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1.
Luciano Farias de Novaes Bruna Luckmann Saratt José Alberto Domingues Rodrigues Suzana Maria Ratusznei Deovaldo de Moraes Rogers Ribeiro Marcelo Zaiat Eugenio Foresti 《Journal of environmental management》2010,91(8):1647-1656
The objective of this work was to assess the effect of agitation rate and impeller type in two mechanically stirred sequencing batch reactors: one containing granulated biomass (denominated ASBR) and the other immobilized biomass on polyurethane foam (denominated AnSBBR). Each configuration, with total volume of 1 m3, treated 0.65 m3 sanitary wastewater at ambient temperature in 8-h cycles. Three impeller types were assessed for each reactor configuration: flat-blade turbine impeller, 45°-inclined-blade turbine impeller and helix impeller, as well as two agitation rates: 40 and 80 rpm, resulting in a combination of six experimental conditions. In addition, the ASBR was also operated at 20 rpm with a flat-blade turbine impeller and the AnSBBR was operated with a draft tube and helix impeller at 80 and 120 rpm. To quantify how impeller type and agitation rate relate to substrate consumption rate, results obtained during monitoring at the end of the cycle, as well as the time profiles during a cycle were analyzed. Increasing agitation rate from 40 rpm to 80 rpm in the AnSBBR improved substrate consumption rate whereas in the ASBR this increase destabilized the system, likely due to granule rupture caused by the higher agitation. The AnSBBR showed highest solids and substrate removal, highest kinetic constant and highest alkalinity production when using a helix impeller, 80 rpm, and no draft tube. The best condition for the ASBR was achieved with a flat-blade turbine impeller at 20 rpm. The presence of the draft tube in the AnSBBR did not show significant improvement in reactor efficiency. Furthermore, power consumption studies in these pilot scale reactors showed that power transfer required to improve mass transfer might be technically and economically feasible. 相似文献
2.
P. Gayán C.R. Forero L.F. de Diego A. Abad F. García-Labiano J. Adánez 《International Journal of Greenhouse Gas Control》2010,4(1):13-22
Chemical-Looping Combustion (CLC) is an emerging technology for CO2 capture because separation of this gas from the other flue gas components is inherent to the process and thus no energy is expended for the separation. Natural or refinery gas can be used as gaseous fuels and they may contain different amounts of light hydrocarbons. This paper presents the combustion results obtained with a Cu-based oxygen carrier using mixtures of CH4 and light hydrocarbons (LHC) (C2H6 and C3H8) as fuel. The effect on combustion efficiency of the fuel reactor temperature, solid circulation flow rate and gas composition was studied in a continuous CLC plant (500 Wth). Full combustions were reached at 1073 and 1153 K working at oxygen to fuel ratios, ? higher than 1.5 and 1.2 respectively. Unburnt hydrocarbons were never detected at any experimental conditions at the fuel reactor outlet. Carbon formation can be avoided working at 1153 K or at ? values higher than 1.5 at 1073 K. After 30 h of continuous operation, the oxygen carrier exhibited an adequate behavior regarding attrition and agglomeration. It can be concluded that no special measures should be taken in a CLC process with Cu-based OC with respect to the presence of LHC in the fuel gas. 相似文献
3.
Jutamas Kaewsuk Worachat Thorasampan Monthon Thanuttamavong Gyu Tae Seo 《Journal of environmental management》2010,91(5):1161-1168
This experimental study was conducted to evaluate a membrane sequencing batch reactor (MSBR) with mixed culture photosynthetic bacteria for dairy wastewater treatment. The study was undertaken in two steps: laboratory and pilot scale experiments. In the first step, kinetics analysis of the MSBR was carried out in a laboratory scale experiment with influent COD concentration of 2500 mg/L. The pilot scale experiment was conducted to investigate the performance of the MSBR and checked the suitability of the kinetics for an engineering design. The kinetic coefficients Ks, k, kd, Y and μm were found to be 174-mg-COD/L, 7.42/d, 0.1383/d, 0.2281/d and 1.69/d, respectively. There were some deviations of COD removal efficiency between the design value and the actual value. From the kinetics estimation, COD effluent from the design was 27 mg/L while the average actual COD effluent from the experiment was 149 mg/L. Due to the different light source condition, the factors relating to light energy (i.e. Lf and IR%) must be incorporated into engineering design and performance prediction with these kinetic coefficients of the photosynthetic MSBR. 相似文献
4.
