Color change of city refuse during composting process

Abstract

Color change of city refuse during composting process was investigated according to the methods of measurement for color of materials based on the CIE 1931 Standard Colorimetric System. Stimulus value Y (the degree of lightness) and chromaticity coordinates (x, y) were determined with Color Analyzer by measuring relative spectral reflectance. Stimulus value Y of city refuse decreased during composting process, but chromaticity coordinates (x, y) scarcely changed. Color of various composts, which were produced from city refuse, straw, hog fecal wastes, tree bark, and tree bark mixed with activated sludge, were also investigated by measuring relative spectral reflectance. The shapes of the reflection spectra of city refuse were different from those of the other composts. Colors of the various composts were similar to each other when specified according to their three attributes: value, hue, and chroma (Munsell renotation). While city refuse was rotting and maturing, stimulus value Yand C/N ratio equally decreased. A positive correlation was found between stimulus value Y and C/N ratio. It was concluded that stimulus value Y can be used as a criterion for determining the degree of maturity of city refuse compost. The correlation between stimulus value Y and C/N ratio of various composts was also investigated. According to the position on the two coordinates having stimulus value Y and C/N ratio as axe s, various composts were classified into three groups: (i) city refuse compost group, (ii) straw compost group, and (iii) tree bark compost group.

Evaluation of city refuse compost maturity: a review

“…Sugahara et al (1979), however, propose a simple technique to determine the degree of darkness with greater precision. This system is based on the CIE 1931 Standard Colorimetric System; the 'stimulus value' Y (degree of lightness) and chromaticity coordinates are determined and the relative spectral reflectance of the compost is measured in a colour analyser.…”

“…The technique was later modified by Inoko (1979). According to these authors, the very mobile, slightly-polymerized components, move towards the periphery of the paper, while the highly polymerized components stay in the centre.…”

“…Both regression equations were deduced from the published results by the authors (Inoko et al, 1979).…”

Evaluation of stability of compost prepared with Korean food wastes

“…Thereafter, it decreased onto 4 on the 50th day of composting, and then did not change any more. Sugahara et al (1979) considered that the compost was mature since the Y value ranged from 11 to 13 during the compo sting of municipal wastes. Even though the Y value reached Sugahara's recommended value for 20 d, it might be difficult to confirm that the compost had matured, due to the continuous decrease of the Yvalue subsequently.…”

Relationship between cation-exchange capacity and degree of maturity of city refuse composts

“…INOKO et al (10) studied the changes in certain organic constituents of city refuse composts. SUGAHARA et al (19) investigated color changes of city refuse during the composting process. INoKo (9) undertook rapid tests to check the maturity of city refuse composts using a paper chromatographic method based on the description of HERTELENDY (8).…”