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It has been an increased interest in using sewage sludge as agricultural fertilizer and soil improvement material, especially as compost with biomass. This paper analyses five samples of composts from bio waste and sewage sludge, with various percentage of sludge, using the following parameters: pH, EC, carbohydrates content, enzymes content and C: N ratio. The results were correlated with FT-IR spectra and germination test in order to assess the stability and maturity of the composts samples. It was also calculated the composition efficiency of compost samples. All tests indicate a favorable environment for microorganisms and a good conversion to complex compounds: amino acids, carbohydrates and products of their biodegradation amines, amides, carboxylic acids, aldehydes, ketones, enzymes, proving they can act as bio fertilizers.

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Our research was focused on developing some new procedures to reduce the biodegradable wastes by composting. The aim of this study was to obtain and asses at laboratory scale the maturity of three compost samples of different proportion of vegetable waste, beech sawdust and sewage sludge by analyzing their FT-IR spectra and C/N ratio. The composting process was monitored by tests performed weekly on the three samples in order to investigate the physical parameters (pH and electroconductivity EC) and chemical parameters. Thus, organic N was determined as aminic N from amino acids content and as total organic N content. Organic C content was determined as monosaccharides content and TOC content. The results were also confirmed by C/N ratios. At the end of the composting process germination tests were performed for 7 days and the GI were determined. All the lab tests showed that the maturity of composts was achieved in all three samples, proving also that sawdust acts as an inhibitor of the activity of microorganisms in the decomposition of complex compounds and the sludge contributes to the improvement of their activity by the addition of nutrients.

1,3,4-oxadiazole-3-methylamino)isophthalate. -(ROMAN, G.; AGACHE*, C.; MANCIULEA, I.; COMANITA, E.; DUMITRESCU, L.; Rev. Roum. Chim. 52 (2007) 12, 1103-1110; Dep. Wood Technol., Transilvania Univ., RO-500036 Brasov, Rom.; Eng.) -H. Toeppel