Kinetics of aerobic cellulose degradation in raw municipal wastewater

2022 ◽  
Vol 802 ◽  
pp. 149852
Author(s):  
Mingu Kim ◽  
Moustafa Elbahrawi ◽  
Azardokht Aryaei ◽  
George Nakhla ◽  
Domenico Santoro ◽  
...  
Keyword(s):  
Municipal Wastewater ◽  
Cellulose Degradation ◽  
Kinetics Of

scholarly journals Thermal Properties of Multilayer Nanocomposites Based on Halloysite Nanotubes and Biopolymers

2018 ◽  
Vol 2 (3) ◽  
pp. 41 ◽  
Author(s):  
Vanessa Bertolino ◽  
Giuseppe Cavallaro ◽  
Stefana Milioto ◽  
Filippo Parisi ◽  
Giuseppe Lazzara
Keyword(s):  
Thermal Properties ◽  
Cellulose Degradation ◽  
Oxidative Degradation ◽  
Middle Layer ◽  
Halloysite Nanotubes ◽  
Hydroxypropyl Cellulose ◽  
Inert Atmosphere ◽  
Scanning Calorimetry ◽  
Dsc Studies ◽  
Kinetics Of

This paper reports a novel procedure to fabricate multilayer composite biofilms based on halloysite nanotubes (HNTs) and sustainable polymers. Among the biopolymers, the non-ionic (hydroxypropyl cellulose) and cationic (chitosan) molecules were selected. The nanocomposites were prepared by the sequential casting of ethanol solutions of hydroxypropyl cellulose and aqueous dispersions of chitosan/HNTs. The composition of the bio-nanocomposites was systematically changed in order to investigate the effect of the hydroxypropyl cellulose/HNTs ratio on the thermal properties of the films, which were investigated by differential scanning calorimetry (DSC) and thermogravimetry (TG). DSC studies were conducted in the static air (oxidative atmosphere), while TG measurements were carried out under nitrogen flow (inert atmosphere). The analysis of DSC data provided the enthalpy and the temperature for the oxidative degradation of the bio-nanocomposites. These results were helpful to estimate the efficacy of the well-compacted middle layer of HNTs as a flame retardant. TG experiments were performed at a variable heating rate and the collected data were analyzed by the Friedman’s method (non-isothermal thermogravimetric approach) with the aim of studying the kinetics of the hydroxypropyl cellulose degradation in the multilayer nanocomposites. This work represents an advanced contribution for designing novel sustainable nanocomposites with excellent thermal behavior as a consequence of their peculiar multilayer structure.

Investigation in the kinetics of thermal and thermo-oxidative degradation of wood treated with fire-retardants and untreated wood

2020 ◽  
pp. 24-29
Author(s):  
Николай Петрович Копылов ◽  
Александр Евгеньевич Кузнецов ◽  
Елена Юрьевна Сушкина ◽  
Владимир Васильевич Яшин
Keyword(s):  
Forest Fires ◽  
Flame Retardants ◽  
Degradation Products ◽  
Cellulose Degradation ◽  
Oxidative Degradation ◽  
Fire Retardant ◽  
Untreated Wood ◽  
Fire Retardants ◽  
Kinetics Of ◽  
Thermo Oxidative Degradation

