Use of lysis and recycle to control excess sludge production in activated sludge treatment: bench scale study and effect of chlorinated organic compounds

2002 ◽  
Vol 46 (10) ◽  
pp. 55-61 ◽  
Author(s):  
M.A. Nolasco ◽  
A.L.O. Campos ◽  
A.M. Springer ◽  
E.C. Pires
Keyword(s):  
Activated Sludge ◽  
Removal Efficiency ◽  
Control Unit ◽  
Pulp And Paper ◽  
Synthetic Wastewater ◽  
Second Phase ◽  
Excess Sludge ◽  
Chlorinated Compounds ◽  
Treatment Unit ◽  
Bench Scale

The most widely used treatment system in the pulp and paper industry - the activated sludge - produces high quantities of sludge which need proper disposal. In this paper a modified activated sludge process is presented. A synthetic wastewater, prepared to simulate the effluent of bleached and unbleached pulp and paper plant wastewater, was submitted to treatment in a bench scale aerobic reactor. The excess sludge was lysed in a mechanical mill - Kaddy™ mill - and totally recycled to the aeration tank. In the first phase the synthetic wastewater, without the chlorinated compounds, was fed to the reactor. In the second phase increasing dosages of the chlorinated compounds were used. Total recycle of excess sludge after disintegration did not produce adverse effects. During the first phase average COD removal efficiency was 65% for the control unit, which operated in a conventional way, and 63% for the treatment unit, which operated with total recycle. During the second phase the COD removal efficiency increased to 77% in the control unit and 75% in the treatment unit. Chlorinated organics removal was 85% in the treatment unit and 86% for the control unit. These differences are not significant.

Upgrading Wastewater Treatment by Water Hyacinth in Developing Countries

1990 ◽  
Vol 22 (7-8) ◽  
pp. 153-160 ◽  
Author(s):  
Pradeep Kumar ◽  
R. J. Garde
Keyword(s):  
Wastewater Treatment ◽  
Water Hyacinth ◽  
Treatment Plant ◽  
Cod Removal ◽  
Treatment System ◽  
Synthetic Wastewater ◽  
Second Phase ◽  
Treatment Unit ◽  
Batch Studies ◽  
New Treatment

With increasing stress on existing wastewater treatment systems, it is necessary either to upgrade the treatment unit(s) or install an entirely new treatment plant. Obviously, the upgrading is preferred over the alternative of having a new system. Keeping this in view, in the present project, an attempt has been made to explore the possibility of upgrading existing facultative ponds using water hyacinth. Bench-scale batch studies were designed to compare the performance of hyacinth treatment system with facultative ponds. Investigations were carried out with synthetic wastewater having COD in the range of 32.5-1090 mg/l. The efficiency of COD removal in water hyacinth ponds was 15-20 percent more than the facultative ponds. Based on the results, an empirical model has been proposed for COD removal kinetics. In the second phase of the project a hyacinth pond was continuously operated. BOD, COD, TS, TN, TP, pH, and DO were regularly monitored. However, the DO of the effluent from hyacinth treatment system was considerably reduced. Effluent should be aerated before it is discharged. The results indicate that the existing facultative ponds can be stalked with water hyacinth to improve their performance as well as hyacinth treatment systems can be installed to support the conventional treatment.

scholarly journals Dynamic changes of bacterial community in activated sludge with pressurized aeration in a sequencing batch reactor

2017 ◽  
Vol 75 (11) ◽  
pp. 2639-2648 ◽  
Author(s):  
Yong Zhang ◽  
Wei-Li Jiang ◽  
Yang Qin ◽  
Guo-Xiang Wang ◽  
Rui-Xiao Xu ◽  
...  
Keyword(s):  
Bacterial Community ◽  
Activated Sludge ◽  
Removal Efficiency ◽  
Sequencing Batch Reactor ◽  
Batch Reactor ◽  
Atmospheric Environment ◽  
Synthetic Wastewater ◽  
Control Group ◽  
Feed Water ◽  
Moderate Pressure

