The Impact of Alum on the Bulking of a Full Scale Activated Sludge Plant

The effect of rain events on effluent quality dynamics was studied at a full scale activated sludge wastewater treatment plant which has a process solution incorporating pre-denitrification in activated sludge with post-nitrification in trickling filters. The incoming wastewater flow varies significantly due to a combined sewer system. Changed flow conditions have an impact on the whole treatment process since the recirculation to the trickling filters is set by the hydraulic limitations of the secondary settlers. Apart from causing different hydraulic conditions in the plant, increased flow due to rain or snow-melting, changes the properties of the incoming wastewater which affects process performance and effluent quality, especially the particle removal efficiency. A comprehensive set of on-line and laboratory data were collected and analysed to assess the impact of rain events on the plant performance.

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The impact of precipitation and external carbon source addition on biological nutrient removal in activated sludge systems – experimental investigation and mathematical modeling

Water Practice & Technology ◽

10.2166/wpt.2012.011 ◽

2012 ◽

Vol 7 (1) ◽

Cited By ~ 4

Author(s):

J. Makinia ◽

J. Drewnowski ◽

M. Swinarski ◽

K. Czerwionka ◽

M. Kaszubowska ◽

...

Keyword(s):

Carbon Source ◽

Activated Sludge ◽

Carbon Sources ◽

Full Scale ◽

Biological Nutrient Removal ◽

Batch Experiments ◽

Carbon Addition ◽

Reference Case ◽

External Carbon Source ◽

The Impact

The aim of this study was to determine the effects of chemical precipitation and addition of external carbon sources on the denitrification capability and enhanced biological phosphorus removal (EBPR) interactions at the ‘Wschod’ WWTP (600,000 PE) in Gdansk (northern Poland). For this purpose, different kinds of batch experiments were carried out with the settled wastewater (without pretreatment and after coagulation-flocculation) and external carbon sources (ethanol and fusel oil). Precipitation of colloidal and particulate organic fractions has a significant effect on denitrification and EBPR. The removal of these two fractions by coagulation-flocculation resulted in the reduced process rates (30–70%). The experimental investigations were supported by both lab-scale and full-scale simulations using a newly developed model as an expansion of the Activated Sludge Model No. 2d (ASM2d). The new model accurately predicted the effects of precipitation and external carbon addition in batch experiments. Full-scale simulations revealed that addition of external carbon source can compensate the effects of precipitation resulting in a similar NO3-N behavior compared to the reference case (without precipitation and external carbon addition). The combined effects of precipitation and addition of external carbon source resulted in a significantly different PO4-P behavior compared to the reference case.

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The Impact of Local Hydrodynamics on High-Rate Activated Sludge Flocculation in Laboratory and Full-Scale Reactors

Processes ◽

10.3390/pr8020131 ◽

2020 ◽

Vol 8 (2) ◽

pp. 131 ◽

Cited By ~ 1

Author(s):

Sophie Balemans ◽

Siegfried E. Vlaeminck ◽

Elena Torfs ◽

Leonie Hartog ◽

Laura Zaharova ◽

...

Keyword(s):

Activated Sludge ◽

High Velocity ◽

Numerical Data ◽

Full Scale ◽

High Rate ◽

Homogeneous Distribution ◽

Local Velocity ◽

Local Conditions ◽

Velocity Gradients ◽

The Impact

High rate activated sludge (HRAS) processes have a high potential for carbon and energy recovery from sewage, yet they suffer frequently from poor settleability due to flocculation issues. The process of flocculation is generally optimized using jar tests. However, detailed jar hydrodynamics are often unknown, and average quantities are used, which can significantly differ from the local conditions. The presented work combined experimental and numerical data to investigate the impact of local hydrodynamics on HRAS flocculation for two different jar test configurations (i.e., radial vs. axial impellers at different impeller velocities) and compared the hydrodynamics in these jar tests to those in a representative section of a full scale reactor using computational fluid dynamics (CFD). The analysis showed that the flocculation performance was highly influenced by the impeller type and its speed. The axial impeller appeared to be more appropriate for floc formation over a range of impeller speeds as it produced a more homogeneous distribution of local velocity gradients compared to the radial impeller. In contrast, the radial impeller generated larger volumes (%) of high velocity gradients in which floc breakage may occur. Comparison to local velocity gradients in a full scale system showed that also here, high velocity gradients occurred in the region around the impeller, which might significantly hamper the HRAS flocculation process. As such, this study showed that a model based approach was necessary to translate lab scale results to full scale. These new insights can help improve future experimental setups and reactor design for improved HRAS flocculation.

