Biomass Retention in Advanced Anaerobic Reactors

1990 ◽  
Vol 22 (1-2) ◽  
pp. 17-24 ◽  
Author(s):  
G. Albagnac

Recognition of the advantages of anaerobic wastewater treatment induced the development of high rate processes, i.e. reactors designed to allow an efficient treatment of even diluted streams. The performance of these advanced reactors is mainly dependent on the retention within the reactor of high bacterial concentrations. The prevailing mechanism is either the formation of bacterial aggregates with good settling characteristics, the development of methanogenic biolayers at the surface of inert carriers or both. During the past decade information on the biology of methanogenic ecosystems became available at an increasing rate. From a practical point of view it can be stated that the biological conversion of organic compounds to methane is reasonably well understood. However the current knowledge on the aggregation and adhesion of methanogenic consortia remains very limited. In most cases reactor start-up procedures are rather long and appear to be more empirical than rational. This paper is a brief presentation on the current knowledge of methanogenic aggregates and biofilms. The fundamental aspects of bacterial adhesion and the modelling of anaerobic biofilms growth are presented elsewhere.

2018 ◽  
Vol 3 (5) ◽  
pp. 39
Author(s):  
Yéssica Elizabeth Barreto Macías ◽  
Colón Avellán Velásquez

El actual trabajo afronta una de las problemáticas más apremiantes de los actuales momentos como es el alto índice de dispendio de drogas en las Instituciones Educativas, que afectan considerablemente a la sociedad ecuatoriana. Su objetivo es analizar los lineamientos que permitan mejorar la orientación familiar, y desarrollar relaciones interpersonales apropiadas que fomenten la unión familiar, practicar principios, fomentar valores morales, y que los jóvenes aprendan a decir “no” ante una eventual propuesta de consumir compuestos prohibidos, que lo único que se consigue es materializarse en un estado no idóneo ante la comunidad, considerar que las consecuencias para la salud son devastadoras, personas que a temprana edad padecen de enfermedades que en muchas ocasiones son gravísimas, causando malestar no solamente propio sino a la familia. Puedo mencionar como aporte de este artículo; y en base a resultados establecidos que resulta primordial e importante mantener la asistencia de un profesional especializado en psicología, diálogos científicos y motivadores, conjuntamente con atención médica provocarán en la persona afectada la erradicación del consumo de drogas. Constan muchos factores que causan gran influencia negativa en las familias, partiendo de que actualmente el mundo vive la tendencia del consumismo lo que influye en sobremanera que exista menos dialogo en el hogar, la aparición de la tecnología es otra de las situaciones adversas. Los profesionales encargados de brindar orientación familiar deben considerar siempre, que el comportamiento del ser humano debe ser comprendido desde el punto de vista de su forma de pensar, solo así se desarrollara una cultura que permita a las familias tomar las decisiones acertadas al momento de formar a sus hijos, lo que en un futuro se evidenciará como seres útiles a la sociedad. PALABRAS CLAVE: Consumo de drogas; orientación familiar; valores morales.  FAMILY COUNSELING, FOR THE PREVENTION OF DRUG USE IN THIRDYEAR HIGH SCHOOL STUDENTS  ABSTRACT  The current work addresses one of the most pressing issues of current times such as the high rate of drug use in educational institutions, which greatly affect Ecuadorian society. Its objective is to analyze the guidelines for improving family orientation, and develop appropriate interpersonal relationships that promote family unity, value the principles, and that young people learn to say "no" to a possible proposal to use prohibited drugs, that the only thing that is achieved is to materialize in an unsuitable state before the community, to consider that the consequences for health are devastating, people who at an early age suffer from diseases that in many occasions are very serious, causing discomfort not only their own but also the family. I can mention as contribution of this article; and based on established results that it is essential and important to maintain the assistance of a professional specialized in psychology, scientific and motivational dialogues, together with medical care, will cause the affected person to eradicate drug use. There are many factors that cause great negative influence on families, based on the fact that the world currently lives the trend of consumerism which greatly influences that there is less dialogue at home, the emergence of technology is another of the adverse situations. The professionals responsible for providing family counseling should always consider that the behavior of the human being should be understood from the point of view of their way of thinking, only in this way will a culture be developed that allows families to make the right decisions when forming to their children, which in the future will be evident as useful beings to society. KEYWORDS: drug use; family orientation; moral values.


