Journal articles: 'Diffused aeration system'

1

Thomas, V. K., B. Chambers, and W. Dunn. "Optimisation of Aeration Efficiency: A Design Procedure for Secondary Treatment Using a Hybrid Aeration System." Water Science and Technology 21, no. 10-11 (1989): 1403–19. http://dx.doi.org/10.2166/wst.1989.0337.

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The fine-bubble diffused air (FBDA) system of aeration is most efficiently operated in low rate activated sludge systems. The aeration technique is, however, subject to poor oxygen transfer efficiency and diffuser clogging under increased loading conditions such as are experienced close to the tank inlet in plug-flow systems. Mechanical, surface aeration systems, though apparently less efficient, do not suffer from these disadvantages. The ideal aeration tank configuration, for optimum aeration efficiency is therefore:–inlet anoxic zone–completely mixed surface aerated zone–plug-flow, fine-bubble diffused air zone with tapered aeration–clarification tanks. An overall aeration efficiency of 1.5-2.0 kg/kwh is predicted for nitrifying systems, together with an increased diffuser lifetime compared to a conventional FBDA tank. The design procedure is illustrated using parameters for a large UK works. Despite greater civil costs, the reduced running costs and NPC of the hybrid system make it an attractive option when compared to a plug-flow FBDA system or a conventional surface aeration plant.

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Amirhor, Parviz, Michael J. Hanscom, Anthony N. Veltri, Justin D. Gould, and Robert P. G. Bowker. "DIFFUSED AERATION ODOR CONTROL SYSTEM." Proceedings of the Water Environment Federation 2001, no. 15 (2001): 473–82. http://dx.doi.org/10.2175/193864701790902941.

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Krampe, J. "Assessment of diffuser pressure loss on WWTPs in Baden-Württemberg." Water Science and Technology 63, no. 12 (2011): 3027–33. http://dx.doi.org/10.2166/wst.2011.634.

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Aeration of activated sludge is a critical treatment step for the operation of activated sludge plants. To achieve a cost effective treatment process, assessing and benchmarking of aeration system performance are important measures. A simple means of gauging the relative condition of a fine bubble diffused aeration system is to evaluate the pressure loss of the diffusers as oxygen transfer tests are rarely applied during the lifetime of an aeration system. This paper shows an assessment of fine bubble diffuser systems in Baden-Württemberg, Germany, based on the results of a questionnaire sent to 941 WWTPs. Apart from the results with regards to the diffuser pressure loss, this paper also presents information on the current state of diffuser technology such as types and materials as well as the diffuser cleaning methods used in Baden-Württemberg. The majority of the WWTPs were equipped with tube diffusers (71%) with 50% of all plants having EPDM membranes installed. Regular mechanical cleaning is the most common cleaning method followed by regular pressure release/air-bumping programs during operations. With regard to the diffuser pressure loss it was found that 50% of the evaluated plants had a diffuser pressure loss that was twice as high as measured for new diffusers.

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Krampe, J. "Full scale evaluation of diffuser ageing with clean water oxygen transfer tests." Water Science and Technology 64, no. 3 (2011): 700–707. http://dx.doi.org/10.2166/wst.2011.694.

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Aeration is a crucial part of the biological wastewater treatment in activated sludge systems and the main energy user of WWTPs. Approximately 50 to 60% of the total energy consumption of a WWTP can be attributed to the aeration system. The performance of the aeration system, and in the case of fine bubble diffused aeration the diffuser performance, has a significant impact on the overall plant efficiency. This paper seeks to isolate the changes of the diffuser performance over time by eliminating all other influencing parameters like sludge retention time, surfactants and reactor layout. To achieve this, different diffusers have been installed and tested in parallel treatment trains in two WWTPs. The diffusers have been performance tested in clean water tests under new conditions and after one year of operation. A set of material property tests describing the diffuser membrane quality was also performed. The results showed a significant drop in the performance of the EPDM diffuser in the first year which resulted in similar oxygen transfer efficiency around 16 g/m3/m for all tested systems. Even though the tested silicone diffusers did not show a drop in performance they had a low efficiency in the initial tests. The material properties indicate that the EPDM performance loss is partly due to the washout of additives.

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Zhu, H., T. Imai, K. Tani, et al. "Improvement of oxygen transfer efficiency in aerated ponds using liquid-film-assisted approach." Water Science and Technology 55, no. 11 (2007): 183–91. http://dx.doi.org/10.2166/wst.2007.353.

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In aerated ponds, oxygen is generally supplied through either diffused or mechanical aeration means. Surface transfer and bubble transfer both contribute significantly to oxygen transfer in a diffused aeration system. In the present study, a liquid-film-forming apparatus (LFFA) is successfully developed on a laboratory scale to improve considerably the surface transfer via the unique liquid film transfer technique. The experimental results show that the volumetric mass transfer coefficient for LFFA alone is found to be as much as 5.3 times higher than that for water surface and that the total volumetric mass transfer coefficient for the liquid film aeration system increases by 37% in comparison with a conventional aeration system. Additionally, by tuning finely the structural parameters of the LFFA, it can also lead to high dissolved oxygen (DO) water with the DO percent saturation greater than 90%. More importantly, this result is accomplished by simply offering a single-pass aeration at a depth as shallow as 26 cm. As a result, the objective of economical energy consumption in aerated ponds can be realized by lowering the aeration depth without sacrificing the aeration efficiency. It is noteworthy that the data presented in this study are acquired either numerically or experimentally.

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de Korte, Kees, and Peter Smits. "Steady State Measurement of Oxygenation Capacity." Water Science and Technology 17, no. 2-3 (1985): 303–11. http://dx.doi.org/10.2166/wst.1985.0139.

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The usual method for OC measurement is the non-steady state method (reaeration) in tapwater or, sometimes, in activated sludge. Both methods are more or less difficult and expensive. The steady state method with activated sludge is presented. Fundamentals are discussed. For complete mixed aeration tanks, plug flow systems with diffused air aeration and carousels the method is described more in detail and the results of measurements are presented. The results of the steady state measurements of the diffused air system are compared with those of the reaeration method in tapwater. The accuracy of the measurements in the 3 systems is discussed. Measurements in other aeration systems are described briefly. It is concluded that the steady state OC measurement offers advantages in comparison with the non-steady state method and is useful for most purposes.