Разработана экспериментальная методика определения механизма огнезащитного действия антипиренов на основе изучения кинетики термической и термоокислительной деструкции древесины. Отработка методики проведена на антипирене MgCl (бишофит). Методика основывается на количественной оценке при термическом разложении древесины выхода продуктов деструкции: CO, CO, дымового аэрозоля. В качестве приборной базы используются хроматографы, фотометр фотоэлектрический для аэрозолей, спектрофотометр. Water with various additives is used during extinguishing forest fires. Fire-retardants are used as additives in most cases. The selection of fire-retardants depends on the level of increase in extinguishing effectiveness at their addition to water. The purpose of this work is to develop an experimental method for evaluating the fireproof effect of flame retardants solutions. This method is based on the investigation of the kinetics of thermal and thermo-oxidative degradation of treated wood with flame retardants and untreated wood. In practice, bischofite and diammonium phosphate are often used as additives. Investigations were conducted using MgCl (bischofite). The explanation of the fireproof effect of the bischofite solution is based on the study of the yield of decomposition products (CO, CO, smoke aerosol) of wood treated with fire-retardant and untreated wood. The instrument base includes chromatographs «Gasochrom 3101», «Tsvet 152», photoelectric photometer for aerosols, spectrophotometer IKS-29. Wood samples were subjected to thermal and thermo-oxidative degradation in nitrogen flow or air flow with a volume velocity of 60 ml · min. Pulse heating in the pyrolysis furnace was carried out in the temperature range from 350 to 550 °C. The significant increase in fire resistance of wood treated with fire-retardant was found as a result of researches using the proposed method. It was shown that the theory of the coating layer, thermal and gas theory of catalytic dehydration are not suitable for explaining the mechanism of fireproof action of an aqueous solution of magnesium halides. Although it is not excluded the inhibition of gas-phase oxidation of cellulose degradation products by hydrogen halides released when heating aqueous solutions of magnesium halides.

On the kinetics of cellulose degradation: looking beyond the pseudo zero order rate equation

Cellulose ◽  
2007 ◽  
Vol 15 (2) ◽  
pp. 193-203 ◽  
Author(s):  
Paolo Calvini ◽  
Andrea Gorassini ◽  
Antonio Luigi Merlani
Keyword(s):  
Rate Equation ◽  
Cellulose Degradation ◽  
Zero Order ◽  
Order Rate ◽  
Kinetics Of ◽  
Order Rate Equation

Primary-secondary flotation of three municipal wastewaters: pilot-scale study

1995 ◽  
Vol 31 (3-4) ◽  
pp. 295-298 ◽  
Author(s):  
M. Krofta ◽  
D. Miskovic ◽  
D. Burgess
Keyword(s):  
Wastewater Treatment ◽  
Municipal Wastewater ◽  
Pilot Scale ◽  
Organic Load ◽  
Municipal Wastewater Treatment ◽  
Theoretical Evaluation ◽  
Filtration System ◽  
Study Results ◽  
Kinetics Of ◽  
Kjeldahl Nitrogen

A pilot system containing a particularly designed configuration of primary flotation unit and a combined flotation-filtration clarifier, was used for advanced municipal wastewater treatment. The system which was investigated demonstrated the feasibility of municipal wastewater treatment by the flotation separation of fluid and coagulated-flocculated solids (Total suspended solids (TSS), organic load, Phosphorous (P), Total Kjeldahl Nitrogen (TKN)) without using microbiological oxidation. The particular objective herein was to create a preliminary approach to theoretical evaluation of positive pilot-study results in the form of two kinetic models. Based on positive pilot results, and kinetic analysis, the following conclusions were reached:A double-stage flotation/filtration system might be a viable alternative for municipal wastewater treatment.Empirical models and prediction developed here reflect the kinetics of the removal of coagulated and flocculated solids by flotation.

The investigation of the advanced treatment of municipal wastewater by modular flotation-filtration systems and reuse for irrigation

1996 ◽  
Vol 33 (10-11) ◽  
pp. 171-179 ◽  
Author(s):  
Milos Krofta ◽  
Dusan Miskovic ◽  
David Burgess ◽  
Edward Fahey
Keyword(s):  
Pilot Study ◽  
Municipal Wastewater ◽  
Full Scale ◽  
Advanced Treatment ◽  
Start Up ◽  
Turbidity Level ◽  
Hydraulic Load ◽  
The Impact ◽  
Kinetics Of ◽  
Pilot Tests

