane (CH4) production rate, CH4 yield while removing volatile solid (VS) effectively. This study, therefore, aims to evaluate temperature-phased anaerobic sequencing batch reactor (TPASBR) system that is a promising approach for the sustainable treatment of organic fraction of municipal solid wastes (OFMSW). TPASBR system is compared with a conventional system, mesophilic two-stage anaerobic sequencing batch reactor system, which differs in operating temperature of 1st-stage. Results demonstrate that TPASBR system can obtain 44% VS removal from co-substrate of sewage sludge and food waste while producing 1.2 m3CH4/m3system/d (0.2 m3CH4/kgVSadded) at organic loading rate of 6.1 gVS/L/d through the synergy of sequencing-batch operation, co-digestion, and temperature-phasing. Consequently, the rapid and balanced anaerobic metabolism at thermophilic stage makes TPASBR system to afford high organic loading rate showing superior performance on OFMSW stabilization. 相似文献
18.
A laboratory-scale anaerobic–anoxic/nitrification sequencing batch reactor (A2N-SBR) fed with domestic wastewater was operated to examine the effect of varying ratios of influent COD/P, COD/TN and TN/P on the nutrient removal. With the increased COD/P, the phosphorus removals exhibited an upward trend. The influent TN/P ratios had a positive linear correlation with the phosphorus removal efficiencies, mainly because nitrates act as electron acceptors for the phosphorus uptake in the A2N-SBR. Moreover, it was found that lower COD/TN ratio, e.g. 3.5, did not significantly weaken the phosphorus removal, though the nitrogen removal first decreased greatly. The optimal phosphorus and nitrogen removals of 94% and 91%, respectively were achieved with influent COD/P and COD/TN ratios of 19.9 and 9.9, respectively. Additionally, a real-time control strategy for A2N-SBR can be undertaken based on some characteristic points of pH, redox potential (ORP) and dissolved oxygen (DO) profiles in order to obtain the optimum hydraulic retention time (HRT) and improve the operating reliability. 相似文献
19.
Nitrogen removal from wastewater is often limited by the availability of reducing power to perform denitrification, especially when treating wastewaters with a low carbon:nitrogen ratio. In the increasingly popular sequencing batch reactor (SBR), bacteria have the opportunity to preserve reducing power from incoming chemical oxygen demand (COD) as poly-beta-hydroxybutyrate (PHB). The current study uses laboratory experiments and mathematical modeling in an attempt to generate a better understanding of the effect of oxygen on microbial conversion of COD into PHB. Results from a laboratory SBR with acetate as the organic carbon source showed that the aerobic acetate uptake process was oxygen-dependent, producing higher uptake rates at higher dissolved oxygen (DO) supply rates. However, at the lower DO supply rates (k(L)a 6 to 16 h(-1), 0 mg L(-1) DO), a higher proportion of the substrate was preserved as PHB than at higher DO supply rates (k(L)a 30, 51 h(-1), DO >0.9 mg L(-1)). Up to 77% of the reducing equivalents available from acetate were converted to PHB under oxygen limitation (Y(PHB/Ac) 0.68 Cmol/Cmol), as opposed to only 54% under oxygen-excess conditions (Y(PHB/Ac) 0.48 Cmol/Cmol), where a higher fraction of acetate was used for biomass growth. It was calculated that, by oxygen management during the feast phase, the amount of PHB preserved (1.4 Cmmol L(-1) PHB) accounted for an additional denitrification potential of up to 18 mg L(-1) nitrate-nitrogen. The trends of the effect of oxygen (and hence ATP availability) on PHB accumulation could be reproduced by the simulation model, which was based on biochemical stoichiometry and maximum rates obtained from experiments. Simulated data showed that, at low DO concentrations, the limited availability of adenosine triphosphate (ATP) prevented significant biomass growth and most ATP was used for acetate transport into the cell. In contrast, high DO supply rates provided surplus ATP and hence higher growth rates, resulting in decreased PHB yields. The results suggest that oxygen management is crucial to conserving reducing power during the feast phase of SBR operation, as excessive aeration rates decrease the PHB yield and allow higher biomass growth. 相似文献
20.
Liu XW Wang YP Huang YX Sun XF Sheng GP Zeng RJ Li F Dong F Wang SG Tong ZH Yu HQ 《Biotechnology and bioengineering》2011,108(6):1260-1267
In the research and application of microbial fuel cell (MFC), how to incorporate MFCs into current wastewater infrastructure is an importance issue. Here, we report a novel strategy of integrating an MFC into a sequencing batch reactor (SBR) to test the energy production and the chemical oxygen demand (COD) removal. The membrane-less biocathode MFC is integrated with the SBR to recover energy from the aeration in the form of electricity and thus reduce the SBR operation costs. In a lab-scale integrated SBR-MFC system, the maximum power production of the MFC was 2.34 W/m(3) for one typical cycle and the current density reached up to 14 A/m(3) . As a result, the MFC contributed to the 18.7% COD consumption of the integrated system and also recovered energy from the aeration tank with a volume fraction of only 12% of the SBR. Our strategy provides a feasible and effective energy-saving and -recovering solution to upgrade the existing activated sludge processes. 相似文献