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Alabdula'aly, A. I., and H. B. Maghrawy. "Radon removal from water supplies by diffused bubble aeration system." Journal of Radioanalytical and Nuclear Chemistry 241, no. 1 (1999): 3–9. http://dx.doi.org/10.1007/bf02347282.

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Chern, Jia-Ming, and Sheng-Ping Yang. "Oxygen Transfer Rate in a Coarse-Bubble Diffused Aeration System." Industrial & Engineering Chemistry Research 42, no. 25 (2003): 6653–60. http://dx.doi.org/10.1021/ie030396y.

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9

Little, J. C., and D. F. McGinnis. "Hypolimnetic oxygenation: predicting performance using a discrete-bubble model." Water Supply 1, no. 4 (2001): 185–91. http://dx.doi.org/10.2166/ws.2001.0083.

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Stratification of water-supply reservoirs frequently results in substantial hypolimnetic oxygen depletion with a resulting negative impact on raw water quality. Hypolimnetic oxygenators are used to add oxygen to the hypolimnion without significantly disrupting the thermal density structure. The three most common devices are the airlift aerator, the Speece Cone, and the bubble-plume diffuser. A discrete-bubble model based on fundamental principles has previously been shown to hold considerable promise for predicting the performance of airlift aerators and the Speece Cone. In this paper, we have further verified this model by comparing its predictions to a series of pilot-scale experimental measurements and have also demonstrated its ability, under somewhat idealized conditions, to predict the full-scale performance of a bubble-plume diffuser in a stratified reservoir. The potential for the diffused-bubble aeration system to increase oxygen demand, and the rate at which nitrogen builds up during operation and de-gasses following destratification, are also considered.

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Pearson, Philip R., Sara E. Duke, Bartholomew W. Green, C. Douglas Minchew, Rachel V. Beecham, and Jin M. Kim. "Evaluation of a Diffused Oxygen Aeration System under On-Farm Harvest Conditions." North American Journal of Aquaculture 68, no. 1 (2006): 47–52. http://dx.doi.org/10.1577/a05-031.1.

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11

Vélez, O. R., and J. Foil. "Low-Cost Wastewater Treatment with the Use of an Intrachannel Clarifier in Oxidation Ditches." Water Science and Technology 19, no. 3-4 (1987): 625–32. http://dx.doi.org/10.2166/wst.1987.0242.

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The oxidation ditches developed by Pasveer of Holland and Muskat in Germany have been used in small communities for many years as a cost effective secondary treatment. Generally designed and operated as part of an extended aeration system, these plants provide from 18 to 30 hours of hydraulic detention time, followed by a 3 to 6 hours settling period in a secondary clari-fier, with 100 per cent of settled solids return to the aeration tank. Because of these design criteria, the oxidation ditches were not widely used in large populations as the aeration system normally used required a relatively low water depth to be efficient -a fact that meant extensive land areas. Recent innovations in the clarification and aeration systems have rendered this treatment attractive again for communities of all sizes. The use of an upflow intrachannel clarifier, in particular, eliminates the need for a separate secondary clarifier, and return sludge pumping and piping. In addition, an innovative diffused aeration system permits the use of channels with a greater water depth, which not only optimizes process as an oxidation ditch but also makes it remarkably competitive in respect to conventional biological treatment systems. This paper deals with this innovative oxidation ditch system, analyzing its conceptual design considerations and economic aspects, and commenting upon its first application in Argentina using low-cost construction technology.

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Al Ba'ba'a, Hasan B., and Ryoichi S. Amano. "A study of optimum aeration efficiency of a lab-scale air-diffused system." Water and Environment Journal 31, no. 3 (2017): 432–39. http://dx.doi.org/10.1111/wej.12261.

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13

Boyd, Claude E. "Deep Water Installation of a Diffused-Air Aeration System in a Shallow Pond." Journal of Applied Aquaculture 5, no. 1 (1995): 1–9. http://dx.doi.org/10.1300/j028v05n01_01.

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14

N. B. MacPhee, R. Gordon, G. A. Gagnon, G. W. Stratton, J. Blanchard, and J. D. Wood. "Evaluation of a Diffused Air Aeration System for a Constructed Wetland Receiving Dairy Wastewater." Transactions of the ASABE 52, no. 1 (2009): 111–19. http://dx.doi.org/10.13031/2013.25952.

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15

Atia, Doaa M., Faten H. Fahmy, Ninet M. Ahmed, and Hassen T. Dorrah. "A New Control and Design of PEM Fuel Cell Powered Air Diffused Aeration System." TELKOMNIKA (Telecommunication Computing Electronics and Control) 10, no. 2 (2012): 291. http://dx.doi.org/10.12928/telkomnika.v10i2.798.

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16

Chern, Jia-Ming, and Shun-Ren Chou. "Effects of Surfactant on Volatile Organic Compound Emission Rates in a Diffused Aeration System." Industrial & Engineering Chemistry Research 41, no. 20 (2002): 5042–48. http://dx.doi.org/10.1021/ie020238r.

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17

Déronzier, G., Ph Duchène, and A. Héduit. "Optimization of oxygen transfer in clean water by fine bubble diffused air system and separate mixing in aeration ditches." Water Science and Technology 38, no. 3 (1998): 35–42. http://dx.doi.org/10.2166/wst.1998.0170.

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The influence of design parameters on the transfer of oxygen was studied in different ring ditches equipped with fine bubble membrane air diffusers and separate mixing. The results produced evidence that the oxygen transfer efficiency (OTE) decreases when the air flow rate per diffuser increases. OTE increases asymptotically with the horizontal water flow (50% for velocity up to 0.5 m/sec). It increases also when the diffuser modules are brought closer together. Theoretical analysis enabled ranking of the impact of the design parameters on which the oxygen transfer is dependent, namely the interfacial area (a) and the oxygen transfer coefficient (Kl). The increase in the air flow rate per diffuser essentially reduces the interfacial area by an increase in the diameter of the initial air bubbles and by a reduction of the contact time due to an acceleration of the “spiral flows” (vertical rotation of water flow). The horizontal rotation of water increases the interfacial area most probably by decreasing the diameter of the initial air bubbles and by a lengthening of the contact time resulting from a reduction in the large spiral flows. Bringing the diffuser modules closer together makes longer the contact time by a reduction in the large spiral flows.

