Pilot-Scale Waste Activated Sludge Alkaline Fermentation, Fermentation Liquid Separation, and Application of Fermentation Liquid To Improve Biological Nutrient Removal

The use of chemicals for sludge bulking control has a direct effect on the biological nutrient removal processes in activated sludge systems designed for this purpose. Chlorine has been used on full scale but information on the use of ozone and hydrogen peroxide is limited to pilot scale tests. The objective of this study was to investigate the effects of chlorine, ozone and hydrogen peroxide on nutrient removal processes when used on a continuous basis for bulking control in a full scale biological nutrient removal activated sludge plant. The full scale studies were conducted over a period of 39 months at the Daspoort sewage works of the City Council of Pretoria. The results indicate that at low dosages the oxidants have limited effects on the nutrient removal processes but at higher levels chlorine had a detrimental effect resulting in the phosphate limit of 1 mg P.1−1 being exceeded. It is concluded that chlorine is the most effective of the three oxidants for bulking control, but that it should be used with caution in order not to upset the biological phosphate removal processes. Ozone at low levels had a small but consistent positive effect on bulking control as well as on nutrient removal. The effects of hydrogen peroxide were very small except at high dosages.

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Two-stage thermophilic-mesophilic anaerobic digestion of waste activated sludge from a biological nutrient removal plant

Water Science & Technology ◽

10.2166/wst.2006.245 ◽

2006 ◽

Vol 53 (8) ◽

pp. 149-157 ◽

Cited By ~ 22

Author(s):

S. Watts ◽

G. Hamilton ◽

J. Keller

Keyword(s):

Anaerobic Digestion ◽

Activated Sludge ◽

Nutrient Removal ◽

Treatment Plant ◽

Single Stage ◽

Biological Nutrient Removal ◽

Waste Activated Sludge ◽

Two Stage ◽

Primary Sludge ◽

Second Stage

A two-stage thermophilic-mesophilic anaerobic digestion pilot-plant was operated solely on waste activated sludge (WAS) from a biological nutrient removal (BNR) plant. The first-stage thermophilic reactor (HRT 2 days) was operated at 47, 54 and 60 °C. The second-stage mesophilic digester (HRT 15 days) was held at a constant temperature of 36–37 °C. For comparison with a single-stage mesophilic process, the mesophilic digester was also operated separately with an HRT of 17 days and temperature of 36–37 °C. The results showed a truly thermophilic stage (60 °C) was essential to achieve good WAS degradation. The lower thermophilic temperatures examined did not offer advantages over single-stage mesophilic treatment in terms of COD and VS removal. At a thermophilic temperature of 60 °C, the plant achieved 35% VS reduction, representing a 46% increase compared to the single-stage mesophilic digester. This is a significant level of degradation which could make such a process viable in situations where there is no primary sludge generated. The fate of the biologically stored phosphorus in this BNR sludge was also investigated. Over 80% of the incoming phosphorus remained bound up with the solids and was not released into solution during the WAS digestion. Therefore only a small fraction of phosphorus would be recycled to the main treatment plant with the dewatering stream.

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Stabilization of combined wastewater sludge: anaerobic processes

Canadian Journal of Civil Engineering ◽

10.1139/l95-032 ◽

1995 ◽

Vol 22 (2) ◽

pp. 223-234 ◽

Cited By ~ 4

Author(s):

B. C. Anderson ◽

D. S. Mavinic ◽

J. A. Oleszkiewicz

Keyword(s):

Activated Sludge ◽

Nutrient Removal ◽

Biogas Production ◽

Reaction Rates ◽

Operational Efficiency ◽

Wastewater Sludge ◽

Biological Nutrient Removal ◽

Waste Activated Sludge ◽

Metabolic Reaction ◽

Mass Reduction

Pilot-scale research was conducted to quantify the effects of stabilizing combined wastewater sludges (primary and biological nutrient removal waste activated sludges), in a common high-rate, single-stage anaerobic digestion operation. Various ratios of primary to waste activated sludge were used, and digester operational efficiency was assessed on the basis of the amount and rate of volatile mass removal, biogas production, and digester supernatant quality. It was found that, depending on the sludge ratio, addition of the biological nutrient removal waste activated sludge decreased digester operational efficiency; for example, almost 20% less volatile mass reduction, up to 25% reduction in metabolic reaction rates, and reduced gas production rates of up to 40% were observed. This was attributed to the presence of the cell membrane encapsulating the fermentable substrates of waste activated sludge, making them less available in the digestion process. It was concluded that, unless some type of pretreatment operation is utilized to liberate these substrates, this type of commonly used codigestion system will be of less benefit to a wastewater treatment plant, especially the smaller facilities which will lose a ready source of power in the form of biogas production, and the full value of the waste activated sludge as a resource will not be realized. Key words: anaerobic sludge digestion, biogas production, biological nutrient removal, biosolids, combined sludge, fermentation, volatile mass reduction.

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Comparison of Yields and Decay Rates for a Biological Nutrient Removal Process and a Conventional Activated Sludge Process

Water Science & Technology ◽

10.2166/wst.1992.0695 ◽

1992 ◽

Vol 26 (9-11) ◽

pp. 2195-2198 ◽

Cited By ~ 8

Author(s):

S. A. McClintock ◽

V. M. Pattarkine ◽

C. W. Randall

Keyword(s):

Activated Sludge ◽

Nutrient Removal ◽

Pilot Scale ◽

Decay Rates ◽

Growth Yields ◽

Biological Nutrient Removal ◽

Activated Sludge Process ◽

Conventional Activated Sludge ◽

Aerobic Process ◽

Solids Retention

Two pilot-scale activated sludge reactors, one VIP (named after Virginia Initiative Plant) biological nutrient removal (BNR) process and one conventional, fully aerobic process, were operated over a range of solids retention times (SRT's) and under the same conditions so that growth yields and specific decay rates could be evaluated and compared. True growth yields (Y's) for the BNR and the conventional processes were equal and were 0.41 gVSS/gCOD. The specific decay rate, b, for the BNR process, 0.063 d, was lower than in the fully aerobic process, 0.110 d-1, indicating that decay occurs at a much lower rate in the anoxic and anaerobic zones of the BNR process.

