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1.
Aims: The aim of the study was to investigate the feasibility of a continuous reactor for psychrophilic anaerobic wastewater treatment by using the sludge from cold natural environment. Methods and Results: Six sludge samples (S1–S6) were collected from different cold natural locations to select sludge with high anaerobic microbial activity under low temperatures. After a 225‐day incubation, the maximum specific methane production rate of a waterfowl lake sediment (S1) at 15°C (70·5 mLCH4 gVSS?1 day?1) was much higher than all other samples. S1 was thus chosen as the seed sludge for the reactor treating synthetic brewery wastewater at 15°C, by immobilizing the micro‐organisms on polyurethane foam carriers. The chemical oxygen demand (COD) removal efficiency reached over 80% after 240‐day operation at an organic loading rate of 5·3 kg m?3 day?1, and significant enrichment of biomass was observed. Clone libraries of the microbial communities in the inoculum had high diversities for both archaea and bacteria. Along with a decrease in microbial community diversities, the dominant bacteria (79·5%) at the end of the operation represented the phylum Firmicutes, while the dominant archaeon (41·5%) showed a similarity of 98% with the psychrotolerant methanogen Methanosarcina lacustris. Conclusions: The possibility of using anaerobic micro‐organisms from cold environments in anaerobic wastewater treatment under psychrophilic conditions is supported by these findings. Significance and Impact of the Study: This study enriches the theory on microbial community and the application on anaerobic treatment of sludge from cold natural environments. 相似文献
2.
Anammox start-up in sequencing batch biofilm reactors using different inoculating sludge 总被引:1,自引:0,他引:1
In this study, anammox bacteria were rapidly enriched in sequencing batch biofilm reactors (SBBRs) with different inoculations. The activated sludge taken from a sequencing batch reactor was used and inoculated to SBBR1, while SBBR2 was seeded with stored anaerobic sludge from an upflow anaerobic fixed bed (2-year stored at 5–15 °C). Nitrogen removal performance, anammox activity, biofilm characteristics and variation of the microbial community were evaluated. The maximum total nitrogen loading rate (NLR) of SBBR1 gradually reached to 1.62 kg?N/(m3/day) with a removal efficiency higher than 88 % and the NLR of SBBR2 reached to 1.43 kg?N/(m3/day) with a removal efficiency of 86 %. SBBR2 was more stable compared to SBBR1. These results, combined with molecular techniques such as scanning electron microscope, fluorescence in situ hybridization, and terminal restriction fragment length polymorphism, indicated that different genera of anammox bacteria became dominant. This research also demonstrates that SBBR is a promising bioreactor for starting up and enriching anammox bacteria. 相似文献
3.
Sequencing batch reactors were used to study anaerobic ammonium oxidation (anammox) process under temperature shock. Both long-term (15–35 °C) and short-term (10–50 °C) temperature effects on nitrogen removal performance were performed. In reactor operation test, the results indicated that ammonium removal rate decreased from 0.35 kg/(m3 day) gradually to 0.059 kg/(m3 day) when temperature dropped from 35 to 15 °C. Although bacteria morphology was not modified, sludge settling velocity decreased with decreasing temperature. In batch test, apparent activation energy (Ea) increased with decreasing temperature, which suggested the activity decrease of anaerobic ammonium oxidizing bacteria (AAOB). Low temperature inhibited AAOB and weakened nitrogen removal performance. The cardinal temperature model with inflection was first used to describe temperature effect on anammox process. Simulated results revealed that anammox reaction could occur at 10.52–50.15 °C with maximum specific anammox activity of 0.50 kg/(kg day) at 36.72 °C. The cold acclimatization of AAOB could be achieved and glycine betaine could slightly improve nitrogen removal performance at low temperature. 相似文献
4.