This study aimed to investigate the organic removal efficiency and microbial population dynamics in activated sludge with pressurized aeration. The activated sludge was fed with synthetic wastewater composed of simple carbon source to avoid the effect of complex components on microbial communities. The pressurized acclimation process was conducted in a bench-scale sequencing batch reactor (SBR) under 0.3 MPa gage pressure. Another SBR was running in atmospheric environment as a control reactor, with the same operation parameters except for the pressure. Bacterial diversity was investigated by Illumina sequencing technology. The results showed that the total organic carbon removal efficiency of the pressurized reactor was significantly higher, while the mixed liquor suspended solids concentrations were much lower than those of the control reactor. Moderate pressure of 0.3 MPa had little effect on Alpha-diversity of bacterial communities due to the similar running conditions, e.g., feed water, solids retention time (SRT) and the cyclic change of dissolved oxygen (DO) concentrations. Although the relative percentage of the bacterial community changed among samples, there was no major change of predominant bacterial populations between the pressurized group and the control group. Pressurized aeration would have a far-reaching impact on microbial community in activated sludge when treating wastewaters being unfavorable to the dissolution of oxygen.

Non-Filamentous Activated Sludge Bulking Caused by Zoogloea

1994 ◽  
Vol 29 (7) ◽  
pp. 301-304 ◽  
Author(s):  
L. Novák ◽  
L. Larrea ◽  
J. Wanner ◽  
J. L. García-Heras
Keyword(s):  
Activated Sludge ◽  
Wave Mode ◽  
Synthetic Wastewater ◽  
Activated Sludge Process ◽  
Volume Changes ◽  
Plant Operation ◽  
Operational Conditions ◽  
Bench Scale ◽  
Sludge Bulking ◽  
Previous State

An abundant growth of zoogloeal colonies was observed periodically during some experiments carried out on a bench-scale plant fed with a complex synthetic wastewater. The plant had a configuration with an enhanced regeneration-denitrification-nitrification (R-D-N) activated sludge process for low alkalinity wastewaters. Several operational changes were undertaken in order to suppress the excessive growth of zoogloeal colonies. They included: (1) changes in the wastewater composition, (2) volume changes in the compartmentalization of the anoxic selector, (3) increase of D.O. concentration in the regeneration and nitrification tanks. Conclusions from the plant operation observations give rise to a hypothesis that none of the operational changes provoked a significant restriction in the abundant zoogloeal growth. When a temporary improvement was observed, after acclimatization on the new operational conditions the microorganisms culture returned to its previous state and continued to grow in a wave-mode. The reason for the appearance of this type of sludge might be closely related to the composition of the synthetic wastewater.

scholarly journals Efficiency studies of modified IFAS-OSA system upgraded by an anoxic sludge holding tank

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Mansour Fazelipour ◽  
Afshin Takdastan ◽  
Seyed Mehdi Borghei ◽  
Neda Kiasat ◽  
Marcin Glodniok ◽  
...  
Keyword(s):  
Control System ◽  
Activated Sludge ◽  
Removal Efficiency ◽  
Biomass Yield ◽  
New Technology ◽  
Cod Removal ◽  
Yield Coefficient ◽  
Excess Sludge ◽  
Fixed Film ◽  
P Removal

AbstractAn upgraded integrated fixed-film activated sludge-oxic settling anoxic (IFAS-OSA) system is a new technology for reducing nutrients and excess sludge. The results showed that the average TN removal efficiency of the IFAS-OSA system was gradually increased up to 7.5%, while the PO4–3-P removal efficiency increased up-to 27%, compared with that of the IFAS system. The COD removal efficiency of the IFAS-OSA system was slightly increased up-to 5.4% and TSS removal efficiency increased up to 10.5% compared with the control system. Biomass yield coefficient (Yobs) in the IFAS and IFAS-OSA systems were 0.44 and 0.24 (gr MLSS/ gr COD). Hence, sludge production decreased by 45%. The average SVI was decreased by 48% in IFAS-OSA system compared with IFAS. This study demonstrated the better performance of the IFAS-OSA system compared to that of the IFAS system.