2001 ◽  
Vol 44 (8) ◽  
pp. 15-25 ◽  
Author(s):  
J.B. van Lier ◽  
F.P. van der Zee ◽  
N.C.G. Tan ◽  
S. Rebac ◽  
R. Kleerebezem

Anaerobic wastewater treatment (AnWT) is considered as the most cost-effective solution for organically polluted industrial waste streams. Particularly the development of high-rate systems, in which hydraulic retention times are uncoupled from solids retention times, has led to a world-wide acceptance of AnWT. In the last decade up to the present, the application potentials of AnWT are further explored. Research shows the feasibility of anaerobic reactors under extreme conditions, such as low and high temperatures. Also toxic and/or recalcitrant wastewaters, that were previously believed not to be suitable for anaerobic processes, are now effectively treated. The recent advances are made possible by adapting the conventional anaerobic high-rate concept to the more extreme conditions. Staged anaerobic reactor concepts show advantages under non-optimal temperature conditions as well as during the treatment of chemical wastewater. In other situations, a staged anaerobic - aerobic approach is required for biodegradation of specific pollutants, e.g. the removal of dyes from textile processing wastewaters. The current paper illustrates the benefits of reactor staging and the yet un-exploited potentials of high-rate AnWT.


2017 ◽  
Vol 2017 ◽  
pp. 1-14 ◽  
Author(s):  
Rodolfo Mastropasqua ◽  
Vincenzo Fasanella ◽  
Alessandra Mastropasqua ◽  
Marco Ciancaglini ◽  
Luca Agnifili

The ciliary body ablation is still considered as a last resort treatment to reduce the intraocular pressure (IOP) in uncontrolled glaucoma. Several ablation techniques have been proposed over the years, all presenting a high rate of complications, nonselectivity for the target organ, and unpredictable dose-effect relationship. These drawbacks limited the application of cyclodestructive procedures almost exclusively to refractory glaucoma. High-intensity focused ultrasound (HIFU), proposed in the early 1980s and later abandoned because of the complexity and side effects of the procedure, was recently reconsidered in a new approach to destroy the ciliary body. Ultrasound circular cyclocoagulation (UC3), by using miniaturized transducers embedded in a dedicated circular-shaped device, permits to selectively treat the ciliary body in a one-step, computer-assisted, and non-operator-dependent procedure. UC3 shows a high level of safety along with a predictable and sustained IOP reduction in patients with refractory glaucoma. Because of this, the indication of UC3 was recently extended also to naïve-to-surgery patients, thus reconsidering the role and timing of ciliary body ablation in the surgical management of glaucoma. This article provides a review of the most used cycloablative techniques with particular attention to UC3, summarizing the current knowledge about this procedure and future possible developments.


Author(s):  
Mohammad Mahmoud Hilal Alsmairat Mohammad Mahmoud Hilal Alsmairat

  The study aimed to identify the reality of educational transformations for primary school students in light of the Corona pandemic from the point of view of school principals in the Northern Jordan Valley. A number of (35) principals in the Northern Jordan Valley were chosen intentionally, and the study reached the following results: the results of the interviews of the respondents showed that the educational relations were limited and transformed from the school system with its elements to the home system with its elements, and to the transfer of the process of receiving the educational authority From administrators and teachers in the school to parents and older brothers at home, and because of the shift in the spatial presence and the abolition of the role of the director and the teacher as an educational process and its transfer to the educational platforms that came during the Corona pandemic, the educational burden and follow-up became entrusted to a very high rate estimated at (80%). As the student’s dependence on himself and his parents, and in light of the results of the study, the researcher made several recommendations for the need to conduct more studies and research Related to the educational reality and its transformations in light of the Corona pandemic at other age and educational stages, and the need to think of solutions to students’ problems resulting from their confinement to educational platforms and their lack of mixing with their peers.


2002 ◽  
Vol 45 (10) ◽  
pp. 321-328 ◽  
Author(s):  
H.J. Gijzen

After the discovery of methane gas by Alessandro Volta in 1776, it took about 100 years before anaerobic processes for the treatment of wastewater and sludges were introduced. The development of high rate anaerobic digesters for the treatment of sewage and industrial wastewater took until the nineteen-seventies and for solid waste even till the nineteen-eighties. All digesters have in common that they apply natural anaerobic consortia of microorganisms for degradation and transformation processes. In view of this, it could be rewarding to evaluate the efficiency of natural ecosystems for their possible application. Examples of high rate anaerobic natural systems include the forestomach of ruminants and the hindgut of certain insects, such as termites and cockroaches. These “natural reactors” exhibit volumetric methane production rates as high as 35 l/l.d. The development of anaerobic reactors based on such natural anaerobic systems could produce eco-technologies for the effective management of a wide variety of solid wastes and industrial wastewater. Important limitations of anaerobic treatment of domestic sewage relate to the absence of nutrient and pathogen removal. A combination of anaerobic pre-treatment followed by photosynthetic post-treatment is proposed for the effective recovery of energy and nutrients from sewage. This eco-technology approach is based on the recognition that the main nutrient assimilating capacity is housed in photosynthetic plants. The proposed anaerobic-photosynthetic process is energy efficient, cost effective and applicable under a wide variety of rural and urban conditions. In conclusion: a natural systems approach towards waste management could generate affordable eco-technologies for effective treatment and resource recovery.


