scholarly journals REDUCTION BY SONICATION OF EXCESS SLUDGE PRODUCTION IN A CONVENTIONAL ACTIVATED SLUDGE SYSTEM: CONTINUOUS FLOW AND LAB‐SCALE REACTOR

2008 ◽  
Vol 29 (12) ◽  
pp. 1307-1320 ◽  
Author(s):  
S. Vaxelaire ◽  
E. Gonze ◽  
G. Merlin ◽  
Y. Gonthier
Keyword(s):  
Activated Sludge ◽  
Continuous Flow ◽  
Excess Sludge ◽  
Conventional Activated Sludge ◽  
Activated Sludge System ◽  
Scale Reactor ◽  
Sludge Production

New approaches to minimize excess sludge in activated sludge systems

2001 ◽  
Vol 44 (10) ◽  
pp. 203-208 ◽  
Author(s):  
G.-H. Chen ◽  
S. Saby ◽  
M. Djafer ◽  
H.-K. Mo
Keyword(s):  
Activated Sludge ◽  
Activated Sludge Process ◽  
Conventional System ◽  
Excess Sludge ◽  
Active Sludge ◽  
New Approaches ◽  
Conventional Activated Sludge ◽  
Sludge Settleability ◽  
Activated Sludge Systems ◽  
Sludge Production

This paper presents three new approaches to reduce excess sludge production in activated sludge systems: 1) modification of conventional activated sludge process with insertion of a sludge holding tank in the sludge return line; 2) chlorination of excess sludge so as to minimize excess sludge production; and 3) utilization of a metabolic uncoupler, 3, 3′, 4′, 5-Tetrachlorosalicylanilide (TCS) to maximize futile activity of sludge microorganisms thereby leading to a reduction of sludge growth. Pilot study was carried out to evaluate this modified activated sludge process (OSA). It has been confirmed that the OSA process is effective in reducing excess sludge; particularly when the ORP level in the sludge holding tank was kept at -250 mV, more than 50% of the excess sludge was reduced. This process can maintain the effluent quality and even perform with a better sludge settleability than a conventional system. Experimental work on the second approach showed that chlorination treatment of excess sludge at a chlorine dose of 0.066 g Cl2/g MLSS reduced the excess sludge by 60%, while concentration of THMS was found below 200 ppb in the treated sludge. However, such sludge chlorination treatment sacrificed sludge settleability. Thus, it is not feasible to introduce the chlorination step to a conventional system. The third approach confirmed that addition of TCS could reduce sludge growth effectively if the TCS concentration is greater than 0.4 ppm. A 0.8-ppm concentration of TCS actually reduced excess sludge by 45%. It was also experimentally demonstrated that presence of TCS increases the portion of active sludge microorganisms over the entire microbial population.

Reduction of excess sludge production using mechanical disintegration devices

2006 ◽  
Vol 54 (5) ◽  
pp. 69-76 ◽  
Author(s):  
G.W. Strünkmann ◽  
J.A. Müller ◽  
F. Albert ◽  
J. Schwedes
Keyword(s):  
Activated Sludge ◽  
Nitrogen Removal ◽  
Activated Sludge Process ◽  
Operational Parameters ◽  
Excess Sludge ◽  
Operational Conditions ◽  
Mechanical Disintegration ◽  
Conventional Activated Sludge ◽  
Removal Capacity ◽  
Sludge Production

The usability of mechanical disintegration techniques for the reduction of excess sludge production in the activated sludge process was investigated. Using three different disintegration devices (ultrasonic homogeniser, stirred media mill, high pressure homogeniser) and different operational parameters of the disintegration, the effect of mechanical disintegration on the excess sludge production and on the effluent quality was studied within a continuously operated, laboratory scale wastewater treatment system with pre-denitrification. Depending on the operational conditions and the disintegration device used, a reduction of excess sludge production of up to 70% was achieved. A combination of mechanical disintegration with a membrane bioreactor process with high sludge age is more energy effective concerning reduction of sludge production than with a conventional activated sludge process at lower sludge ages. Depending on the disintegration parameters, the disintegration has no, or only minor, negative effect on the soluble effluent COD and on the COD-removal capacity of the activated sludge process. Nitrogen-removal was slightly deteriorated by the disintegration, whereas the system used was not optimised for nitrogen removal before disintegration was implemented.

