Enrichment and application of nitrifying activated sludge in membrane bioreactors

Abstract In this study, nitrifying bacteria were enriched in a membrane bioreactor (MBR, R1) and their bioaugmentation effectiveness was evaluated in another two MBRs (R2 and R3). Nitrifying activated sludge (NAS) with high nitrification activity of up to 3,000 mg-N/(L·d)−1 was successfully enriched in R1. The results showed that chemical oxygen demand concentration of 100–200 mg/L had no negative effect on NAS enrichment but reduced the ratio of bacterial nitrifiers. Moreover, the cell concentration of nitrifying bacteria in NAS, which was 3.1 × 1011 cells/L, was similar to that of the commercial bacterium agent. For the bioaugmentation test, the reactor inoculated with 14% NAS achieved a 23% higher NH4+-N removal efficiency than that of the uninoculated reactor. Along with the improvement of nitrification performance, the bacterial nitrifiers abundance and microbial richness remarkably increased after bioaugmentation. These results suggested that the MBR system could efficiently enrich nitrifying bacteria using organic carbon containing culture medium, and potentially act as a side-stream reactor to enhance the nitrification function of the wastewater treatment plant.

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Savings with upgraded performance through improved activated sludge denitrification in the combined activated sludge–biofilter system of the Southpest Wastewater Treatment Plant

Water Science & Technology ◽

10.2166/wst.2008.232 ◽

2008 ◽

Vol 57 (8) ◽

pp. 1287-1293 ◽

Cited By ~ 1

Author(s):

A. Jobbágy ◽

G. M. Tardy ◽

Gy. Palkó ◽

A. Benáková ◽

O. Krhutková ◽

...

Keyword(s):

Wastewater Treatment ◽

Activated Sludge ◽

Wastewater Treatment Plant ◽

Biological Treatment ◽

Treatment Plant ◽

Oxygen Demand ◽

Process Efficiency ◽

Initial Value ◽

Initial Profile ◽

Biological Treatment System

The purpose of the experiments was to increase the rate of activated sludge denitrification in the combined biological treatment system of the Southpest Wastewater Treatment Plant in order to gain savings in cost and energy and improve process efficiency. Initial profile measurements revealed excess denitrification capacity of the preclarified wastewater. As a consequence, flow of nitrification filter effluent recirculated to the anoxic activated sludge basins was increased from 23,000 m3 d−1 to 42,288 m3 d−1 at an average preclarified influent flow of 64,843 m3 d−1, Both simulation studies and microbiological investigations suggested that activated sludge nitrification, achieved despite the low SRT (2–3 days), was initiated by the backseeding from the nitrification filters and facilitated by the decreased oxygen demand of the influent organics used for denitrification. With the improved activated sludge denitrification, methanol demand could be decreased to about half of the initial value. With the increased efficiency of the activated sludge pre-denitrification, plant effluent COD levels decreased from 40–70 mg l−1 to < 30–45 mg l−1 due to the decreased likelihood of methanol overdosing in the denitrification filter

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Evaluating the treatment performance of a full scale Activated Sludge Plant in Islamabad, Pakistan

Water Practice & Technology ◽

10.2166/wpt.2012.016 ◽

2012 ◽

Vol 7 (1) ◽

Cited By ~ 1

Author(s):

S. S. Fatima ◽

S. Jamal Khan

Keyword(s):