2001 ◽  
Vol 44 (8) ◽  
pp. 7-14 ◽  
Author(s):  
J. Weijma ◽  
A.J.M. Stams

An overview on methanol conversion in high-rate anaerobic reactors is presented, with the focus on technological as well as microbiological aspects. The simple C1-compound methanol can be degraded anaerobically in a complex way, in which methanogens, sulfate reducing bacteria and homoacetogens interact cooperatively or competitively at substrate level. This interaction has large technological implications as it determines the final product of methanol mineralization, methane or carbon dioxide. The degradation route of methanol may be entirely different when environmental conditions change. Direct methanogenesis from methanol seems the predominant mineralization route under mesophilic conditions both in the absence and the presence of sulfate. Under thermophilic conditions methanol oxidation to carbon dioxide and hydrogen appears to play an important role. The UASB technology for mesophilic digestion of methanolic waste has presently reached full-scale maturity. The potential of methanol as feedstock for anaerobic processes is discussed.


2016 ◽  
Vol 9 (1) ◽  
Author(s):  
Bu-Chun Si ◽  
Jia-Ming Li ◽  
Zhang-Bing Zhu ◽  
Yuan-Hui Zhang ◽  
Jian-Wen Lu ◽  
...  

2020 ◽  
Vol 83 ◽  
pp. 01063
Author(s):  
Štefan Slávik

Start-up is a modern entrepreneurship form designed to realize original business ideas, mostly based on new technologies and the Internet. It evolves in the development cycle, which is determined by the business idea development cycle and the financing cycle. The purpose of the paper is to describe and analyse the business idea. The business idea is characterized by its content, circumstances of its origin, degree of originality and evidence of this originality. Start-ups are dominated by business ideas based on the application of information and communication technologies, the business idea is most often created by combining professional and business experience, but its originality is from the international point of view only average and the level of legal protection is quite rare.


Cancers ◽  
2021 ◽  
Vol 13 (19) ◽  
pp. 4942
Author(s):  
Maria Grazia Ronga ◽  
Marco Cavallone ◽  
Annalisa Patriarca ◽  
Amelia Maia Leite ◽  
Pierre Loap ◽  
...  

The development of innovative approaches that would reduce the sensitivity of healthy tissues to irradiation while maintaining the efficacy of the treatment on the tumor is of crucial importance for the progress of the efficacy of radiotherapy. Recent methodological developments and innovations, such as scanned beams, ultra-high dose rates, and very high-energy electrons, which may be simultaneously available on new accelerators, would allow for possible radiobiological advantages of very short pulses of ultra-high dose rate (FLASH) therapy for radiation therapy to be considered. In particular, very high-energy electron (VHEE) radiotherapy, in the energy range of 100 to 250 MeV, first proposed in the 2000s, would be particularly interesting both from a ballistic and biological point of view for the establishment of this new type of irradiation technique. In this review, we examine and summarize the current knowledge on VHEE radiotherapy and provide a synthesis of the studies that have been published on various experimental and simulation works. We will also consider the potential for VHEE therapy to be translated into clinical contexts.


1992 ◽  
Vol 26 (3-4) ◽  
pp. 601-605 ◽  
Author(s):  
H.-S. Shin ◽  
K.-H. Lim ◽  
H.-S. Park

Aerobic upflow sludge blanket(AUSB) process is a new biological wastewater treatment method applying the concept of the self-immobilization to activated sludge. Two sets of AUSB system with different mixing velocities of 3 rpm(R1) and 6 rpm(R2) were operated for high-rate treatment of synthetic wastewater. The COD removal efficiency in R2 was higher than R1 at the same loading rate up to 7 kg/m3·day. However, in R1, the sludge bulking was observed at the end of the experiment. The chocolate colored granules were formed about 5 days after the start-up. The morphological study on the granular sludge consortia was made with both scanning electron and optical microscopes. The granules were 0.5-2.5 mm in diameter and mainly consisted of bacteria with pili-like appendages and filamentous bacteria, which were thought to be Sphaerotilus natans and Beggiatoa. In R1, the long multicellular filaments causing bulking were prevalent in the granule, while in R2 overgrowth of filamentous bacteria was prevented with appropriate shear stress resulting in higher MLSS density. Experimental results indicated that granulation could be controlled by physical stress on granular sludge.


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