Biological Aerated Filter Process Research Articles

Study on BAF Lipid Phosphorus Biomass and SOUR Active Tests

By taking the fillings from the wastewater treatment reactor of a practically stable operation of the BAF, it is to test the lipid phosphorus biomass both in the bio-film and floc in the fillings, and active changing laws of microbes. The experiments show that BAF sewage treatment results from the joint action of bio-film and biological floc. The experiments provide theoretical foundations for the operating mechanism of BAF, packing height and the optimization of backwash time. Due to its high efficiency, energy saving, small area, easy operation and management, Biological Aerated Filter (BAF) technology has become a research focus[1] of a biological wastewater treatment technology in recent years. BAF process is characterized of a lot of filler in the activated sludge, besides the bio-film on the fillings. This sludge contains active living organisms, shed bio-film, suspended matters from the raw sewage and other adsorptions from the wastewater. They are collectively referred to as biological floc. When oxidating and decomposing organic matters in the sewage, it intercepts and adsorb sunken substances. Throughout BAF operation process, it is as irreplaceable as the bio-film.

Degradation of 4-Nitrophenol Using a Coupled Photocatalytic–Biological Aerated Filter Process

4-Nitrophenol (4-NP) was degraded using a coupled photocatalytic–biological aerated filter (BAF) process. Effects of different initial 4-NP concentrations on its degradation by using solo photocatalytic oxidation or BAF process are discussed. Degradation efficiency of 4-NP using BAF process after a short-duration photocatalytic pretreatment (PC) were studied in detail. Intermediates of 4-NP degradation were characterized by UV–vis spectrophotometry, high-performance liquid chromatography, high-performance liquid chromatography/mass spectrometry, and ion chromatography. Possible mechanisms of 4-NP degradation using photocatalytic–BAF process were discussed. Short-duration PC was used to decrease chemical oxygen demand and improve biodegradability of 4-NP. It was found that PC of 4-NP for 2.5 h, during which period about 20%–50% chemical oxygen demand removal occurred, could be coupled to second-stage biological treatment for achieving enhanced biodegradation of 4-NP. The as-prepared N-TiO2/γ-Al2O3 granules were used as photocatalyst, photocatalytic–BAF technique was used to degrade 4-NP, and then the catalyst separated from wastewater automatically after photoreaction, which addressed the problem of in catalyst separation. Results indicated that this comprehensive process was simple and effective for the treatment of this typical nonbiodegradable nitrophenols wastewater.

Study on Papermaking Processes Wastewater Treatment

In this paper, Cost-effectiveness of various straw pulp wastewater treatment technologies were compared in detail, moreover the separate and combined process of Coagulation Sedimentation, Anaerobic Baffled Reactor, Sequencing Batch Reactor and Biological Aerated Filter processes were researched. The test result has showed that when addition dosage of PAM and PAC is 4mg/L and 80mg/L in Coagulation Sedimentation separately, and ABR HRT is 10h, the biodegradability of the straw wastewater increased from 0.25 after pretreatment to about 0.45. As the best SBR HRT is 8h, the CODcr removal rate was about 62%, the BOD5 removal rate was 70.7% averagely, and the treatment effectiveness is steady correspondingly. But in combined process, the CODcr removal rate of SBR unit is significantly increased to 78%, the CODcr removal rate of whole system is higher than 90%. Finally, the BAF has been applied to the advanced treatment on outwater of two biological treatment. The experimental results show that there is a good efficiency on the advanced treatment of the using the method, the CODcr of outwater is 78 mg/L, the BOD5 is 28 mg/L, the chroma is 32 times, the SS is 38 mg/L, and the treated water not only meets the state's new discharge standards (GB3544-2008), but also satisfies the requirements of reuse water, and the cost of whole treatment is only RMB 1.80 yuan / m3 wastewater.