The co-digestion of residues from the pre-treatment process of waste vegetable oil (OW) and pig manure (PM) was performed under different OW/PM feed ratios (1:0, 1:1 and 1:3 v/v) and at organic loading rates ranging from 0.25 to 3.1 kg VS m?3 day?1 in lab-scale single-phase (SP) and two-phase (TP) systems. From the experiments, it was observed that digestion of OW alone was inhibitory for the anaerobic degradation. Mixing OW with PM neutralized the negative effects of lipids accumulation and high VS removal efficiencies were realized in both systems (63 and 71 % in SP system and 69 and 72 % in TP system, at 1:1 and 1:3 OW/PM mixtures, respectively). Under the same operational conditions, the methane yield was 0.30 and 0.22 m3 CH4 kg?1 VS removed for the SP anaerobic digester and 0.30 and 0.27 m3 CH4 kg?1 VS removed for the TP configuration. Additionally, TP digestion presented more stable operation and higher treatment capacity. 相似文献
5.
Vojtech Kouba P. Widiayuningrum L. Chovancova P. Jenicek J. Bartacek 《Journal of industrial microbiology & biotechnology》2016,43(7):965-975
Energy consumption of municipal wastewater treatment plants can be reduced by the anaerobic pre-treatment of the main wastewater stream. After this pre-treatment, nitrogen can potentially be removed by partial nitritation and anammox (PN/A). Currently, the application of PN/A is limited to nitrogen-rich streams (>500 mg L?1) and temperatures 25–35 °C. But, anaerobically pretreated municipal wastewater is characterized by much lower nitrogen concentrations (20–100 mg L?1) and lower temperatures (10–25 °C). We operated PN/A under similar conditions: total ammonium nitrogen concentration 50 mg L?1 and lab temperature (22 °C). PN/A was operated for 342 days in a 4 L moving bed biofilm reactor (MBBR). At 0.4 mg O2 L?1, nitrogen removal rate 33 g N m?3 day?1 and 80 % total nitrogen removal efficiency was achieved. The capacity of the reactor was limited by low AOB activity. We observed significant anammox activity (40 g N m?3 day?1) even at 12 °C, improving the applicability of PN/A for municipal wastewater treatment. 相似文献
6.
Riparian zones are an important strategy to mitigate N and P export to streams. However, their efficiency with respect to nitrate (NO3 ?), ammonium (NH4 +), or soluble reactive phosphorus (SRP) in groundwater remains uncertain in the US Midwest. This study investigates water table fluctuations and NO3 ?, NH4 +, and SRP concentration dynamics in two riparian zone types (outwash vs. glacial till) common in the upper US Midwest. During low water table periods, NO3 ? removal was 93 % at WR (outwash site), and 75 % at LWD (glacial till site); but during high water table periods, NO3 ? removal efficiencies dropped to 50 % at WR, and 14 % at LWD. Median seasonal mass fluxes of NO3 ? removed at WR (9.4–21.7 mg N day?1 m?1 of stream length) and LWD (0.4–1.9 mg N day?1 m?1) were small compared to other riparian zones in glaciated landscapes. The WR site was a small SRP sink (0.114 and 0.118 mg day?1 m?1 during the dry period and wet period, respectively), while LWD acted as a small SRP source to the stream (0.004 mg day?1 m?1 during the dry period; 0.075 mg day?1 m?1 during the wet period). Both LWD and WR acted as sources of NH4 + to the stream with mass fluxes ranging from 0.17 to 7.75 mg N day?1 m?1. Although riparian zones in the US Midwest provide many ecosystem services, results suggest they are unlikely to efficiently mitigate N and P pollution in subsurface flow. 相似文献
7.
