An activated sludge process without excess sludge production

An activated sludge process which produces no excess sludge was developed. The process is very simple as a small amount of return sludge is ozonated and then returned to the aeration tank. The ozonation enhances biodegradability of activated sludge, which is biologically oxidized in the aeration tank. A full-scale plant for treating 450m3/d of municipal wastewater was constructed and has been operated successfully for 9 months. The amount of excess sludge eliminated is directly proportional to the amount of ozone dosed to the sludge. At the ozone dosing rate of 0.034 kg/kg-SS, complete elimination of excess sludge has been achieved when 4 times more amount of sludge is ozonated than that of the excess sludge expected in the treatment without ozonation. After 5 months of operation without any withdrawal of excess sludge, small amount of inorganic substances like sand and silt accumulated in the sludge. On the other hand, inert organic substances does not seem to accumulate. As for effluent quality, BOD and nitrogen were kept good. Although effluent SS was 2–15 mg/l higher compared to a control without ozonation, it has been well below the discharge limit.

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Effect of important operational parameters on performance of coarse pore filtration activated sludge process

Water Science & Technology ◽

10.2166/wst.2002.0246 ◽

2002 ◽

Vol 46 (9) ◽

pp. 229-236 ◽

Cited By ~ 19

Author(s):

M.R. Alavi Moghaddam ◽

H. Satoh ◽

T. Mino

Keyword(s):

Activated Sludge ◽

Aeration Tank ◽

Activated Sludge Process ◽

Operational Parameters ◽

Solid Retention Time ◽

Effluent Quality ◽

Membrane Pores ◽

Filtration Membrane ◽

Operation Pressure ◽

Filter Clogging

A coarse pore filter can be applied inside the aeration tank instead of sedimentation tank for liquid separation from the sludge. It has pores, which are irregular in shape, and much bigger than micro-filtration membrane pores in size. The objective of the study was to investigate the effect of important operational parameters such as flux, aeration intensity, and solid retention time (SRT) on the performance of the coarse pore filtration activated sludge process. The effect of these parameters was studied in laboratory scale experiments. It was found that the flux had a significant role in the effluent quality of this system. The effluent SS and turbidity were not changed significantly at different aeration intensities. Three SRTs, 10, 30 and longer days (without excess sludge) were used for three reactors to check the effect of this parameter on the system performance. The results of the reactors with SRTs about 10 and 30 days have shown very good effluent quality without any filter clogging for more than 4 months operation. For the reactor with long SRT, the filter clogging was observed after about 80 days of operation, which caused the increase of the operation pressure and deterioration in the effluent quality for a few days.

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Systematic Modeling of Municipal Wastewater Activated Sludge Process and Treatment Plant Capacity Analysis Using GPS-X

Sustainability ◽

10.3390/su12198182 ◽

2020 ◽

Vol 12 (19) ◽

pp. 8182

Author(s):

Nuhu Dalhat Mu’azu ◽

Omar Alagha ◽

Ismail Anil

Keyword(s):

Activated Sludge ◽

Suspended Solids ◽

Systematic Approach ◽

Municipal Wastewater ◽

Treatment Plant ◽

Oxygen Demand ◽

Plant Performance ◽

Capacity Analysis ◽

Activated Sludge Process ◽

Effluent Quality

Mathematical modeling has become an indispensable tool for sustainable wastewater management, especially for the simulation of complex biochemical processes involved in the activated sludge process (ASP), which requires a substantial amount of data related to wastewater and sludge characteristics as well as process kinetics and stoichiometry. In this study, a systematic approach for calibration of the activated sludge model one (ASM1) model for a real municipal wastewater ASP was undertaken in GPS-X. The developed model was successfully validated while meeting the assumption of the model’s constant stoichiometry and kinetic coefficients for any plant influent compositions. The influences of vital ASP parameters on the treatment plant performance and capacity analysis for meeting local discharge limits were also investigated. Lower influent chemical oxygen demand in mgO2/L (COD) could inhibit effective nitrification and denitrification, while beyond 250 mgO2/L, there is a tendency for effluent quality to breach the regulatory limit. The plant performance can be satisfactory for handling even higher influent volumes up to 60,000 m3/d and organic loading when Total Suspended Solids/Volatile Suspended Solids (VSS/TSS) and particulate COD (XCOD)/VSS are maintained above 0.7 and 1, respectively. The wasted activated sludge (WAS) has more impact on the effluent quality compared to recycle activated sludge (RAS) with significant performance improvement when the WAS was increased from 3000 to 9000 m3/d. Hydraulic retention time (HRT) > 6 h and solids retention time (SRT) < 7 days resulted in better plant performance with the SRT having greater impact compared with HRT. The plant performance could be sustained for a quite appreciable range of COD/5-day Biochemical Oxygen Demand (BOD5 in mgO2/L) ratio, Mixed Liquor Suspended Solid (MLSS) of up to 6000 mg/L, and when BOD5/total nitrogen (TN) and COD/TN are comparatively at higher values. This work demonstrated a systematic approach for estimation of the wastewater treatment plant (WWTP) ASP parameters and the high modeling capabilities of ASM1 in GPS-X when respirometry tests data are lacking.

