Acute and Chronic Responses of Activated Sludge Viability and Performance to Silica Nanoparticles

Impact of marginal availability and severe deficiency of nitrogen on the growth of glycogen accumulating organisms (GAOs) and performance of anaerobic/aerobic activated sludge systems treating nutrient deficient wastewater was investigated at marginal availability and severe deficiency of phosphorus. Two continuous-flow lab-scale systems were operated simultaneously fed by model winery wastewater, one with marginal availability and the other one at severe deficiency of nitrogen. In the second experimental stage, marginal availability of P was converted into severe deficiency by interrupting external dosing.Common practice of dosing N- and P-sources to marginal availability caused enhanced proliferation of filamentous bacteria leading to poor biomass settling and instable operation. At marginal N-availability accumulation of GAOs started when conditions became deficient for phosphorus. In severe lack of nitrogen GAOs overgrew filaments, and outcompeted phosphorous accumulating organisms (PAOs) initially present in the seed. Stable and good performance could be maintained even after withdrawal of phosphorous dosing.

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Ionic Liquids and Calcium Oxide Grafted with Allylmalonic Acid Applied to Support the Peroxide Crosslinking of an Ethylene–Propylene Copolymer

Materials ◽

10.3390/ma13153260 ◽

2020 ◽

Vol 13 (15) ◽

pp. 3260

Author(s):

Magdalena Maciejewska

Keyword(s):

Ionic Liquids ◽

Silica Nanoparticles ◽

Calcium Oxide ◽

Crosslink Density ◽

Ethylene Propylene ◽

Rubber Compounds ◽

Curing Characteristics ◽

And Performance ◽

Crosslinking Reactions ◽

Thermal Stability Of

Nanosized calcium oxide (CaO) featuring a surface grafted with allylmalonic acid (ALA) was used to increase the efficiency of the peroxide crosslinking of an ethylene–propylene copolymer (EPM) filled with silica nanoparticles. In this study, 1-butyl-3-methylimidazolium ionic liquids (ILs) with different anions were applied to improve the dispersion of CaO/ALA and silica nanoparticles in the EPM copolymer, as well as to catalyze the interfacial crosslinking reactions. In this article, we discuss the effects of CaO/ALA and ILs on the curing characteristics, vulcanization temperature, crosslink density, mechanical properties, and thermal stability of EPM, as well as the resistance of EPM to weather aging. The CaO/ALA with ILs reduced the vulcanization time of the rubber compounds without a significant effect on the vulcanization temperature. Their application resulted in an increased vulcanizate crosslink density, as well as improved tensile strength compared to the pure peroxide system. The influence of 1-butyl-3-methylimidazolium ILs on EPM vulcanization and performance depends on the anion present in the molecules of the ionic liquid. The most active IL seems to be that with the tetrafluoroborate anion.

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Synthesis and characterization of modified activated sludge for biological oxidation with isolation studies and performance evaluation

Separation and Purification Technology ◽

10.1016/j.seppur.2014.11.044 ◽

2015 ◽

Vol 141 ◽

pp. 179-187 ◽

Cited By ~ 7

Author(s):

Lokeshkumar P. Ramteke ◽

Parag R. Gogate

Keyword(s):

Performance Evaluation ◽

Activated Sludge ◽

Synthesis And Characterization ◽

Biological Oxidation ◽

And Performance

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Sludge reduction and performance analysis of a modified sludge reduction process

Water Science & Technology ◽

10.2166/wst.2013.797 ◽

2013 ◽

Vol 69 (5) ◽

pp. 934-940 ◽

Cited By ~ 11

Author(s):

Zhen Zhou ◽

Weimin Qiao ◽

Can Xing ◽

Yingjun Wang ◽

Chunying Wang ◽

...

Keyword(s):

Activated Sludge ◽

Nitrogen Concentration ◽

Oxygen Demand ◽

Reduction Process ◽

Ammonium Nitrogen ◽

Aeration Tank ◽

Sludge Reduction ◽

Oxidation Reduction ◽

Solids Retention ◽

And Performance

A modified sludge process reduction activated sludge (SPRAS) technology was developed by inserting a sludge process reduction (SPR) module, composed of an aeration tank and a settler, before the activated sludge system was proposed in this study. Compared with the anaerobic/anoxic/aerobic (AAO) process, the SPRAS resulted in a remarkable decrease in sludge production by 76.6%; sludge decay owing to lengthy solids retention time (about 121.5 d) could be the major cause. During the 217-day operation, the oxidation-reduction potential (ORP) (from 54 to −198 mV) and pH (from 7.8 to 5.0) at the bottom of the SPR settler gradually decreased, and low ORP and pH were in favor of sludge reduction in the SPRAS system. The insertion of the SPR module improved the removal efficiencies of suspended solids, chemical oxygen demand and ammonium nitrogen, and total nitrogen concentration in the effluent was reduced from 23.89 ± 4.82 to 14.16 ± 3.98 mg/L by 50% influent bypassing the SPR module. These results indicated that the SPRAS process could produce much less excess sludge and guarantee better effluent quality than the AAO process.