Sohair I. Abou-Elela Mohamed A. Elekhnawy Magdy T. Khalil Mohamed S. Hellal 《International journal of phytoremediation》2017,19(11):1023-1028
The effect of hydraulic loading rate (HLR) and hydraulic retention time (HRT) on the bioremediation of municipal wastewater using a pilot scale subsurface horizontal flow constructed treatment wetland (HFCTW) vegetated with Cyprus papyrus was investigated. Different HLRs were applied to the treatment system namely 0.18, 0.10, and 0.07 m3/m2. d with corresponding HRTs of 1.8, 3.2, and 4.7 days, respectively. The flow rate was 8 m3/d, and the average organic loading rate (OLR) was 0.037 kg BOD/m3/d. Results showed that the performance of the HFCTW was linearly affected by decreasing the HLR and increasing the HRT. The highest treatment efficiency was achieved at HRT (4.7 days) and HLR (0.07 m3/m2. d). The percentage reductions of chemical oxygen demand (COD), biochemical oxygen demand (BOD), and total suspended solids (TSS) were 86%, 87%, and 80%, respectively. Satisfactory nutrient removal was obtained. Also, removal of 2–3 logs of bacterial indicators of pollution was achieved. The dry biomass of Cyperus was 7.7 kg/m2 and proved to be very efficient in nitrification processes due to high diversity of the roots that increase the treatment surface area. 相似文献
8.
The C:N ratio of the pharmaceutical wastewaters is usually suitable for a combination of the anaerobic pretreatment with the high COD removal and aerobic posttreatment with the efficient biological N removal. This kind of anaerobic-aerobic process was tested in semipilot scale by using a UASB reactor and an activated sludge system with a predenitrification (total volume 100 1). It was found that at a total HRT of 2.3 days an average of 97.5% of COD and 73.5% of total N was removed. The UASB reactor was operated at 30°C with a volumetric loading rate of 8.7 kg.m-3.d-1, the efficiency of COD removal was 92.2%. The processes, which take part in the biological removal of nitrogen, especially the nitrification, were running with lower rates than usually observed in aerobic treatment systems.Abbreviations AAO
anaerobic anoxic oxic configuration
- AOO
anaerobic oxic oxic configuration
- B
V
volumetric organic loading rate (kg COD.m-3. d-1)
- dB
x
specific COD removal rate (mg COD. g-1 VSS. d-1)
- DNR
denitrification rate (mg N–NO3. g-1 VSS. h-1)
- ECOD
efficiency of COD removal (%)
- HRT
hydraulic retention time (d)
- NR
nitrification rate (mg N–NO3. g-1 VSS. h-1)
- R
recirculation ratio (%)
- SBP
specific biogas production (m3.kg-1 removed COD)
- SRT
solids retention time; sludge age (d)
- SS
suspended solids (g.1-1)
- UASB
upflow anaerobic sludge blanket reactor
- VSS
volatile suspended solids (g.1-1) 相似文献
9.
Hiroyuki Okamoto Kimito Kawamura Takashi Nishiyama Takao Fujii Kenji Furukawa 《Biodegradation》2013,24(1):99-110
A plug-flow type anaerobic ammonium oxidation (anammox) reactor was developed using malt ceramics (MC) produced from carbonized spent grains as the biomass carriers for anammox sludge. Partial nitrified effluent of the filtrate from the sludge dehydrator of a brewery company was used as influent to a 20 L anammox reactor using MC. An average volumetric nitrogen removal rate (VNR) of 8.78 kg-N/m3/day was maintained stably for 76 days with 1 h of HRT. In a larger anammox reactor (400 L), an average VNR of 4.84 kg-N/m3/day could be maintained for 86 days during the treatment of low strength synthetic inorganic wastewater. As a result of bacterial community analysis for the 20 L anammox reactor, Asahi BRW1, probably originating from the wastewater collected at Asahi Breweries, was detected as the dominant anammox bacterium. These anammox reactors were characterized by a high NH4-N removal capacity for low strength wastewater with a short hydraulic retention time. 相似文献
10.
Jun Zhou Hongyu Wang Kai Yang Bin Ji Dan Chen Huining Zhang Yuchong Sun Jun Tian 《Bioprocess and biosystems engineering》2016,39(2):277-284
A continuous-upflow biofilter packed with sponge iron was constructed for nitrate removal under an anaerobic atmosphere. Microbacterium sp. W5, a nitrate reducing and Fe(II) oxidizing strain, was added to the biofilter as an inoculum. The best results were achieved when NO3 ?-N concentration was 30 mg/L and Fe2+ was 800 mg/L. Nitrite in influent would inhibit nitrate removal and aqueous Fe2+ resulted in encrustation. Fe(II)EDTA would prevent cells from encrustation and the maximum nitrogen removal efficiency was about 90 % with Fe(II)EDTA level of 1100 mg/L. Nitrate reduction followed first-order reaction kinetics. Characteristics of biofilms were analyzed by X-ray fluorescence spectroscopy. 相似文献
11.
