Fate of Emerging Contaminants in High-Rate Activated Sludge Systems

High-rate activated sludge (HRAS) systems are designed to shift the energy-intensive processes to energy-saving and sustainable technologies for wastewater treatment. The high food-to-microorganism (F/M) ratios and low solid retention times (SRTs) and hydraulic retention times (HRTs) applied in HRAS systems result in the maximization of organic matter diversion to the sludge which can produce large amounts of biogas during anaerobic digestion, thus moving toward energy-neutral (or positive) treatment processes. However, in addition to the energy optimization, the removal of emerging contaminants (ECs) is the new challenge in wastewater treatment. In the context of this study, the removal efficiencies and the fates of selected ECs (three endocrine disruptors (endocrine disrupting chemicals (EDCs))—nonylphenol, bisphenol A and triclosan, and four pharmaceuticals (PhACs)—ibuprofen, naproxen, diclofenac and ketoprofen) in HRAS systems have been studied. According to the results, EDCs occurred in raw wastewater and secondary sludge at higher concentrations compared to PhACs. In HRAS operating schemes, all compounds were poorly (<40%) to moderately (<60%) removed. Regarding removal mechanisms, biotransformation was found to be the dominant process for PhACs, while for EDCs sorption onto sludge is the most significant removal mechanism affecting their fates and their presence in excess sludge.

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Intelligent control system based on blackboard concept for wastewater treatment processes

Water Science & Technology ◽

10.2166/wst.1998.0506 ◽

1998 ◽

Vol 37 (12) ◽

pp. 77-85 ◽

Cited By ~ 1

Author(s):

T. Ohtsuki ◽

T. Kawazoe ◽

T. Masui

Keyword(s):

Wastewater Treatment ◽

Control System ◽

Activated Sludge ◽

Intelligent Control ◽

Software Agents ◽

High Rate ◽

Target System ◽

Activated Sludge Process ◽

Intelligent Control System ◽

Treatment Processes

An intelligent control system for wastewater treatment processes has been developed and applied to fullscale, high-rate, activated sludge process control. In this control system, multiple software agents that model the target system using their own modeling method collaborate by using data stored in an abstracted database named ‘blackboard’. The software agents, which are called ‘expert modules’, include a fuzzy expert system, a fuzzy controller, a theoretical activated sludge model, and evaluators of raw data acquired by various online sensors including a respirometer. In this paper, the difficulties of controlling an activated sludge system by using a single conventional strategy are briefly reviewed, then our approach to overcome these difficulties by using multiple modeling methods in the framework of an ‘intelligent control system’ is proposed. Case studies of applications to a high-rate activated sludge process that treats BOD and nitrogen of human excrement are also presented.

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Rehabilitation and Upgrading of the Beni Suef City Wastewater Treatment Plant

Water Science & Technology ◽

10.2166/wst.1990.0238 ◽

1990 ◽

Vol 22 (7-8) ◽

pp. 131-138

Author(s):

Ahmed Fadel

Keyword(s):

Wastewater Treatment ◽

Activated Sludge ◽

Wastewater Treatment Plant ◽

Treatment Plant ◽

Primary Treatment ◽

High Rate ◽

Shock Load ◽

Economic Evaluations ◽

Activated Sludge Process ◽

Trickling Filter

Many of Egypt's cities have existing treatment plants under operation that have been constructed before 1970. Almost all of these treatment plants now need rehabilitation and upgrading to extend their services for a longer period. One of these plants is the Beni Suef City Wastewater Treatment Plant. The Beni Suef WWTP was constructed in 1956. It has primary treatment followed by secondary treatment employing intermediate rate trickling filters. The BOD, COD, and SS concentration levels are relatively high. They are approximately 800, 1100, and 600 mg/litre, respectively. The Beni Suef city required the determination of the level of work needed for the rehabilitation and upgrading of the existing 200 l/s plant and to extend its capacity to 440 l/s at year 2000 A description of the existing units, their deficiencies and operation problems, and the required rehabilitation are presented and discussed in this paper. Major problems facing the upgrading were the lack of space for expansion and the shortage of funds. It was, therefore, necessary to study several alternative solutions and methods of treatment. The choice of alternatives was from one of the following schemes: a) changing the filter medium, its mode of operation and increasing the number of units, b) changing the trickling filter to high rate and combining it with the activated sludge process, for operation by one of several possible combinations such as: trickling filter-solids contact, roughing filter-activated sludge, and trickling filter-activated sludge process, c) dividing the flow into two parts, the first part to be treated using the existing system and the second part to be treated by activated sludge process, and d) expanding the existing system by increasing the numbers of the different process units. The selection of the alternative was based on technical, operational and economic evaluations. The different alternatives were compared on the basis of system costs, shock load handling, treatment plant operation and predicted effluent quality. The flow schemes for the alternatives are presented. The methodology of selecting the best alternative is discussed. From the study it was concluded that the first alternative is the most reliable from the point of view of costs, handling shock load, and operation.

