Kinetic Performance of Oil-field Produced Water Treatment by Biological Aerated Filter

The biological aerated filter （BAF） was used to treat the oil-field produced water. The removal efficiency for oil, COD, BOD and suspended solids （SS） was 76.3%-80.3%, 31.6%-57.9%, 8.6.3%-96.3% and76.4%--82.7%, respectively when the hydraulic loading rates varied from 016m·h^-1 to 1.4m·h^-1. The greatest partof removal, for example more than 80% of COD removal, occurred on the top 100cm of the media in BAF. The kinetic .performance of BAF indicated that the relationship of BOD removal efficiency with the hydraulic loadingrates, in biological aerated filters could be described by c1/c1=l-exp（-2.44/L^0.59）. This equation could be used topredict the B OD.removal efficiency at different hydraulic loading rates.

Kinetics of COD Removal in a Biological Aerated Filter in the Presence of 2,4,6-Trinitrophenol （Picric Acid）

An empirical model for COD removal in a biological aerated filter （BAF） in the presence of 2,4,6-trinitrophenol （TNP） was developed, which related effluent COD to influent COD or hydraulic loading rate along the bed height. The overall reaction rate for substrate biodegradation could be described as pseudo first order. The experimental data of COD removal against reactor height were used to calculate the parameters in the empirical model. The COD concentration at different reactor height was expressed as a function of influent COD concentration and hydraulic loading rate, ln（C0/C）=0.124H/QC0^0.77 and ln（C/C0）=-5.63H/L^0.94, respectively, under the experimental condition. The models may be used to predict the COD removal profiles along the reactor height at different hydraulic loading rates and influent COD concentration for design, selection and sizing of BAF.

Application of a novel backwashing process in upflow biological aerated filter

To improve the efficiency of backwashing in upflow biological aerated filter （BAF）, a novel backwashing process named air-water siphon backwashing （AWSB） was proposed and applied on laboratory scale. The effects of backwashing on turbidity and suspended solid （SS） in backwashing efluent using this new backwashing process were compared with those of traditional backwashing process, namely air-water backwashing （AWB）. In AWB, the turbidity of backwashing efluent maintained 100 NUT when consumed 60 min and 10.5 L water. However, in AWSB, it declined to 44 NUT, consumed 40 min, and 7 L water. The COD removal of BAF after backwashing was also analyzed. The average removal rate of COD in the reactor backwashed by AWB and AWSB was 89.34% and 90.91%, respectively. Compared with AWB, the backwashing interval had been prolonged 35%. The volume of backwashing water in that AWSB was only 66.7% of that in AWB. The results demonstrated that AWSB required less water and took shorter backwashing timerelative to AWB to achieve the same turbidity of backwashing efluent, and AWSB was more effective in removing fouling than that of AWB. More significant advantage of AWSB was that the backwashing interval was effectively prolonged

Effect of media heights on the performance of biological aerated filter

The optimum media height of carbon oxidation and nitrification in a down-flow biological aerated filter was determined, and the distribution of the heterotrophic and nitrifying populations through studying the changes of organic carbon contents and ammonia concentration at different media height was got. The results showed that as a down flow BAF with granular media, the active layer of nitrifiers was deeper than heterotrophs in BAF. And the optimum media height for the removal of SS, COD Cr and NH + 4-N was 40 cm,60 cm and 80 cm respectively. The removal efficiency of SS, COD Cr and NH + 4-N was 79.1%, 63.9% and 96.4% respectively under the influent COD Cr and NH + 4-N of 122.1 mgCOD Cr /L and 14.84 mgNH + 4-N/L, the influent flux of 15.8 L/h, air to liquid ratio of 3∶1.

Treatment of Slightly Polluted Wastewater in an Oil Refinery Using a Biological Aerated Filter Process

The slightly polluted wastewater from oil refinery contains some COD, oil pollutants and suspended solids （SS）. A small-scale fixed film biological aerated filter （BAF） process was used to treat the wastewater. The influences of hydraulic retention time （HRT）, air/water volume flow ratio and backwashing cycle on treatment efficiencies were investigated. The wastewater was treated by the BAF process under optimal conditions： the HRT of 1.0 h, the air/water volume flow ratio of about 5 ： 1 and the backwashing cycle of every 4-7 days. The results showed that the average removal efficiency of COD, oil pollutants and SS was 84.5%, 94.0% and 83.4%, respectively. And the average effluent concentration of COD, oil pollutants and SS was 12.5, 0.27, 14.5 mg·L^-1, respectively. The experimental results demonstrated that the BAF process is a suitable and highly efficient method to treat the wastewater.