Valuation of OSA process and folic acid addition as excess sludge minimization alternatives applied in the activated sludge process

2015 ◽  
Vol 73 (4) ◽  
pp. 734-739 ◽  
Author(s):  
C. L. Martins ◽  
V. F. Velho ◽  
S. R. A. Ramos ◽  
A. S. C. D. Pires ◽  
E. C. N. F. A. Duarte ◽  
...  
Keyword(s):  
Folic Acid ◽  
Activated Sludge ◽  
Effluent Treatment ◽  
Activated Sludge Process ◽  
Excess Sludge ◽  
Control Phase ◽  
Activated Sludge System ◽  
Acid Addition ◽  
Sludge Minimization ◽  
Sludge Production

The aim of this study was to investigate the ability of the oxic-settling-anaerobic (OSA)-process and the folic acid addition applied in the activated sludge process to reduce the excess sludge production. The study was monitored during two distinct periods: activated sludge system with OSA-process, and activated sludge system with folic acid addition. The observed sludge yields (Yobs) were 0.30 and 0.08 kgTSS kg–1 chemical oxygen demand (COD), control phase and OSA-process (period 1); 0.33 and 0.18 kgTSS kg–1 COD, control phase and folic acid addition (period 2). The Yobs decreased by 73 and 45% in phases with the OSA-process and folic acid addition, respectively, compared with the control phases. The sludge minimization alternatives result in a decrease in excess sludge production, without negatively affecting the performance of the effluent treatment.

Performance of coarse pore filtration activated sludge system

2002 ◽  
Vol 46 (11-12) ◽  
pp. 71-76 ◽  
Author(s):  
M.R. Alavi Moghaddam ◽  
H. Satoh ◽  
T. Mino
Keyword(s):  
Activated Sludge ◽  
Pore Size ◽  
Small Scale ◽  
Aeration Tank ◽  
Activated Sludge Process ◽  
Trickling Filter ◽  
Conventional Activated Sludge ◽  
Activated Sludge System ◽  
Scale Reactor

A coarse pore filter can be applied inside the aeration tank to facilitate the separation of sludge from liquid instead of sedimentation. This filter has pores, which are irregular in shape, and the pore size is bigger than those of MF. The objectives of the study were to maintain as much as MLSS in the activated sludge process with coarse pore filter and to investigate the performance under high MLSS condition. Small-scale reactor results so far show good quality of effluent specially after starting the sludge bulking in the system in terms of SS, TOC, DOC and turbidity. The average carbon removal for 62 days operation of this system was about 94% (based on effluent DOC) and 87% (based on effluent TOC). The average sludge yield in this system is about 0.44 kg MLSS/kg TOC which is about 0.24 kg MLSS/kg BOD. This amount is less than those of conventional activated sludge and trickling filter.

An innovative approach to reduce excess sludge production in the activated sludge process

1994 ◽  
Vol 30 (9) ◽  
pp. 11-20 ◽  
Author(s):  
H. Yasui ◽  
M. Shibata
Keyword(s):  
Activated Sludge ◽  
Biomass Concentration ◽  
Experimental Period ◽  
Aeration Tank ◽  
Activated Sludge Process ◽  
Biological Degradation ◽  
Excess Sludge ◽  
Conventional Activated Sludge ◽  
New Process ◽  
Sludge Production

A new process has been developed to reduce excess sludge production, in which both excess sludge digestion and wastewater treatment are conducted simultaneously in the same aeration tank. The ozonation enhances biological degradation of the activated sludge, which is decomposed in a subsequent biological treatment. A considerable amount of biomass is mineralized biologically in proportion to the amount of recirculated biomass from the ozonation stage to the biological stage. It was observed that the amount of excess sludge is reduced to nearly zero when 1.2 kg/m3-aeration tank volume of biomass is recirculated in a day from the biological stage to the ozonation stage at a BOD loading of 1.0 kg/m3/d. A biomass concentration of 4200 mg/L was maintained at 1.0 kg-BOD/m3/d without drawing excess sludge for 6 weeks of experimental period under ozone dose of 0.05 g-O3/g-SS and recirculation rate at 0.3 d−1. Only a limited difference in the effluent quality was observed between the new process and the conventional activated sludge process.

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