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18

Mirzaei, Saeideh, and Beata Gorczyca. "Removal of trihalomethanes from high organic matter water sources using aeration: a feasibility study." Water Quality Research Journal 55, no. 2 (2020): 184–97. http://dx.doi.org/10.2166/wqrj.2020.016.

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Abstract In this study, diffused aeration was applied to remove trihalomethane (THM) compounds from chlorinated, treated water containing high dissolved organic carbon (DOC) of 6.8 ± 1.2 mg/L. Increasing air-to-water volumetric ratio (rA/W) from 16 to 39 enhanced total THM (TTHM) removal from 60 to 70% at 20 °C and from 30 to 50% at 4 °C. Although bromodichloromethane has lower Henry's law constant than chloroform (CF), it was removed by a higher degree than CF in some aeration trials. Albeit obtaining high removals in aeration, TTHM reformed, and their concentration surpassed the Canadian guideline of 100 ppb in about 24 hours at 20 °C and 40 hours at 10 °C in all attempted air-to-water ratios. The water age in the system investigated in this study varied from 48 hours in midpoint chlorine boosting stations to 336 hours in the nearest endpoint. This study showed that THM removal by aeration is not a viable solution to control the concentration of these disinfection by-products in high-DOC treated water and in distribution systems where water age exceeds 24 hours; unless, it is going to be installed at the distribution endpoints.

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Ashley, K. I., D. S. Mavinic, and K. J. Hall. "Effects of orifice size and surface conditions on oxygen transfer in a bench scale diffused aeration system." Environmental Technology 11, no. 7 (1990): 609–18. http://dx.doi.org/10.1080/09593339009384903.

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20

Mesdaghinia, A. "Fixed Activated Sludge Makes Sewage Treatment Simple." Water Science and Technology 18, no. 7-8 (1986): 193–98. http://dx.doi.org/10.2166/wst.1986.0290.

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The objective of this research was to conduct a bench scale study of fixed activated sludge treating domestic sewage. Two different units employing diffused aeration with plastic and aluminum media were studied in four separate phases. Data indicated that the system could produce a high quality effluent without any requirements for sludge recycling through the system. Suspended solids concentrations of 3–6 mg/l, BOD5 concentrations of 4 – 12 mg/l and COD concentrations of 35–45 mg/l were found in the effluent with wastewater retentions ranging from 3–15 hours, whereas an indication of nitrification was observed in higher detention periods. As far as the type of media was concerned, the plastic and aluminum media did not differ significantly once the microbes had grown on the media.

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Al-Sharekh, H. A., and M. F. Hamoda. "Removal of organics from wastewater using a novel biological hybrid system." Water Science and Technology 43, no. 1 (2001): 321–26. http://dx.doi.org/10.2166/wst.2001.0063.

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This paper summarizes the results obtained using the hybrid aerated submerged fixed-film (HASFF) process. HASFF is an innovative system comprising a four-compartment reactor having an array of fixed ceramic plates maintained under diffused aeration to support attached biomass, with activated sludge recycle to promote suspended growth in the reactor. Wastewater from a municipal treatment plant was fed to the reactor and its activated sludge was used for recycling in the hybrid system. Four pilot units were operated in the plant at various hydraulic retention times, HRTs (2, 4, 6 and 8 h), using primary-settled wastewater under organic loading rates up to 0.7 g BOD/gMLTVS · d. Data obtained showed that the overall BOD percentage removal efficiencies were consistently above 94.0% at all HRTs including the 2 hours while the COD percentage removal efficiencies ranged between 65.7–76%. The effluent's mean filtered BOD concentration ranged between 4.5–7.5 mg/l whereas the mean filtered COD concentration ranged between 70.0–89.6 mg/l. Increasing the hydraulic loading rate by four-folds from 0.08 to 0.32 m3/m2 · d had a minor effect on the unit's BOD and COD percentage removal efficiencies indicating a robust biological process that is resilient to hydraulic shock loads, thereby offering a viable upgrading option.

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Liu, Jun, Songbo Li, Weiqiang He, et al. "Roles of Granular Sludge Size Restricting and Organic Degradation in an Extended Filamentous AGS System Using Agnail Aeration Device." Water 15, no. 11 (2023): 2009. http://dx.doi.org/10.3390/w15112009.

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This work investigated the role of an agnail device (manually made from a comb) on sludge size restriction and organic degradation in extended filamentous aerobic granular sludge-sequencing batch reactors (AGS-SBRs) with artificial wastewater. Two identical SBRs (R1 and R2) were employed in this experiment. Extended filamentous AGS with a large size was achieved in both SBRs by seeding the dewatering the sludge on day 40. R1 (the control) did not use the agnail aeration device, and the extended filamentous AGS system was finally disintegrated. However, R2 promptly employed the agnail device on days 56–59, the extended filamentous AGS size obviously decreased from 4.8 mm to 2.5 mm, and the dominant filamentous species, including Proteobacteria, Acidobacteria, and Choroflexi, gradually shrank at a low level, acting as a framework for AGS recovery. This was because enough nutrients diffused into the inside of small sludge for the filamentous living. Simultaneously, the sludge volume indexes (SVI5 and SVI30) sharply decreased from 155.8–103.9 to 51.7–46.6 mL/g, and the mixed liquid suspended solids (MLSSs) and extracellular polymeric substances (EPSs) in R2 both increased and were kept at 5816 mg/L and 69.1 mg/g·MLVSS, respectively. These contributed to enhancing the sludge’s structural stability to avoid AGS failure. COD and NH4+-N in R2 were both degraded by simultaneous nitrification and denitrification (SND) processes throughout the experiment, which was not significantly influenced before or after the agnail aeration device was employed. These results indicate that the agnail device can effectively restrict AGS size and limit the extended filamentous overgrowth with nutrient diffusion into the sludge’s interior, which can prevent AGS disintegration. In addition, this device had no significant influence on organic degradation.

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Li, Huiru, Shaohua Wu, and Chunping Yang. "Performance and Biomass Characteristics of SBRs Treating High-Salinity Wastewater at Presence of Anionic Surfactants." International Journal of Environmental Research and Public Health 17, no. 8 (2020): 2689. http://dx.doi.org/10.3390/ijerph17082689.