Using a biological aerated filter to treat mixed water-borne volatile organic compounds and assessing its emissions

A biological aerated filter （BAF） was evaluated as a fixed-biofilm process to remove water-borne volatile organic compounds （VOCs） from a multiple layer ceramic capacitor （MLCC） manufacturing plant in southern Taiwan. The components of VOC were identified to be toluene, 1,2,4-trimethylbenzene, 1,3,5-trimethylbenzene, bromodichloromethane and isopropanol （IPA）. The full-scale BAF was constructed of two separate reactors in series, respectively, using 10- and 15-cm diameter polypropylene balls as the packing materials and a successful preliminary bench-scale experiment was performed to feasibility. Experimental results show that the BAF removed over 90% chemical oxygen demand （COD） from the influent with （1188 ± 605） mg/L of COD. A total organic loading of 2.76 kg biochemical oxygen demand （BOD）/（m3 packing·d） was determined for the packed bed, in which the flow pattern approached that of a mixed flow. A limited VOC concentration of （0.97 ± 0.29） ppmv （as methane） was emitted from the BAF system. Moreover, the emission rate of VOC was calculated using the proposed formula, based on an air-water mass equilibrium relationship, and compared to the simulated results obtained using the Water 9 model. Both estimation approaches of calculation and model simulation revealed that 0.1% IPA （0.0031-0.0037 kg/d） were aerated into a gaseous phase, and 30% to 40% （0.006-0.008 kg/d） of the toluene were aerated.

Synergism of Novel Sequence Bio-ecological Process and Biological Aerated Filter for Sewage Treatment in Cold Climate

A lab-scale integrated treatment system including the novel sequence bio-ecological process （SBEP） and biological aerated filter （BAF） for a sewage mixture （chemistry laboratory wastewater and domestic sewage） was presented in this paper. The main objective of the study was to test the contribution of artificial aeration, recir-culation ratio and mass concentration of steel slag on pollutant removal in winter when the plants are dormant. It had been shown that SBEP and BAF play different roles in removing contaminants from wastewater. During the airflow experiment, the removal efficiency of COD and TP in SBEP was higher than that in BAF, whereas BAF can compensate for the deficiency of SBEP where no significant improvement on ammonium nitrogen removal is ob-served. Yet, the removal etticiencies of COD,TP and NH4^＋ -N in SBEP could be improved apparently when ditterent recireulation ratio or various mass concentration of steel were applied. Especially, when the airflow of 0.06 L·h^-1, the recirculation ratio rate of 80% and the mass concentration of steel of 2.2-2.4 g·L^-1 were applied, thehighest efficiency of 94.6%, 77.9% and 80.7% for COD, TP and NH4^＋ -N were achieved,-respectively,The integrated treatment system of SBEP and BAF was proved to be an effective wastewater treatment technique and a better alternative to treat domestic sewage.

Using a zeolite medium biofilter to remove organic pollutant and ammonia simultaneously

A pilot scale zeolite medium biological aerated filter(ZBAF) was designed and used to treat municipal wastewater. It showed that ZBAF could simultaneously remove chemical oxygen demand(COD), ammonia-N and turbidity to satisfied degree at a hydraulic retention time(HRT) of 0.95 h. Their average removal efficiencies were 73.9%, 88.4% and 96.2% with the corresponding average effluent concentrations of 43.4 mg/L, 3.5 mg/L and 3.7 NTU, respectively. These effluent items met with the water quality standard of the treated water reused for cooling water. The COD removal volumetric loading rate increased proportionally with its applied volumetric loading rate with its maximum of 7.1 kg/(m 3·d). Ammonia-N removal loading rate also increased proportionally with its applied loading rate at HRT of longer than 0.95 h and the feasible maximum removal loading rate was 0.9 kg/(m 3·d). The COD loading rate did not affect the ammonia-N removal efficiency significantly when it was lower than 5.5 kg/(m 3·d). ZBAF has good application prospect for its low cost and high removal efficiency in the future.

Treatment performance of integrated biological aerated filter by orthogonal experiments

Biological aerated filters have many advantages such as small volume and high treatment efficiency. This research focused on sewage treatment performance of integrated biological aerated filter (IBAF) under different conditions such as aeration, hydraulic retention time and the height of fillers layer, to identify the turn of marked affecting factor of removal performance through orthogonal experiments, optimize the function parameter of IBAF, reveal the regularity of sewage treatment of IBAF under different conditions, and adopt suitable measures to guarantee excess water quality of IBAF.