Mohammad Ali Li-Yuan Chai Hai-Ying Wang Chong-Jian Tang Xiao-Bo Min Xu Yan Cong Peng Yu-Xia Song Ping Zheng 《Biodegradation》2016,27(2-3):131-144
The short-cut nitrification (SCN) performance of an airlift reactor (ALR) was investigated under increasing bicarbonate condition. The sequential increase of bicarbonate from 2.5 to 7.0 g/L accelerated the nitrite accumulation and improved the NAP to 99 %. With the increase of bicarbonate dose to 11 g/L, the ammonium removal efficiency and the ammonium removal rate (ARR) were improved to 95.1 % and 0.57 kg/m3/day, respectively. However, the elevation of bicarbonate concentration from 11.0 to 14.0 g/L gradually depreciated the nitrite accumulation percentage to 62.5 %. Then, the reactor was operated in increasing ammonium strategy to increase the nitrogen loading rate (NLR) to 1.1 kg/m3/day under 700 mg/L influent ammonium concentration. The ARR and nitrite production rate were elevated to 1.1 and 0.9 kg/m3/day, respectively. The SCN performance was improved to 1.8 kg/m3/day (NLR) by the subsequent progressive shortening of HRT to 4.8 h at ammonium concentration of 350 mg/L, which was 1.6 times higher than that of the increasing ammonium strategy. Chemical analysis with EDS, FTIR and XRD confirmed the presence of CaCO3 precipitates on biomass surface during the long-term operation under high bicarbonate conditions. The attachment of precipitates to the SCN sludge helped to improve the biomass settleability and finally enhanced the SCN performance of the ALR. 相似文献
12.
Comparison of startup and anaerobic wastewater treatment in UASB, hybrid and baffled reactor 总被引:2,自引:0,他引:2
M. Hutňan M. Drtil L. Mrafková J. Derco J. Buday 《Bioprocess and biosystems engineering》1999,21(5):439-445
An experimental study was carried out to compare the performance of selected anaerobic high rate reactors operated simultaneously at 37?°C. The three reactors, namely upflow anaerobic sludge bed reactor (UASB), hybrid of UASB reactor and anaerobic filter (anaerobic hybrid reactor – AHR) and anaerobic baffled reactor (ABR), were inoculated with the anaerobic digested sludge from municipal wastewater treatment plant and tested with synthetic wastewater. This wastewater contained sodium acetate and glucose with balanced nutrients and trace elements (COD 6000?mg?·?l?1). Organic loading rate (B v ) was increased gradually from an initial 0.5?kg?·?m?3?·?d?1 to 15?kg?·?m?3?·?d?1 in all the reactors. From the comparison of the reactors' performance, the lowest biomass wash-out resulted from ABR. In the UASB, significant biomass wash-out was observed at the B v 6?kg?·?m?3?·?d?1, and in the AHR at the B v 12?kg?·?m?3?·?d?1. The demand of sodium bicarbonate for pH maintenance in ABR was two times higher as for UASB and AHR. The efficiency of COD removal was comparable for all three reactors – 80–90%. A faster biomass granulation was observed in the ABR than in the other two reactors. This fact is explained by the kinetic selection of filamentous bacteria of the Methanotrix sp. under a high (over 1.5?g?·?l?1) acetate concentration. 相似文献
13.