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Sodium dodecylbenzene sulfonate (SDBS) and sodium dodecyl sulfate (SDS), as two anionic surfactants, have diffused into environments such as surface water and ground water due to extensive and improper use. The effects on the removal performance and microbial community of sequencing batch reactors (SBRs) need to be investigated in the treatment of saline wastewater containing 20 g/L NaCl. The presence of SDS and SDBS could decrease the removal efficiencies of ammonia nitrogen and total phosphorus, and the effect of SDS was more significant. The effect of surfactants on the removal mainly occurred during the aeration phase. Adding SDS and SDBS can reduce the content of extracellular polymeric substances (EPS). In addition, SDS and SDBS also can reduce the inhibition of high salinity on sludge activity. A total of 16 s of rRNA sequencing analysis showed that the addition of surfactants reduced the diversity of microbial communities; besides, the relative abundance value of the dominant population Proteobacteria increased from 91.66% to 97.12% and 93.48% when SDS and SDBS were added into the system, respectively.

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Li, Er, and Xiangying Zeng. "Evaluating the performance of fine bubble diffused aeration systems in cylindrical aeration tanks by fuzzy c-means algorithm." Water Science and Technology 84, no. 2 (2021): 404–19. http://dx.doi.org/10.2166/wst.2021.232.

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Abstract In order to make a comprehensive evaluation of the performance of fine bubble diffused aeration systems in cylindrical aeration tanks, the following parameters are considered: distribution of DO concentration in the horizontal direction of the different water depth of an aeration tank, distribution of DO concentration in the vertical direction of the aeration tank, distribution of DO concentration in all the points of the aeration tank and ratio of total mass increment of DO in the aeration tank to total mass of oxygen in aeration air. The aeration characteristic criterion (ACC) is proposed to synthesize these parameters, and weighted sums of the similarity degrees derived from the extensions of fuzzy c-means (FCM) are used to construct ACC. The results show that compared with total volumetric oxygen transfer coefficient () and specific standard oxygen transfer efficiency (), ACC is demonstrated to be more marked and sensitive for the performance evaluation of the fine bubble diffused aeration systems equipped with fine-pore aeration tubes. Moreover the performance of aeration systems equipped with different layouts of fine-pore aeration tubes is comparatively studied, and their performance from best to worst is ring-type diffuser &gt; square-type diffuser &gt; parallel-lines-type diffuser &gt; cross-type diffuser.

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Sokolova, Ala, and Mindaugas Rimeika. "THE INFLUENCE OF AERATOR MOUNTING AND WASTEWATER TREATMENT PLANT DESIGN ON THE PERFORMANCE OF AERATION SYSTEMS." Mokslas - Lietuvos ateitis 2, no. 5 (2010): 97–102. http://dx.doi.org/10.3846/mla.2010.099.

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The paper analyzes the impact of the way of mounting a tube diffuser, the design of an aeration tank and the presence of a fixed carrier on the operational parameters of aeration systems used in small wastewater treatment plants. It was found out that the vertically mounted tube diffuser decreased standard oxygen transfer rate (SOTR) of the aeration system by approximately 20% and standard oxygen transfer efficiency (SOTE) by 25% comparing to the horizontally mounted tube diffuser. It was also defined that the design of the aeration tank might have an impact on the operation parameters of the aeration system: when the centre shell used to protect a diffuser was dismantled from a test tank, SOTR and SOTE increased by approximately 20%. It was also established that the presence of the fixed carrier in the aeration tank did not have an impact on the performance of aeration systems. Finally, research was carried out to compare the operational parameters of two diffusers of different types offered on the market and used in small wastewater treatment plants. It was found out that the performance different type diffusers might vary considerably.

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Hamoda, Mohamed F., and Hamed A. Al-Sharekh. "Performance of a combined biofilm-suspended growth system for wastewater treatment." Water Science and Technology 41, no. 1 (2000): 167–75. http://dx.doi.org/10.2166/wst.2000.0026.

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This paper summarizes the results obtained using the hybrid aerated submerged fixed-film (HASFF) reactor which utilizes suspended as well as attached biomass for the treatment of wastewater. The HASFF reactor consists of four compartments with an array of fixed ceramic plates maintained under diffused aeration to support attached biomass with suspended biomass recycle to promote suspended growth in the reactor. Wastewater from a municipal treatment plant was fed to the reactor and its activated sludge was used for recycling in the hybrid system. Four pilot units were operated in the plant at various HRTs (2, 4, 6 and 8 hrs) with flow rates in the range of 0.32 to 1.2 m3/d, using primary-settled wastewater under organic loading rates up to 0.7 g BOD/g BVS.d. The data obtained showed that the overall BOD removal efficiencies were consistently above 94.0% at all HRTs, while the COD removal efficiencies ranged between 65.7–76%. The effluents' mean filtered BOD concentrations were between 4.5–7.5 mg/l whereas the mean filtered COD concentrations ranged between 70.0–89.6 mg/l. Increasing the hydraulic loading rate four-fold from 0.08 to 0.32 m3/m2.d had minor effect on the reactor's BOD and COD removal efficiencies indicating a robust biological process that is resilient to flow variation, thereby offering a viable treatment option for small plants. The HASFF process achieved organic removal and nitrification in a single reactor, with minimal sludge production. The organic removal rate was equally high at all HRTs whereas nitrification was directly proportional to the HRT, being higher at longer HRTs. The suspended biomass activity exceeded that of the attached biomass at shorter HRTs while the opposite was true at longer HRTs.

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Hamoda, Mohamed F., and Hamed A. Al-Sharekh. "Sugar wastewater treatment with aerated fixed-film biological systems." Water Science and Technology 40, no. 1 (1999): 313–21. http://dx.doi.org/10.2166/wst.1999.0062.

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Wastewater effluents from the sugar industry contain high concentrations of organic materials which are sometimes discharged into the municipal wastewater collection system and processed in wastewater treatment plants along with domestic wastewater. This study examined the performance of a four-compartment, fixed-film system in which the biofilm is attached to submerged ceramic tiles under diffused aeration, known as the aerated submerged fixed-film (ASFF) process. Field experiments were conducted using four ASFF units each of about 100 1 capacity operated at different hydraulic loading rates to provide hydraulic residence time (HRT) of 2, 4, 6 and 8 hours. Process performance was evaluated under both normal operation with domestic wastewater and under pulse and prolonged organic shock loads with sugar wastewater. The influent and effluent of the process was analyzed for solids, BOD, COD, and nitrogen forms to determine both carbonaceous and nitrogenous substrate removal. The ASFF process was found to be able to handle continuous severe organic loads increasing from about 5 to 120 g BOD/m2.d with slight decrease in organic removal efficiency from 97.9% to 88.5% for BOD and from 73.6 to 67.8% for COD. Nitrification was similarly decreased but at higher rates. The system was also able to cope with pulse injection of sugar wastewater and recovery to normal steady-state COD values was achieved in 10 hours for the 200 g COD/l spikes. An increase in the organic loading rate was accompanied by an increase in biofilm specific oxygen uptake rate until reaching a maximum which determines the optimum loading rate for process operation. Substrate removal rates were evaluated for process design.