The performance of polyurethane rotating discs (RBC-1) versus polystyrene rotating discs (RBC-2) for the treatment of an up-flow anaerobic sludge blanket (UASB) reactor effluent fed with domestic wastewater was investigated. Both RBC units were operated at the same organic loading rate (OLR) of 10.5 gCOD/m2 d. and a hydraulic retention time (HRT) of 2.5 h. The residual values of COD fractions (CODsuspended, CODcolloidal and CODsoluble) in the treated effluent of RBC-1 and RBC-2 were similar. However, the removal efficiency of ammonia in the RBC-1 (87 ± 4%) was significantly higher than that found for RBC-2 i.e. 24 ± 6%. Moreover, RBC-1 achieved a substantial removal efficiency of 99.0 ± 1% for Escherichia coli (E. coli), while RBC-2 removed 91.2 ± 0.3%. Based on these results, optimization of RBC-1 treating UASB reactor effluent was extensively performed. The RBC-1 was operated at an OLR's of 4.0, 11 and 23 gCOD/m2 d. The results obtained showed that increasing the OLR from 11.0 to 23.0 gCOD/m2 d and decreasing the HRT from 2.5 to 1.25 h significantly declined the effluent quality of CODtotal and ammonia. However, the residual values of CODtotal and ammonia remained unaffected when increasing the OLR from 4.0 to 11.0 gCOD/m2 d and by decreasing the HRT from 5 to 2.5 h. Bacteriological examination showed that the mean residual count of E. coli remained at a level of 104/100 ml, in the effluent of RBC-1 independent on the imposed HRT. Accordingly, it is recommended to operate RBC-1 for treatment of anaerobically pre-treated sewage at an OLR of 11 gCOD/m2 d and an HRT of 2.5 h.A feed-less (ammonia limitation) period of 9.0 days followed by 9.0 days feeding with high OLR of 26 gCOD/m2 d. (raw sewage) was investigated to elaborate, if the nitrifiers of the RBC-1 are capable to convert ammonia to nitrate after totally 18 days when retuning back to the normal operating conditions. The results of the experiment clearly show a strong and immediate detrimental effect of imposing high OLR of 26 gCOD/m2 d on the nitrification process in the nitrifying RBC unit. However, after returning back to the original OLR of 10.6 gCOD/m2 d, the nitrification efficiency in the RBC unit was recovered within 2–3 days. 相似文献
5.
