scholarly journals Fate of selected pharmaceutically active compounds in the integrated fixed film activated sludge process

2017 ◽  
Vol 75 (11) ◽  
pp. 2680-2691 ◽  
Author(s):  
K. J. Murray ◽  
W. J. Parker ◽  
L. M. Bragg ◽  
M. R. Servos
Keyword(s):  
Activated Sludge ◽  
Municipal Wastewater ◽  
Nitrification Rate ◽  
Process Conditions ◽  
Batch Reactors ◽  
Experimental Conditions ◽  
Conventional Activated Sludge ◽  
Fixed Film ◽  
Solids Retention ◽  
Biomass Activity

The potential for integrated fixed film activated sludge (IFAS) processes to achieve enhanced transformation of pharmaceuticals relative to conventional activated sludge (CAS) processes was assessed. Previous studies have focused on direct comparisons of parallel reactors with and without fixed film carriers and little information is available on the impacts of how varying operating parameters impact the differences in observed pharmaceutical compound (PC) transformation capabilities between CAS reactors and those equipped with both an activated sludge (AS) and fixed film carriers. The testing was carried out using bench scale sequencing batch reactors fed with authentic municipal wastewater and operated at selected combinations of temperature and solids retention time (SRT). PC transformation efficiencies were assessed in a 22 factorial design that employed the IFAS and CAS processes, operated in parallel under identical process conditions. Nitrification rate testing that was conducted to obtain insight into the biomass activity demonstrated that IFAS consistently had improved nitrification kinetics despite lower mixed liquor volatile suspended solids levels thereby demonstrating the contribution of the biofilm to nitrification. Increased transformation of atenolol (ATEN; ranging from 10–60%) and trimethoprim (TRIM; ranging from 30–50%) in the IFAS equipped reactors relative to their respective activated sludge (AS) controls was observed under all experimental conditions. Negligible transformation of carbamazepine was observed in both reactors under all conditions investigated. More than 99% of acetaminophen was transformed in both configurations under all conditions. There was no correspondence between nitrification activity and TRIM removal in the control AS while conditions that stimulated nitrification in the control AS also resulted in enhanced removal of ATEN. The results of this study indicate that the integration of biofilms in AS processes enhances transformation of some PCs.

Validating the Colloid model to optimise the design and operation of both moving-bed biofilm reactor and integrated fixed-film activated sludge systems

2014 ◽  
Vol 69 (7) ◽  
pp. 1552-1557 ◽  
Author(s):  
J. Albizuri ◽  
P. Grau ◽  
M. Christensson ◽  
L. Larrea
Keyword(s):  
Activated Sludge ◽  
Oxygen Demand ◽  
Biofilm Reactor ◽  
Nitrification Rate ◽  
Moving Bed Biofilm Reactor ◽  
Moving Bed ◽  
Fixed Film ◽  
Solids Retention ◽  
Lower Effect ◽  
Activated Sludge Systems

The paper presents a systematic study of simulations, using a previously calibrated Colloid model, from which it was found that: (i) for pure moving-bed biofilm reactor (MBBR) processes with tertiary nitrification conditions (no influent chemical oxygen demand (COD)), dissolved oxygen = 5 mg/L and residual NH4-N > 4 mgN/L, a nitrification rate of 1.2 gN/(m2d) was obtained at 10 °C. This rate decreases sharply when residual NH4-N is lower than 2 mgN/L, (ii) for MBBR systems with predenitrification–nitrification zones and COD in the influent (soluble and particulate), the nitrification rate (0.6 gN/(m2d)) is half of that in tertiary nitrification due to the effect of influent colloidal XS (particulate slowly biodegradable COD) and (iii) for integrated fixed-film activated sludge (IFAS) processes the nitrification rate in the biofilm (0.72 gN/(m2d)) is 20% higher than for the pure MBBR due to the lower effect of influent XS since it is adsorbed onto flocs. However, it is still 40% lower than the tertiary nitrification rate. In the IFAS, the fraction of the nitrification rate in suspension ranges from 10 to 70% when the aerobic solids retention time varies from 1.4 to 6 days.