Wastewater Treatment ◽

Activated Sludge ◽

Wastewater Treatment Plant ◽

Suspended Solids ◽

Treatment Plant ◽

Oxygen Demand ◽

Full Scale ◽

Operational Parameter ◽

Mixed Liquor ◽

Treatment Performance

In this study, the performance of wastewater treatment plant located at sector I-9 Islamabad, Pakistan, was evaluated. This full scale domestic wastewater treatment plant is based on conventional activated sludge process. The parameters which were monitored regularly included total suspended solids (TSS), mixed liquor suspended solids (MLSS), mixed liquor volatile suspended solids (MLVSS), biological oxygen demand (BOD), and chemical oxygen demand (COD). It was found that the biological degradation efficiency of the plant was below the desired levels in terms of COD and BOD. Also the plant operators were not maintaining consistent sludge retention time (SRT). Abrupt discharge of MLSS through the Surplus Activated sludge (SAS) pump was the main reason for the low MLSS in the aeration tank and consequently low treatment performance. In this study the SRT was optimized based on desired MLSS concentration between 3,000–3,500 mg/L and required performance in terms of BOD, COD and TSS. This study revealed that SRT is a very important operational parameter and its knowledge and correct implementation by the plant operators should be mandatory.

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Enhancing nitrogen removal efficiency in a dyestuff wastewater treatment plant with the IFFAS process: the pilot-scale and full-scale studies

Water Science & Technology ◽

10.2166/wst.2017.522 ◽

2017 ◽

Vol 77 (1) ◽

pp. 70-78 ◽

Cited By ~ 4

Author(s):

Yanjun Mao ◽

Xie Quan ◽

Huimin Zhao ◽

Yaobin Zhang ◽

Shuo Chen ◽

...

Keyword(s):

Wastewater Treatment ◽

Activated Sludge ◽

Removal Efficiency ◽

Nitrogen Removal ◽

Treatment Plant ◽

Oxygen Demand ◽

Pilot Scale ◽

Full Scale ◽

Nitrification And Denitrification ◽

Dyestuff Wastewater

Abstract The activated sludge (AS) process is widely applied in dyestuff wastewater treatment plants (WWTPs); however, the nitrogen removal efficiency is relatively low and the effluent does not meet the indirect discharge standards before being discharged into the industrial park's WWTP. Hence it is necessary to upgrade the WWTP with more advanced technologies. Moving bed biofilm processes with suspended carriers in an aerobic tank are promising methods due to enhanced nitrification and denitrification. Herein, a pilot-scale integrated free-floating biofilm and activated sludge (IFFAS) process was employed to investigate the feasibility of enhancing nitrogen removal efficiency at different hydraulic retention times (HRTs). The results showed that the effluent chemical oxygen demand (COD), ammonium nitrate (NH4+-N) and total nitrogen (TN) concentrations of the IFFAS process were significantly lower than those of the AS process, and could meet the indirect discharge standards. PCR-DGGE and FISH results indicated that more nitrifiers and denitrifiers co-existed in the IFFAS system, promoting simultaneous nitrification and denitrification. Based on the pilot results, the IFFAS process was used to upgrade the full-scale AS process, and the effluent COD, NH4+-N and TN of the IFFAS process were 91–291 mg/L, 10.6–28.7 mg/L and 18.9–48.6 mg/L, stably meeting the indirect discharge standards and demonstrating the advantages of IFFAS in dyestuff wastewater treatment.

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Sensitivity of Effluent Variables in Activated Sludge Process

Chemical Product and Process Modeling ◽

10.1515/cppm-2017-0028 ◽

2017 ◽

Vol 13 (2) ◽

Author(s):

B Vivekanandan ◽

K Jeyannathann ◽

A. Seshagiri Rao

Keyword(s):