Daniela Sotirchos de Oliveira Ana Claudia Prinholato Suzana Maria Ratusznei Jos Alberto Domingues Rodrigues Marcelo Zaiat Eugênio Foresti 《Journal of environmental management》2009,90(10):3070-3081
The objective of this work was to study the technological feasibility of treating wastewater from a personal care industry (PCI-WW) in a mechanically stirred anaerobic sequencing batch biofilm reactor (AnSBBR) containing immobilized biomass on polyurethane foam. An assessment was made on how system efficiency and stability would be affected by: increasing organic load; supplementation of nutrients and alkalinity; and different feed strategies. The AnSBBR operated with 8-h cycles, stirring speed of 400 rpm, temperature of 30 °C, and treated with 2.0 L wastewater per cycle. First the efficiency and stability of the AnSBBR were studied when submitted to an organic loading rate (OLR) of 3.1–9.4 gCOD/(L d), and when the PCI-WW was supplemented with nutrients (sucrose, urea, trace metals) and alkalinity. The AnSBBR was shown to be robust and presented stability and removal efficiency exceeding 90%. At an OLR of 12.0 gCOD/(L d) efficiency became difficult to maintain due to the presence of commercial cleansers and disinfectants in the wastewater lots. In a subsequent stage the AnSBBR treated the wastewater supplemented with alkalinity, but with no nutrients at varying feed strategies and maintaining an OLR of approximately 9.0 gCOD/(L d). The first strategy consists of feeding 2.0 L of the influent batchwise [OLR of 9.4 gCOD/(L d)]. In the second 1.0 L of influent was fed-batchwise and an additional 1.0 L was fed fed-batchwise [OLR of 9.2 gCOD/(L d)], i.e., in relation to the first strategy the feed volume was maintained but supplied in different periods. In the third strategy 1.0 L of treated effluent was maintained in the reactor and 1.0 L of influent was fed fed-batchwise [OLR of 9.0 gCOD/(L d)], i.e., in relation to the first strategy the feed volume was different but the feed period was the same and the OLR was maintained by increasing the influent concentration. Comparison of the first and second strategies revealed that organic matter removal efficiency was unaffected (exceeding 90%). The third strategy resulted in a reduction in average removal efficiency from 91 to 83% when compared to the first one. A kinetic study resulted in first order kinetic parameters ranges from 0.42 to 1.46 h−1 at OLRs from 3.1 to 12.0 gCOD/(L d), respectively, and the second feed strategy [OLR of 9.2 gCOD/(L d)] was shown to be the most favorable. 相似文献
6.
Natália C. Archilha Catarina S.A. Canto Suzana M. Ratusznei José A.D. Rodrigues Marcelo Zaiat Eugenio Foresti 《Journal of environmental management》2010,91(8):1756-1765
The objective of this work was to analyze the effect of the interaction between feeding strategy and COD/sulfate ratio on the removal efficiency of sulfate and organic matter from a synthetic wastewater. An anaerobic sequencing batch reactor with recirculation of the liquid phase and containing immobilized biomass on polyurethane foam (AnSBBR) was used. The AnSBBR with a total volume of 3.7 L, treated 2.0 L synthetic wastewater in 8-h cycles at 30 ± 1 °C and was inoculated with anaerobic biomass from a UASB. Two feeding strategies were assessed: (a) batch and (b) batch followed by fed-batch. In strategy (a) the reactor was fed in 10 min with 2 L wastewater containing sulfate and carbon sources. In strategy (b) 1.2 L wastewater (containing only the sulfate source) was fed during the first 10 min of the cycle and the remaining 0.8 L (containing only the carbon source) in 240 min. The COD/sulfate ratios assessed were 1 and 3. Based on these values and on the concentrations of organic matter (0.5–11.25 gCOD/L) and sulfate (0.5 and 2.5 gSO42?/L), the sulfate and organic matter loading rates applied equaled 1.5 and 4.5 gSO42?/L d for sulfate and 1.5, 4.5 and 13.5 gCOD/L d for organic matter. After stabilization of the system time profiles were run of monitored parameters (COD, sulfate, sulfide and sulfite). In general, the reactor showed to be robust for use in the anaerobic treatment of wastewaters containing sulfate. Gradual feeding (strategy b) of the carbon source favored sulfate reduction, resulting in sulfate removal efficiencies of 84–98% and organic matter removal efficiencies of 48–95%. The best results were observed under COD/sulfate ratio equal to 1 (loading rates of 1.5 and 4.5 gSO42?/L d for sulfate, and 1.5 and 4.5 gCOD/L d for organic matter). When COD/sulfate ratio was 3 (loading rates of 1.5 and 4.5 gSO42?/L d for sulfate, and 4.5 and 13.5 gCOD/L d for organic matter) the effect of feed mode became less significant. These results show that the strategy batch followed by fed-batch is more advantageous for COD/sulfate ratios near the stoichiometric value (0.67) and higher organic matter and sulfate concentrations. 相似文献
7.