Performance of simultaneous nitrification and denitrification in lateral flow biological aerated filter

A new wastewater treatment facility—lateral flow biological aerated filter (LBAF) was developed aiming at solving energy consumption and operational problems in wastewater treatment facilities in small towns. It has the function of nitrification and removing organic substrate. In this study, we focused on the denitrification performance of LBAF and its possible mechanism under thorough aeration. We identified the existence of simultaneous nitrification and denitrification (SND) by analyzing nitrogenous compounds along the flow path of LBAF and supportive microbial microscopy, and studied the effects of air/water ratio and hydraulic loading on the performance of nitrogen removal and on SND in LBAF to find out the optimal operation condition. It is found that for saving operation cost, aeration can be reduced to some degree that allows desirable removal efficiency of pollutants, and the optimal air/water ratio is 10:1. Hydraulic loading less than 0.43 m h?1 hardly affects the nitrification and denitrification performance; whereas higher hydraulic loading is unfavorable to both nitrification and denitrification, far more unfavorable to denitrification than to nitrification.

Effects of Phosphorus Concentration on the Treatment of Domestic Wastewater by a Combination of Hydrolytic Acidification and Biological Aerated Filter Filled with Mussel Shells

The combination of hydrolytic acidification and biological aerated filter （BAF） filled with mussel shells was used to treat domestic wastewater, and the removal rates of chemical oxygen demand （COD）, ammonia nitrogen （NH3-N） and total phosphorus （TP） by the system were analyzed under different TP concentrations. When TP concentration ranged from 12.39 to 14.69 mg/L, the removal rate of COD was the best, over 90.92% ; as TP concentration varied from 2.26 to 2.61 mg/L, the removal rates of NH3-N and TP were the best, up to 100.00% and 76.38% respectively. The results show that it is feasible to use mussel shells as the media of BAF, and TP concentration has certain influence on the performance of the system dealing with domestic wastewater.

Enhanced Nutrient Removal with Upflow Biological Aerated Filter for Reclaimed Water

A two-stage upflow biological aerated filter was designed as an advanced treatment process to optimize the operating parameters and study the correlative factors influencing the efficiency of nitrification, denitrification and phosphorus removal. The experimental results showed that the final effluent of the two-stage upflow biofilter process operated in series could meet the stringent limits of the reclaimed water for the total nitrogen of 2 mg/L, and total phosphorus of 0.3 mg/L. The high treatment efficiency allowed the reactor operating at very high hydraulic loadings and reaching nearly complete nitrification and denitrifieation.

Preparation of biological aerated filter media with coal fly ash and coal gangues

A novel kind of filter media has been studied using in biological aerated filter process which is produced by waste coal fly ash and coal gangues.The specific surface area and sum of braking and ware rate are viewed as the main factor for determining preparation conditions,including calcination temperature (in the range of 900 ℃ to 1250 ℃),proportion of coal gangue (in the range of 0 to 25%) and soaking time (in the range of 0 to 40 min).The effects of sintering conditions on the main property parameters are researched and the reasons have been analyzed.Considered with all factors,the optimum technological conditions are chosen as follows:the calcination temperature is 1050 ℃ ;the soaking time is 10 min and the proportion of coal gangue is 5%.When at these condition,the main property parameters of the filter media in the technological conditions are 1.6 m 2 /g for the specific surface area and 2.96 % for sum of braking and are rate respectively.Finally,a scanning electron microscope is used for analyzing the microstructure of the filter media.

Characteristics of integrated biological aerated filter in municipal wastewater treatment

In this paper, the characteristics of integrated biological aerated filter (IBAF) applied to municipal wastewater treatment were studied in a pilot scale experiment. The experimental results showed that IBAF has high efficiencies in removing organic pollutants, such as CODCr and SS, in municipal wastewater. The removal rates of CODCr and SS can reach over 90% and 80%, respectively, when COD and SS in the influent are 234 mg L1 and 112 mg L1, hydraulic retention time (HRT) is 8 h, and the aerated intensity is in the range of (0.5 to 0.6) L m2 s1.

Hydrodynamic behaviour of the lateral flow biological aerated filter

Pulsed signal experiment was carried out to determine the hydrodynamic behaviours of lateral flow biological aerated filter(LBAF). With the analysis of experimental results, LBAF is viewed as an approximate plug flow reactor, and hydraulic retention time distribution function was derived based on LBAF. The results show that flow rate and aeration strength are two critical factors which influence flow patterns in LBAF reactor. The hydrodynamic behaviour analysis of LBAF is the theoretical basis of future research on improving capacity factor and developing kinetic model for the reactor.