Selector Volume in Pulp and Paper Activated Sludge Wastewater Treatment Plants – Bench Scale and Pilot Plant Studies

1994 ◽  
Vol 29 (5-6) ◽  
pp. 303-311
Author(s):  
J. Wessberg ◽  
T. Welander ◽  
M. Jönsson
Keyword(s):  
Activated Sludge ◽  
Pilot Plant ◽  
Wastewater Treatment Plants ◽  
Pulp And Paper ◽  
Volume Index ◽  
Sludge Volume Index ◽  
Bench Scale ◽  
Reference Process ◽  
Kraft Mill

Laboratory activated sludge reactors were operated on effluent wastewater from a kraft mill. Two of the three reactors were initially preceded with a “normal” size aerated selector, 2% of the total aerated volume, with unsatisfactory sludge volume index development. When the selectors were replaced by larger ones, 13% of the aerated volume, the sludge volume index could be kept below 50 ml/g for the selector processes while continuing to be higher and more unstable in the reference process. A pilot plant, operated in situ on the same wastewater, showed a comparable improvement in sludge volume index when its selector, 7% of the total volume, was replaced by one that constituted 13% of the total volume, corresponding to a selector load of 3 g BOD / g VSS * d. According to studies of the COD balance around one bench scale selector, the COD removal mechanism in the selector was respiration/assimilation rather than uptake/storage.

Excess sludge reduction in activated sludge processes by integrating biomass alkaline heat treatment

2001 ◽  
Vol 44 (2-3) ◽  
pp. 437-444 ◽  
Author(s):  
M. Rocher ◽  
G. Roux ◽  
G. Goma ◽  
A. Pilas Begue ◽  
L. Louvel ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Wastewater Treatment ◽  
Activated Sludge ◽  
Waste Treatment ◽  
Ralstonia Eutropha ◽  
Synthetic Wastewater ◽  
Waste Activated Sludge ◽  
Excess Sludge ◽  
Wastewater Treatment Process ◽  
Activated Sludge Processes

With new EC regulations, alternative treatment and disposal techniques of the excess sludge produced by activated sludge wastewater treatment plants have to be developed. To decrease activated sludge production yield, microbial cell lysis can be amplified to enhance cryptic growth (biomass growth on lysates). Cell breakage techniques (thermal, alkaline and a combination) were studied to generate Ralstonia eutropha (strain model) and waste activated sludge lysates and to evaluate their biodegradability. Gentle treatment conditions by alkaline waste treatment (20 min at 60°C and pH 10 by NaOH addition) allowed waste activated sludge to be solubilized by a two step process (instantaneous and post-treatment) giving a dissolved organic carbon released by the total suspended solids treated of 267 mgDOC.g-1TSS. The biodegradation of the soluble fraction of the lysates by fresh sludge reached 75 and 90% after 48 and 350 hrs of incubation respectively. A validation on a laboratory scale by insertion of a liquor alkaline heat treatment loop in a biological synthetic wastewater treatment process was carried out. A reduction of 37% of the excess sludge was obtained without altering the purification yield of the process.

Performance evaluation of various aerobic biological systems for the treatment of domestic wastewater at low temperatures

2008 ◽  
Vol 58 (4) ◽  
pp. 819-830 ◽  
Author(s):  
N. Sundaresan ◽  
L. Philip
Keyword(s):  
Performance Evaluation ◽  
Activated Sludge ◽  
Fluidized Bed ◽  
Removal Efficiency ◽  
Biological Systems ◽  
Domestic Wastewater ◽  
Cod Removal ◽  
Synthetic Wastewater ◽  
Activated Sludge Process ◽  
Cod Removal Efficiency