M. Tayyeb Javed W. Nimmo Asif Mahmood Naseem Irfan 《Journal of environmental management》2009,90(11):3429-3435
An experimental investigation was performed to study the effect of oxygenated liquid additives, H2O2, C2H5OH, C2H4(OH)2 and C3H5(OH)3 on NOx removal from flue gases by the selective non-catalytic reduction (SNCR) process using urea as a reducing agent. Experiments were performed with a 150 kW pilot scale reactor in which a simulated flue gas was generated by the combustion of methane operating with 6% excess oxygen in flue gases. The desired levels of initial NOx (500 ppm) were achieved by doping the fuel gas with ammonia. Experiments were performed throughout the temperature range of interest, i.e. from 800 to 1200 °C for the investigation of the effects of the process additives on the performance of aqueous urea DeNOx. With H2O2 addition a downward shift of 150 °C in the peak reduction temperature from 1130 to 980 °C was observed during the experimentation, however, the peak reduction efficiency was reduced from 81 to 63% when no additive was used. The gradual addition of C2H5OH up to a molar ratio of 2.0 further impairs the peak NOx reduction efficiency by reducing it to 50% but this is accompanied by a downward shift of 180 °C in the peak reduction temperature. Further exploration using C2H4(OH)2 suggested that a 50% reduction could be attained for all the temperatures higher than 940 °C. The use of C3H5(OH)3 as a secondary additive has a significant effect on the peak reduction efficiency that decreased to 40% the reductions were achievable at a much lower temperature of 800 °C showing a downward shift of 330 °C. 相似文献
8.
A new contact oxidation filtration separation integrated bioreactor (CFBR) was used to treat municipal wastewater. The CFBR was made up of a biofilm reactor (the upper part of the CFBR) and a gravitational filtration bed (the lower part of the CFBR). Polyacrylonitrile balls (50 mm diameter, 237 m2/m3 specific surface, 90% porosity, and 50.2% packing rate) were filled into the biofilm reactor as biofilm attaching materials and anthracite coal (particle size 1–2 mm, packing density 0.947 g/cm3, non-uniform coefficient (K80 = d80/d10) < 2.0) was placed into the gravitational filtration bed as filter media. At an organic volumetric loading rate of 2.4 kg COD/(m3 d) and an initial filtration velocity of 5 m/h in the CFBR, the average removal efficiencies of COD, ammonia nitrogen, total nitrogen and turbidity were 90.6%, 81.4%, 64.6% and 96.7% respectively, but the treatment process seemed not to be effective in phosphorus removal. The average removal efficiency of total phosphorus was 60.1%. Additionally, the power consumption of the CFBR was less than 0.15 kWh/m3 of wastewater treated, and less than 1.5 kWh/kg BOD5 removal. 相似文献
9.
Carl Linderholm Alberto Abad Tobias Mattisson Anders Lyngfelt 《International Journal of Greenhouse Gas Control》2008,2(4):520
Chemical-looping combustion, CLC, is a technology with inherent separation of the greenhouse gas CO2. The technique uses an oxygen carrier made up of particulate metal oxide to transfer oxygen from combustion air to fuel. In this work, an oxygen carrier consisting of 60% NiO and 40% NiAl2O4 was used in a 10 kW CLC reactor system for 160 h of operation with fuel. The first 3 h of fuel operation excepted, the test series was accomplished with the same batch of oxygen carrier particles. The fuel used in the experiments was natural gas, and a fuel conversion to CO2 of approximately 99% was accomplished. Combustion conditions were very stable during the test period, except for the operation at sub-stoichiometric conditions. It was shown that the methane fraction in the fuel reactor exit gas was dependent upon the rate of solids circulation, with higher circulation leading to more unconverted methane. The carbon monoxide fraction was found to follow the thermodynamical equilibrium for all investigated fuel reactor temperatures, 660–950 °C. Thermal analysis of the fuel reactor at stable conditions enabled calculation of the particle circulation which was found to be approximately 4 kg/s, MW. The loss of fines, i.e. the amount of elutriated oxygen carrier particles with diameter <45 μm, decreased during the entire test period. After 160 h of operation the fractional loss of fines was 0.00022 h−1, corresponding to a particle life time of 4500 h. 相似文献
10.
