Determination and Sorting of Asbestos-Containing Material by Visual Observation

Abstract

Abstract:A rapid method for the determination of asbestos fiber at an intermediate treatment facility for construction and demolition waste (CDW) is required. Although the rapid method which involves visual observation has been developed, the determination accuracy and time are unknown. The purpose of this study was to determine the identification rate of asbestos-containing material (ACM: > 0.1w%), the time required for asbestos fiber determination by visual observation, and the asbestos content in CDW. After participating in a short training course for ACM determination, persons who did not have any knowledge of asbestos fiber determination were able to determine ACM in CDW by visual observation. Using the results of visual observation, an ACM sorting model was formulated. The model enabled simulation of asbestos content after sorting by inputting asbestos content distribution into CDW before sorting. However, 0.35 w% of asbestos still remained in the non-ACM fraction, i.e., the content was > 0.1 w%. The relationship between the number of sorters and the total sorting time for disaster waste from the Great East Japan Earthquake was presented. It was found that a very long time and a large number of people were required for sorting.

Grouping by Visual Appearance of Construction and Demolition Waste for Sorting Time Reduction with the Aim of Removing Asbestos-Containing Materials

“…Figure 1 shows the compositions of At and Nt before sorting, and Ad and Nd after sorting. According to the authors' research [18], the standard observation time and the shifting time for DVL were 1.7 s/cm 2 and 1 s/p, respectively.…”

“…Then, the particles were numbered using an oil-based marking pen. A portion of the 225 particles were used in previous research [18,19] and the other 127 CDW particles (hereinafter, referred to as "CDWP") were used in this study.…”

“…ACMds were identified and sorted from CDWPs as follows: first, texture-like fibers compacted on the surface of CDWP were identified and then, fibers having the characteristics of asbestos on the cross section were identified, i.e., the asbestos fibers should be fascicular and non-uniform [18] (Figure 3). Therefore, an independent and uniform fiber (e.g., cotton or glass wool) is not asbestos (Figure 4).…”

“…The authors previously investigated the separation efficiency of ACM from CDW particles by adopting the method of determination by visual observation with a loupe (DVL) [18]. A long time was required to examine the entire surface of a CDW particle.…”