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.

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.

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.

scholarly journals Optimization of Ozonation Process for the Reduction of Excess Sludge Production from Activated Sludge Process of Sago Industry Wastewater Using Central Composite Design

2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
B. Subha ◽  
M. Muthukumar
Keyword(s):  
Activated Sludge ◽  
Central Composite Design ◽  
Retention Time ◽  
Acidic Ph ◽  
Activated Sludge Process ◽  
Excess Sludge ◽  
Cod Reduction ◽  
Ozonation Time ◽  
Central Composite ◽  
Sludge Production

Sago industries effluent containing large amounts of organic content produced excess sludge which is a serious problem in wastewater treatment. In this study ozonation has been employed for the reduction of excess sludge production in activated sludge process. Central composite design is used to study the effect of ozone treatment for the reduction of excess sludge production in sago effluent and to optimise the variables such as pH, ozonation time, and retention time. ANOVA showed that the coefficient determination value (R2) of VSS and COD reduction were 0.9689 and 0.8838, respectively. VSS reduction (81%) was achieved at acidic pH 6.9, 12 minutes ozonation, and retention time of 10 days. COD reduction (87%) was achieved at acidic pH 6.7, 8 minutes of ozonation time, and retention time of 6 days. Low ozonation time and high retention time influence maximum sludge reduction, whereas low ozonation time with low retention time was effective for COD reduction.

A full-scale operation of a novel activated sludge process without excess sludge production

1996 ◽  
Vol 34 (3-4) ◽  
pp. 395-404 ◽  
Author(s):  
H. Yasui ◽  
K. Nakamura ◽  
S. Sakuma ◽  
M. Iwasaki ◽  
Y. Sakai
Keyword(s):  
Activated Sludge ◽  
Inorganic Compounds ◽  
Material Balance ◽  
Full Scale ◽  
Aeration Tank ◽  
Total Biomass ◽  
Activated Sludge Process ◽  
Excess Sludge ◽  
Conventional Activated Sludge ◽  
Operation Costs

The authors have presented a new concept of excess sludge elimination treatment with recirculation of sludge via ozonation in the activated sludge process. This paper is intended to clarify the potential application of the process to municipal and industrial wastewater treatments. In a full-scale operational experiment lasting 10 months under 550 kg/d of BOD loading, no excess sludge was needed to be withdrawn and no significant accumulation of inorganic solids occurred in the aeration tank. Most of the inorganic compounds in the sludge were released to the soluble phase. Material balance indicated that one-third of ozonated sludge was mineralized via the recirculation treatment, and thereby the requirement of sludge mass to be treated was 3.3 times as much as sludge to be eliminated. Effluent TOC was slightly higher than under the conventional activated sludge process, indicating that refractory TOC was released from the sludge eliminated by treatment. The amount of released TOC corresponded to less than 2 weight % of eliminated sludge under recirculation rates below 30% of total biomass in the aeration tank in a day, but increased at higher recirculation rates. The operation costs associated with the process were estimated to be lower than those of conventional dewatering and disposal.

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