Denitrifying biofilm processes for wastewater treatment: developments and perspectives

2021 ◽  
Vol 7 (1) ◽  
pp. 40-67
Author(s):  
Lan Wu ◽  
Wei Wei ◽  
Juan Xu ◽  
Xueming Chen ◽  
Yiwen Liu ◽  
...  
Keyword(s):  
Wastewater Treatment ◽  
Electron Acceptor ◽  
Growth Kinetics ◽  
Redox Zonation

Biofilms can retain microorganisms with very different growth kinetics and different electron acceptor preferences, due to their natural redox zonation.

scholarly journals Research on System Optimizing of AAO-BAF Wastewater Treatment Process

2018 ◽  
Vol 53 ◽  
pp. 04028
Author(s):  
Shoubin Zhang ◽  
Wei Sun ◽  
Wenhai Jiao ◽  
Liping Qiu ◽  
Jingxiu Zhong ◽  
...  
Keyword(s):  
Wastewater Treatment ◽  
Electron Acceptor ◽  
Phosphorus Removal ◽  
Treatment Process ◽  
Treatment System ◽  
Research Progress ◽  
Combined Processes ◽  
Wastewater Treatment Process ◽  
Combined Process ◽  
Wastewater Treatment System

To meet the more strict discharging standard, some combined processes have emerged to realize denitrification and phosphorus removal of wastewater more efficiently. Among them, AAO-BAF combined process was an efficient one. The AAO-BAF system was composed of AAO reactor and BAF. The AAO process was the main unit to complete phosphorus removal and denitrification. The BAF process, external nitrification unit, was mainly used to provide enough electron acceptor for denitrifying bacteria in AAO reactor, which could enhance the efficiency of denitrification of the whole system. So the system optimizing was essential to AAO-BAF combined process. In this paper, the research progress of AAO-BAF wastewater treatment system was summarized and some system optimizing methods were raised too.

scholarly journals Benchmarking biological nutrient removal in wastewater treatment plants: influence of mathematical model assumptions

2012 ◽  
Vol 65 (8) ◽  
pp. 1496-1505 ◽  
Author(s):  
Xavier Flores-Alsina ◽  
Krist V. Gernaey ◽  
Ulf Jeppsson
Keyword(s):  
Wastewater Treatment ◽  
Electron Acceptor ◽  
Nutrient Removal ◽  
Wastewater Treatment Plants ◽  
Treatment Plant ◽  
Critical Discussion ◽  
Decay Rates ◽  
Biological Nutrient Removal ◽  
Nitrogen And Phosphorus ◽  
Reference Case

This paper examines the effect of different model assumptions when describing biological nutrient removal (BNR) by the activated sludge models (ASM) 1, 2d & 3. The performance of a nitrogen removal (WWTP1) and a combined nitrogen and phosphorus removal (WWTP2) benchmark wastewater treatment plant was compared for a series of model assumptions. Three different model approaches describing BNR are considered. In the reference case, the original model implementations are used to simulate WWTP1 (ASM1 & 3) and WWTP2 (ASM2d). The second set of models includes a reactive settler, which extends the description of the non-reactive TSS sedimentation and transport in the reference case with the full set of ASM processes. Finally, the third set of models is based on including electron acceptor dependency of biomass decay rates for ASM1 (WWTP1) and ASM2d (WWTP2). The results show that incorporation of a reactive settler: (1) increases the hydrolysis of particulates; (2) increases the overall plant's denitrification efficiency by reducing the SNOx concentration at the bottom of the clarifier; (3) increases the oxidation of COD compounds; (4) increases XOHO and XANO decay; and, finally, (5) increases the growth of XPAO and formation of XPHA,Stor for ASM2d, which has a major impact on the whole P removal system. Introduction of electron acceptor dependent decay leads to a substantial increase of the concentration of XANO, XOHO and XPAO in the bottom of the clarifier. The paper ends with a critical discussion of the influence of the different model assumptions, and emphasizes the need for a model user to understand the significant differences in simulation results that are obtained when applying different combinations of ‘standard’ models.