Andrew C. Mitchell Adrienne J. Phillips Randy Hiebert Robin Gerlach Lee H. Spangler Alfred B. Cunningham 《International Journal of Greenhouse Gas Control》2009,3(1):90-99
In order to develop subsurface CO2 storage as a viable engineered mechanism to reduce the emission of CO2 into the atmosphere, any potential leakage of injected supercritical CO2 (SC-CO2) from the deep subsurface to the atmosphere must be reduced. Here, we investigate the utility of biofilms, which are microorganism assemblages firmly attached to a surface, as a means of reducing the permeability of deep subsurface porous geological matrices under high pressure and in the presence of SC-CO2, using a unique high pressure (8.9 MPa), moderate temperature (32 °C) flow reactor containing 40 millidarcy Berea sandstone cores. The flow reactor containing the sandstone core was inoculated with the biofilm forming organism Shewanella fridgidimarina. Electron microscopy of the rock core revealed substantial biofilm growth and accumulation under high-pressure conditions in the rock pore space which caused >95% reduction in core permeability. Permeability increased only slightly in response to SC-CO2 challenges of up to 71 h and starvation for up to 363 h in length. Viable population assays of microorganisms in the effluent indicated survival of the cells following SC-CO2 challenges and starvation, although S. fridgidimarina was succeeded by Bacillus mojavensis and Citrobacter sp. which were native in the core. These observations suggest that engineered biofilm barriers may be used to enhance the geologic sequestration of atmospheric CO2. 相似文献
11.
C.R. Forero P. Gayán F. García-Labiano L.F. de Diego A. Abad J. Adánez 《International Journal of Greenhouse Gas Control》2010,4(5):762-770
Chemical-Looping Combustion (CLC) is an emerging technology for CO2 capture because separation of this gas from the other flue gas components is inherent to the process and thus no energy is expended for the separation. Natural or refinery gas can be used as gaseous fuels and they may contain different amounts of sulphur compounds, such as H2S and COS. This paper presents the combustion results obtained with a Cu-based oxygen carrier using mixtures of CH4 and H2S as fuel. The influence of H2S concentration on the gas product distribution and combustion efficiency, sulphur splitting between the fuel reactor (FR) and the air reactor (AR), oxygen carrier deactivation and material agglomeration was investigated in a continuous CLC plant (500 Wth). The oxygen carrier to fuel ratio, ?, was the main operating parameter affecting the CLC system. Complete fuel combustion were reached at 1073 K working at ? values ≥1.5. The presence of H2S did not produce a decrease in the combustion efficiency even when working with a fuel containing 1300 vppm H2S. At these conditions, the great majority of the sulphur fed into the system was released in the gas outlet of the FR as SO2, affecting to the quality of the CO2 produced. Formation of copper sulphide, Cu2S, and the subsequent reactivity loss was only detected working at low values of ? ≤ 1.5, although this fact did not produce any agglomeration problem in the fluidized beds. In addition, the oxygen carrier was fully regenerated in a H2S-free environment. It can be concluded that Cu-based oxygen carriers are adequate materials to be used in a CLC process using fuels containing H2S although quality of the CO2 produced is affected. 相似文献
12.