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Hung, C. H., and W. C. Boyle. "The effect of acid cleaning on a fine pore ceramic diffuser aeration system." Water Science and Technology 44, no. 2-3 (2001): 211–18. http://dx.doi.org/10.2166/wst.2001.0772.

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Fine pore ceramic diffuser aeration, a very competitive high efficiency system, is widely used in aerobic biological processes for providing dissolved oxygen and mixing. Concern has been registered regarding the maintenance of these systems and their susceptibility to diffuser fouling. Selected ceramic diffusers, removed from the Madison Metropolitan Sewage District (MMSD) Nine Springs Wastewater Treatment Plant, Wisconsin, U.S.A., were fractured and analyzed in an attempt to identify the elemental components of the internal foulants and to evaluate the effect of acid cleaning on diffuser performance. The fouling condition of diffusers were initially characterized by dynamic wet pressure (DWP) measurements. Microimages taken from the non acid-treated diffuser profile using scanning electronic microscopy revealed the structural difference of internal foulants which may correspond to the stage of foulant formation. For diffuser samples from the MMSD facility, calcium phosphate minerals were predominant foulants, although some calcium carbonate and organic carbon have also accumulated. The clogging of diffuser internal void space was verified by observing thin sections of diffuser cross-sections. Selected diffusers were then treated with strong acid to study its effectiveness in removing internal foulant by acid soaking. Even though the acid treated diffusers showed significant reduced DWP values, acid treatment, the common diffuser cleaning technique, does not completely remove these internal foulants. This may be the reason why the acid-treated diffusers never reached like-new conditions. Furthermore, once these acid-treated diffusers are installed back to the aeration tank, these dewatered foulant sections may very well behave as seed for future clogging.

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Behnisch, J., M. Schwarz, J. Trippel, M. Engelhart, and M. Wagner. "Improving aeration systems in saline water (part II): effect of different salts and diffuser type on oxygen transfer of fine-bubble aeration systems." Water Science and Technology 83, no. 11 (2021): 2778–92. http://dx.doi.org/10.2166/wst.2021.185.

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Abstract The objective of the present study is to investigate the different effects on the oxygen transfer of fine-bubble aeration systems in saline water. Compared to tap water, oxygen transfer increases due to the inhibition of bubble coalescence. In Part I of the present study, we investigated in laboratory-scale experiments the effect of design of diffuser membrane. The objective of Part II is the assessment of effects of different salts, diffuser type and diffuser density. We measured the concentration of various salts (MgCl2; CaCl2; Na2SO4; NaCl; KCl) above which coalescence is fully inhibited and oxygen transfer reaches its maximum (referred to as the critical coalescence concentration; CCC). For this purpose, we developed a new analytical approach, which enables investigation of the coalescence behaviour of any aeration system and (mixed) salt solution quickly and easily by evaluating the results of oxygen transfer tests. To investigate the transferability to large scale and the effect of diffuser type and density, we repeated lab-scale experiments in a 17,100 L pilot-scale test tank and carried out additional tests with tube and plate diffusers at different diffuser densities. The results show that despite the higher pressure drop, diffusers with dense slit density and smaller slits are to be recommended in order to improve efficiency of aeration systems in saline water.

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Namdev,, Mritunjay, Dr Vivek Soni,, and Arpit Saxena. "Process Calculation & Design of Sewage Treatment Plant (Sequential Batch Reactor) of Sehore Town Madhya Pradesh." International Scientific Journal of Engineering and Management 04, no. 03 (2025): 1–9. https://doi.org/10.55041/isjem02568.

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Designing a Sewage Treatment Plant (STP) based on Sequencing Batch Reactor (SBR) technology involves several key considerations. SBR technology is a type of activated sludge process where wastewater is treated in batch mode rather than continuous flow. Screened, de-gritted sewage shall be fed into the Cyclic Activated Sludge Process / SBR Process Basins for biological treatment to remove BOD, COD, Suspended Solids, Biological Nitrogen and Phosphorous. SBR / Cyclic Activated Sludge Process shall work on Cyclic / Batch mode in single step. It shall perform biological organic removal, Nitrification, DE nitrification and Biological Phosphorous removal. It shall be capable of simultaneous sludge stabilization. The oxygen required shall be supplied through fixed type fine bubble diffused aeration system with auto control of oxygen level in tank. The system shall have a SVI < 120 for higher settling rates and should be designed in such a way that growth of filamentous bacteria is restricted. Complete operation of SBR / Cyclic Activated Sludge Process including decanting rate, sludge recirculation and wasting of excess sludge shall be controlled by PLC. Treated Sewage from SBR / Cyclic Activated Sludge Process units shall be collected in Chlorination tank for its disinfection. Treated effluent from this STP will have discharge standards laid down by National Green Tribunal, during Apr 2019, Therefore, the revised standards i.e. BOD5 < 10 mg/l, TSS < 20 mg/l, pH between 5.5 – 9.0, Nitrogen (Total) Sewerage network and STP of Sehore Town 11 < 10 mg/l, COD < 50 mg/l, Phosphorus Dissolved < 1 mg/l and Faecal Coliforms < 100 MPN / 100 ml (230 Acceptable) will have to be maintained before reuse or discharge. Keywords: STP, SBR, Reuse, Population Forecasting, BOD, COD

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Odize, Victory O., John Novak, Haydee De Clippeleir, et al. "Reverse flexing as a physical/mechanical treatment to mitigate fouling of fine bubble diffusers." Water Science and Technology 76, no. 7 (2017): 1595–602. http://dx.doi.org/10.2166/wst.2017.171.

