Is the Anaerobic Digestion (AD) sustainable from the energy point of view?

2021 ◽  
Vol 231 ◽  
pp. 113857
Author(s):  
Carlos E. Gómez-Camacho ◽  
Raffaele Pirone ◽  
Bernardo Ruggeri
1988 ◽  
Vol 110 (4) ◽  
pp. 585-591
Author(s):  
Jhy-Horng Wang ◽  
Ming-Te Tsai

The instability caused by fluid leakage leads to limited performance in turbomachines. This instability may be improved by using flexible bearing supports with anisotropic stiffness. With a simplified model this effect is investigated, including the influence of many parameters. The results show that the optimum range of anistropy is strongly dependent on the parameters of the rotor-bearing system. In this paper an explanation from an energy point of view is presented to clarify the different stability behaviors with anisotropic bearing support.


2021 ◽  
Vol 8 (3) ◽  
pp. 1444-1453
Author(s):  
Mahmood Al Ramahi ◽  
Gábor Keszthelyi-Szabó ◽  
Sándor Beszédes

This work evaluates the effect of hydrothermal carbonization (HTC) as a pretreatment and post-treatment technique to anaerobic digestion (AD) of dairy sludge. HTC's effect on AD was evaluated based on energy recovery, nutrient transformation, and hydrochar utilization. The first approach was executed by performing HTC under a range of temperatures before mesophilic AD. HTC optimal pretreatment temperature was 210 °C for 30 min residence time. HTC pretreatment significantly increased the methane yield potential by 192%, the chemical oxygen demand removal by 18%, and the sludge biodegradability during AD by 30%. On the other hand, the application of HTC after AD (post-treatment) increased the total energy production, i.e., in addition to methane, a hydrochar with a caloric value of 10.2 MJ/kg was also obtained. Moreover, HTC post-treatment improved the steam gasification performance of the AD digestate. From the fertilizer quality point of view, HTC implementation generally boosted the concentrations of macro, micro, and secondary nutrients, suggesting its suitability for use as a liquid fertilizer. Overall, the findings of the present study indicate that if bioenergy production were the main target, HTC post-treatment following AD would lead to the most promising outcomes.


2012 ◽  
Vol 65 (10) ◽  
pp. 1839-1846 ◽  
Author(s):  
S. I. Pérez-Elvira ◽  
F. Fdz-Polanco

Experimental data obtained from the operation in a pilot plant are used to perform mass and energy balances to a global process combining units of thermal hydrolysis (TH) of secondary sludge, anaerobic digestion (AD) of hydrolysed secondary sludge together with fresh primary sludge, and cogeneration from biogas by using a gas engine in which the biogas produces electricity and heat from the exhaust gases. Three scenarios were compared, corresponding to the three digesters operated: C (conventional AD, 17 days residence time), B (combined TH + AD, same time), and A (TH + AD at half residence time). The biogas production of digesters B and A was 33 and 24% better, respectively when compared with C. In the case of the combined TH + AD process (scenarios A and B), the key factors in the energy balance were the recovery of heat from hot streams, and the concentration of sludge. The results of the balances showed that for 8% DS concentration of the secondary sludge tested in the pilot plant, the process can be energetically self-sufficient, but a fraction of the biogas must by-pass the gas engine to be directly burned. From an economic point of view, scenario B is more profitable in terms of green energy and higher waste removal, while scenario A reduces the digester volume required by a half. Considering a population of 100,000 inhabitants, the economic benefit is 87,600 €/yr for scenario A and 132,373 €/yr for B. This value can be increased to 223,867 €/yr by increasing the sludge concentration of the feeding to the TH unit to a minimum value that allows use of all the biogas to produce green energy. This concentration is 13% DS, which is still possible from a practical point of view. Additional benefits gained with the combined TH + AD process are the enhancement of the digesters rheology and the possibility of getting Class A biosolids. The integration study presented here set the basis for the scale-up to a demonstration plant.


RSC Advances ◽  
2015 ◽  
Vol 5 (27) ◽  
pp. 20783-20787 ◽  
Author(s):  
Weiqiang Lv ◽  
Yaxing Zhu ◽  
Yinghua Niu ◽  
Weirong Huo ◽  
Kang Li ◽  
...  

van der Waals interaction (vdW) in both on-axis and off-axis attachments of 1D Ag nano-structures are investigated by molecular static calculations to understand the thermodynamics of 1D OA growth from an energy point of view.


2017 ◽  
Vol 1 (4) ◽  
Author(s):  
Roberth Patricio Zambrano Ubillús

Actualmente,   la obesidad es una de las enfermedades nutricionales que afectan con gran significación la población ecuatoriana y en especial la manabita y esto se debe a lo variada que resulta la gastronomía en la provincia, partiendo de esta idea, se desarrolló esta investigación, especialmente con el objetivo de realizar una revisión bibliográfica que resumiera  los  aspectos  más  importantes  relacionados  con  los  riesgos  que  implican  el sobrepeso y la obesidad desde el punto de vista energético y también para caracterizar la situación actual de la población representada por los estudiantes que cursan el primer año de bachillerato en la Unidad Educativa “ITSUP”. Para ello se utilizó la población adolescente de los estudiantes que cursan el bachillerato en cualquiera de sus modalidades de la institución antes mencionada. Se llevó a cabo un control antropométrico de peso/talla de los estudiantes antes señalados, con la finalidad de poder evaluar, calcular  y sacar el diagnóstico del índice de masa corporal   de ingreso   de cada uno de ellos. Se concluyó que el síndrome de la obesidad se debe a varias causas y factores, como el cultural, el amplio surtido de alimentos en la región, y lo económico que éstos resultan; se concluye además  en que una cuarta parte de los adolescentes del instituto, presentan un peso por encima del adecuado.  Palabras claves: Obesidad, sobrepeso, riesgos, balance energético, nutrición Risks involved in overweight and obesity for health from the energy point of view Abstract  Nowadays,  obesity  is  one  of  the  nutritional  diseases  with  great  significance  on    the Ecuadorian population and especially the Province of  Manabi and this is due to the varied cuisine resulting in the province, based on this idea, this research was carried out, especially in order to perform a literature review to summarize the most important aspects of the risks involved overweight and obesity from the energy point of view and also to characterize the  current status of the population represented by the students in the first year of bachelor of Education Unit "ITSUP". For this adolescent population of students in the school in any of the aforementioned modes institution was used. Conducted an anthropometric control weight / height of the students mentioned above, in order to be able to evaluate, calculate and make the diagnosis of body mass index entry each. It was concluded that the syndrome of obesity to various causes and factors, such as cultural, the wide range of food in the region, ; It is also concluded that a quarter of high school adolescents, have a weight above adequate.  Keywords: Obesity, overweight, risk, energy balance, nutrition


Author(s):  
Xiang Zhang ◽  
Jianping Peng ◽  
Xiaorong Gao ◽  
Jie Bai ◽  
Jianqiang Guo

The industrial component under loading change its mechanical characteristics by stress. It is very important to make clear the distribution of the applied stress in the component to reduce the failure. In this paper, magnetic Barkhausen noise (MBN) method is used to evaluate the stress of DC01 steel. Combined with theory for both magnetic domain and magnetization, this work analyzed MBN signal from energy point of view. Magnetic strength corresponding to the maximum MBN shows a downward trend with the increase of tensile stress. Plots of energy against stress showed a relationship providing a convenient method for detecting stress levels by MBN.


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