The objective of this study was to provide clarified municipal wastewater effluent at the turbidity level of less than 2.0 NTU and reuse for landscape irrigation (golf course). For that purpose, during pilot -study first was used a combined flotation-filtration module-clarifier alone (Alternative I). A particularly designed configuration of the primary flotation unit and combined flotation-filtration clarifier, as a modular clarification system was used in the next step of the investigation (Alternative II). In addition, start up of the full scale plant was performed as well. In the first phase of this study, the impact of the type and concentration of coagulant and flocculant was tested. As a result, mechanisms of flocculation were proposed. Only under the moderate hydraulic loads (75.7-151.4 LPM) during pilot tests by Alternative I, was it possible to reach satisfactory turbidity reduction. By the Alternative II, the clarification performance was improved under the higher hydraulic load (302.8 LPM). The kinetics of the investigated flotation systems were assesed by empirical flotation models. Based on the pilot-study, Alternative II is recommended in order to reduce the high solids loadings under a higher hydraulic load, and it provided irrigation water at a required rate of 3785 m3/d during start up and optimization of the full scale plant.

Effect of adding different levels of probiotic on in vitro gas production

2009 ◽  
Vol 2009 ◽  
pp. 187-187
Author(s):  
M Besharati ◽  
A Taghizadeh ◽  
A Ansari
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Nutritive Value ◽  
Cellulose Degradation ◽  
Gas Production ◽  
Nutrient Digestibility ◽  
Production Performance ◽  
Attractive Alternative ◽  
Kinetics Of ◽  
Different Levels

Probiotics present an attractive alternative to the use of chemical and hormonal promoters in the livestock growth production industry. Preparations that contain micro-organisms have been safely used for many years and are generally accepted by both the farmer and the final consumer. Saccharomyces cerevisiae supplementation in ruminant diets can increase DMI, production performance, cellulose degradation, and nutrient digestibility (Callaway and Martin, 1997). The gas measuring technique has been widely used for the evaluation of nutritive value of feeds. Gas measurement provides useful data on digestion kinetics of both soluble and insoluble fractions of feedstuffs (Getachew et al., 1998). In the gas method, kinetics of fermentation can be studied on a single sample and therefore a relatively small amount of sample is required or a larger number of samples can be evaluated at time. The purpose of this study was to study effect of adding different levels of Saccharomyces cerevisiae on in vitro gas production from a dried grape by-product.

Kinetics of PAA Demand and its Implications on Disinfection of Wastewaters

2006 ◽  
Vol 41 (4) ◽  
pp. 398-409 ◽  
Author(s):  
Dario Falsanisi ◽  
Ronald Gehr ◽  
Domenico Santoro ◽  
Adele Dell'Erba ◽  
Michele Notarnicola ◽  
...  
Keyword(s):  
Municipal Wastewater ◽  
Treatment Plant ◽  
Total Coliform ◽  
Microbial Inactivation ◽  
Inactivation Kinetics ◽  
Municipal Wastewater Treatment ◽  
Experimental Conditions ◽  
Batch Tests ◽  
The United Kingdom ◽  
Kinetics Of

Abstract Disinfectant demand and microbial inactivation rate are essential issues for assessing disinfection performance and proper design of disinfecting systems. In the United Kingdom and Italy, peracetic acid (PAA) has recently become an accepted disinfectant for treating wastewaters prior to reuse in agriculture, and its use is likely to spread worldwide due to its efficacy as well as the benign nature of the by-products produced. In this paper, overall PAA demand during the advanced disinfection of municipal wastewater for agricultural reuse was evaluated under different experimental conditions. Batch tests were carried out using primary and secondary settled effluents sampled at the City of Taranto municipal wastewater treatment plant. PAA dosages ranged from 1.5 to 8.5 mg/L and from 21 to 40 mg/L for the secondary and primary settled effluents, respectively. Residual PAA was measured after contact times ranging from 1 to 60 min. Results showed that after a strong and almost instantaneous initial disinfectant consumption, the PAA consumption followed first-order kinetics with both effluents. The effluent characteristics affected the values of the parameters in the consumption model. PAA disinfection efficacy was assessed in terms of total coliform and Escherichia coli indicator organism reduction; better results were achieved with the latter. The approximate solution of Hom's model established by Haas and Joffe was used to model inactivation kinetics of both microbial targets.

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