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Achieving energy neutrality has shifted focus towards aeration system optimization, due to the high energy consumption of aeration processes in modern advanced wastewater treatment plants. A study on fine bubble diffuser fouling and mitigation, quantified by dynamic wet pressure (DWP), oxygen transfer efficiency and alpha was carried out in Blue Plains, Washington, DC. Four polyurethane fine bubble diffusers were installed in a pilot reactor column fed with high rate activated sludge from a full scale system. A mechanical cleaning method, reverse flexing (RF), was used to treat two diffusers (RF1, RF2), while two diffusers were kept as a control (i.e., no reverse flexing). There was a 45% increase in DWP of the control diffuser after 17 months of operation, an indication of fouling. RF treated diffusers (RF1 and RF2) did not show significant increase in DWP, and in comparison to the control diffuser prevented about 35% increase in DWP. Hence, reverse flexing potentially saves blower energy, by reducing the pressure burden on the air blower which increases blower energy requirement. However, no significant impact of the RF treatment in preventing a decrease in alpha-fouling (αF) of the fine pore diffusers, over time in operation was observed.

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Libra, J. A., A. Schuchardt, C. Sahlmann, J. Handschag, U. Wiesmann, and R. Gnirss. "Comparison of the efficiency of large-scale ceramic and membrane aeration systems with the dynamic off-gas method." Water Science and Technology 46, no. 4-5 (2002): 317–24. http://dx.doi.org/10.2166/wst.2002.0615.

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The aeration systems of two full-scale activated sludge basins were compared over 2.5 years under the same operating conditions using dynamic off-gas testing. Only the material of the diffuser was different, membrane vs. ceramic tube diffusers. The experimental design took the complexity and dynamics of the system into consideration. The investigation has shown that, although the membrane diffusers have higher initial standard oxygen transfer efficiency (SOTE) and standard aeration efficiency (SAE), these decreased over time, while the SAE of the ceramic diffusers started lower, but increased slightly over the whole period. Measurement of air distribution in the basins along with dissolved oxygen concentration profiles have provided important information on improving process control and reducing energy costs. The results show that dynamic off-gas testing can effectively be used for monitoring the aeration system and to check design assumptions under operating conditions. The information can be used to improve the design of new aeration systems or in retro-fitting existing basins.

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Drewnowski, Jakub, Anna Remiszewska-Skwarek, Sylwia Duda, and Grzegorz Łagód. "Aeration Process in Bioreactors as the Main Energy Consumer in a Wastewater Treatment Plant. Review of Solutions and Methods of Process Optimization." Processes 7, no. 5 (2019): 311. http://dx.doi.org/10.3390/pr7050311.

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Due to the key role of the biological decomposition process of organic compounds in wastewater treatment, a very important thing is appropriate aeration of activated sludge, because microorganisms have to be supplied with an appropriate amount of oxygen. Aeration is one of the most energy-consuming processes in the conventional activated sludge systems of wastewater treatment technology (may consume from 50% to 90% of electricity used by a plant), which makes it the most cost-generating process incurred by treatment plants. The paper presents the construction of aeration systems, their classification as well as parameters and factors that significantly affect the aeration process e.g., oxygen transfer efficiency, diffuser fouling, methods of dealing with diffuser fouling, diffuser selection. Additionally, there are briefly presented “smart control” systems in wastewater treatment and effect of application control strategy based on Supervisory Control and Data Acquisition system connected with the decrease in the energy consumption for aeration of bioreactors with activated sludge. It is noted that before the process is optimized, the system should be equipped with suitable metering devices. Only when relevant data is available, the improvements can be carried out. However, it’s important, that the operator should regularly maintain good condition and high efficiency of diffusers.

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Duchène;, Ph, E. Cotteux, and S. Capela. "Applying fine bubble aeration to small aeration tanks." Water Science and Technology 44, no. 2-3 (2001): 203–10. http://dx.doi.org/10.2166/wst.2001.0771.

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Because the aeration system in an activated sludge plant typically represents a large part of the total energy requirements, designers and operators need accurate oxygen transfer information to make the aeration system as energy efficient as possible. This paper presents clean water tests performed at 38 wastewater treatment plants. The Specific Aeration Efficiency results (SAE, kgO2/kWh) are reported for: (1) large open channels (volume higher than 1000 m3), (2) small open channels, (3) total floor coverage cylindrical tanks, and (4) cylindrical tanks with a grid arrangement. Some practical guidelines can be drawn, some of them being: (1) high SAE can be achieved at small aeration tanks (&lt;1000m3), applying cylindrical tanks with a total floor coverage arrangement of diffusers, volumetric blowers, and moderate air flow rates per diffuser area; (2) the high investment cost of this configuration can be justified with respect to a grid layout characterized by spiral liquid circulation which affects the oxygen transfer; (3) small open channels can meet sufficient SAE values but fail to meet in this range of tank volumes those of total floor coverage cylindrical tanks.

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Capela, S., M. Roustan, and A. Héduit. "Transfer number in fine bubble diffused aeration systems." Water Science and Technology 43, no. 11 (2001): 145–52. http://dx.doi.org/10.2166/wst.2001.0677.

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On the basis of full-scale data from 58 clean water tests performed in 26 activated sludge tanks equipped with fine bubble diffusers and of a theoretical approach, it can be stated that fine bubble aeration systems with total floor coverage arrangement provide higher kLa values and the lowest spiral liquid circulation. An efficiency criterion for oxygen transfer ( NT) was defined on the basis of the dimensional analysis. The transfer number NT allows us to take account of the impact of vertical liquid circulation movements on oxygen transfer. The values of NT calculated from the results of full scale nonsteady-state clean water tests vary from 5.3×10-5 to 9.1×10-5 and are directly dependent upon the arrangement of air diffusers. It has been shown that the highest transfer numbers corresponded to the total floor coverage arrangement and the average calculated NT values is 7.7×10-5, independently of the diffuser density and of the gas velocity, over the ranges studied. The lowest transfer numbers are obtained when the diffusers are located in separate grids, and the transfer number is reduced with increasing air flow rate.

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Schraa, Oliver, Leiv Rieger, and Jens Alex. "Development of a model for activated sludge aeration systems: linking air supply, distribution, and demand." Water Science and Technology 75, no. 3 (2016): 552–60. http://dx.doi.org/10.2166/wst.2016.481.