Activated Sludge ◽

Flow Rate ◽

Oxygen Transfer Rate ◽

Treatment Plant ◽

Oxygen Demand ◽

Maximum Flow ◽

Activated Sludge Process ◽

Flow Conditions ◽

Treated Effluent ◽

Influent Flow

Abstract The quality of a treated effluent changes when there is a sudden variation in the influent flow to the wastewater treatment plant during dry, rain, and storm weather conditions. In this study, various influent flow conditions in an activated sludge process are considered that affect the sensitivity of effluent variables such as chemical oxygen demand (COD), biological oxygen demand (BOD), nitrate nitrogen (SNO), ammonical nitrogen (SNH), and total nitrogen (TN) with respect to varying internal recycle flow rate (Qa), sludge recycle flow rate (Qr), sludge wastage flow rate (Qw) and oxygen transfer rate co-efficient of aerobic tanks (KLa(3,4,5)). The analysis has been carried out based on benchmark simulation model no.1 (BSM 1) plant layout which comprises of two models namely activated sludge model no.1 (ASM 1) and simple one dimensional (Simple 1-D) Takacs model. Based on the present analysis, it is observed that the changes in influent flow rate have larger impact on the effluent variables. This variation can be subdued by introducing additional tanks to smoothen the perturbations or using internal recycle rate from the fifth tank in order to maintain the flow around the optimal influent flow rate. The sludge wastage rate has a greater impact on all effluent variables except nitrogenous variables during maximum flow conditions.

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The Impact of Selected Parameters on the Condition of Activated Sludge in a Biologic Reactor in the Treatment Plant in Nowy Targ, Poland

Water ◽

10.3390/w12102657 ◽

2020 ◽

Vol 12 (10) ◽

pp. 2657

Author(s):

Elwira Nowobilska-Majewska ◽

Piotr Bugajski

Keyword(s):

Wastewater Treatment ◽

Statistical Analysis ◽

Activated Sludge ◽

Partial Correlation ◽

Oxygen Uptake Rate ◽

Treatment Plant ◽

Oxygen Demand ◽

Test Results ◽

Partial Correlation Analysis ◽

The Impact

The aim of this study was to determine the condition of activated sludge in the biologic reactor located in the collective wastewater treatment plant in Nowy Targ (Poland) based on OUR tests in the aspect of the impact of sludge’s concentration in the biologic reactor and dependence of BOD5/TN and BOD5/TP in wastewater flowing into the biologic reactor. The analysis was conducted based on test results from 61 samples of activated sludge taken from the biologic reactor and 61 samples of wastewater flowing into the biologic reactor. The analysis included the concentration of sludge in the biologic reactor. The following indicators were analyzed in wastewater flowing into the reactor: biochemical oxygen demand (BOD5), total nitrogen (TN) and total phosphorus (TP). The statistical analysis concerning the impact of the analyzed factors on oxygen uptake rate (OUR) tests was developed based on the Pearson’s correlation coefficient and partial correlation of many variables. Based on the results of the partial correlation analysis, nomograms were developed to determine the condition of activated sludge microorganisms (OUR) based on the BOD5/TN and BOD5/TP connection and knowledge of the sludge concentration in the bioreactor of the treatment plant. The presented nomograms can be formulated for each bioreactor based on activated sludge technology related the load of organic and biogenic pollutants in the wastewater flowing into the bioreactor and the concentration of the sludge in the bioreactor.

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A titration technique for on-line nitrification monitoring in activated sludge

Water Science & Technology ◽

10.2166/wst.1998.0514 ◽

1998 ◽

Vol 37 (12) ◽

pp. 103-110 ◽

Cited By ~ 4

Author(s):

Krist Gernaey ◽

Herwig Bogaert ◽

Peter Vanrolleghem ◽

Alessandro Massone ◽

Alberto Rozzi ◽

...

Keyword(s):

Activated Sludge ◽

Treatment Plant ◽

Estimation Method ◽

Sample Pretreatment ◽

Mixed Liquor ◽

Titration Curves ◽

N Removal ◽

Nitrification Kinetics ◽

On Line ◽

Simple Slope

A titrimetric method to monitor nitrification was applied on a pilot activated sludge plant for biological N removal. Mixed liquor was sampled from the aerobic compartment of the treatment plant and a titration in-sensor experiment was performed. Interpretation of the cumulative base addition curves resulting from each titration in-sensor experiment was done using both a simple slope extrapolation method and a model-based non-linear parameter estimation method. The NH4+-N concentrations obtained with both methods correlated well with the NH4+-N concentrations measured on the effluent of the pilot plant using an on-line NH4+-N analyser. Contrary to most physical/chemical NH4+-N analysers, no sample pretreatment of the mixed liquor is needed for the measurements. It is shown in detail that interpretation of the titration curves yields information about the nitrification kinetics too, which can be an important advantage for process control purposes.