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

Water Science & Technology ◽

10.2166/wst.1996.0456 ◽

1996 ◽

Vol 34 (3-4) ◽

pp. 395-404 ◽

Cited By ~ 40

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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Operation and Performance of a New Activated Sludge Process: The Contact Stabilization Extended Aeration Hybrid

Water Science & Technology ◽

10.2166/wst.1982.0069 ◽

1982 ◽

Vol 14 (1-2) ◽

pp. 367-380

Author(s):

B H Paepcke ◽

P H Jones

Keyword(s):

Activated Sludge ◽

Municipal Wastewater ◽

Lower Cost ◽

Treatment Plant ◽

Aeration Tank ◽

Activated Sludge Process ◽

Municipal Wastewater Treatment ◽

Process Stability ◽

Aeration Process ◽

And Performance

In this study the operation and performance of a contact stabilization process operating under the extended aeration mode is examined. Data was obtained during a detailed plant study carried out at a full scale municipal wastewater treatment plant. This new hybrid activated sludge process has good process stability like the conventional extended aeration process, but achieves this with a significantly smaller aeration tank volume and therefore lower cost.

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

Water Science & Technology ◽

10.2166/wst.1994.0434 ◽

1994 ◽

Vol 30 (9) ◽

pp. 11-20 ◽

Cited By ~ 117

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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Integration of membrane filtration into the activated sludge process in municipal wastewater treatment

Water Science & Technology ◽

10.2166/wst.1998.0686 ◽

1998 ◽

Vol 38 (4-5) ◽

pp. 429-436 ◽

Cited By ~ 8

Author(s):

N. Engelhardt ◽

W. Firk ◽

W. Warnken

Keyword(s):

Wastewater Treatment ◽

Activated Sludge ◽

Pilot Plant ◽

Membrane Filtration ◽

Large Scale ◽

Municipal Wastewater ◽

Aeration Tank ◽

Activated Sludge Process ◽

Municipal Wastewater Treatment ◽

New Process

Energy-efficient membrane modules for microfiltration are available to realize a new process engineering in municipal wastewater treatment. The microfiltration membrane ensures that all microorganisms are retained in the aeration tank. A content of mixed-liquor suspended solids of e.g. 15 gMLSS/l can easily be achieved in a large scale plant. Thus the aeration tank is considerably reduced in size. A secondary clarifier is no longer needed. A filtration and a disinfection can be dismissed. A pilot plant gives first knowledge on the application of the activated sludge process with submersed membrane filtration. Based on the tests' results and the knowledge gained during the operation of the pilot plant, a WWTP with membrane filtration for 3000 inhabitants is designed. The costs of investment and operation are estimated.

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Modelling of activated sludge for textile wastewaters

Water Science & Technology ◽

10.2166/wst.1998.0570 ◽

1998 ◽

Vol 38 (4-5) ◽

pp. 9-17 ◽

Cited By ~ 16

Author(s):

F. Germirli Babuna ◽

D. Orhon ◽

E. Ubay Çokgör ◽

G. Insel ◽

B. Yaprakli

Keyword(s):

Activated Sludge ◽

Comprehensive Evaluation ◽

Component Model ◽

Activated Sludge Process ◽

Experimental Basis ◽

Model Simulations ◽

Effluent Quality ◽

Model Based ◽

Major Process ◽

Textile Wastewaters

A comprehensive evaluation of four different textile wastewaters was carried out to set the experimental basis for the modelling of activated sludge process. Experiments involved beside conventional characterization, detailed COD fractionation and assessment of major kinetic and stoichiometric coefficients by means of respirometric measurements. A multi-component model based on the endogenous decay concept was used for the kinetic interpretation and design of activated sludge. The fate and variation of major process components affecting effluent quality with the sludge age were evaluated by means of model simulations.

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