Evaluation Of Inverse Anaerobic Fluidized Bed Reactor For Treating High Strength Organic Wastewater
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Inverse fluidization particles having specific gravity less than one are carried out in the reactor. The carrier particles chosen for this study was perlite having specific surface area of 7010m2/m3 and lowenergy requirements for fluidization. Before starting up the reactor physical properties of the carrier material were determined. 1mm diameter perlite particle is found to have a specific density of 295kg/m3. It was used for the treatment of distillery waste and performance studies were carried out for 85 days. Once the down flow anaerobic fluidized bed system reached the steady state, the organic load was increased step wise by reducing Hydraulic Retention Time (HRT) from2days to 0.19 day, while maintaining the constant feed of COD concentration.Most particles are covered with a thin biofilm of uniform thickness. This system achieved 87% COD removal at an Organic loading rate (OLR) of 35 kg of COD/m3/d.Keywords:
Fluidization
Perlite
Hydraulic retention time
Particle (ecology)
Specific gravity
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A pressurized fixed bed biofilm reactor was developed by combining the pressurized biological contact oxidation process and the single-stage BAF.The influence of pressure,organic loading rates and influent temperature on the removal of organic matters was investigated.The results reveal that with increasing of the pressure,the removal rate of COD is increased and then decreased.When the pressure is 0.18 to 0.21 MPa,the highest removal rate of COD is 95.4%.Under the optimal pressure condition,the reactor has stronger resistance to organic loading and low temperature.The optimal process parameters are pressure of 0.18 to 0.21 MPa,organic loading rate of 8.8 to 10.9 kgCOD/(m3·d),influent temperature of 23 ℃ to 29 ℃,HRT of 0.58 h,air/water ratio of 3 ∶1 to 6 ∶1,backwash cycle of 6 to 8 d and backwash time of 18 to 22 min.Under the optimal operational conditions,the average removal rate of COD is 94.6%.The effluent quality meets the first level A criteria specified in Discharge Standard of Pollutants for Municipal Wastewater Treatment Plant(GB 18918-2002) and reaches the standard of reclaimed water reuse.
Degradation
Hydraulic retention time
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A single unit anaerobic granular bed baffled reactor (GRABBR) is proposed as an alternative to a separately operated two-phase anaerobic digestion system. This overcomes the problems related to wastewater treatment at high loading rates which usually results in accumulation of intermediate acid products, and consequently inhibits methanogenesis. This study was carried out to evaluate the stability of a five compartment GRABBR system when treating synthetic glucose wastewater at various operational conditions. The reactor was started with volumetric organic loading rate (OLR) of 1 kg chemical oxygen demand (COD)/m3 day, equivalent to 120 h hydraulic retention time (HRT), and loading rates were gradually increased at suitable intervals to up to 20 kg COD/m3 day (6 h HRT). At steady state, the overall soluble COD (SCOD) removal was over 95% under all applied loading conditions. At lower loadings, the reactor operated as a completely mixed system, and most of the treatment was achieved in the first compartment. At higher loadings, the entire system transformed into different phases, acidogenesis being dominant near the influent point, whilst methanogenesis was the main activity in the compartments near the effluent point. Granule breaking and flotation was observed in the acidogenic zone, whilst the methanogenic zone retained its original granular form. High assimilation rate of influent nitrogen was observed in the first compartment with the formation of nongranular biomass, identified as Klebsiella pneumoniae. The success of GRABBR as a single unit two-phase anaerobic digestion system could save the cost of an extra unit traditionally employed to achieve similar goals in treatment of high strength wastewaters.
Acidogenesis
Hydraulic retention time
Sparging
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The self-designed new A/O biological fluidized bed was used to treat food processing wastewater.The designed capacity is 800 m3/d.When the influent concentrations of COD,NH_3-N,SS and oil are 957.6 mg/L to 6 841.4 mg/L,11.5 mg/L to 42.3 mg/L,50.3 mg/L to 982.5 mg/L and 6.2 mg/L to 22.7 mg/L respectively,the obtained effluent quality can meet the classⅠcriteria of Integrated Wastewater Discharge Standard(GB 8978-1996).Biogas and wastewater are co-recycled in the new jet aeration internal-loop anaerobic fluidized bed,the wastewater and anaerobic sludge are mixed enough in it.When the recycle ratio,HRT and average volume loading are 1.2,24 h and 2.06 kg/(m3·d)to 3.96 kg/(m3·d)respectively,the COD removal rate and the largest biogas production can reach about 80% and 180.5 m3/d respectively.In the new horizontal aerobic three-phase fluidized bed,the ratio of height to length and width is only designed at 0.47 and 0.64,but there is good fluidization effect in this reactor.Otherwise,the three-phase separator is designed successfully so that the high biomass concentration is kept in the two new reactors,which ensures high efficiency and low energy consumption of industrial organic wastewater treatment.