Optimal sludge retention time for a bench scale MBR treating municipal sewage

2008 ◽  
Vol 57 (3) ◽  
pp. 319-322 ◽  
Author(s):  
A. Pollice ◽  
G. Laera ◽  
D. Saturno ◽  
C. Giordano ◽  
R. Sandulli
Keyword(s):  
Activated Sludge ◽  
Membrane Bioreactor ◽  
Municipal Wastewater ◽  
Operating Conditions ◽  
Municipal Sewage ◽  
Process Conditions ◽  
Physical Parameters ◽  
Municipal Wastewater Treatment ◽  
Bench Scale ◽  
Conventional Activated Sludge

Membrane bioreactors allow for higher sludge concentrations and improved degradation efficiencies with respect to conventional activated sludge. However, in the current practice these systems are often operated under sub-optimal conditions, since so far no precise indications have yet been issued on the optimal operating conditions of MBR for municipal wastewater treatment. This paper reports some results of four years of operation of a bench scale membrane bioreactor where steady state conditions were investigated under different sludge retention times. The whole experimental campaign was oriented towards the investigation of optimal process conditions in terms of COD removal and nitrification, biomass activity and growth, and sludge characteristics. The membrane bioreactor treated real municipal sewage, and four different sludge ages were tested (20, 40, 60, and 80 days) and compared with previous data on complete sludge retention. The results showed that the the biology of the system, as assessed by the oxygen uptake rate, is less affected than the sludge physical parameters. In particular, although the growth yield was observed to dramatically drop for SRT higher than 80 days, the biological activity was maintained under all the tested conditions. These considerations suggest that high SRT are convenient in terms of limited excess sludge production without losses of the treatment capacity. Physical characteristics such as the viscosity and the filterability appear to be negatively affected by prolonged sludge retention times, but their values remain within the ranges normally reported for conventional activated sludge.

Floc size distribution and bacterial activities in membrane separation activated sludge processes for small-scale wastewater treatment/reclamation

1997 ◽  
Vol 35 (6) ◽  
pp. 37-44 ◽  
Author(s):  
Boran Zhang ◽  
Kazuo Yamamoto ◽  
Shinichiro Ohgaki ◽  
Naoyuki Kamiko
Keyword(s):  
Wastewater Treatment ◽  
Activated Sludge ◽  
Municipal Wastewater ◽  
Membrane Separation ◽  
Small Scale ◽  
Nitrification Rate ◽  
Floc Size ◽  
Denitrification Activity ◽  
Concentration Changes ◽  
Activated Sludge Processes

Activated sludges taken from full-scale membrane separation processes, building wastewater reuse system (400m3/d), and two nightsoil treatment plants (50m3/d) as well as laboratory scale membrane separation bioreactor (0.062m3/d) were analyzed to characterize membrane separation activated sludge processes (MSAS). They were also compared with conventional activated sludges(CAS) taken from municipal wastewater treatment plants. Specific nitrification activity in MSAS processes averaged at 2.28gNH4-N/kgMLSS.h were higher than that in CAS processes averaged at 0.96gNH4-N/kgMLSS.h. The denitrification activity in both processes were in the range of 0.62-3.2gNO3-N/kgMLSS.h without organic addition and in the range of 4.25-6.4gNO3-N/kgMLSS.h with organic addition. The organic removal activity in nightsoil treatment process averaged at 123gCOD/kgMLSS.h which was significantly higher than others. Floc size distributions were measured by particle sedimentation technique and image analysis technique. Flocs in MSAS processes changed their sizes with MLSS concentration changes and were concentrated at small sizes at low MLSS concentration, mostly less than 60 μm. On the contrary, floc sizes in CAS processes have not much changed with MLSS concentration changes and they were distributed in large range. In addition, the effects of floc size on specific nitrification rate, denitrification rate with and without organic carbon addition were investigated. Specific nitrification rate was decreased as floc size increased. However, little effect of floc size on denitrification activity was observed.

Dynamic modeling of nitrogen removal for a three-stage integrated fixed-film activated sludge process treating municipal wastewater

2017 ◽  
Vol 41 (2) ◽  
pp. 237-247 ◽  
Author(s):  
Paul Moretti ◽  
Jean-Marc Choubert ◽  
Jean-Pierre Canler ◽  
Pierre Buffière ◽  
Olivier Pétrimaux ◽  
...  
Keyword(s):  
Activated Sludge ◽  
Dynamic Modeling ◽  
Nitrogen Removal ◽  
Municipal Wastewater ◽  
Activated Sludge Process ◽  
Fixed Film

Nitrification in activated sludge batch reactors is linked to protozoan grazing of the bacterial population

2005 ◽  
Vol 51 (9) ◽  
pp. 791-799 ◽  
Author(s):  
Penny Petropoulos ◽  
Kimberley A Gilbride
Keyword(s):  
Activated Sludge ◽  
Bacterial Population ◽  
Grazing Pressure ◽  
Nitrification Rate ◽  
Batch Reactors ◽  
Ammonia Oxidizing Bacteria ◽  
Bacterial Concentration ◽  
Batch Cultures ◽  
Protozoan Grazing ◽  
Swimming Bacteria

