Treatment of municipal wastewater in a hybrid process using a new suspended carrier with large surface area

2004 ◽  
Vol 49 (11-12) ◽  
pp. 207-214 ◽  
Author(s):  
M. Christensson ◽  
T. Welander
Keyword(s):  
Activated Sludge ◽  
Surface Area ◽  
Pilot Plant ◽  
Suspended Solids ◽  
Municipal Wastewater ◽  
Large Surface Area ◽  
Hybrid Process ◽  
Nitrification Rate ◽  
Suspended Carrier ◽  
Activated Sludge Processes

An activated sludge/biofilm hybrid process treating municipal wastewater was studied in pilot plant trials. A new type of suspended carrier, with large effective surface area, was employed in the process with the aim of enhancing nitrification. The pilot plant was operated for 1.5 years in five different configurations including pre-denitrification in all five and enhanced biological phosphorus removal in the final two. The wastewater temperature ranged between 11°C and 20°C, and the nominal dissolved oxygen (DO) level was 5-6 mg/L. The nitrification rate obtained on the new carrier within the hybrid stage was in the range of 0.9-1.2 g NH4-N/m2/d corresponding to a volumetric rate of 19-23 g NH4-N/m3/h (total nitrification including nitrification in the suspended solids). More than 80% of the total nitrification took place on the carrier (and the remainder in the suspended solids). The nitrification rate was shown to correlate with DO, decreasing when the DO was decreased. The results supported the idea of using the new carrier as a tool to upgrade plants not having nitrification today or improve nitrification in activated sludge processes not reaching necessary discharge levels. The large surface area present for nitrification makes it possible to obtain high nitrification rates within limited volumes. The possibility to keep the total suspended solid content low (<3 g/L) and avoiding problems with the filament Microthrix parvicella, are other beneficial properties of the hybrid process.

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.

Improving nitrogen removal in predenitrification-nitrification biofilters

2004 ◽  
Vol 48 (11-12) ◽  
pp. 419-428 ◽  
Author(s):  
L. Larrea ◽  
A. Abad ◽  
J. Gayarre
Keyword(s):  
Dissolved Oxygen ◽  
Activated Sludge ◽  
Nitrogen Removal ◽  
Suspended Solids ◽  
Complete Removal ◽  
Cod Removal ◽  
Nitrification Rate ◽  
Removal Rates ◽  
N Removal ◽  
Activated Sludge Processes

The effect on NH4-N removal rates in nitrification biofilters of filtered biodegradable COD and particulate COD leaving predenitrification biofilters was studied in a lab scale plant configured with the separated system of biofilters for secondary nitrogen removal from urban wastewaters. Applying a typical COD load of 11 kg/m3.day to the predenitrification biofilter and maximizing its COD removal by adding nitrates or by operating an improved control of the internal recycle, only 60% removal of filtered biodegradable COD was found. This value corresponds to the complete removal of the readily biodegradable substrate (30% of influent filtered COD) and 36% of filtered slowly biodegradable substrate (50% of influent COD). The remaining 64% of the latter entered the nitrification biofilter, causing competition between heterotrophs and nitrifiers for dissolved oxygen in the inner layers of the biofilm. Consequently the nitrification rate had relatively low values (0.5 kgN/m3.d) at 14°C despite using dissolved oxygen levels of 6 mg/l. This behaviour may explain the lower nitrification rates obtained in some cases of nitrification biofilters compared to those in tertiary nitrification after activated sludge processes. The particulate COD entering the nitrification biofilter is associated with the suspended solids leaving the denitrification biofilter which are adsorbed by the external layers of the biofilm, increasing its thickness. The activity of the nitrifiers was affected because of a lack of oxygen when the thickness was left to grow considerably. Therefore no significant particulate COD effect is expected to occur as long as backwashing is carried out with the appropriate frequency.