Biogas
Fluidization
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Abstract This paper describes the application of the inverse fluidization technology to the anaerobic digestion of dairy wastewater. Two reactors were investigated: the inverse fluidized bed reactor and the inverse turbulent reactor. In these reactors, a granular floating solid is expanded by a down‐flow current of effluent or an up‐flow current of gas, respectively. The carrier particles (Extendospheres(™)) were chosen for their large specific surface area (20,000 m2m−3) and their low energy requirements for fluidization (gas velocity of 1.5 mm s−1, 5.4 m h−1). Organic load was increased stepwise by reducing hydraulic retention time from more than 60 days to 3 days, while maintaining constant the feed COD concentration. Both reactors achieved more than 90% of COD removal, at an organic loading rate of 10–12 kgCOD m−3d−1, respectively. The performances observed were similar or even higher than that of other previously tested fluidized bed technologies treating the same wastewater. It was found that the main advantages of this system are: low energy requirement, because of the low fluidization velocities required; there is no need of a settling device, because solids accumulate at the bottom of the reactor, so they can be easily drawn out and particles with high‐biomass content can be easily recovered. Lipid phosphate concentration has been revealed as a good method for biomass estimation in biofilms since it only includes living biomass. Key words: Anaerobic processwastewater treatmentgranular floating carrierinverse fluidization technologyphospholipid analysis
Fluidization
Settling
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AbstractIn this study, a new biocarrier made up of low-density polypropylene of surface area 524 mm2 per particle and of density 870 kg/m3 was used in the treatment of wastewater using fluidized bed reactor. Holdup studies were performed for various bed heights (0.2–0.8 m) to predict the operating conditions. The effect of bed height (0.6, 0.8, and 1 m), hydraulic retention time (6.25, 8.33, 12.5, and 24 h), superficial gas velocity (0.0016, 0.00212, 0.00265, and 0.00318 m/s), and concentration (910, 1,820, 2,840, and 3,940 mg/l) on the percentage of COD reduction were studied. For bed height of 0.8 m, optimum holdup and maximum COD reduction was obtained. From the results, it was observed that percentage of COD reduction was increased with the increase in superficial gas velocity but it was decreased with the decrease in initial concentration. A maximum COD reduction of 96.7% at a superficial gas velocity of 0.00318 m/s was obtained for a wastewater of concentration of 910 mg/l and HRT of 24 h.Keywords: Fluidized bed reactorBio carrierHoldupWastewaterChemical oxygen demand
Hydraulic retention time
Particle density
Superficial velocity
Fluidization
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A 9.8-L hybrid UASFB reactor, in which the lower half was occupied by a sludge blanket and the upper half by small floating polyethylene media, was evaluated using wine distillery vinasse as substrate. The reactor was operated for a total period of 232 days at 33 + 1°C. Continuous feeding of the reactor was started with an initial OLR of 2.9 g COD/L·d and then it was increased step wise to 19.5 g COD/L·d by increasing the feed COD, while maintaining a constant HRT (1.05 d). The reactor was equipped with a continuous internal recirculation system from top to the bottom at the rate of 9 L/h (upflow velocity = 0.83 m/h) upto day 159 and then it was reduced to about half on day 160 onwards. It was observed that the reduced recirculation rate did not affect the performance of the reactor with an average CODt and CODs removal efficiencies of 82 and 88%, respectively. A maximum gas production rate of 6.7 L CH4/Lreactor·d was achieved for the highest OLR applied. The specific activity analysis depicts that the activity of the attached biomass was more than 2 times higher than that of the granular sludge. The efficiency of liquid mixing was good through out this study. The packing medium had a dual role in the retention of the biomass inside the reactor: i.e. entrapment of biomass within the support and filtration of the granular biomass, preventing it from going out of the reactor. ADM1_10 model simulated well the dynamic evolutions of the main variables in the liquid as well as in the gas phases.
Vinasse
Hydraulic retention time
Hybrid reactor
Filtration (mathematics)
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Hydraulic retention time
Volatile fatty acids
Carbon fibers
Retention time
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Biogas
Hydraulic retention time
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Citations (24)
The anaerobic attached film expanded bed reactor (AAFEB) has been found to be effective for the treatment of low strength soluble organic wastes anaerobically, at reduced temperatures, short retention times, and high organic loading rates. The process consists of inert particles, approximately 500 microns in apparent diameter, packed in a cylindrical column which expand slightly with the upward flow of liquid through the column. The AAFEB permits the maintenance of high solids retention times (SRT) values with low hydraulic retention times (HRT) values. Three reactors fed a soluble synthetic waste consisting of glucose and nutrient salts at concentrations ranging from 50 to 600 mg/1 COD were monitored over a period of nine months of start up and six months of operation. The effects of temperature, influent substrate concentration, and hydraulic flow rate on process efficiency were measured. Process efficiency was evaluated in terms of soluble COD removal and other parameters. In addition an organic carbon mass balance was evaluated to verify the experimental results. Biofilm thickness and biomass concentration were also measured. This study presents an analysis of the key process variables which affect AAFEB operation and presents two simplified first order equations relating the process efficiency to the net specific growth rate of the film and specific substrate utilization. The high effectiveness of this process is believed to be due to the large surface area to volume ratio created by the inert support media which enabled a large active mass of attached microorganisms to remain in the reactor at high liquid flow rates. Microbial mass concentrations exceeding 30 g/l were common in thisreactor. The rate limiting step in the overall process was the biochemical reactions and not mass transfer. A preliminary energy consumption comparison was made between the AAFEB and conventional aerobic treatment processes.
Inert
Hydraulic retention time
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Citations (31)