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During the design of a water resource recovery facility, it is becoming industry practice to use simulation software to assist with process design. Aeration is one of the key components of the activated sludge process, and is one of the most important aspects of modelling wastewater treatment systems. However, aeration systems are typically not modelled in detail in most wastewater treatment process modelling studies. A comprehensive dynamic aeration system model has been developed that captures both air supply and demand. The model includes sub-models for blowers, pipes, fittings, and valves. An extended diffuser model predicts both oxygen transfer efficiency within an aeration basin and pressure drop across the diffusers. The aeration system model allows engineers to analyse aeration systems as a whole to determine biological air requirements, blower performance, air distribution, control valve impacts, controller design and tuning, and energy costs. This enables engineers to trouble-shoot the entire aeration system including process, equipment and controls. It also allows much more realistic design of these highly complex systems.

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Rosso, Diego, Lu-Man Jiang, David M. Hayden, et al. "Towards more accurate design and specification of aeration systems using on-site column testing." Water Science and Technology 66, no. 3 (2012): 627–34. http://dx.doi.org/10.2166/wst.2012.187.

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Fine-pore diffuser systems are selected for their potential energy efficiency, and during design their propensity for fouling and for an increase in pressure drop with time must be considered. Both fouling and pressure-drop increase cause an increase in blower power requirements. This paper presents a new approach to improve this design procedure, without altering the technical structure of the classical approach. While the administrative and bidding milestones are being carried out (i.e., in the first 6 months of the project milestones), an independent aeration team can test candidate diffusers suitable for design in an aeration column in situ. An extended fouling test in the plant's aeration tanks allows the collection of site-specific aeration performance data. These improve the accuracy of the design process, and limit the reliance on safety factors.

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Gillot, S., and A. Héduit. "Prediction of alpha factor values for fine pore aeration systems." Water Science and Technology 57, no. 8 (2008): 1265–69. http://dx.doi.org/10.2166/wst.2008.222.

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The objective of this work was to analyse the impact of different geometric and operating parameters on the alpha factor value for fine bubble aeration systems equipped with EPDM membrane diffusers. Measurements have been performed on nitrifying plants operating under extended aeration and treating mainly domestic wastewater. Measurements performed on 14 nitrifying plants showed that, for domestic wastewater treatment under very low F/M ratios, the alpha factor is comprised between 0.44 and 0.98. A new composite variable (the Equivalent Contact Time, ECT) has been defined and makes it possible for a given aeration tank, knowing the MCRT, the clean water oxygen transfer coefficient and the supplied air flow rate, to predict the alpha factor value. ECT combines the effect on mass transfer of all generally accepted factors affecting oxygen transfer performances (air flow rate, diffuser submergence, horizontal flow).

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Chern, Jia-Ming, and Cheng-Fu Yu. "Oxygen Transfer Modeling of Diffused Aeration Systems." Industrial & Engineering Chemistry Research 36, no. 12 (1997): 5447–53. http://dx.doi.org/10.1021/ie9700627.

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Stenstrom, Michael K. "Upgrading Existing Activated Sludge Treatment Plants with Fine Pore Aeration Systems." Water Science and Technology 22, no. 7-8 (1990): 245–51. http://dx.doi.org/10.2166/wst.1990.0251.

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Over the past ten years aeration systems development in the United States has centered around fine pore diffuser upgrades to existing activated sludge plants. A variety of older aeration systems have been replaced with new diffuser systems which include full floor coverage systems, composed of ceramic or plastic discs, ceramic and plastic tubes, and membrane tubes or discs. This manuscript reports on aeration system upgrades at six different full scale treatment plants. Seven different devices were evaluated using the off-gas analysis technique. Diffuser cleaning methods were also evaluated. Results are presented which show the economic incentives for upgrading and the increased plant capacity which resulted from increased aeration efficiency. It was found that the effects of process operation, such as step feed, F/M, MLSS concentration, mean cell retention time and air flux had a major impact on transfer efficiency. The effects of diffuser fouling and cleaning methods are presented.

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Mostefa, Gafsi, Kettab Ahmed, and Abdelkader Djehiche. "Study of the Oxygen Transfer Efficiencies in the Different Methods Used in the Technique of Hypolimnetic Aeration." Advanced Materials Research 452-453 (January 2012): 1014–19. http://dx.doi.org/10.4028/www.scientific.net/amr.452-453.1014.

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Thermal stratification of lakes and reservoirs can result in substantial hypolimnetic oxygen depletion, which may have a negative impact on the cold-water fisheries, the drinking water treatment process, and water quality downstream of hydropower reservoirs. Several techniques of aeration are presented in this study, to describe their effectiveness in control of physical and chemical parameters, that compromising the balance ecological and the thermal stratification in water supplies. As a result, we demonstrate that the most efficient hypolimnetic aeration system is the bubble plume diffuser; although an accidental destratification may occur. In hypolimnetic aeration systems, the aeration system by bubble plume appears to be the most economic and perhaps the simplest among the systems used in Stanley lake (Colorado, U.S.A), even as other researches select Speece Cone aeration system, or the full airlift systems, or the TVA line diffuser. The purpose of this study is to show the oxygen transfer efficiencies in the different methods used in the technique of hypolimnetic aeration, and their effect on the preservation of the thermal stratification. As well, this study concentrate on the economic and technical sides associated to these aeration systems.

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Kossay K. Al-Ahmady, Dr. "EFFECT OF AIRFLOW RATE AND SUBMERGENCE OF DIFFUSERS ON OXYGEN TRANSFER CAPACITY OF DIFFUSED AERATION SYSTEMS." AL-Rafdain Engineering Journal (AREJ) 14, no. 1 (2006): 27–38. http://dx.doi.org/10.33899/rengj.2006.46257.

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Warriner, R., and T. C. Rooney. "Experience with Ceramic Plate Diffusers in Large Activated Sludge Plants." Water Science and Technology 25, no. 4-5 (1992): 127–34. http://dx.doi.org/10.2166/wst.1992.0487.

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Fine pore aeration systems were evaluated in a U.S.EPA sponsored study of oxygen transfer efficiency in 26 activated sludge plants. Two plants in the study, those of the Milwaukee Metropolitan Sewerage District, had aeration systems composed of flat plates grouted into containers placed flush with the basin floor. The remaining plants in the study had aeration systems utilizing various disk, dome, and tube devices that are now in far more widespread use than the flat plates. The District's aeration basins gave better oxygen transfer efficiency than the other ceramic diffuser systems studied. The difference may have been the result of the high tank area to diffuser area ratio and the low air flux rates associated with the plate systems. At one MMSD plant there were also four basins with recently installed ceramic disk diffuser systems. This provided an opportunity for side-by-side comparisons between the disks and the flat plates in containers. An analysis of diffuser system first costs and energy costs indicated that the ceramic plate system could be cost effective at higher power costs, but not at the prices presently paid by the District for power.