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Integrated side-stream reactor for biological nutrient removal and minimization of sludge production

Water Science & Technology ◽

10.2166/wst.2015.067 ◽

2015 ◽

Vol 71 (7) ◽

pp. 1056-1064 ◽

Cited By ~ 9

Author(s):

M. Coma ◽

S. Rovira ◽

J. Canals ◽

J. Colprim

Keyword(s):

Activated Sludge ◽

Nutrient Removal ◽

Wastewater Treatment Plants ◽

Pilot Scale ◽

Biological Nutrient Removal ◽

Slight Reduction ◽

Nitrogen And Phosphorus ◽

Effluent Quality ◽

Side Stream ◽

Sludge Production

Integrated processes to reduce in situ the sludge production in wastewater treatment plants are gaining attention in order to facilitate excess sludge management. In contrast to post-treatments, such as anaerobic digestion which is placed between the activated sludge system and dewatering processes, integrated technologies are placed in the sludge return line. This study evaluates the application of an anoxic side-stream reactor (SSR) which creates a physiological shock and uncouples the biomass metabolism and diverts the activity from assimilation for biosynthesis to non-growth activities. The effect of this system in biological nutrient removal for both nitrogen and phosphorus was evaluated for the anaerobic, anoxic and aerobic reactors. The RedOx potential within the SSR was maintained at −150 mV while the sludge loading rate was modified by increasing the percentage of recycled activated sludge feed to the SSR (0 and 40% at laboratory scale and 0, 10, 50 and 100% at pilot scale). The use of the SSR presented a slight reduction of phosphorus removal but maintained the effluent quality to the required discharge values. Nitrogen removal efficiency increased from 75 to 86% while reducing the sludge production rate by 18.3%.

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Modeling the biotransformation of trimethoprim in biological nutrient removal system

Water Science & Technology ◽

10.2166/wst.2018.098 ◽

2018 ◽

Vol 2017 (1) ◽

pp. 144-155

Author(s):

Olumuyiwa O. Ogunlaja ◽

Wayne J. Parker

Keyword(s):

Activated Sludge ◽

Nutrient Removal ◽

Pilot Scale ◽

Biological Nutrient Removal ◽

Ammonia Oxidizing Bacteria ◽

Nitrification Inhibition ◽

Batch Tests ◽

Microbial Groups ◽

Polyphosphate Accumulating Organisms ◽

Removal System

Abstract A pilot scale biological nutrient removal (BNR) process, batch experiments and modeling exercises were employed to investigate the removal and biotransformation of trimethoprim (TMP) in a BNR activated sludge process. The concentrations of the active microbial groups – ammonia oxidizing bacteria (AOB), ordinary heterotrophic organisms (OHOs) and polyphosphate accumulating organisms (PAOs) – in the BNR bioreactor were quantified through modeling of the pilot bioreactor. The overall TMP removal efficiency for the pilot BNR process was 64 ± 14% while the TMP biotransformation efficiencies in the anaerobic, anoxic and aerobic zones were 22 ± 20%, 27 ± 8% and 36 ± 5% respectively. Batch tests with and without nitrification inhibition showed that AOB played a role in the biotransformation of TMP in BNR activated sludge. A pseudo first order model which incorporated the contributions of PAOs, OHOs and AOB to the overall biodegradation of TMP was found to describe the biodegradation of TMP in batch tests with and without nitrification inhibition. This model showed that PAOs, OHOs and AOB contributed towards the biotransformation of TMP in aerobic BNR activated sludge with the biotransformation rate constants following the trend of kAOB > kOHOs > kPAOs.

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Effect of addition of anaerobic fermented OFMSW (organic fraction of municipal solid waste) on biological nutrient removal (BNR) process: preliminary results

Water Science & Technology ◽

10.2166/wst.1998.0078 ◽

1998 ◽

Vol 38 (1) ◽

pp. 327-334 ◽

Cited By ~ 7

Author(s):

P. Pavan ◽

P. Battistoni ◽

P. Traverso ◽

A. Musacco ◽

F. Cecchi

Keyword(s):

Nutrient Removal ◽

Fermentation Process ◽

Organic Waste ◽

Anaerobic Fermentation ◽

Pilot Scale ◽

Biological Nutrient Removal ◽

Organic Fraction ◽

P Release ◽

Pure Methanol ◽

P Removal

The paper presents results coming from experiments on pilot scale plants about the possibility to integrate the organic waste and wastewater treatment cycles, using the light organic fraction produced via anaerobic fermentation of OFMSW as RBCOD source for BNR processes. The effluent from the anaerobic fermentation process, with an average content of 20 g/l of VFA+ lactic acid was added to wastewater to be treated in order to increase RBCOD content of about 60-70 mg/l. The results obtained in the BNR process through the addition of the effluent from the fermentation unit are presented. Significant increase of denitrification rate was obtained: 0.06 KgN-NO3/KgVSS d were denitrified in the best operative conditions studied. -Vmax shows values close to those typical of the pure methanol addition (about 0.3 KgN-NO3/KgVSS d). A considerable P release (35%) was observed in the anaerobic step of the BNR process, even if not yet a completely developed P removal process.

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