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The Impact of a Chemostat Discharge Containing Oil Degrading Bacteria on the Biological Kinetics of a Refinery Activated Sludge Process

Water Science & Technology ◽

10.2166/wst.1988.0276 ◽

1988 ◽

Vol 20 (11-12) ◽

pp. 131-136 ◽

Cited By ~ 7

Author(s):

A. D. Wong ◽

C. D. Goldsmith

Keyword(s):

Activated Sludge ◽

Retention Time ◽

Waste Treatment ◽

Treatment Plant ◽

Utilization Rate ◽

Activated Sludge Process ◽

Kinetic Evaluation ◽

Degrading Bacteria ◽

Waste Treatment Plant ◽

The Impact

The effect of discharging specific oil degrading bacteria from a chemostat to a refinery activated sludge process was determined biokinetically. Plant data for the kinetic evaluation of the waste treatment plant was collected before and during treatment. During treatment, the 500 gallon chemostatic growth chamber was operated on an eight hour hydraulic retention time, at a neutral pH, and was fed a mixture of refinery wastewater and simple sugars. The biokinetic constants k (days−1), Ks (mg/L), and K (L/mg-day) were determined before and after treatment by Monod and Lineweaver-Burk plots. Solids discharged and effluent organic concentrations were also evaluated against the mean cell retention time (MCRT). The maximum utilization rate, k, was found to increase from 0.47 to 0.95 days−1 during the operation of the chemostat. Subsequently, Ks increased from 141 to 556 mg/L. Effluent solids were shown to increase slightly with treatment. However, this was acceptable due to the polishing pond and the benefit of increased ability to accept shock loads of oily wastewater. The reason for the increased suspended solids in the effluent was most likely due to the continual addition of bacteria in exponential growth that were capable of responding to excess substrate. The effect of the chemostatic addition of specific microbial inocula to the refinery waste treatment plant has been to improve the overall organic removal capacity along with subsequent gains in plant stability.

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Respirometry for determination of the influents SS-concentration

Water Science & Technology ◽

10.2166/wst.1996.0031 ◽

1996 ◽

Vol 33 (1) ◽

pp. 311-323 ◽

Cited By ~ 2

Author(s):

A. Witteborg ◽

A. van der Last ◽

R. Hamming ◽

I. Hemmers

Keyword(s):

Experimental Design ◽

Activated Sludge ◽

Substrate Concentration ◽

Full Scale ◽

Activated Sludge Process ◽

Respiration Rates ◽

On Line ◽

Large Measurement ◽

Set Up

A method is presented for determining influent readily biodegradable substrate concentration (SS). The method is based on three different respiration rates, which can be measured with a continuous respiration meter which is operated in a cyclic way. Within the respiration meter nitrification is inhibited through the addition of ATU. Simulations were used to develop the respirometry set-up and decide upon the experimental design. The method was tested as part of a large measurement programme executed at a full-scale plant. The proposed respirometry set-up has been shown to be suitable for a semi-on-line determination of an influent SS which is fully based on the IAWQ #1 vision of the activated sludge process. The YH and the KS play a major role in the principle, and should be measured directly from the process.