Protozoa feed upon free-swimming bacteria and suspended particles inducing flocculation and increasing the turnover rate of nutrients in complex mixed communities. In this study, the effect of protozoan grazing on nitrification was examined in activated sludge in batch cultures maintained over a 14-day period. A reduction in the protozoan grazing pressure was accomplished by using either a dilution series or the protozoan inhibitor cycloheximide. As the dilutions increased, the nitrification rate showed a decline, suggesting that a reduction in protozoan or bacterial concentration may cause a decrease in nitrification potential. In the presence of cycloheximide, where the bacterial concentration was not altered, the rates of production of ammonia, nitrite, and nitrate all were significantly lower in the absence of active protozoans. These results suggest that a reduction in the number or activity of the protozoans reduces nitrification, possibly by limiting the availability of nutrients for slow-growing ammonia and nitrite oxidizers through excretion products. Furthermore, the ability of protozoans to groom the heterotrophic bacterial population in such systems may also play a role in reducing interspecies competition for nitrification substrates and thereby augment nitrification rates.Key words: nitrification, activated sludge, protozoan grazing, ammonia-oxidizing bacteria, cycloheximide.

Full-scale evaluation of an integrated fixed-film activated sludge (IFAS) process for enhanced nitrogen removal

1996 ◽  
Vol 33 (12) ◽  
pp. 155-162 ◽  
Author(s):  
Clifford W. Randall ◽  
Dipankar Sen
Keyword(s):  
Activated Sludge ◽  
Nitrogen Removal ◽  
Plug Flow ◽  
Treatment Plant ◽  
Nitrification Rate ◽  
A Value ◽  
Fixed Film ◽  
Control Section ◽  
The Media ◽  
Retrofit Design

One of the two trains of the 37,000 m3/d Annapolis, Maryland step aeration activated sludge treatment plant was modified for single-sludge anoxic-aerobic operation, and then fixed-film media were integrated into the aerobic zone to enhance nitrification. Rope-like Ringlace media was selected for integration, and 30,000 meters were installed in a volume of 475 m3 for a pilot demonstration. The purpose of the integrated fixed-film media was to upgrade the short hydraulic retention time (HRT) basin (6 hrs nominal) for efficient, year-round nitrogen removal without construction to increase basin volume. An engineering study had concluded that upgrading the facility for year round complete nitrification, without nitrogen removal, would cost US$24 million. The modified train was operated for 12 months, six in the plug-flow MLE configuration, and six in a step-feed configuration. The integrated Ringlace media increased the nitrification rate per unit volume to 225% of that observed in the control section, attaining a value of 1.75 kg/d NH3-N per linear meter at 15°C. The media also increased denitrification in the aerobic media section to the extent that between 30 and 88% of the nitrates formed in the section were denitrified within it, permitting a potential 25% or more reduction in the volume of the anoxic zone. An IFAS retrofit design was developed which incorporated step-feed operation, and reduced the projected construction cost to US$9.2 million.

scholarly journals LCA of a Membrane Bioreactor Compared to Activated Sludge System for Municipal Wastewater Treatment

Membranes ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 421
Author(s):  
Dimitra C. Banti ◽  
Michail Tsangas ◽  
Petros Samaras ◽  
Antonis Zorpas
Keyword(s):  
Wastewater Treatment ◽  
Life Cycle ◽  
Activated Sludge ◽  
Membrane Bioreactor ◽  
Municipal Wastewater ◽  
Wastewater Treatment Plants ◽  
Treatment Plant ◽  
Real Data ◽  
Municipal Wastewater Treatment ◽  
Conventional Activated Sludge

Membrane bioreactor (MBR) systems are connected to several advantages compared to the conventional activated sludge (CAS) units. This work aims to the examination of the life cycle environmental impact of an MBR against a CAS unit when treating municipal wastewater with similar influent loading (BOD = 400 mg/L) and giving similar high-quality effluent (BOD < 5 mg/L). The MBR unit contained a denitrification, an aeration and a membrane tank, whereas the CAS unit included an equalization, a denitrification, a nitrification, a sedimentation, a mixing, a flocculation tank and a drum filter. Several impact categories factors were calculated by implementing the Life Cycle Assessment (LCA) methodology, including acidification potential, eutrophication potential, global warming potential (GWP), ozone depletion potential and photochemical ozone creation potential of the plants throughout their life cycle. Real data from two wastewater treatment plants were used. The research focused on two parameters which constitute the main differences between the two treatment plants: The excess sludge removal life cycle contribution—where GWPMBR = 0.50 kg CO2-eq*FU−1 and GWPCAS = 2.67 kg CO2-eq*FU−1 without sludge removal—and the wastewater treatment plant life cycle contribution—where GWPMBR = 0.002 kg CO2-eq*FU−1 and GWPCAS = 0.14 kg CO2-eq*FU−1 without land area contribution. Finally, in all the examined cases the environmental superiority of the MBR process was found.