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Frey, W. "A Comparison of Different Aeration Systems." Water Science and Technology 25, no. 4-5 (1992): 143–49. http://dx.doi.org/10.2166/wst.1992.0489.

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Aeration tests have been performed under operation conditions and in clean water in order to obtain information on the economy of different aeration systems. The results of investigations using jet aerators membrane diffusers and surface aerators are reported. The aeration tanks used for the tests were tanks with circulating mixed liquor. Typical α-values are reported for different systems tested and operational experiences are also included.

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Thatcher, K. "Fine Bubble Aeration Using a High Density Diffuser System." Water Science and Technology 26, no. 9-11 (1992): 2437–40. http://dx.doi.org/10.2166/wst.1992.0756.

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Current developments with the activated sludge processes with highly concentrated effluents highlight the requirement to (a) reduce energy usage (b) promote the production of high quality effluent. Having observed the efforts being made to improve plant performance we became aware that current methods had to be improved. It was also noted that a period of stagnation had occurred in the development of effective aeration systems. Improved aeration methods are needed which would allow for oxygen transfer efficiencies to be greater than 2kg/kWh. Such oxygen transfer rates should be continually variable in line with the oxygen demand prevailing at any given time. In our study of activated sludge plants we found that operational and electrical/mechanical maintenance was proving to be time consuming and very costly. With these problems in mind we have designed and developed the Fine Bubble High Density Diffuser System.

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Maulianawati, Diana, Hendri Kiing, Dena Pramita Dewi, Heni Irawati, and Muhammad Amien. "The Application of Different Types of Diffusers for African Catfish (Clarias gariepinus) Culture in Biofloc Systems: Effects on Growth and Water Quality." Journal of Aquaculture and Fish Health 13, no. 1 (2024): 69–79. http://dx.doi.org/10.20473/jafh.v13i1.43013.

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Applying biofloc technology in the intensive and extensive culture of Clarias gariepinus can improve water quality and be used to feed fish. Aeration systems were a critical unit supporting biofloc and water quality. This study's objective was assessment to various types of diffusers on the growth and water quality in a C. gariepinus culture. Two types of diffusers unit were prepared for the experiment, there are air tube diffuser (AT) and air stone diffuser (AS). Growth parameters, water quality, and volume of biofloc were observed within 30 days. The survival rate, weight gain, average body weight, and specific growth rate of C. gariepinus were higher in the tanks that used air tubes (98%, 485.29 %, 7.52 g, 5.89%) than in the tanks that used air stones (92 %, 385.94 %, 5.98 g, 5.23%). The volume of biofloc range from 5.40-18.80 ml/L in AT tanks and 4.60-14.00 ml/L in AS tanks. There is no significant difference (p > 0.05) in water quality parameters and FCR value. However, using the air tube diffuser showed better results with the growth performance, survival rate, and formation of biofloc.

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Piotrowski, Robert, and Tomasz Ujazdowski. "Designing Control Strategies of Aeration System in Biological WWTP." Energies 13, no. 14 (2020): 3619. http://dx.doi.org/10.3390/en13143619.

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The paper presents the complete design processes of novel aeration control systems in the SBR (sequencing batch reactor) wastewater treatment plant (WWTP). Due to large energy expense and a high influence on biological processes, the aeration system plays a key role in WWTP operation. The paper considers the aeration system for a biological WWTP located in the northeast of Poland. This system consists of blowers, the main collector pipeline, three aeration lines with different diameters and lengths, and diffusers. Classical control systems applied for this type of installation are based on PID (proportional–integral–derivative) controllers, the settings of which are often found experimentally. The article presents the optimization of these settings and the design of an alternative control algorithm—the fuzzy controller.

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Oprina, Gabriela, Florentina Bunea, Irina Pincovschi, and Lucian Mandrea. "ASPECTS OF HYDRODYNAMICS AND MASS TRANSFER IN DIFFUSED AERATION SYSTEMS." Environmental Engineering and Management Journal 9, no. 4 (2010): 565–71. http://dx.doi.org/10.30638/eemj.2010.079.

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McWhirter, John R., and Joseph C. Hutter. "Improved oxygen mass transfer modeling for diffused/subsurface aeration systems." AIChE Journal 35, no. 9 (1989): 1527–34. http://dx.doi.org/10.1002/aic.690350913.

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Reinius, L. G., and J. Hultgren. "Evaluation of the Efficiency of a New Aeration System at Henriksdal Sewage Treatment Plant." Water Science and Technology 20, no. 4-5 (1988): 85–92. http://dx.doi.org/10.2166/wst.1988.0156.

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Henriksdal sewage treatment plant is the largest plant in Stockholm with a design flow of 370 000 m3/d. In one aeration tank of eleven a new fine-bubble aeration system has been in operation since August 1985. The tank is divided into 6 equal parts. The first part is an anoxic zone and the other five are aeration zones with tapered diffusers. Several instruments are installed in the block including separate air flow monitors in each of the five zones and D.O.-probes in the inlet and outlet of the zones. Equipment for flow measurement of settled sewage and return sludge is also installed. Every instrument is connected to a computer for data acquisition. To evaluate the efficiency of the aeration system the oxygenation transfer capacity has been calculated from the oxygen massbalance equation for each zone as a function of air flow. To solve this equation the respiration has to be known and this is done by a simple respirometer for samples of the MLSS in each zone. When the KLa-values are known as functions of the air flow the mass balance equation can be used to calculate the respiration rate in each zone. The computer has been logging data for 2 2 months, and it is possible to calculate the respiration rates in the different zones every hour during this period. It is very important to know the respiration along the tank and how it varies to get the optimal tapering of the diffusers when it is time to change the aeration system in the other 10 tanks. The calculations show a different pattern in the respiration over the year depending on the rate of nitrification. Another use of the calculation of the oxygenation transfer efficiency is to recognize if any long-term change occurs due to clogging of the diffusers.

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Journal articles on the topic 'Diffused aeration system'

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