Seong Jin Lim Yeong Hee Ahn Eun Young Kim Ho Nam Chang 《Biotechnology and Bioprocess Engineering》2006,11(6):538-543
A packed bed reactor (PBR) was fed with nitrate containing synthetic wastewater or effluent from a sequencing batch reactor
used for nitrification. The C source introduced into the PBR consisted of volatile fatty acids (VFAs) produced from anaerobic
acidogenesis of food wastes. When nitrate loading rates ranged from 0.50 to 1.01 kg N/m3·d, the PBR exhibited 100∼98.8% NO3
−-N removal efficiencies and nitrite concentrations in the effluent ranged from 0 to 0.6 NO2
−-N mg/L. When the PBR was further investigated to determine nitrate removal activity along the bed height using a nitrate
loading rate less than 1.01 kg N/m3·d, 100% nitrate removal efficiency was observed. Approximately 83.2% nitrate removal efficiency was observed in the lower
50% of the packed-bed height. When reactor performance at a C/N ratio of 4 and a C/N ratio of 5 was compared, the PBR showed
better removal efficiency (96.5%) of nitrate and less nitrite concentration in the effluent at the C/N ratio of 5. VFAs were
found to be a good alternative to methanol as a carbon source for denitrification of a municipal wastewater containing 40
mg-N/L. 相似文献
14.
In this study, a three-stage-integrated process using the hydrogenic process (BioH2), methanogenic process (BioCH4), and a microbial fuel cell (MFC) was operated using molasses wastewater. The contribution of individual processes to chemical oxygen demand (COD) removal and energy production was evaluated. The three-stage integration system was operated at molasses of 20 g-COD L?1, and each process achieved hydrogen production rate of 1.1 ± 0.24 L-H2 L?1 day?1, methane production rate of 311 ± 18.94 mL-CH4 L?1 day?1, and production rate per electrode surface area of 10.8 ± 1.4 g m?2 day?1. The three-stage integration system generated energy production of 32.32 kJ g-COD?1 and achieved COD removal of 98 %. The contribution of BioH2, BioCH4, and the MFC reactor was 20.8, 72.2, and, 7.0 % of the total COD removal, and 18.7, 81.2, and 0.16 % of the total energy production, respectively. The continuous stirred-tank reactor BioH2 at HRT of 1 day, up-flow anaerobic sludge blanket BioCH4 at HRT of 2 days, and MFC reactor at HRT of 3 days were decided in 1:2:3 ratios of working volume under hydraulic retention time consideration. This integration system can be applied to various configurations depending on target wastewater inputs, and it is expected to enhance energy recovery and reduce environmental impact of the final effluent. 相似文献
15.
Comparison of the Bacterial Communities in Anaerobic, Anoxic, and Oxic Chambers of a Pilot A2O Process Using Pyrosequencing Analysis 总被引:1,自引:0,他引:1
Byung-Chun Kim Seil Kim Taesub Shin Hyunook Kim Byoung-In Sang 《Current microbiology》2013,66(6):555-565
A2O process is a sequential wastewater treatment process that uses anaerobic, anoxic, and oxic chambers for nitrogen and phosphorus removal. In this study, the bacterial communities among these chambers were compared, and the diversity of the bacteria involved in nitrogen and phosphorus removal was surveyed. A pilot-scale A2O process (50 m3 day?1) was operated for more than 6 months, and bacterial 16S rRNA gene diversity was analyzed using pyrosequencing. A total of 7,447 bacterial sequence reads were obtained from anaerobic (1,546), anoxic (2,158), and oxic (3,743) chambers. Even though there were differences in the atmospheric condition and functionality, no prominent differences could be found in the bacterial community of the three chambers of the pilot A2O process. All sequence reads, which were taxonomically analyzed using the Eztaxon-e database, were assigned into 638 approved or tentative genera. Among them, about 72.2 % of the taxa were contained in the phyla Proteobacteria and Bacteroidetes. Phosphate-accumulating bacteria, Candidatus Accumulibacter phosphatis, and two other Accumulibacter were found to constitute 3.1 % of the identified genera. Ammonia-oxidizing bacteria, Nitrosomonas oligotropha, and four other phylotypes in the same family, Nitrosomonadaceae, constituted 0.2 and 0.9 %, respectively. Nitrite-oxidizing bacteria, Nitrospira defluvii, and other three phylotypes in the same family, Nitrospiraceae, constituted 2.5 and 0.1 %, respectively. In addition, Dokdonella and a phylotype of the phylum Chloroflexi, function in nitrogen and/or phosphate removal of which have not been reported in the A2O process, constituted the first and third composition among genera at 4.3 and 3.8 %, respectively. 相似文献
16.