Nitrification and mass balance with a membrane bioreactor for municipal wastewater treatment

1996 ◽  
Vol 34 (1-2) ◽  
pp. 129-136 ◽  
Author(s):  
Fan Xiao-Jun ◽  
Vincent Urbain ◽  
Yi Qian ◽  
Jacques Manem
Keyword(s):  
Wastewater Treatment ◽  
Activated Sludge ◽  
Membrane Bioreactor ◽  
Suspended Solids ◽  
Municipal Wastewater ◽  
Rate Coefficients ◽  
Nitrification Rate ◽  
Municipal Wastewater Treatment ◽  
Effluent Quality

The overall performance of the Membrane Bioreactor (MBR) process for municipal wastewater treatment was studied to determine the characteristics of activated sludge under different Sludge Retention Times (SRT) and Hydraulic Retention Times (HRT). The experiment lasted over a period of 300 days, which included 4 runs. The effluent quality of the MBR process in terms of COD and suspended solids, was excellent under all conditions tested. Specific nitrification rates of the activated sludge were measured at steady state in each run. Similar maximum nitrification rate values were obtained through batch experiments with either only NH4Cl or raw wastewater as substrate. Mass balances of the process in terms of COD, nitrogen and inorganic suspended solids were made, and it was found that 28%, 42%, and 48% of influent COD were converted into activated sludge at SRTs of 20, 10, and 5 days, respectively. The COD/VSS ratio of the activated sludge seems to be dependent on mass loading rate. The estimated true yield and decay rate coefficients of the activated sludge were 0.61 kgCOD/kgCOD and 0.050 d−1, respectively. In the completely aerobic system, nitrogen balances were always close to 100%.

Replacement of secondary clarification by membrane separation - results with plate and hollow fibre modules

1998 ◽  
Vol 38 (4-5) ◽  
pp. 383-393 ◽  
Author(s):  
Berthold Günder ◽  
Karlheinz Krauth
Keyword(s):  
Activated Sludge ◽  
Suspended Solids ◽  
Municipal Wastewater ◽  
Hollow Fibre ◽  
Treated Wastewater ◽  
Stable Operation ◽  
Membrane Systems ◽  
Process Technology ◽  
Mixed Liquor ◽  
Activated Sludge Processes

Submerged membrane systems can replace the final clarification step to separate mixed liquor suspended solids (MLSS) from treated wastewater in the activated sludge processes. Mixed liquor suspended solids concentrations as high as 20 g/l can be maintained compared with the typical 3–4 g/l for conventional activated sludge/secondary clarifier systems. This leads to much smaller reactor volumes. In addition, excellent, solid free effluent qualities can be achieved with this process technology. One major challenge, when applying membrane technology to municipal wastewater treatment systems, is handling the flow variations typically encountered by these systems. This paper reports about the parallel investigation of two membrane-systems installed within a 7 m3 and a 9 m3 bioreactor. One membrane system used submerged plate modules (80 m2 membrane surface), the other hollow fibre modules (83.4 m2). The emphasis of this first investigation was the hydraulic performance and elasticity of the membrane systems. At MLSS concentrations of 15 g/l and hydraulic retention times of 6 hours, flux rates of 15 l/m2 h under permanent operation and up to 30 l/m2 h for short periods of time were achieved (standardised to a temperature of 10°C). A stable operation at these rates could be achieved for a full 4 months period without chemical cleaning of the membranes. Future studies will focus on nutrient removal aspects and the energy consumption of the systems.

Suspended carrier technology allows upgrading high-rate activated sludge plants for nitrogen removal via process intensification

2000 ◽  
Vol 41 (4-5) ◽  
pp. 5-12 ◽  
Author(s):  
E.v. Münch ◽  
K. Barr ◽  
S. Watts ◽  
J. Keller
Keyword(s):  
Wastewater Treatment ◽  
Activated Sludge ◽  
Residence Time ◽  
Nitrogen Removal ◽  
Wastewater Treatment Plant ◽  
Pilot Plant ◽  
Treatment Plant ◽  
Carbon Removal ◽  
Suspended Carrier ◽  
Plastic Media