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A comparison of NH4/NO3 control strategies for alternating activated sludge processes

Water Science & Technology ◽

10.2166/wst.1999.0194 ◽

1999 ◽

Vol 39 (4) ◽

pp. 93-102 ◽

Cited By ~ 1

Author(s):

L. J. S. Lukasse ◽

K. J. Keesman ◽

A. Klapwijk ◽

G. van Straten

Keyword(s):

Activated Sludge ◽

Time Delays ◽

Control Strategies ◽

Treatment Plant ◽

Biological Processes ◽

Effluent Quality ◽

N Removal ◽

Activated Sludge Reactor ◽

The Difference ◽

Activated Sludge Processes

Four control strategies for N-removal in alternating activated sludge plants (ASP's) are compared: 1. timer-based, 2. switching the aeration on/off when depletion of nitrate/ammonium is detected, 3. switching the aeration on/off when ammonium crosses an upper/lower-bound, 4. the newly developed adaptive receding horizon optimal controller (ARHOC) as presented in Lukasse et al. (1997). The comparison is made by simulating the controllers' application to an alternating continuously-mixed activated sludge reactor preceded by a small anoxic reactor for predenitrification. The biological processes in the reactors are modelled by the activated sludge model no. 1. Realistic influent patterns, measured at a full-scale wastewater treatment plant, are used. The results show that three totally different controllers (timer-based, NH4-bounds based and ARHOC) can achieve a more or less equal effluent quality, if tuned optimally. The difference mainly occurs in the sensitivity to suboptimal tunings. The timer-based strategy has a higher aeration demand. The sensitivity of the ARHOC controller to sub-optimal tuning, known measurement time delays and changing plant loads is significantly less than that of the other controllers. Also its tuning is more natural and explicit.

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The effects of a full-scale anaerobic side-stream reactor on sludge decay and biomass activity

Water Science & Technology ◽

10.2166/wst.2019.104 ◽

2019 ◽

Vol 79 (6) ◽

pp. 1081-1091 ◽

Cited By ~ 2

Author(s):

V. F. Velho ◽

G. Andreottola ◽

P. Foladori ◽

R. H. R. Costa

Keyword(s):

Activated Sludge ◽

Mass Balance ◽

Oxygen Demand ◽

Full Scale ◽

Sludge Reduction ◽

Solid Mass ◽

Anaerobic Conditions ◽

Side Stream ◽

Biomass Activity ◽

Heterotrophic Biomass

Abstract A full-scale anaerobic side-stream reactor (ASSR) for sludge reduction was monitored in terms of sludge production and compared with the previous conventional activated sludge configuration (CAS). A detailed solid mass balance was calculated on the whole full-scale plant to estimate the sludge reduction associated with the ASSR. The activity of the biomass, which undergoes alternation of aerobic and anaerobic conditions, was investigated by the respirometric test. The ASSR promoted a reduction of heterotrophic biomass activity and the substrate consumption rate in the activated sludge implemented with ASSR (AS + ASSR) was 36% smaller than in the CAS period. The solid mass balance indicated a sludge reduction of 28%. During the 270-day operation, the observed sludge yield passed from 0.438 kgTSS/kgCOD in the CAS to 0.315 in the AS + ASSR configuration. The solubilization of chemical oxygen demand (COD), NH4+-N and orthophosphate were verified under anaerobic conditions. The results suggest that the possible mechanisms of sludge reduction were the increase of the system sludge retention time (SRT) by ASSR addition, and the reduction in heterotrophic biomass activity added to the organic compounds' hydrolysis.

