Activated sludge and other aerobic suspended culture processes

Cowan, Robert M.; Alagappan, Gunaseelan; Ellis, Timothy G.; Higgins, Matthew J.; Uberoi, Vikas

doi:10.2175/106143097x134786

Cited by 3 publications

(1 citation statement)

References 105 publications

(123 reference statements)

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“…The most important microorganism indicator of good, stable and healthy activated sludge quality and wastewater treatment stability is the presence of free swimming and stalked ciliates along the rotifers [ 43 ]. It is known that crawling ciliates are playing an important role in the young to medium age activated sludge as they improve flocculation and remove loosely attached bacteria from the flocs [ 44 ]. The existence of the species Aspidisca cicada indicates that oxygenation is good in the aeration area of the tanks.…”

Section: Discussionmentioning

confidence: 99%

Biological Activated Sludge from Wastewater Treatment Plant before and during the COVID-19 Pandemic

Roman

Sava

Iluțiu-Varvara

et al. 2022

IJERPH

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The COVID-19 pandemic and the related measures brought a change in daily life that affected the characteristics of the municipal wastewater and further, of the biological activated sludge. The activated sludge process is the most widely used biological wastewater treatment process in developed areas. In this paper, we aim to show the situation of specific investigations concerning the variation of the physicochemical parameters and biological composition of the activated sludge from one conventional wastewater treatment plant from a metropolitan area. The investigations were carried out for three years: 2019, 2020 and 2021. The results showed the most representative taxa of microorganisms: Microtrix, Aspidisca cicada, Vorticella convallaria, Ciliata free of the unknown and Epistylis and Rotifers. Even if other microorganisms were found in the sludge flocs, their small presence did not influence in any way the quality of the activated sludge and of the wastewater treatment process. That is why we conclude that protozoa (especially Flagellates and Ciliates) and rotifers were the most important. Together with the values and variation of the physicochemical parameters, they indicated a good, healthy, and stable activated sludge, along with an efficient purifying treatment process, no matter the loading conditions.

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Section: Discussionmentioning

confidence: 99%

Biological Activated Sludge from Wastewater Treatment Plant before and during the COVID-19 Pandemic

Roman

Sava

Iluțiu-Varvara

et al. 2022

IJERPH

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Characterization of Immobilized Poly-l-aspartate as a Metal Chelator

Gutiérrez

Miller

Gonzalez-Redondo

et al. 1999

Environ. Sci. Technol.

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Poly-l-aspartic acid (PLAsp), which consists of ca. 50 Asp residues in a linear polypeptide, has been immobilized on controlled pore glass (CPG) and evaluated for its selectivity and binding strength in the complexation of metal ions from aqueous solutions. The carboxylate side chain of Asp (pK a = 5.4 ± 0.2) is thought to be primarily responsible for chelation of the target metals. Of the several metals evaluated, Eu3+, Ce3+, La3+, Cu2+, and Pb2+ exhibited good binding capacities. Quantitative determination of single-element capacities were determined for Cu2+ (12 ± 1 μmol/g PLAsp-CPG) and La3+ (7.1 ± 0.3 μmol/g PLAsp-CPG). Isotherms were constructed from breakthrough curves using a flow injection system. These curves were used to evaluate the effective site capacity and formation constants. A combination of moderate and strong binding sites for Pb2+ was detected, while moderate binding of Cd2+ was observed with a minimal number of strong binding sites. Several cations showed little to no binding by PLAsp-CPG (e.g., Na+, Ca2+, Mg2+, Mn2+, Co2+, and Ni2+). Propensity for metal binding seems to follow the trend seen for binding to carboxylates in such ligands as acetate. The polydentate binding available from the polypeptide chain significantly enhanced the binding strength with equilibrium constants in excess of 108 observed for the strong binding sites. The binding selectivity was complementary, in many cases, with the results previously reported for poly-l-cysteine immobilized on CPG.

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Enhanced Wet Air Oxidation: Synergistic Rate Acceleration upon Effluent Recirculation

Birchmeier¹,

Hill²,

Houtman³

et al. 1999

Ind. Eng. Chem. Res.

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Wet air oxidation (WAO) reactions of cellobiose, phenol, and syringic acid were carried out under mild conditions (155°C; 0.93 MPa O 2 ; soluble catalyst, Na 5 [PV 2 Mo 10 O 40 ]). Initial oxidation rates were rapid but decreased to small values as less reactive oxidation products accumulated. Recalcitrant oxidation products were consumed more rapidly, however, if additional cellobiose or phenol was added, a procedure equivalent to recirculation of WAO-reactor effluent. A halffraction, factorial investigation was used to correlate rate enhancement with individual experimental variables: using a two-level design, effluents from the WAO of cellobiose were combined with unreacted cellobiose and WAO resumed. The effluents were degraded more rapidly than could be accounted for by residence time alone. Correlations identified by the factorial investigation were consistent with oxidation of recalcitrant compounds by highly reactive intermediates generated during the initially rapid radical-chain autoxidation of unreacted cellobiose.

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Activated sludge and other aerobic suspended culture processes

Cited by 3 publications

References 105 publications

Biological Activated Sludge from Wastewater Treatment Plant before and during the COVID-19 Pandemic

Biological Activated Sludge from Wastewater Treatment Plant before and during the COVID-19 Pandemic

Characterization of Immobilized Poly-l-aspartate as a Metal Chelator

Enhanced Wet Air Oxidation: Synergistic Rate Acceleration upon Effluent Recirculation

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