Environmental performance of an integrated fixed-film activated sludge (IFAS) reactor treating actual municipal wastewater during start-up phase

2015 ◽  
Vol 72 (10) ◽  
pp. 1840-1850 ◽  
Author(s):  
Nitin Kumar Singh ◽  
Absar Ahmad Kazmi ◽  
Markus Starkl
Keyword(s):  
Activated Sludge ◽  
Pathogenic Bacteria ◽  
Municipal Wastewater ◽  
Oxygen Demand ◽  
Pilot Scale ◽  
Lessons Learned ◽  
Present System ◽  
Salmonella Spp ◽  
Start Up ◽  
Fixed Film

The present study summarizes the start-up performance and lessons learned during the start-up and optimization of a pilot-scale plant employing integrated fixed film activated sludge (IFAS) process treating actual municipal wastewater. A comprehensive start-up was tailored and implemented to cater for all the challenges and problems associated with start-up. After attaining desired suspended biomass (2,000–3,000 mg/L) and sludge age (∼7 days), the average biological oxygen demand (BOD) and chemical oxygen demand (COD) removals were observed as 77.3 and 70.9%, respectively, at optimized conditions, i.e. hydraulic retention time (HRT), 6.9 h; return sludge rate, 160%. The influent concentrations of COD, BOD, total suspended solids, NH3-N, total nitrogen and total phosphorus were found to be in the range of 157–476 mg/L, 115–283 mg/L, 152–428 mg/L, 23.2–49.3 mg/L, 30.1–52 mg/L and 3.6–7.8 mg/L, respectively, and the minimum effluent concentrations were achieved as ∼49 mg/L, 23 mg/L, 35 mg/L, 2.2 mg/L, 3.4 mg/L and 2.8 mg/L, respectively, at optimum state. The present system was found effective in the removal of pathogenic bacteria (Escherichia coli, 79%; Salmonella spp., 97.5%; Shigella spp., 92.9%) as well as coliforms (total coliforms, 97.65%; faecal coliforms, 80.35%) without any disinfection unit. Moreover it was observed that the time required for the stabilization of the plant was approximately 3 weeks if other parameters (sludge age, HRT and dissolved oxygen) are set to optimized values.

Removal Efficiency of Environmental Endocrine Disrupting Chemicals Pollutants-Phthalate Esters in Northern WWTP

2013 ◽  
Vol 807-809 ◽  
pp. 694-698
Author(s):  
Rong Xin Huang ◽  
Zhen Xing Wang ◽  
Gang Liu ◽  
Qi Jin Luo
Keyword(s):  
Activated Sludge ◽  
Removal Efficiency ◽  
Municipal Wastewater ◽  
Removal Rate ◽  
Phthalate Esters ◽  
Endocrine Disrupting Chemicals ◽  
Treatment Plant ◽  
Activated Sludge Process ◽  
Wastewater Reclamation ◽  
Conventional Activated Sludge

In order to guarantee the reliability and security of reclaiming water, research on the removal efficiency of the environmental endocrine chemicals (EDCs) --the Phthalate Esters (PAEs) in conventional secondary activated sludge and wastewater reclamation and reuse process was undergoing at Harbin wastewater treatment plant (WWTP). The wastewater samples were colleted from every unit effluent of WWTP. The results showed that contamination of EDCs were presented in municipal wastewater at Harbin and the concentrations of the four PAEs were 21.01μg/L for Di-n-butyl Phthalate (DBP); 9.63μg/L for Di-n-octyl Phthalate (DnOP); 4.56μg/L for Diethyl Phthalate (DEP); 1.96μg/L for Dimethyl Phthalate (DMP) respectively in the influent. The conventional activated sludge has good removal efficiencies performance on DMP, DEP and DBP. With the increasing of molecular weight and branch chains of PAEs contaminations, the removal rate of the four PAEs in the conventional activated sludge process decreased from 99.82%(DMP)，90.60%(DEP)，90.10%(DBP) to the only 45.13% removal rate for DnOP, which was mostly removed from primary treatment but no from secondary activated sludge process; Coagulation-air flotation plus filtration process was not a feasible way to remove PAEs from reclaiming treatment units.

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