Studies were undertaken on the performance evaluation of three different types of aerobic reactors, namely, activated sludge process, fluidized bed reactor and submerged bed reactor. Initially synthetic wastewater was used for stabilizing the system and later domestic wastewater of IIT Madras was used as the feed for the biological systems. The hydraulic retention time was maintained as 24 h. The seed sludge was collected from IIT Madras sewage treatment plant. The inlet COD to the reactors with synthetic wastewater was 1,000±20 mg/L and with real wastewater, it was 150 to 350 mg/L. The performance of the reactors was evaluated based on the soluble COD and nitrogen removal efficiency. The pH, temperature, dissolved oxygen (DO) and mixed liquid suspended solid (MLSS) concentration were measured periodically. The reactors were acclimatized at 35°C in batch mode and changed to continuous mode at 30°C. After the systems attained its steady state at a particular temperature, the temperature was reduced from 35°C to 5°C stepwise, with each step of 5°C. The start-up time for submerged bed reactor was slightly more than fluidized and conventional activated sludge process. The COD removal efficiency of the three reactors was higher with synthetic wastewaters as compared to actual domestic wastewater. Submerged bed reactor was more robust and efficient as compared to activated sludge and fluidized bed reactors. The COD removal efficiency of the reactors was relatively good until the operating temperature was maintained at 15°C or above. At 10°C, submerged bed reactor was able to achieve 40% COD removal efficiency whereas; the fluidized bed and conventional ASP reactors were showing only 20% COD removal efficiency. At 5°C, almost all the systems failed. Submerged bed reactor showed around 20% COD removal efficiency. However, this reactor was able to regain its 90% of original efficiency, once the temperature was raised to 10°C. At higher temperatures, the nitrification efficiency of the reactors was above 80–90%. As the temperature reduced the nitrification efficiency has reduced drastically. In summary, submerged bed reactors seems to be a better option for treating domestic wastewaters at low temperature regions.

Treatment of a milkpowder/butter wastewater using the AAO activated sludge configuration

1997 ◽  
Vol 36 (10) ◽  
pp. 79-86 ◽  
Author(s):  
Michael J. Donkin ◽  
John M. Russell
Keyword(s):  
Activated Sludge ◽  
Removal Efficiency ◽  
Nutrient Removal ◽  
Phosphorus Removal ◽  
Suspended Solids ◽  
Synthetic Wastewater ◽  
Biological Nutrient Removal ◽  
In Series ◽  
Aerobic Reactor ◽  
Original Size

A laboratory-scale nutrient removal activated sludge system, based on the AAO configuration, was used to treat a synthetic wastewater from a milkpowder/butter factory. In this system, substrate is fed to anaerobic and anoxic selectors in series with an aerobic reactor. Sludge is returned to the anaerobic selector, and mixed liquor from the aerobic reactor is recycled to the anoxic selector. The overall system is operated at an HRT of 7 days and a nominal sludge age of 20 days. This system was prone to prolonged bulking periods, with filamentous bacteria Sphaerotilus natans, Type 0411 and Haliscomenobacter hydrossis being identified in the mixed liquors, although effective clarifier operation prevented loss of suspended solids. Theory suggests that selectors may be used to circumvent low F:M bulking, and to bring about enhanced biological nutrient removal. An investigation of the initial design revealed that relatively high nitrite levels were present in the system, and a larger anoxic selector with an HRT of 820 minutes was substituted for the original one with an HRT of 48 minutes. This resulted in a decrease in nitrite and a equivalent increase in nitrate in the system. Overall nitrogen removal remained unchanged at 66%, and SVI levels did not improve. On resetting the anoxic selector to its original size, the effect was not reversed. Phosphorus removal efficiency was detrimentally affected by the anoxic sizing experiment (49% to 20%), and this may be linked to the raised level of nitrate in the system. COD removal efficiency remained excellent throughout the trial at over 90% removal.