Alejandro Zepeda Chérif Ben-Youssef Susana Rincón Flor Cuervo-López Jorge Gómez 《Biodegradation》2013,24(3):377-385
The kinetic behavior, oxidizing ability and tolerance to m-cresol of a nitrifying sludge exposed to different initial concentrations of m-cresol (0–150 mg C L?1) were evaluated in a sequencing batch reactor fed with 50 mg NH4 +-N L?1 and operated during 4 months. Complete removal of ammonium and m-cresol was achieved independently of the initial concentration of aromatic compound in all the assays. Up to 25 mg m-cresol-C L?1 (C/N ratio of 0.5), the nitrifying yield (Y-NO3 ?) was 0.86 ± 0.05, indicating that the nitrate was the main product of the process; no biomass growth was detected. From 50 to 150 mg m-cresol-C L?1 (1.0 ≤ C/N ≤ 3.0), simultaneous microbial growth and partial ammonium-to-nitrate conversion were obtained, reaching a maximum microbial total protein concentration of 0.763 g L?1 (247 % of its initial value) and the lowest Y-NO3 ? 0.53 ± 0.01 at 150 mg m-cresol-C L?1. m-Cresol induced a significant decrease in the values of both specific rates of ammonium and nitrite oxidation, being the ammonium oxidation pathway the mainly inhibited. The nitrifying sludge was able to completely oxidize up to 150 mg m-cresol-C L?1 by SBR cycle, reaching a maximum specific removal rate of 6.45 g m-cresol g?1 microbial protein-N h?1. The number of SBR cycles allowed a metabolic adaptation of the nitrifying consortium since nitrification inhibition decreased and faster oxidation of m-cresol took place throughout the cycles. 相似文献
17.
M. F. Basri S. Yacob M. A. Hassan Y. Shirai M. Wakisaka M. R. Zakaria L. Y. Phang 《World journal of microbiology & biotechnology》2010,26(3):505-514
This is a scale-down study of a 500-m3 methane recovery test plant for anaerobic treatment of palm oil mill effluent (POME) where biomass washout has become one of the problems because of the continuous mixing of effluent during anaerobic treatment of POME. Therefore, in this study, anaerobic POME treatment using a scaled down 50-l bioreactor which mimicked the 500-m3 bioreactor was carried out to improve biogas production with and without biomass sedimentation. Three sets of experiments were conducted under different conditions in terms of biomass sedimentation applied to the system. The first experiment was operated under semi-continuous mode whereas the second and third experiments were operated based on mix and settle mode. As expected, biomass retention improved the anaerobic process as the POME treatment incorporated with mix and settle system were able to operate at an organic loading rate (OLR) of 3.5 and 6.0 kg COD/m3/day respectively, while the semi-continuous operated anaerobic treatment only achieved OLR of 3.0 kg COD/m3/day. The highest biogas and methane production rates achieved were 2.42 m3/m3 of reactor/day and 0.992 m3/m3 of reactor/day, respectively at OLR 6.0 kg COD/m3/day. The biomass or solids retention in the reactors was represented by the total solids measured in this study. 相似文献
18.