Treatment of sulfate-rich and low pH wastewater by sulfate reducing bacteria with iron shavings in a laboratory

2013 ◽  
Vol 69 (3) ◽  
pp. 595-600 ◽  
Author(s):  
Xiaoye Liu ◽  
Wenqi Gong ◽  
Lin Liu
Keyword(s):  
Wastewater Treatment ◽  
Organic Compounds ◽  
Electron Acceptor ◽  
Sulfate Reducing Bacteria ◽  
Low Ph ◽  
Synthetic Wastewater ◽  
Acidic Environment ◽  
Terminal Electron Acceptor ◽  
Sulfate Reducing ◽  
Reducing Bacteria

Sulfate-rich wastewater is an indirect threat to the environment especially at low pH. Sulfate reducing bacteria (SRB) could use sulfate as the terminal electron acceptor for the degradation of organic compounds and hydrogen transferring SO42− to H2S. However their acute sensitivity to acidity leads to a greatest limitation of SRB applied in such wastewater treatment. With the addition of iron shavings SRB could adapt to such an acidic environment, and 57.97, 55.05 and 14.35% of SO42− was reduced at pH 5, pH 4 and pH 3, respectively. Nevertheless it would be inhibited in too acidic an environment. The behavior of SRB after inoculation in acidic synthetic wastewater with and without iron shavings is presented, and some glutinous substances were generated in the experiments at pH 4 with SRB culture and iron shavings.

Biological Sulfur and Nitrogen Removal from Wastewater

2012 ◽  
Vol 550-553 ◽  
pp. 2170-2173
Author(s):  
Xiao Liu ◽  
Deng Ling Jiang ◽  
Yang Yong
Keyword(s):  
Wastewater Treatment ◽  
Reaction Mechanism ◽  
Energy Saving ◽  
Electron Acceptor ◽  
Nitrogen Removal ◽  
Operating Conditions ◽  
The Novel ◽  
Ammonium Oxidation ◽  
New Techniques ◽  
High Sulfate

Based on the summary of biotechnology principles and common processes for the separated desulfurization and denitrogenation in organic wastewater treatment, two novel biotechnologies for simultaneous sulfur and nitrogen removal, which developed from sulfide-dependent denitrification (denitrification with sulfide as electron donor) and sulfate-dependent ANAMMOX (anaerobic ammonium oxidation with sulfate as electron acceptor), were introduced. The reaction mechanism, operating conditions and functional organisms for the new techniques were described. It is considered that the novel process of simultaneous sulfur and nitrogen removal would be of grate benefit to the treatment of wastewater with high sulfate and ammonia in efficiency-improving, energy-saving and resource recovery.

MODELLING OF CHLORIDE INFLUENCE UPON ACTIVATED SLUDGE COMMUNITY GROWTH/CHLORIDŲ ĮTAKOS VEIKLIOJO DUMBLO BIOCENOZĖS DINAMIKAI MODELIAVIMAS/МОДЕЛИРОВАНИЕ ВЛИЯНИЯ ХЛОРИДОВ НА ДИНАМИКУ БИОЦЕНОЗА АКТИВНОГО ИЛА

2009 ◽  
Vol 17 (2) ◽  
pp. 114-120 ◽  
Author(s):  
Audra Skaisgirienė ◽  
Jolanta Janutėnienė ◽  
Petras Vaitiekūnas
Keyword(s):  
Wastewater Treatment ◽  
Activated Sludge ◽  
Growth Kinetics ◽  
Biological Treatment ◽  
Enzyme Preparation ◽  
Sewage Treatment ◽  
Treatment Quality ◽  
Active Sludge ◽  
Enzyme Preparations ◽  
Community Growth

