Process state evaluation of alternating Oxic—Anoxic Activated Sludge using ORP, pH and DO

Paul, Etienne; Plisson-Saune, Stephan; Mauret, M.; Cantet, J.

doi:10.1016/s0273-1223(98)00469-7

Cited by 53 publications

(5 citation statements)

References 9 publications

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“…Macroelectrodes have been shown to be valuable tools for direct detection of ORP in streams or lakes, wastewater treatment reactors, and water distribution systems due to the speed of analysis, low maintenance cost, and availability of necessary equipment. For example, it has previously been shown that on-line monitoring of ORP can be a reliable and effective technique for control of the activated sludge process, sludge digestion, biological nutrient removal, and chemical oxidation/reduction processes ( − ). ORP values can also provide significant information for disinfection in pool, spa, and potable water since they are related to the kill time of Escherichia coli bacteria in water ().…”

Section: Introductionmentioning

confidence: 99%

Miniaturized Redox Potential Probe for In Situ Environmental Monitoring

Jang

Lee

Bhadri

et al. 2005

Environ. Sci. Technol.

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Aerosol growth by heterogeneous reactions of diverse carbonyls in the presence and absence of acidified seed aerosols was studied in a 4 m long flow reactor (2.5 cm i.d.) and a 2-m3 indoor Teflon film chamber under darkness. The acid catalytic effects on heterogeneous aerosol production were observed for diverse carbonyls in various ranges of humidities and compositions of seed inorganic aerosols. Particle population data measured by a scanning mobility particle sizer were used to calculate organic aerosol growth. To accountforthe aerosol growth contributed by heterogeneous reactions, the increase in organic aerosol mass was normalized bythe organic mass predicted by partitioning or the square of predicted organic mass. The carbonyl heterogeneous reactions were accelerated in the presence of acid catalysts (H2SO4), leading to higher aerosol yields than in their absence. The experimental data from aerosol yields in the flow reactorwere semiempirically fitted to the model parameters to predict the organic aerosol growth. The model parameters consist of environmental characteristics and molecular structure information of organic carbonyls. Basicity constants of carbonyls were used to describe the proton affinity of carbonyls for the acid catalysts. Particle environmental factors, such as humidity, temperature, and inorganic seed composition, were expressed by excess acidity and the parameters obtained from an inorganic thermodynamic model. A stepwise regression analysis of the aerosol growth model for the experimental data revealed that either the chemical structure information of carbonyls or characteristic environmental parameters are statistically significant in the prediction of organic aerosol growth. It was concluded thatthis model approach is applicable to predict secondary organic aerosol formation by heterogeneous reaction.

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Section: Introductionmentioning

confidence: 99%

Miniaturized Redox Potential Probe for In Situ Environmental Monitoring

Jang

Lee

Bhadri

et al. 2005

Environ. Sci. Technol.

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“…The alternate cycles is an automatically controlled process, where the intermittent aeration of the continuously fed bioreactor is managed on the basis of on-line signals of dissolved oxygen (DO) and oxidation reduction potential (ORP), which are processed in real time by the control device. In particular, these signals, coming from consolidated and inexpensive probes, are able to indirectly detect the exhaustion of the ammonia, during the aerobic phases, and of the nitrates, during the anoxic phases. − Therefore, the control device can establish the optimal alternation of the aerobic and anoxic phases with relation to the actual influent loadings.…”

Section: Methodsmentioning

confidence: 99%

Operation and Maintenance of Full-Scale Municipal Membrane Biological Reactors: A Detailed Overview on a Case Study

Fatone

Battistoni

Pavan

et al. 2007

Ind. Eng. Chem. Res.

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This paper deals with the long-term operation of a full-scale municipal membrane bioreactor, focusing mainly on the membrane section. The ultrafiltration chamber, equipped with 12 130 m2 of submerged hollow-fiber membranes, was installed after an existing alternating oxic/anoxic bioreactor. Attention is paid to a number of practical details, from the effectiveness of different sieves to the impact of the operating parameters on the membrane performances; finally, data of the energy consumptions and items of the operating costs are presented. Starting from the pretreatments, while the wedge wire sieve (openings = 1 mm) involved the visible accumulation of fibers and trash in the filtration chamber, the punched holes (holes diameter = 1.5 mm) involved less than 100 milligrams of dry trash per liter of mixed liquor, demonstrating that they suited the following membrane system. Moving on to the off-line equalization basin, a volume of one-fifth of the bioreactor was sufficient to cope with the normal fluctuations of the municipal inloadings. As for the membrane section, a net flux of 26 LMH and chemical maintenance cleaning in place once a week with only hypochlorite (around 300 mgCl L-1) was a sustainable practice to keep the long-term permeability (adjusted at 20 °C) stable in the range 220−240 LMH bar-1. Under this operating protocol, increases of specific aeration for membrane scouring from 0.12 to 0.19 Nm3 m-2 h-1 did not lead to permeability gains that might justify the increased power requirements. This evidence allows us to conclude that 0.12 Nm3 m-2 h-1 was sustainable for the normal operation of the hollow-fiber membranes. Irreversible membrane fouling (permeability decrease up to 150−160 LMH bar-1) was observed because of irregular discharges of municipal landfill leachate, which, from one side, caused a drastic deflocculation of the activated sludge (sludge volume index (SVI) increased from 110 up to 250 mL gMLSS) and, from the other side, involved a probable incoming of recalcitrant compounds that might have acted as foulants. The power requirements of the whole treatment facility were always lower than 0.6 kWh m-3 thanks to the general good utilization of the air supplied. The specific operating costs related to the energy consumptions and chemicals purchase were in the range 0.06−0.08 euro m-3.

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“…In particular the ammonia disappering during the aerobic phase is identified by an optimal condition on the DO or ORP profile versus time, and nitrates disappearing in the anoxic phase is identified by the ORP profile versus time at the end of the denitrification phase. Further, set points for DO and ORP values and the time-out for the length of the aerobic and anoxic phases are adopted to avoid over aeration to better manage the process (Paul et al 1998;Battistoni & Chemitec 1999).…”

Section: The Alternate Cycles Processmentioning

confidence: 99%

Switching small WWTPs from extended to intermittent aeration: process behaviour and performances

Eusebi

Carletti

Cola

et al. 2008

Water Science and Technology

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The paper presents the one year results obtained by a small wastewater treatment plant (WWTP) located in a decentralized area. The plant was organized, reusing current structures, introducing an equalization tank, an anoxic selector and the alternate cycles (AC) as technology in the biological process. The experimentation data processed show the excellent quality of the effluent with high removal efficencies for all the macropollutants. Also, the anoxic selector effect allows, in the critical winter period, the decrease in the filamentous bacteria total number, a net improvement of the settling behaviour with an average solid maximum flux value of 3.8 kgMLSSm(-2) h(-1) and a good mixed liquor settleability. The alternate cycles process flexibility consents to well manage the high fluctuations of the influent loadings. The costs comparison of AC process and extended aeration confirms the sustainability of the upgrading.

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Process state evaluation of alternating Oxic—Anoxic Activated Sludge using ORP, pH and DO

Cited by 53 publications

References 9 publications

Miniaturized Redox Potential Probe for In Situ Environmental Monitoring

Miniaturized Redox Potential Probe for In Situ Environmental Monitoring

Operation and Maintenance of Full-Scale Municipal Membrane Biological Reactors: A Detailed Overview on a Case Study

Switching small WWTPs from extended to intermittent aeration: process behaviour and performances

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