Nicolas Berguerand Anders Lyngfelt 《International Journal of Greenhouse Gas Control》2008,2(2):169-179
Tests were made in a 10 kWth chemical-looping combustor with a petroleum coke as the solid fuel and the oxygen carrier ilmenite, an iron titanium oxide. The fuel reactor is fluidized by steam and the oxygen carrier reacts with the volatiles released as well as the gasification intermediates CO and H2. A constant fuel flow corresponding to a thermal power of 5.8 kW was introduced into the fuel reactor and a total of 11 h of operation was reached. The effects of particle circulation and carbon stripper operation on solid fuel conversion, conversion of gas from the fuel reactor and CO2 capture were investigated. The actual CO2 capture ranged between 60% and 75% while the solid fuel conversion was in the range of 66–78%. The low values of solid fuel conversion reflect loss of char due to low efficiency of the fuel reactor cyclone. The incomplete conversion of the gas from the fuel reactor is expressed as oxygen demand. The oxygen demand corresponds to the fraction of oxygen lacking to achieve full gas conversion and was typically 25%, due to presence of CH4, CO and H2 from the fuel reactor. Typical ratios of CH4, CO and H2 over the total gaseous carbon from the fuel reactor are respectively 5, 10 and 25%. Low loss of non-combustible fines from the system indicates very low attrition of the oxygen carrier. 相似文献
13.
T.T.H. Pham S.K. Brar R.D. Tyagi R.Y. Surampalli 《Journal of environmental management》2010,91(8):1657-1664
Fenton oxidation pretreatment was investigated for enhancement of biodegradability of wastewater sludge (WWS) which was subsequently used as substrate for the production of value- added products. The Response surface method with fractional factorial and central composite designs was applied to determine the effects of Fenton parameters on solubilization and biodegradability of sludge and the optimization of the Fenton process. Maximum solubilization and biodegradability were obtained as 70% and 74%, respectively at the optimal conditions: 0.01 ml H2O2/g SS, 150 [H2O2]0/[Fe2+]0, 25 g/L TS, at 25 °C and 60 min duration. Further, these optimal conditions were tested for the production of a value added product, Bacillus thuringiensis (Bt) which is being used as a biopesticide in the agriculture and forestry sector. It was observed that Bt growth using Fenton oxidized sludge as a substrate was improved with a maximum total cell count of 1.63 × 109 CFU ml?1 and 96% sporulation after 48 h of fermentation. The results were also tested against ultrasonication treatment and the total cell count was found to be 4.08 × 108 CFU ml?1 with a sporulation of 90%. Hence, classic Fenton oxidation was demonstrated to be a rather more promising chemical pre-treatment for Bt - based biopesticide production using WWS when compared to ultrasonication as a physical pre-treatment. 相似文献
14.
《International Journal of Greenhouse Gas Control》2007,1(1):19-30
This paper presents application of the chemical looping combustion (CLC) method in natural gas-fired combined cycles for power generation with CO2 capture. A CLC combined cycle consisting of single CLC-reactor system, an air turbine, a CO2-turbine and a steam cycle has been designated as the base-case cycle. The base-case cycle can achieve net plant efficiency of about 52% at an oxidation temperature of 1200 °C. In order to achieve a reasonable efficiency at lower oxidation temperatures, reheat is introduced into the air turbine by employing multi CLC-reactors. The results show that the single reheat CLC-combined cycle can achieve net plant efficiency of above 51% at oxidation temperature of 1000 °C and above 53% at the oxidation temperature of 1200 °C including CO2 compression to 110 bar. The double reheat cycle results in marginal efficiency improvement as compared to the single reheat cycle. The CLC-cycles are also compared with a conventional combined cycle with and without post-combustion capture in amine solution. All the CLC-cycles show higher net plant efficiencies with close to 100% CO2 capture as compared to a conventional combined cycle with post-combustion capture, which is very promising. 相似文献
15.
