Effects of Chlorination on the Adhesion Strength and Deflocculation of Activated Sludge Flocs

Mascarenhas, T.; Mikkelsen, Lene Haugaard; Nielsen, Per Halkjær

doi:10.2175/106143004x141915

Cited by 7 publications

(2 citation statements)

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“…digestion. An adhesion model was used to determine the effect on floc strength of chlorinating activated sludge for control of filamentous bacteria (Mascarenhas et al, 2004). One of the two activated sludge flocs studied showed no impact on floc strength from chlorination while the other floc showed a decrease in floc strength which led to deflocculation.…”

Section: Design Operation and Controlmentioning

confidence: 99%

Activated Sludge and Other Aerobic Suspended Culture Processes

Ellis¹,

Schmit²,

Jahan³

et al. 2005

Water Environment Research

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PROCESS MODELING AND KINETICSModels. Full-scale modeling was conducted at the Tougas wastewater treatment plant (WWTP) in Nantes, France (Printemps et al., 2004). Despite the simplicity of the model used, good agreement was obtained between the model and the nitrogen balance within the plant. Daily sludge production was also modeled adequately. Ekama and Wentzel (2004) developed and validated a simple model for predicting the inorganic suspended solids concentrations in ordinary and biological nutrient removal activated sludge systems. Model predictions were heavily influenced by the degree of enhanced biological phosphorus removal (EBPR) occurring. Transient phenomena during batch tests for parameter determination for the calibration of activated sludge models (ASM) were observed . Errors in yield, maximum specific growth rate, and half saturation coefficient averaged 3,12, and 17% respectively. These transient phenomena were hypothesized to be the result of a sequence of 1158 intracellular reactions induced by the transient change in substrate concentration occurring in the batch tests.A suspended solids mass balance model was developed and calibrated using the operating data from a full-scale recirculating activated sludge plant . The model predicted a maximum of 25% reduction in solids loading to the secondary clarifiers when aeration tank settling was employed during rainfall events. Oliveira-Esquerre, evaluated steady state and dynamic models for predicting performance of a pulp and paper mill aerated lagoon effluent. Multiple linear and partial least squares regressions were compared in the developed neural network model. With limited sampling data the multilayer perception neural network model was more accurate at predicting effluent concentrations than the functional-link neural network model . Recurrent neural network and modified genetic algorithm models were used to optimize a fed-batch reactor (Chen, Nguang et al., 2004). The simulation provided accuracy within 8% of measured values. Guisasola et al. (2004) modeled the behavior of the polyphosphate accumulating organisms (PAO) under anaerobic/aerobic conditions and under just aerobic conditions by using the ASM2 and AnOx models with two hypotheses (PAO-hypothesis and ordinary heterotrophic organism (OHO)-hypothesis). They observed that since the storage of the phosphate in the aerobic phase was related with the ordinary heterotrophic organisms, OHO hypothesis results characterized the experimental data more accurately than the PAO hypothesis. 1159 Saikaly and Oerther (2004) examined the competition of six bacterial species in lab-scale activated sludge systems containing three limiting nutrients (resources) operated at solids retention times of 2.3 to 5.7 d. Their investigation demonstrated that the natural oscillations of bacterial communities ensure that the degree of diversity of a system (as measured by the number of coexisting bacterial species) will be larger than the number of limiting resources. Zinn et al. (2004) investigated growth models...

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Section: Design Operation and Controlmentioning

confidence: 99%

Activated Sludge and Other Aerobic Suspended Culture Processes

Ellis¹,

Schmit²,

Jahan³

et al. 2005

Water Environment Research

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show abstract

“…1 However, chlorination oen causes side effects on wastewater treatment performance by deocculating activated sludge resulting in poor effluent water quality. 19,20 There is also a concern about the development of chlorine-resistant lamentous bacteria in sludge. 3,21 Other types of toxicants such as cetyl trimethylammonium bromide (CTAB), ozone and hydrogen peroxide are generally too costly to use, and they generate harmful disinfection byproducts (DPBs), odor and chemical scum.…”

Section: Introductionmentioning

confidence: 99%

Filamentous sludge bulking control by nano zero-valent iron in activated sludge treatment systems

Sun

Zhang

et al. 2014

Environ. Sci.: Processes Impacts

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Sludge bulking causes loss of biomass in the effluent and deterioration of effluent water quality. This study explored the use of nano zero-valent iron (NZVI with an average particle size of 55 ± 11 nm) for sludge bulking control. In two Modified Ludzack-Ettinger (MLE) activated sludge treatment systems, a single dose of NZVI at the final concentration of 100 mg Fe per L in the mixed liquor reduced the number of filamentous bacteria Type 021N by 2-3 log units (a reduction of 99.9 and 96.7% in MLE tank #1 and #2, respectively). The side effect of the use of NZVI depended on sludge bulking conditions and biomass concentration. In the system with sludge bulking and significant sludge loss (average biomass concentration of 1022 ± 159 COD mg per L or at the ratio of 0.098 g Fe per g biomass COD), the use of NZVI increased effluent COD, NH4(+)-N and NO2(-)-N concentrations, as also evident with the loss of nitrifying populations and nitrifying activities resulting in more than 40 days to have the full recovery of the activated sludge system. In contrast, in the system with the early stages of bulking and the biomass concentration of 1799 ± 113 COD mg per L (at the ratio of 0.056 g Fe per g biomass COD), the effluent water quality and overall bioreactor performance were only slightly affected for a few days.

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Role of extracellular polymeric substances (EPS) production in bioaggregation: application to wastewater treatment

Ding

Bourven

Guibaud

et al. 2015

Appl Microbiol Biotechnol

199

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This paper reviews the formation, structure, and stability of bioaggregates with an emphasis on the composition and distribution of extracellular polymeric substances (EPS) and their role in bioaggregation. Bioaggregation is ubiquitous in natural environment and is of great importance in biological wastewater treatment processes. It greatly influences the flocculability, settleability, and dewaterability for flocs and sludge retention and shear resistance for biofilms. The physico-chemical and microbial structures of bioaggregates are dependent on operational conditions as well as microbial diversity and spatial distribution. The formation of bioaggregates is mediated by the physico-chemical interactions as well as the microbial interactions such as EPS production and quorum sensing. EPS are composed of a mixture of macromolecules including proteins, polysaccharides, humic-like substances, and nucleic acids, which entrap the microbial cells in a three-dimensional matrix. The composition and physico-chemical characteristics of EPS have significant influence on the maintenance of the bioaggregate structure and the process performance of the wastewater treatment. However, the mechanisms of bioaggregation are still unclear and the conclusions on the role of EPS were mostly drawn from the established correlations and hypotheses. This paper expects to provide up-to-date knowledge on bioaggregation and insights for further studies and applications.

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Effects of Chlorination on the Adhesion Strength and Deflocculation of Activated Sludge Flocs

Cited by 7 publications

References 0 publications

Activated Sludge and Other Aerobic Suspended Culture Processes

Activated Sludge and Other Aerobic Suspended Culture Processes

Filamentous sludge bulking control by nano zero-valent iron in activated sludge treatment systems

Role of extracellular polymeric substances (EPS) production in bioaggregation: application to wastewater treatment

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