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A study on thermal drying of wood

Haghi A. K., Haghi R. K.

International Journal of Applied Mechanics and Engineering

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2007

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Vol. 12, no 3

865-873

EN

Drying is a complex operation involving transient transfer of heat and mass along with several rate processes, such as physical or chemical transformations, which in turn, may cause changes in product quality. This article surveys the impacts of convective, infrared and microwave drying on the strength of dried wood. The effects of drying methods on mechanical properties have been studied for many materials, but wood products have seldom been the subject. Spruce wood samples (length = 140 mm and diameter = 21.0 mm) were dried using the following drying regimes: convective (1000 C and 400 C), microwave (480, 790, and 1000 W power) and infrared (100% power). The dried sampies were then subjected to tensile loading in order to evaluate the mechanical properties. It is concluded that the microwave drying can improve the strength of dried samples significantly.

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Status and countermeasures of sewage sludge treatment and disposal in Beijing

Xiaoying Z., Yuwen Z., Hongying R.

Zeszyty Naukowe. Inżynieria Środowiska / Politechnika Opolska

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2003

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Vol. 291, z. 4

511-517

EN

The problem of sewage sludge treatment and disposal is becoming more and more serious with the rapid development of sewage treatment in Beijing. In this paper, the status and problems of Beijing sewage sludge treatment and disposal are analyzed, and the components of sludge are also analyzed. At present, a sewage sludge treatment and disposal center is in operation in Beijing, treating and disposing the sludge from the 5 existing wastewater treatment plants in Beijing. It is an achievement, but also has certain problems which are needed to be solved for the safety use of sludge. The analysis of sludge components shows that there are rich plant nutrients and organics in the sludge, and also a large number of pathogenic microorganisms which needed to be killed. The concentrations of certain kinds of heavy metals exceed the Chinese standards of sludge for agricultural purpose. So it is very important to adopt rational and effective treatment processes to make sludge harmless before it is used for agricultural purpose or other purposes. The countermeasures probed here include: establish relative standards concerning sewage sludge treatment and disposal, study techniques of sludge volume reduction and thermal drying, study the utilization of sludge as resources, establish sewage sludge treatment and disposal center and improve the sewage sludge treatment and disposal processes.

3

Wykorzystanie suszonych termicznie komunalnych osadów ściekowych

Gromiec M. J., Korczak-Niedzielska M.

Inżynieria i Ochrona Środowiska

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2000

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T. 3, nr 1/2

211-218

PL

Technologie przeróbki i unieszkodliwiania osadów ściekowych wejdą w okres znacznych zmian związanych z przyjęciem prawodawstwa Unii Europejskiej. Jednym z ważnych kierunków rozwoju tej dziedziny jest termiczne suszenie osadów. Praca przedstawia charakterystykę wysuszonego osadu i jego wykorzystanie do różnych celów. Dodatkowo zaprezentowano możliwości zastosowania termicznego suszenia osadów w Polsce.

EN

Sludge treatment and disposal will enter a period of significant change driven by legislation in European Union. One of the most important development in this field is thermal drying of sludge. This paper describes the characteristic of the dried sludge and its applications in various fields. In addition possibilities for the application of thermal sludge drying in Poland are discussed.