A.N.M. Peeters A.P.C. Faaij W.C. Turkenburg 《International Journal of Greenhouse Gas Control》2007,1(4):396-417
We performed a detailed analysis of the potential future costs and performance of post-combustion CO2 absorption in combination with a natural gas combined cycle (NGCC). After researching state-of-the-art technology, an Excel model was created to analyze possible developments in the performance of energy conversion, CO2 capture, and CO2 compression. The input variables for the three time frames we used were based on literature data, product information, expert opinions, and our own analysis. Using a natural gas price of 4.7 €/GJ, we calculated a potential decrease in the costs of electricity from 5.6 €ct/kWh in the short term to 4.8 €ct/kWh in the medium term and 4.5 €ct/kWh in the long term. The efficiency penalty is calculated to decline from 7.9%-points LHV in the short term to 4.9%-points and 3.7%-points in the medium and long terms, respectively. In combination with NGCC improvements, this may cause an improvement in the net efficiency, including CO2 capture, from 49% in the short term to 55% and 58% in the medium and long terms, respectively. The total capital costs including capital costs of the NGCC ware calculated to decline from 880 in the short term to 750 and 690 €/kW in the medium and long terms, respectively, with a decline in the incremental capital costs due to capture from 350 in the short term to 270 and 240 €/kW in the medium and long terms, respectively. Finally, the avoidance costs may decline from 45 €/tCO2 in the short term to 33 €/tCO2 in the medium term and 28 €/tCO2 in the long term. 相似文献
16.
Treatment of domestic wastewater using an anaerobic baffled reactor followed by a duckweed pond for agricultural purposes 总被引:2,自引:0,他引:2
The treatment and reuse of domestic wastewater using an anaerobic baffled reactor (ABR) followed by a duckweed pond (DWP)
were the main theme of the present study. The ABR was fed continuously with domestic wastewater at four HRTs ranging from
8 to 24 h and corresponds to organic loading rates ranging from 0.67 to 2.1 kg COD/m3/day. The ABR effluent was fed to a DWP operating at 10 and 15 days. The performance of the ABR at the four HRTs gave satisfactory
results. Chemical oxygen demand (COD) removal was between 68 and 82%. Fecal coliform removal was between 1 to 2 logs. The
12- and 18-h hydraulic retention times (HRTs) gave close results, as indication of the possible selection of the 12-h HRT
as the optimum operation for the ABR based on economic advantage. The ABR compartmentalized structure gave results higher
than those produced by the one-stage digester and similar to those produced by the two-phase anaerobic digestion process.
Duckweed ponds as post-treatment operated at 10 days and 15 days gave the best results at 15-day HRT, where it was possible
to remove 73.4% of nitrogen and 65% of phosphorus and produce protein-rich dry duckweed of 105 kg/ha/day on average. The removal
of fecal coliform (FC) in duckweed ponds was 3–4 logs. The final treated domestic sewage characteristics proved its compliance
with the Egyptian standards for reuse in restricted irrigation. 相似文献
17.
J. Sánchez-Martín J. Beltrán-Heredia C. Solera-Hernández 《Journal of environmental management》2010,91(10):2051-2058
A new tannin-based coagulant-flocculant (Tanfloc) was tested for water treatment at a pilot plant level. Four types of water sample were treated: surface water (collected from a river), and municipal, textile industry (simulated by a 100 mg L?1 aqueous solution of an acid dye), and laundry (simulated by a 50 mg L?1 aqueous solution of an anionic surfactant) wastewaters. The pilot plant process consisted of coagulation, sedimentation, and filtration. The experiments were carried out with an average coagulant dosage of 92.2 mg L?1 (except in the case of the surface water for which the dosage was 2 mg L?1). The efficacy of the water purification was notable in every case: total turbidity removal in the surface water and municipal wastewater, about 95% dye removal in the case of the textile industry wastewater, and about 80% surfactant removal in the laundry wastewater. Filtration improved the removal of suspended solids, both flocs and turbidity, and slightly improved the process as a whole. The efficiency of Tanfloc in these pilot studies was similar to or even better than that obtained in batch trials. 相似文献
18.