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Assessing biomass diversity and performance of an activated sludge process treating saline table olive processing wastewater

Environmental Technology ◽

10.1080/09593330.2018.1447603 ◽

2018 ◽

Vol 40 (20) ◽

pp. 2608-2619 ◽

Cited By ~ 3

Author(s):

Asma Lazrak ◽

Laila Mandi ◽

Theodore N. Djeni ◽

Mounsef Neffa ◽

Naaila Ouazzani

Keyword(s):

Activated Sludge ◽

Activated Sludge Process ◽

Table Olive ◽

And Performance

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Common stresses affecting activated sludge health and performance - what the four-assay set can tell us

Water Science & Technology ◽

10.2166/wst.2004.0161 ◽

2004 ◽

Vol 50 (3) ◽

pp. 49-55 ◽

Cited By ~ 3

Author(s):

F. Archibald ◽

F. Young

Keyword(s):

High Temperature ◽

Activated Sludge ◽

Early Warning ◽

Kraft Mill ◽

And Performance

Previously, we developed a novel biological early warning (BEW) system for directly monitoring the health and performance of activated sludge, the “four-assay set”. In the present work, the four-assay set has been used to measure the effects of four common stresses on activated sludge biomass: high temperature; pH; anoxia; and starvation. The results demonstrate both the utility of the Paprican four-assay set as a biomass-evaluating and BEW tool, and the tolerances of a typical kraft mill activated sludge for these four stresses.

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Microscopic and enzymatic investigations on biofilms of wastewater treatment systems

Water Science & Technology ◽

10.2166/wst.1997.0004 ◽

1997 ◽

Vol 36 (1) ◽

pp. 21-30 ◽

Cited By ~ 1

Author(s):

Tanja Gschlößl ◽

Ingrid Michel ◽

Marion Heiter ◽

Christian Nerger ◽

Verena Rehbein

Keyword(s):

Wastewater Treatment ◽

Activated Sludge ◽

Wastewater Treatment Plants ◽

Biological Properties ◽

Organic Substances ◽

Operational Conditions ◽

Sludge Flocs ◽

And Performance ◽

The Stability

In biological wastewater treatment inorganic and organic substances are fixed and metabolized by mixed populations of microorganisms forming either activated sludge flocs or biofilms. Not only the type of wastewater but also the operational conditions promote the development of an adapted biocenosis of microorganisms with specialized enzymatic functions. Understanding the biological properties of the microorganisms, it is possible to assess the prevailing conditions in their natural environment. Regular microscopic and enzymatic investigations of activated sludge and biofilms thus improve the assessment of the stability of the processes and support troubleshooting in wastewater treatment plants. While the role of bacteria is often discussed, the importance of ciliated protozoes and metazoes for the maintenance of the stability of biofilm systems is rarely mentioned. In this paper we intend to show some new results of direct microscopic observations in different sorts of biofilm systems focussing upon ciliated protozoes and metazoes. Practical results will demonstrate the relation between enzymatic analysis, microscopic investigations and performance of biofilm systems.

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Improved design and control of industrial and municipal nutrient removal plants using dynamic models

Water Science & Technology ◽

10.2166/wst.1997.0357 ◽

1997 ◽

Vol 35 (10) ◽

pp. 53-61 ◽

Cited By ~ 5

Author(s):

F. Coen ◽

B. Vanderhaegen ◽

I. Boonen ◽

P. A. Vanrolleghem ◽

P. Van Meenen

Keyword(s):

Activated Sludge ◽

Municipal Wastewater ◽

Dynamic Models ◽

Treatment Plant ◽

Industrial Plant ◽

Operational Cost ◽

Municipal Wastewater Treatment ◽

And Performance ◽

Improved Design ◽

And Control

Dynamic simulation can be used to improve the design and performance of the activated sludge process. This is illustrated by means of two case studies:The simulation of a full scale industrial plant treating nitrogen-rich wastewater by an intensive nitrification-denitrification process. By means of simulation the most important operational cost (dosage of an external carbon source) was optimised and a control strategy was proposed.The simulation of a municipal wastewater treatment plant with the extension of nitrogen removal. Based on simulation the feasibility of the redesign was evaluated. In both cases the wastewater composition was characterised and the biological model (the activated sludge IAWQ-model No. 1) calibrated. By means of respirometry and standard laboratory analyses it was possible to estimate the COD fractions of the wastewater and the parameters for heterotrophic and autotrophic growth of biomass.

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