The Oxley Creek wastewater treatment plant is a conventional 185,000 EP BOD removal activated sludge plant that is to be upgraded for nitrogen removal to protect its receiving water bodies, the Brisbane River and Moreton Bay. Suspended carrier technology is one possible way of upgrading this activated sludge wastewater treatment plant for nitrogen removal. Freely moving plastic media is added to the aeration zone, providing a growth platform for nitrifying bacteria and increasing the effective solids residence time (SRT). This paper presents the results from operating a pilot plant for 7 months at the Oxley Creek WWTP in Brisbane, Australia. Natrix Major 12/12 plastic media, developed by ANOX (Lund, Sweden), was trialed in the pilot plant. The pilot plant was operated with a mixed liquor suspended solids concentration of 1220 mg/L and a total hydraulic residence time of 5.4 hours, similar to the operating conditions in the full-scale Stage 1&2 works at the Oxley Creek WWTP. The plastic carriers were suspended in the last third of the bioreactor volume, which was aerated to a DO setpoint of 4.0 mg/L. The first third of the bioreactor volume was made anoxic and the second third served for carbon removal, being aerated to a DO setpoint of 0.5 mg/L. The results from the pilot plant indicate that an average effluent total inorganic nitrogen concentration (ammonia-N plus NOx−N) of less than 12 mg/L is possible. However, the effluent ammonia concentrations from the pilot plant showed large weekly fluctuations due to the intermittent operation of the sludge dewatering centrifuge returning significant ammonia loads to the plant on three days of the week. Optimising denitrification was carried out by lowering the DO concentration in the influent and in the carbon removal reactor. The results from the pilot plant study show that the Oxley Creek WWTP could be upgraded for nitrogen removal without additional tankage, using suspended carrier technology.

Predicting the Fate of Volatile Organic Compounds in Municipal Wastewater Treatment Plants

1992 ◽  
Vol 25 (4-5) ◽  
pp. 383-389 ◽  
Author(s):  
H. Melcer ◽  
J. Bell ◽  
D. Thompson
Keyword(s):  
Volatile Organic Compounds ◽  
Activated Sludge ◽  
Organic Compounds ◽  
Pilot Plant ◽  
Municipal Wastewater ◽  
Dynamic Models ◽  
Treatment Plant ◽  
Full Scale ◽  
Volatile Organic ◽  
Plant Data

Pilot plant and full scale investigations were carried out to determine the fate of selected volatile organic compounds (VOCs) in activated sludge aeration basins. Treatability parameters for each VOC were estimated from these investigations and used to calibrate TOXCHEM, computer-based steady state and dynamic models developed to predict the fate of VOCs in municipal activated sludge systems. The pilot plant was fed with wastewater from two different municipal sources. It was operated in parallel with a municipal treatment plant and was found to adequately simulate the performance of the full scale plant. Data suggest that the current models, calibrated with pilot plant data, may produce useful predictions of the fate of VOCs in full scale plants.

Replacement of Secondary Clarification by Membrane Separation—Results with Tubular, Plate and Hollow Fibre Modules

1999 ◽  
Vol 40 (4-5) ◽  
pp. 311-320 ◽  
Author(s):  
Berthold Günder ◽  
Karlheinz Krauth
Keyword(s):  
Activated Sludge ◽  
Suspended Solids ◽  
Membrane Separation ◽  
Membrane Surface ◽  
Hollow Fibre ◽  
Stable Operation ◽  
Membrane Systems ◽  
Process Technology ◽  
Mixed Liquor ◽  
Activated Sludge Processes

Membrane separation systems can replace the final clarification step to separate mixed liquor suspended solids (MLSS) in the activated sludge processes. Mixed liquor suspended solids concentrations as high as 20 g/l can be obtained compared with the typical 3-4 g/l for conventional activated sludge/secondary clarifier systems. This leads to much smaller reactor volumes. In addition, excellent, solids free effluent qualities can be achieved with this process technology. This paper reports about the parallel investigation of three membrane systems installed within or outside bioreactors of 7 to 9 m3 volume and flow rates from 1 to 3 m3/h. The different membrane modules were investigated: plate module (80 m2 membrane surface), hollow fibre module (80 m2) and tubular module (45 m2). At MLSS concentrations up to 25 g/l and water temperatures from 10 to 25°C a stable operation of the membrane systems was achieved for a period of more than one year. The energy consumption was approximately 1.5 kWh/m3 for the plate and hollow fibre and 3.0 kWh/m3 for the tubular module system.