Landfill leachate contains high concentrations of organic matter, color, heavy metals and toxic substances. This study presents the feasibility of a commercial nanofiltration membrane (NF-300) in the removal of pollutants from a landfill leachate generated from the Treatment Stabilization and Disposal Facility in Gujarat state of India. Two different leachate samples (Leachates A and B) were collected from the downstream side of closed landfill cells A and B. The average quality of the leachate was 67 719 mg/L COD, 217 mg/L ammonical nitrogen, 22 418 mg/L BOD, 3847 mg/L chlorides and 909 mg/L sulphate. The operating variables studied were applied pressure (4–20 atm), feed flowrate (5–15 L/min) and pH (2, 4, 5.5 and 6.7). It was observed that the solute rejection (RO) increased with increase in feed pressure and decreased with increase in feed concentration at constant feed flowrate. In the present study, the rejection of cations followed the sequence: RO (Cr3+) > RO (Ni2+) > RO (Zn2+) > RO (Cu2+) > RO (Cd2+) for leachates A and B. The order of solute rejection sequence is inversely proportional to the diffusion coefficients. The rejection of sulphate ions by the NF-300 membrane was 83 and 85%, while the rejection of chlorides was 62 and 65% for leachates A and B, respectively. The NF-300 membrane was characterized by using the combined-film theory-Spiegler–Kedem (CFSK) model based on irreversible thermodynamics and the ion transport model based on the extended Nernst–Planck equation. The membrane transport parameters were estimated using the Levenberg–Marquadt method. The estimated parameters were used to predict the membrane performance and the predicted values are in good agreement with the experimental results. 相似文献
19.
Kuravappullam Vedaiyan Radha 《环境质量管理》2023,32(3):301-312
This study focuses on a lab-scale rotating biological contactor (RBC) treating vegetable oil wastewater with high BOD and COD. The fabricated RBC was checked for efficiency in degrading polluted wastewater under different operating conditions. The maximum removal efficiencies for BOD and COD were 95.75% and 89%, respectively. This high removal percentage was obtained with 30% submergence of 10 discs rotating at 8 rpm. For the first time, bio-kinetic models were applied to the experimental results for vegetable oil wastewater. The best fit was obtained with the modified Stover-Kincannon and Grau model. The saturation constant (Ks) values were 1.872 and 3.024 g/L/d for BOD and COD, respectively, for the modified Stover-Kincannon and Grau model. For the Grau second-order model, the saturation constant was 1.416 and 3.744 g/L/d for BOD and COD, respectively. The predicted effluent BOD and COD values of the modified Stover–Kincannon model fitted almost exactly with the experimental values. This clearly predicts that this model can be best used to predict effluent BOD and COD concentration in a Rotating Biological contactor treating vegetable oil wastewater. The kinetic parameters determined in this study can be used to improve the design and operation of continuous mode RBC systems. 相似文献
20.
J.C. Abanades M. Alonso N. Rodriguez 《International Journal of Greenhouse Gas Control》2011,5(3):512-520
A novel concept for capturing CO2 from biomass combustion using CaO as an active solid sorbent of CO2 is discussed and experimentally tested. According to the CaO/CaCO3 equilibrium, if a fuel could be burned at a sufficiently low temperature (below 700 °C) it would be possible to capture CO2 “in situ” with the CaO particles at atmospheric pressure. A subsequent step involving the regeneration of CaCO3 in a calciner operating at typical conditions of oxyfired-circulating fluidized combustion would deliver the CO2 ready for purification, compression and permanent geological storage. Several series of experiments to prove this concept have been conducted in a 30 kW interconnected fluidized bed test facility at INCAR-CSIC, made up of two interconnected circulating fluidized bed reactors, one acting as biomass combustor-carbonator and the other as air-fired calciner (which is considered to yield similar sorbent properties than those of an oxyfired calciner). CO2 capture efficiencies in dynamic tests in the combustor-carbonator reactor were measured over a wide range of operating conditions, including different superficial gas velocities, solids circulation rates, excess air above stoichiometric, and biomass type (olive pits, saw dust and pellets). Biomass combustion in air is effective at temperatures even below the 700 °C, necessary for the effective capture of CO2 by carbonation of CaO. Overall CO2 capture efficiencies in the combustor-carbonator higher than 70% can be achieved with sufficiently high solids circulation rates of CaO and solids inventories. The application of a simple reactor model for the combined combustion and CO2 capture reactions allows an efficiency factor to be obtained from the dynamic experimental test that could be valuable for scaling up purposes. 相似文献