Biodegradation behavior of natural organic matter (NOM) in a biological aerated filter (BAF) as a pretreatment for ultrafiltration (UF) of river water

In this study, biodegradation of natural organic matter (NOM) in a biological aerated filter (BAF) as pretreatment of UF treating river water was investigated. Photometric measurement, three-dimensional excitation-emission matrix (EEM) fluorescence spectroscopy and liquid chromatography with online organic carbon detector (LC-OCD) were used to investigate the fate of NOM fractions in the BAF + UF process. Results showed that the BAF process could effectively remove particles and parts of dissolved organic matter, which led to a lower NOM loading in the UF system, but different NOM fractions showed different biodegradation potentials. Further biodegradation batch experiments confirmed this observation and identified that polysaccharides and proteins (quantified using photometric methods) contained a large proportion of readily biodegradable matter while humic substances were mainly composed of inert organic substances. According to EEM measurements, it is evident that protein-like substances were more readily eliminated by microorganisms than humic-like substances. LC-OCD data also supported the phenomena that the polysaccharides and large-size proteins were more degradable than humic substances.

Effects of average velocity on the growth and surface topography of biofilms attached to the reclaimed wastewater drip irrigation system laterals

Emitter clogging, a phenomenon commonly seen in reclaimed wastewater drip irrigation systems, is a severe obstacle to the wide applications and popularization of the irrigation technology. Some experiments showed that the emitter clogging was tightly related to biofilms formation attached to the irrigation system. In this paper, two types of wastewaters reclaimed respectively by fluidized-bed reactor (FBR) process and biological aerated filter (BAF) process were chosen as the experiment objects and then the effects of the average velocity on the growth and topography of biofilms attached to the irrigation laterals were studied. The parameters of biofilms reached their maximal values at a critical velocity of 0.45 m/s. The formation of biofilms was primarily controlled by the transport of the nutrients and suspended particles within the laterals when the average velocity is below the critical velocity, whereas it was primarily controlled by the hydraulic shear force when above the critical velocity. The main mechanism for emitter clogging was that the biofilms detached from laterals accumulated and grew at the inlets and outlets of emitters. A similar variation pattern was observed for both reclaimed wastewaters. However, the growth of biofilms for BAF process was more affected by the shear force than that for FBR process, since the nutrients and suspended particles for BAF were larger than those for FBR.

Study on Wastewater Treatment by Biological Aerated Filter

In order to study the pollutants removal effect, the reactor operating conditions were studied with Biological Aerated Filter (BAF) process. The results showed that when HRT was at 8h, the effluent COD and ammonia nitrogen were 37 mg/L and 8.6 mg/L with the aeration flow was 0.3 m3/h, the effluent COD and ammonia nitrogen were 53 mg/L and 12.2 mg/L respectively. And the range of effluent pH is at 6.0-8.8. Furthermore the effluent COD was stable, while the effluent ammonia nitrogen will gradually affect by aeration flow. So the BAF process for residential sewage treatment is feasible.

Ammonium nitrogen removal characteristics of zeolite media in a Biological Aerated Filter (BAF) for the treatment of textile wastewater

The main objective of this study is to evaluate ammonium nitrogen removal characteristics of zeolite media in Biological Aerated Filter (BAF) process for treatment of textile wastewater. Several biofilters were conducted to compare the performance of natural zeolite with sand and granular activated carbon (GAC) as packing media. The removal of NH 4 +-N on the BAF reactor packed with natural zeolite media was more efficient than that with sand and GAC. After biofilm was well developed on the surface of zeolite media, the removal of NH 4 +-N by ion exchange, nitrification, and biological synthesis was estimated as 35.1%, 40.2%, and 22.3%, respectively. The natural zeolite pretreated with heat and HCl solution showed higher ammonium removal efficiency than that with NaOH solution. No significant difference on ammonium adsorption capacity was observed when nature zeolite was neither pretreated by heat nor hydrochloric acid solution. This study shows that natural zeolites has the feasibility to be chosen as a useful media in BAF process for the treatment of textile wastewater.