Takahisa Ogawa Ayako Kimura Harumi Sakuyama Takahiro Ishikawa Shigeru Shigeoka 《Bioscience, biotechnology, and biochemistry》2013,77(12):1957-1964
Euglena gracilis has the ability to accumulate a storage polysaccharide, a β-1,3-glucan known as paramylon, under aerobic conditions. Under anaerobic conditions, E. gracilis cells degrade paramylon and synthesize wax esters. Cytosolic fructose-1,6-bisphosphatase (FBPase) appears to be a key enzyme in gluconeogenesis and position branch point of carbon partitioning between paramylon and wax ester biosynthesis. We herein identified and characterized cytosolic FBPase from E. gracilis. The Km and Vmax values of EgFBPaseIII were 16.5 ± 1.6 μM and 30.4 ± 7.2 μmol min?1 mg protein?1, respectively. The activity of EgFBPaseIII was not regulated by AMP or reversible redox modulation. No significant differences were observed in the production of paramylon in transiently suppressed EgFBPaseIII gene expression cells by RNAi (KD-EgFBPaseIII); nevertheless, FBPase activity was markedly decreased in KD-EgFBPaseIII cells. On the other hand, the growth of KD-EgFBPaseIII cells was slightly higher than that of control cells. 相似文献
19.
Donna L. Sutherland Clive Howard-Williams Matthew H. Turnbull Paul A. Broady Rupert J. Craggs 《Journal of applied phycology》2014,26(3):1317-1329
There has been renewed interest in the combined use of high-rate algal ponds (HRAP) for wastewater treatment and biofuel production. Successful wastewater treatment requires year-round efficient nutrient removal while high microalgal biomass yields are required to make biofuel production cost-effective. This paper investigates the year-round performance of microalgae in a 5-ha demonstration HRAP system treating primary settled wastewater in Christchurch, New Zealand. Microalgal performance was measured in terms of biomass production, nutrient removal efficiency, light absorption and photosynthetic potential on seasonal timescales. Retention time-corrected microalgal biomass (chlorophyll a) varied seasonally, being lowest in autumn and winter (287 and 364 mg m?3day?1, respectively) and highest in summer (703 mg m?3day?1), while the conversion efficiency of light to biomass was greatest in winter (0.39 mg Chl- a per μmol) and lowest in early summer (0.08 mg Chl- a per μmol). The percentage of ammonium (NH4–N) removed was highest in spring (79 %) and summer (77 %) and lowest in autumn (47 %) and winter (53 %), while the efficiency of NH4–N removal per unit biomass was highest in autumn and summer and lowest in winter and spring. Chlorophyll-specific light absorption per unit biomass decreased as total chlorophyll increased, partially due to the package effect, particularly in summer. The proportional increase in the maximum electron transport rate from winter to summer was significantly lower than the proportional increase in the mean light intensity of the water column. We concluded that microalgal growth and nutrient assimilation was constrained in spring and summer and carbon limitation may be the likely cause. 相似文献
20.
Jin-Young Jung Sang-Min Lee Pyong-Kyun Shin Yun-Chul Chung 《Biotechnology and Bioprocess Engineering》2000,5(6):456-459
A pilot scale experiment was performed for a year to develop a two-phase anaerobic process for piggery wastewater treatment
(COD: 6,000 mg/L, BOD: 4,000 mg/L, SS: 500 gm/L, pH 8.4, alkalinity 6,000 mg/L). The acidogenic reactor had a total volume
of 3 m3, and the methanogenic reactor, an, anaerobic up-flow sludge filter, combining a filter and a sludge bed, was also of total
volume 3 m3 (1.5 m3 of upper packing material). Temperatures of the acidogenic and methanogenic reactors kept at 20°C and 35°C., respectively.
When the pH of the acidogenic reactor was controlled at 6.0–7.0 with HCl, the COD removal efficiency increased from 50 to
80% over a period of six months, and as a result, the COD of the final effluent fell in the range of 1,000–1,500 mg/L. BOD
removal efficiency over the same period was above 90%, and 300 to 400 mg/L was maintained in the final effluent. The average
SS in the final effluent was 270 mg/L. The methane production was 0.32 m3 CH4/kg CODremoved and methane content of the methanogenic reactor was high value at 80–90%., When the pH of the acidogenic reactor was not
controlled over the final two months, the pH reached 8.2 and acid conversion decreased compared with that of pH controlled,
while COD removal was similar to the pH controlled operation. Without pH control, the methane content in the gas from methanogenic
reactor improved to 90%, compared to 80% with pH control. 相似文献