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PARAMETERS FOR DYNAMIC SIMULATION OF W ASTEW ATER TREATMENT PLANTS WITH HIGH-RATE AND LOW-RATE ACTIVATED SLUDGE TANKS

Water Science & Technology ◽

10.2166/wst.1994.0194 ◽

1994 ◽

Vol 30 (4) ◽

pp. 211-214 ◽

Cited By ~ 11

Author(s):

E. Brands ◽

M. Liebeskind ◽

M. Dohmann

Keyword(s):

Wastewater Treatment ◽

Activated Sludge ◽

Dynamic Simulation ◽

Municipal Wastewater ◽

Wastewater Treatment Plants ◽

High Rate ◽

Yield Coefficient ◽

Municipal Wastewater Treatment ◽

Municipal Wastewater Treatment Plants ◽

Low Rate

This study shows a comparison of important parameters for dynamic simulation concerning the highrate and low-rate activated sludge tanks of several municipal wastewater treatment plants. The parameters for the dynamic simulation of the single-stage process are quite well known, but parameters for the high-ratellow-rate activated sludge process are still missi ng, although a considerable number of wastewater treatment plants are designed and operated that way. At present any attempt to simulate their operation is restricted to the second stage due to missing data concerning growth rate, decay rate, yield coefficient and others.

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Evaluation of flocculation and dissolved air flotation as an advanced wastewater treatment

Water Science & Technology ◽

10.2166/wst.2001.0470 ◽

2001 ◽

Vol 43 (8) ◽

pp. 83-90 ◽

Cited By ~ 7

Author(s):

A. C. Pinto Filho ◽

C. C. Brandão

Keyword(s):

Wastewater Treatment ◽

Domestic Wastewater ◽

High Rate ◽

Advanced Treatment ◽

Dissolved Air Flotation ◽

Anaerobic Reactor ◽

Treatment Processes ◽

Domestic Wastewater Treatment ◽

Air Flotation ◽

Dissolved Air

A bench scale study was carried out in order to evaluate the applicability of dissolved air flotation (DAF) as an advanced treatment for effluents from three different domestic wastewater treatment processes, namely: (i) a tertiary activated sludge plant ; (ii) an upflow sludge blanket anaerobic reactor (UASB); and (iii) a high-rate stabilization pond.

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Evaluation of Integrated Fixed Film Activated Sludge Wastewater Treatment Processes at High Mean Cells Residence Time and Low Temperatures

Journal of Environmental Engineering ◽

10.1061/(asce)0733-9372(2005)131:11(1550) ◽

2005 ◽

Vol 131 (11) ◽

pp. 1550-1556 ◽

Cited By ~ 16

Author(s):

Tongchai Sriwiriyarat ◽

Clifford W. Randall

Keyword(s):

Wastewater Treatment ◽

Activated Sludge ◽

Residence Time ◽

Low Temperatures ◽

Treatment Processes ◽

Fixed Film

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Biosolids odor reduction by solids inventory management in the secondary activated sludge treatment system

Water Science & Technology ◽

10.2166/wst.2009.852 ◽

2009 ◽

Vol 59 (2) ◽

pp. 241-247 ◽

Cited By ~ 2

Author(s):

K. Sekyiamah ◽

H. Kim

Keyword(s):

Activated Sludge ◽

Inventory Management ◽

Process Parameters ◽

Treatment Plant ◽

Treatment System ◽

Sludge Treatment ◽

System A ◽

Treatment Processes ◽

Dominant Process ◽

And Control

A wastewater treatment plant consists of unit processes designed to achieve specific waste reduction goals. Offensive odors associated with these treatment processes are a constant source of public complaints. The purpose of this study was to statistically determine the process parameters that influence the formation of volatile sulfur compounds (VSCs) in the secondary treatment system. A statistical model was developed to relate the process parameters to the formation of VSCs in this system. The model established that F/M ratio, sludge blanket depth and SSV60 were the dominant process parameters that influenced the formation of VSCs in the secondary sedimentation basin. This model provides a useful tool for plant engineers to predict and control the VSC formation in a secondary activated sludge treatment system.

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Modeling Mass Transfer in Biological Wastewater Treatment Processes

Water Science & Technology ◽

10.2166/wst.1986.0059 ◽

1986 ◽

Vol 18 (6) ◽

pp. 35-45 ◽

Cited By ~ 14

Author(s):

John C. Kissel

Keyword(s):

Mass Transfer ◽

Computer Simulation ◽

Wastewater Treatment ◽

Biological Treatment ◽

Process Models ◽

High Rate ◽

Biological Wastewater Treatment ◽

Trickling Filter ◽

Treatment Processes ◽

Individual Effects

Parameters characterizing intrasolid, liquid/solid, and gas/liquid mass transport phenomena in biological treatment systems are required if mass transfer is to be included in process models. Estimates of such parameters are presented and discussed. Collective and individual effects of mass transfer resistances are illustrated by computer simulation of a high-rate trickling filter.

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