Growth kinetics, i.e. the relationship between specific growth rate and the concentration of a substrate, is one of the basic tools in the modelling of activated sludge community growth. The above‐described conventional growth kinetics derived from single‐substrate‐controlled laboratory experiments have invariably been used for describing both growth and substrate utilization in wastewater treatment. After technological processes various mineral substances, such as chlorides, get into water bodies. These substances are not removed from wastewater by the biological treatment method. The purpose of this study is to determine the concentrations of chlorides, investigate the influence of enzyme preparations upon wastewater treatment quality during biological process modelling. Kinetics of microbial growth was designed using the model of Monad. To analyse the chloride influence on the biooxidation process a series of laboratory tests was carried out: biochemical oxygen consumption (BOD), activated sludge concentration and other indexes. It is found experimentally that a 400 mg/l concentration of chlorides disarranges the activity of microorganisms and activated sludge is no longer suitable for biological treatment. Also, we investigated the effect of enzyme preparation on effluence on sewage treatment. As chloride concentrations are increased in a tank without an enzyme, bacterial spores contained in the enzyme preparation produce a renewing effect upon active sludge. Santrauka Mikroorganizmų augimo dinamika, t. y. priklausomybė tarp jų savitojo augimo spartos ir substrato koncentracijos, yra vienas iš svarbiausių veiksnių modeliuojant veikliojo dumblo kinetiką. Laboratorinėmis sąlygomis buvo atlikti eksperimentiniai nuotekų valymo tyrimai kompleksiškai įdėjus į substratą ir chloridų kaip papildomos užtaršos bei fermentinio preparato. Rezultatams palyginti buvo atlikti tyrimai ir be fermentinio preparato. Po įvairių technologinių procesų į valymo įrenginius patenka tokios mineralinės medžiagos kaip chloridai. Šios medžiagos biologiniu valymo būdu iš nuotekų nepašalinamos. Darbe nagrinėjama, kokios chloridų koncentracijos turi įtakos biologinio nuotekų valymo kokybei, veikliojo dumblo augimo dinamikai bei substrato biodegradacijai. Eksperimentų metu nustatytos tiriamų teršalų koncentracijos, turėjusios įtakos biologiniam valymo procesui: 400 mg Cl– /l ir didesnės sutrikdo mikroorganizmų veiklą, veiklusis dumblas biologiniam nuotekų valymui tampa netinkamas. Darbe modeliuojama veikliojo dumblo mikroorganizmų biocenozės dinamika, atliekant aerobinį nuotekų valymą. Nagrinėtas atvejis, kai nuotekų užtarša yra didesnė chloridų koncentracija. Veikliojo dumblo biocenozės dinamikai modeliuoti pasirinktas Monodo modelis. Atlikus eksperimentą nustatyti degradacijos koeficientai kd. Gautas Monodo diferencialinės lygties sprendinys, nusakantis veikliojo dumblo dinamiką. Skaitiniais metodais išspręsta veikliojo dumblo augimą bei substrato biodegradaciją nusakanti diferencialinių lygčių sistema. Įvertinus eksperimentų rezultatus nustatyti veikliojo dumblo sistemos degradacijos koeficientai įdėjus fermentinio preparato. Rezultatai parodė, kad fermentinis preparatas teigiamai veikia mikroorganizmų augimą t. y. veikliojo dumblo koncentracija mažėja lėčiau. Резюме Кинетика биомассы микроорганизмов, т. е. зависимость между концентрацией активного ила и концентрацией субстрата, один из важнейших аспектов в моделировании динамики активного ила. В лабораторных условиях были проведены экспериментальные исследования сточных вод в комплексе с добавлением в субстрат хлоридов как дополнительного загрязнения и ферментного препарата. Для сравнения результатов были проведены параллельные эксперименты без ферментного препарата. В результате технологических процессов в очистные сооружения попадают разные минеральные вещества, как, например, хлориды. Эти вещества методом биологической очистки не удаляются. В настоящей работе были исследованы концентрации хлоридов, влияющие на качество биологической очистки сточных вод, качество и кинетику активного ила и биодеградацию субстрата. Для определения влияния хлоридов на биологические процессы были проведены лабораторные исследования по определению биохимического потребления кислорода (БПК), концентрации активного ила и др. В результате эксперимента было установлено, что концентрация хлоридов, составляющая 400 мг/л и больше, поражает работу микроорганизмов, активный ил становится непригодным для биологической очистки cточных вод. Также исследовалось влияние ферментного препарата на качество очистки. Моделируя кинетику динамики активного ила, получено решение дифференциального уравнения, в котором идентифицированы коэффициенты деградации ила kd. В результате эксперимента определены коэффициенты деградации на систему активного ила в резервуаре с ферментным препаратом, т. е. концентрация активного ила уменьшается медленнее. Можно сделать вывод, что ферментный препарат эффективно влияет на концентрацию микроорганизмов.

The Ordered Phase Formation in Ti-Al-Ga Alloys

1970 ◽  
Vol 28 ◽  
pp. 440-441
Author(s):  
Shiro Fujishiro ◽  
Harold L. Gegel
Keyword(s):  
Thermal Stability ◽  
High Temperature ◽  
Titanium Alloys ◽  
Growth Kinetics ◽  
Stoichiometric Composition ◽  
Good Potential ◽  
Alpha Titanium ◽  
Cold Rolled ◽  
Kinetics Of ◽  
Thermal Stability Of

Ordered-alpha titanium alloys having a DO19 type structure have good potential for high temperature (600°C) applications, due to the thermal stability of the ordered phase and the inherent resistance to recrystallization of these alloys. Five different Ti-Al-Ga alloys consisting of equal atomic percents of aluminum and gallium solute additions up to the stoichiometric composition, Ti3(Al, Ga), were used to study the growth kinetics of the ordered phase and the nature of its interface.The alloys were homogenized in the beta region in a vacuum of about 5×10-7 torr, furnace cooled; reheated in air to 50°C below the alpha transus for hot working. The alloys were subsequently acid cleaned, annealed in vacuo, and cold rolled to about. 050 inch prior to additional homogenization

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