A Pilot Study on Enhancing Nitrification by Bioaugmentation

2012 ◽  
Vol 518-523 ◽  
pp. 569-574
Author(s):  
Qiong Wan ◽  
Lei Li ◽  
Dang Cong Peng
Keyword(s):  
Pilot Study ◽  
Activated Sludge ◽  
Pilot Plant ◽  
Municipal Wastewater ◽  
Removal Rate ◽  
Experimental Results ◽  
Main Stream ◽  
Reject Water ◽  
Side Stream ◽  
N Removal

Enhancing nitrification from municipal wastewater by bioaugmentation was investigated in a pilot plant operated in A2/O process. Reject water was used to cultivate nitrifier in O/A process (side stream), and the exceed sludge in side stream was used to bioaugmentation. The experimental results showed that bioaugmentation was very effective for enhancing nitrification. After nitrifier bioaugmentation, the NH4+-N removal rate was improved more than 30% in main stream. And AUR and NUR of the activated sludge increased from 2.61 mgNH4+-N /(gMLSS•h) and 2.38 mgNO2--N/(gMLSS•h) to 5.32 mgNH4+-N /(gMLSS•h) and 3.81 mgNO2--N/(gMLSS•h), which was as 2.04 times and 1.60 times as those of before bioaugmentation in main stream respectively.

scholarly journals Systematic Modeling of Municipal Wastewater Activated Sludge Process and Treatment Plant Capacity Analysis Using GPS-X

2020 ◽  
Vol 12 (19) ◽  
pp. 8182
Author(s):  
Nuhu Dalhat Mu’azu ◽  
Omar Alagha ◽  
Ismail Anil
Keyword(s):  
Activated Sludge ◽  
Suspended Solids ◽  
Systematic Approach ◽  
Municipal Wastewater ◽  
Treatment Plant ◽  
Oxygen Demand ◽  
Plant Performance ◽  
Capacity Analysis ◽  
Activated Sludge Process ◽  
Effluent Quality

Mathematical modeling has become an indispensable tool for sustainable wastewater management, especially for the simulation of complex biochemical processes involved in the activated sludge process (ASP), which requires a substantial amount of data related to wastewater and sludge characteristics as well as process kinetics and stoichiometry. In this study, a systematic approach for calibration of the activated sludge model one (ASM1) model for a real municipal wastewater ASP was undertaken in GPS-X. The developed model was successfully validated while meeting the assumption of the model’s constant stoichiometry and kinetic coefficients for any plant influent compositions. The influences of vital ASP parameters on the treatment plant performance and capacity analysis for meeting local discharge limits were also investigated. Lower influent chemical oxygen demand in mgO2/L (COD) could inhibit effective nitrification and denitrification, while beyond 250 mgO2/L, there is a tendency for effluent quality to breach the regulatory limit. The plant performance can be satisfactory for handling even higher influent volumes up to 60,000 m3/d and organic loading when Total Suspended Solids/Volatile Suspended Solids (VSS/TSS) and particulate COD (XCOD)/VSS are maintained above 0.7 and 1, respectively. The wasted activated sludge (WAS) has more impact on the effluent quality compared to recycle activated sludge (RAS) with significant performance improvement when the WAS was increased from 3000 to 9000 m3/d. Hydraulic retention time (HRT) > 6 h and solids retention time (SRT) < 7 days resulted in better plant performance with the SRT having greater impact compared with HRT. The plant performance could be sustained for a quite appreciable range of COD/5-day Biochemical Oxygen Demand (BOD5 in mgO2/L) ratio, Mixed Liquor Suspended Solid (MLSS) of up to 6000 mg/L, and when BOD5/total nitrogen (TN) and COD/TN are comparatively at higher values. This work demonstrated a systematic approach for estimation of the wastewater treatment plant (WWTP) ASP parameters and the high modeling capabilities of ASM1 in GPS-X when respirometry tests data are lacking.

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