Pilot-scale studies on biological treatment of hypersaline wastewater at low temperature

2005 ◽  
Vol 52 (10-11) ◽  
pp. 129-137 ◽  
Author(s):  
Y.Z. Peng ◽  
G.B. Zhu ◽  
S.Y. Wang ◽  
D.S. Yu ◽  
Y.W. Cui ◽  
...  
Keyword(s):  
Low Temperature ◽  
Activated Sludge ◽  
Removal Efficiency ◽  
Biological Treatment ◽  
Halophilic Bacteria ◽  
Plug Flow ◽  
Pilot Scale ◽  
Ammonia Removal ◽  
Bench Scale ◽  
Seawater Salinity

In order to investigate the feasibility of biological treatment of hypersaline wastewater produced from toilet flushing with seawater at low temperature, pilot-scale studies were established with plug-flow activated sludge process at low temperature (5–9°C) based on bench-scale experiments. The critical salinity concentration of 30g/L, which resulted from the cooperation results of the non-halophilic bacteria and the halophilic bacteria, was drawn in bench-scale experiments. Pilot-scale studies showed that high COD removal efficiency, higher than 80%, was obtained at low temperature when 30 percent seawater was introduced. The salinity improved the settleability of activated sludge, and average sludge value dropped down from 38% to 22.5% after adding seawater. Seawater salinity had a strong negative effect on notronomonas and nitrobacter growth, but much more on the nitrobacter. The nitrification action was mainly accomplished by nitrosomonas. Bench-scale experiments using two SBRs were carried out for further investigation under different conditions of salinities, ammonia loadings and temperatures. Biological nitrogen removal via nitrite pathway from wastewater containing 30 percent seawater was achieved, but the ammonia removal efficiency was strongly related not only to the influent ammonia loading at different salinities but also to temperature. When the ratio of seawater to wastewater was 30 percent, and the ammonia loading was below the critical value of 0.15kgNH4+-N/(kgMLSS.d), the ammonia removal efficiency via nitrite pathway was above 90%. The critical level of ammonia loading was 0.15, 0.08 and 0.03kgNH4+-N/(kgMLSS.d) respectively at the different temperature 30°C, 25°C and 20°C when the influent ammonia concentration was 60–80mg/L and pH was 7.5–8.0.

Variation in Sludge Settleability with Temperature

1980 ◽  
Vol 15 (1) ◽  
pp. 73-82 ◽  
Author(s):  
J.G. Henry ◽  
E.E. Salenieks
Keyword(s):  
Activated Sludge ◽  
Effect Of Temperature ◽  
Organic Load ◽  
Limiting Factor ◽  
Appreciable Effect ◽  
Loading Rates ◽  
Bench Scale ◽  
Filamentous Bulking ◽  
Filamentous Microorganisms ◽  
Sludge Settleability

Abstract This study examined the effect of temperature on the settleabi1ity of activated sludge at various organic loading rates. Five completely mixed, bench-scale, activated sludge plants, operating under similar conditions at 5, 10 and 19°C, were continuously fed diluted, settled sewage supplemented with carbohydrate (sucrose). Hydraulic loading rates, MLSS and pH were maintained at constant levels during the experiments to eliminate these factors are variables. Dissolved oxygen was kept in excess of 3 mg/1 so that it would not be a limiting factor. Sludge Volume Indices (SVI ) and zone settling velocities were used to indicate changes in sludge settleability. Microscopic examination of the activated sludge indicated significant differences in the morphological features of filamentous microorganisms present at the two temperature extremes. At 19°C, the predominant forms were characterized by long curving trichomes, occasionally falsely branching, containing short cylindrical cells. At 5 °C, much smaller straight filaments, composed of long, narrow, rod-shaped cells appeared to be the principal microorganisms responsible for bulking. Various other filamentous forms were always present at each of the temperatures studied. Stirred sludge settling tests of moderately bulking sludges generally exhibited much higher settling velocities and lower SVI's than unstirred bulking samples. However, extremely filamentous bulking sludge exhibited comparable stirred and unstirred settling velocity and SVI values. The standard SVI test was found to be an inadequate indicator of the extent of bulking when trying to correlate the SVI failures from bench-scale performance with the results from continuous units. Lower temperature had no appreciable effect on COD removal efficiency as long as bulking did not cause a loss of solids in the effluent. However, results suggested that less than half the organic load could be accepted at 5°C, that could be handled at 19°C, before filamentous bulking occurred. A plot of loading versus temperature for various SVI's provided a visual indication of the safe loading limit below which bulking was unlikely to occur. The study clearly demonstrated that temperature can have a significant effect on sludge settleability.

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