Pilot study on the advanced treatment of landfill leachate using a combined coagulation, fenton oxidation and biological aerated filter process

Mature landfill leachate is typically non-biodegradable. A combination process was developed that includes coagulation, Fenton oxidation, and biological aerated filtering to treat biologically-produced effluent. In this process, coagulation and Fenton oxidation were applied in order to reduce chemical oxygen demand (COD) organic load, and enhance biodegradability. Poly-ferric sulfate (PFS) at 600 mgl(-1) was found to be a suitable dosage for coagulation. For Fenton oxidation, an initial pH of 5, a total reaction time of 3h, and an H(2)O(2) dosage of 5.4mmoll(-1), with a (H(2)O(2))/n(Fe(2+)) ratio of 1.2 and two-step dosing were selected to achieve optimal oxidation. Under these optimal coagulation and Fenton oxidation conditions, the COD removal ratios were found to be 66.67% and 56%, respectively. Following pretreatment with coagulation and Fenton oxidation, the landfill leachate was further treated using a biological aerated filter (BAF). Our results show that COD was reduced to 75mgl(-1), and the color was less than 10 degrees.

Treatment of wastewater containing azo dye reactive brilliant red X-3B using sequential ozonation and upflow biological aerated filter process

In this work, the treatment of wastewater containing azo dye reactive brilliant red X-3B using sequential ozonation and upflow biological aerated filter process has been studied. Decolorization was almost complete after 120 min with an ozone concentration of 34.08 mg/L, the biological oxygen demand for 5 days (BOD 5)/chemical oxygen demand (COD) ratio increased from 0.102 to 0.406, which was more effective for the subsequent upflow biological aerated filter (UBAF) to reduce COD concentration. Under the conditions of gas/liquid = 3, hydraulic load = 4.8 m 3/m 3.d, T = 20–25 °C, the mass ratio of ozone to dye = 4.5, pH 11, the COD and color of the effluent were less than 40 mg/L and 20 Pt–Co units, respectively, and the average decolorization and COD removal efficiency were 97% and 90%, respectively. The experimental results showed that the combination of ozone oxidation and upflow biological aerated filter was a promising technique to treat wastewater containing azo dye.

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.

Backwash Based Methodology for the Estimation of Solids Retention Time in Biological Aerated Filter

The concept of solids retention time (SRT) was used for describing the growth of biofilm in a biological aerated filter (BAF) system. The SRT profile was obtained from the change in solids accumulation, estimated from the head loss profile data before and after backwash using the Carmen-Kozeny equation. The SRT profile along the filter bed depth showed the SRT of about 2 days for the lower layer and about 6 days for the upper layer. The overall SRT was determined by the direct estimation of excess solids mass during backwash and of solids retained in the filter bed. The ideal characteristic SRT distribution was maintained by regular backwash, for organic removal and nitrification. The SRT for high organic removal and nitrification is demonstrated by the SRT distribution along the filter bed in this BAF process.

Treatment of acid rose dye containing wastewater by ozonizing – biological aerated filter

The ozonizing – biological aerated filter process was used to treat the acid rose dye containing wastewater. The most suitable conditions were identified as follows: the mass ratio of ozone to dye = 4.5, temperature t = 18–25 °C, HRT = 3 h and gas/liquid = 4:1. Experimental results showed that ozonizing process had an excellent de-color efficiency and could improve the biodegradability of wastewater. With ozonizing the BOD/COD ratio increased from 0.18 to 0.36, and as a result, the subsequent biological aerated filter could be more effective for further reducing COD and SS concentrations, especially for wastewater with low concentration of SS and COD. After treatment the effluent COD was less than 40 mg/L, SS about 50 mg/L and color less than 20°. It can meet the water quality standards of the treated water reused for industry cooling water.