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Incentivizing Peace

10.1093/oso/9780190699512.001.0001 ◽

2018 ◽

Cited By ~ 4

Author(s):

Jaroslav Tir ◽

Johannes Karreth

Keyword(s):

World War Ii ◽

Civil Wars ◽

Full Scale ◽

Armed Conflicts ◽

East Timor ◽

Low Level ◽

Self Interest ◽

The World ◽

Economic Tools ◽

The Impact

Civil wars are one of the most pressing problems facing the world. Common approaches such as mediation, intervention, and peacekeeping have produced some results in managing ongoing civil wars, but they fall short in preventing civil wars in the first place. This book argues for considering civil wars from a developmental perspective to identify steps to assure that nascent, low-level armed conflicts do not escalate to full-scale civil wars. We show that highly structured intergovernmental organizations (IGOs, e.g. the World Bank or IMF) are particularly well positioned to engage in civil war prevention. Such organizations have both an enduring self-interest in member-state peace and stability and potent (economic) tools to incentivize peaceful conflict resolution. The book advances the hypothesis that countries that belong to a larger number of highly structured IGOs face a significantly lower risk that emerging low-level armed conflicts on their territories will escalate to full-scale civil wars. Systematic analyses of over 260 low-level armed conflicts that have occurred around the globe since World War II provide consistent and robust support for this hypothesis. The impact of a greater number of memberships in highly structured IGOs is substantial, cutting the risk of escalation by over one-half. Case evidence from Indonesia’s East Timor conflict, Ivory Coast’s post-2010 election crisis, and from the early stages of the conflict in Syria in 2011 provide additional evidence that memberships in highly structured IGOs are indeed key to understanding why some low-level armed conflicts escalate to civil wars and others do not.

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Effects of pH shock on microaerobic activated sludge system with a graphene oxide/nano-magnetic powder composite

Nordic Pulp & Paper Research Journal ◽

10.1515/npprj-2020-0022 ◽

2020 ◽

Vol 35 (3) ◽

pp. 457-463

Author(s):

Huixia Lan ◽

Xiangzhi Wang ◽

Shixin Qi ◽

Da Yang ◽

Hao Zhang

Keyword(s):

Graphene Oxide ◽

Activated Sludge ◽

High Throughput Sequencing ◽

Impact Resistance ◽

Magnetic Powder ◽

Blank Group ◽

Activated Sludge System ◽

Ph Shock ◽

Dominant Bacteria ◽

The Impact

AbstractUsing the acclimated activated sludge from the pulping middle-stage effluent, the effect of pH shock on the micro-oxygen activated sludge system with a nano-magnetic powder/graphene oxide composite was studied. The results showed that the removal rates of chemical oxygen demand (CODCr) and ultraviolet adsorption at 254 nm (UV254) decreased. Also, the sludge settling performance was poor due to the impact of pH, but the impact resistance of nano-magnetic powder/graphene oxide group (MGO group) was higher and the recovery was faster. Results of high throughput sequencing indicated that the diversity of microbial community was reduced by the impact of pH, but it was significantly higher in MGO group than in the blank group. The dominant bacteria after pH shock or recovery in both of the system had a large difference. The percentage of the dominant bacteria in the MGO group was higher than that in the blank group. The MGO group had higher electron transfer system (ETS) activity which made the system having a strong pH impact resistance.

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Nitrification preservation in activated sludge during curative bulking chlorination

Water Science & Technology ◽

10.2166/wst.2003.0590 ◽

2003 ◽

Vol 47 (11) ◽

pp. 85-92 ◽

Cited By ~ 2

Author(s):

E. Cotteux ◽

P. Duchene

Keyword(s):

Activated Sludge ◽

Pilot Plant ◽

Wastewater Treatment Plants ◽

Oxygen Uptake Rate ◽

Ammonia Concentration ◽

Synthetic Wastewater ◽

Biological Wastewater Treatment ◽

Simple Method ◽

Method Of Measurement ◽

The Impact

The bulking that occurs in biological wastewater treatment plants using activated sludge is very often controlled by the injection of sodium hypochlorite into the return activated sludge (RAS) stream. In the present study undertaken at two pilot plants fed with synthetic wastewater, the impact of the pass frequency of the sludge at the chlorine dosing point on the nitrifying flora is analysed. The pass frequency is one for the pilot plant 1 and two for the pilot plant 2. A dose of chlorine of 4.85 ± 0.05 g/kg/MLVSS per day was applied at both pilots. The preservative effect on nitrifying activity of the lowest concentration of chlorine at the dosing point and therefore of the highest pass frequency was evidenced. Among other tools, a simple method of measurement of the oxygen uptake rate enabled us to monitor the effect of chlorination on nitrification before recording an increase in the ammonia concentration in the bulking.

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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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