Performances of lateral flow biological aerated filter in treating domestic wastewater

A new biological aerated filter?lateral flow biological aerated filter(LBAF) is developed. The effects of air/water ratio, hydraulic loading and the length of LBAF on pollutants removal efficiency are tested. The results show that under optimal technological conditions when hydraulic loading is 0.43 m3 m?2 h?1 and air/water ratio is 10:1, the average removal efficiencies of COD, SS, NH3-N, and TN reach 88.01%, 95.18%, 78.97% and 52.58%, respectively. An LBAF has a large pollutants handling capacity; is less liable to be blocked, and has a longer operation cycle in comparison with a traditional BAF.

Development of Biofilter Devices for Nutrient Removal From Wastewater

Nutrient pollution still remains one of the greatest challenges to water quality contributing to harmful contaminations water sources,and costly impacts on the economy.This review considers the development of the biofilters,focusing on the design features that have the most influence on their technical and economic performance.Modern biofilters,based on SAF technology,are particularly suitable for sewage treatment works with throughput rates up to 1,000m^3/d.The main advantages of SAF plants include high quality effluent,low power usage and small footprint.A wide range of filter media are available for different designs,which could be configured for both aerobic and anaerobic treatment in BOD and/or ammonia reduction applications.The two most important parameters for filter media are their Specific Surface Area(SSA,m^2/m^3)and Void Fraction(percentage of void volume or porosity).However,due to the risk of clogging by suspended solids or excess sludge the media used for this application should be limited to about 500m^2/m^3.In tertiary treatment or river restoration applications where the influents tend lack any readily biodegradable substrates,SAF design provides the most appropriate choice for further development to produce effluents with very low nutrient levels.

Removal of nitrogen and phosphorus in a combined A^2/O-BAF system with a short aerobic SRT

A bench-scale anaerobic/anoxic/aerobic process-biological aerated filter （A^2/O-BAF） combined system was carded out to treat wastewater with lower C/N and C/P ratios. The A^2/O process was operated in a short aerobic sludge retention time （SRT） for organic pollutants and phosphorus removal, and denitrification. The subsequent BAF process was mainly used for nitrification. The BAF effluent was partially returned to anoxic zone of the A^2/O process to provide electron acceptors for denitrification and anoxic P uptake. This unique system formed an environment for reproducing the denitdfying phosphate-accumulating organisms （DPAOs）. The ratio of DPAOs to phosphorus accumulating organisms （PAOs） could be maintained at 28% by optimizing the organic loads in the anaerobic zone and the nitrate loads into the anoxic zone in the A^2/O process. The aerobic phosphorus over-uptake and discharge of excess activated sludge was the main mechanism of phosphorus removal in the combined system. The aerobic SRT of the A^2/O process should meet the demands for the development of aerobic PAOs and the restraint on the nitrifiers growth, and the contact time in the aerobic zone of the A^2/O process should be longer than 30 min, which ensured efficient phosphorus removal in the combined system. The adequate BAF effluent return rates should be controlled with 1--4 mg/L nitrate nitrogen in the anoxic zone effluent of A^2/O process to achieve the optimal nitrogen and phosphorus removal efficiencies.

Performance of a double-layer BAF using zeolite and ceramic as media under ammonium shock load condition

An experiment was carried out to investigate the anti-ammonium shock load capacity of a biological aerated filter （BAF） composed of a double-layer bed. This bed was made up of a top layer of ceramic and a bottom layer of zeolite. The experiment shows that the anti-ammonium shock load process can be divided into two processes： adsorption and release. In the adsorption process, the total removal efficiency of ammonia nitrogen by zeolite and ceramic was 94%. In the release process, the ammonia nitrogen concentration increased significantly and then gradually returned to the normal level four hours after the shock load. The results indicated that the double-layer BAF had a high level of adaptability to the short-term ammonium shock load and long-term operation. The main factors influencing the dynamic process of ammonia nitrogen adsorption were the filter bed height, ammonia nitrogen concentration of influent, and flow rate. The bed depth service time （BDST） model was used to predict the relationship between the filter bed height and breakthrough time at different flow rates, and the results are reliable.

Research on DAF-BAF process in textile wastewater treatment

This experiment researches textile wastewater, adopts a BAF process that has developed quickly in recent years, and makes use of dissolved air flotation as a pretreatment process that can effectively make up for BAF’s lack of removing Chromaticity color. Performance effect, influencing factor, control condition have been reviewed and parameters of correlation have been analyzed in this experiment. The experiment and actual performance results indicate that this process is an effective way to remove the COD, suspended solid and colority with the value of 100 mg/L, 50 mg/L and 70 multiple respectively. The effluent meets the requirement of the standards of national sewage discharge. This process features a simple schematic, small location, continuous, reliable performance, strong shock and loading resistance and easy operation. Experimental data can provide scientific evidence and technical support for engineering practice of this process.