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Biodegradation of aniline

Water Science & Technology ◽

10.2166/wst.1997.0358 ◽

1997 ◽

Vol 36 (10) ◽

pp. 53-63 ◽

Cited By ~ 18

Author(s):

Shabbir H. Gheewala ◽

Ajit P. Annachhatre

Keyword(s):

Activated Sludge ◽

Ammonia Oxidation ◽

Oxygen Demand ◽

Domestic Wastewater ◽

Inhibitory Effect ◽

Synthetic Wastewater ◽

Nitrifying Bacteria ◽

Aquatic Life ◽

Oxidation Rates ◽

Batch Tests

Discharge of aniline to the environment must be controlled as aniline is toxic to aquatic life and also exerts additional oxygen demand due to nitrification reaction involved during its biodegradation. Organic carbonaceous removal by heterotrophs during aniline biodegradation releases NH4+ which is the substrate for autotrophic nitrifying bacteria. However, aniline is toxic to nitrifying bacteria and severely inhibits their activity. Accordingly, batch and continuous studies were conducted to assess the biodegradation of aniline and its inhibitory effect on nitrification. Synthetic wastewater was used as feed with aniline as sole carbon source for mixed microbial population. Experiments were conducted at ambient temperatures of 30–32°C. An aerobic activated sludge Unit was operated at an HRT of about 13 hours and SRT of about 12 days. Biomass from aerobic activated sludge process treating domestic wastewater was acclimatized to synthetic wastewater Containing aniline. Removal efficiencies more than 95% were obtained for feed aniline concentrations upto 350 mg/l with insignificant inhibition of nitrification due to aniline. Ammonia oxidation rates of about 20–115 mgNH4N/l/d were observed. Batch tests were carried out to test the inhibitory effects of high initial aniline concentrations on nitritication. Carbonaceous removal by heterotrophs proceeded rapidly within 4–6 hours with nitrification picking up as soon as aniline concentration dropped below 3–4 mg/l. For higher initial aniline concentration more than 250 mg/l, complete nitrification did not take place even after aniline Concentration dropped below 3–4 mg/l.

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Shifts in the Microbial Community of Activated Sludge with Different COD/N Ratios or Dissolved Oxygen Levels in Tibet, China

Sustainability ◽

10.3390/su11082284 ◽

2019 ◽

Vol 11 (8) ◽

pp. 2284 ◽

Cited By ~ 1

Author(s):

Jin Xu ◽

Peifang Wang ◽

Yi Li ◽

Lihua Niu ◽

Zhen Xing

Keyword(s):

Dissolved Oxygen ◽

Activated Sludge ◽

Sewage Treatment ◽

Treatment Plant ◽

Oxygen Demand ◽

Operational Taxonomic Unit ◽

Carbon To Nitrogen Ratio ◽

Urban Sewage ◽

Treatment Performance ◽

Nitrogen Ratio

In this study, we examined the influence of the organic carbon-to-nitrogen ratio (chemical oxygen demand (COD/N)) and dissolved oxygen (DO) levels on the removal efficiency of pollutants and on the change in total microflora in the cyclic activated sludge system (CASS) in the Nyingchi prefecture in Tibet. The results demonstrated that the treatment performance was the best when the COD/N ratio was 7:1 or the DO levels were 2–2.5 mg/L in comparison with four different tested COD/N ratios (4:1, 5:1, 7:1, and 10:1) and DO concentrations (0.5–1, 1–2, 2–2.5, and 2.5–3.5 mg/L). The treatment performance can be explained by the relative operational taxonomic unit richness and evenness of the microbial communities in activated sludge. Evident microbial variance was observed, especially different COD/N ratios and DO concentrations, which were conducive to the disposal of urban sewage in plateaus. The results help to understand sewage treatment under different COD/N ratios or DO concentrations on plateaus. This work provides practical guidance for the operation of any wastewater treatment plant on a plateau.

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