Making a trickling filter/solids contact process work for cold weather nitrification and phosphorus removal

It is anticipated that the West Windsor Pollution Control Plant (WWPCP) (Windsor, Ontario, Canada) will be required to be upgraded from its current chemical primary treatment to full secondary treatment, with phosphorus removal maintained. A steering committee established effluent design objectives for effluent suspended solids and total 5-day biochemical oxygen demand of 15 mg/L, total phosphorus of 0.5 mg/L, and ammonia-nitrogen of 3 mg/L. Four processes were tested; among these, the trickling filter/solids contact (TF/SC) process had not been tested previously for consistent nitrification in colder climates where average monthly wastewater temperatures fall to 9 to 10°C. A novel TF/SC treatment scheme was identified that took advantage of the low biochemical oxygen demand of the WWPCP's chemical primary effluent and used higher density cross-flow media than had previously been used in the TF/SC process to achieve nitrification. In initial testing, the TF/SC process nitrified successfully but failed to meet the other objectives. A detailed diagnosis showed that the best process configuration had not been tested and that the pilot design was flawed in several respects. The inclusion of a sludge reaeration tank, the substitution of a flocculator-clarifier for a conventional scraper clarifier, and the elimination of head losses causing excessive floc breakup corrected the problem. In testing over a year-long period, the TF/SC process consistently met the target objectives, moving it up from fourth place to a tie with the other first-ranked process, the biological aerated filter (BAF). Capital costs were found to be lower than for the activated-sludge process and the BAF processes.

Operational Experience with Biological Aerated Filters1

AbstractYorkshire Water has two full‐scale biological aerated filters in operation. The first was installed at North Bierley sewage‐treatment works for the tertiary nitrification of humus―tank effluent to secure consent compliance and ascertain if anticipated future standards could be achieved. The second was recently commissioned at Hedon sewage‐treatment works for secondary treatment, as part of an evaluation of compact plant to meet the requirements of the urban waste water treatment Directive at coastal sites.The plant at North Bierley (near Bradford) is constructed mainly of steel and is designed to achieve an effluent quality of 10 mg/l suspended solids, 10 mg/l BOD, and 5 mg/l ammoniacal nitrogen. The plant at Hedon (near Hull) is constructed of concrete and is designed to achieve a 30 mg/l suspended solids and 25 mg/l BOD standard. Both plants have proved to be capable of meeting their respective effluent requirement.For each works, the paper describes (i) the identification of the problem, (ii) the reasons for selecting the biological aerated filter process, (iii) details of the plant, (iv) operating experiences, and (v) plant performance.

Reclamation and Reuse of Wastewater by Biological Aerated Filter Process

The Biological Aerated Filter process (BAF process) is ideal for reclamation and reuse of wastewater. It features excellent removal of organic matter and SS. Moreover, it features easy maintenance and achieves energy-saving and space-conservation. Results of applying this BAF process for the reclamation and reuse of domestic-type wastewater in an office building, castor oil containing industrial wastewater in an aluminium rolling mill, and industrial wastewater in a paper mill are summarized in the following. Treatment of office building domestic-type wastewater. Combining the BAF process with sand filtration and ozonation processes, in the office building's water reuse facility, achieved favorable treatment yielding an effluent with a BOD of less than 5 mg/liter and SS of less than 1 mg/liter. In the course of the investigation, however, it was found that certain types of algicides for eliminating water moss in the cooling tower had a negative effect on the BAF process, which lasted for some time but which eventually disappeared. Treatment of aluminium rollingmill industrial wastewater. Treatment of castor oil containing influent (BOD: 40 mg/liter and n-Hexane extracts: 40 mg/liter) by the BAF process yielded an effluent with a BOD level of 5 mg/liter and a value of 10 mg/liter n-Hexane extracts. Light shielding was effective for preventing the generation of slime. Treatment of paper mill industrial wastewater. Paper mill industrial wastewater was treated through a combined treatment comprising the coagulation and sedimentation process (Pellet Blanket Separator; PBS), the BAF process, and the activated carbon adsorption process. The resulting effluent had the COD down to 30 mg/liter and the SS to 5 mg/liter. Under normal circumstances, only the coagulation and sedimentation process and the BAF process were sufficient for achieving target treatment values. There was no need to carry out the activated carbon adsorption process.