Reducing the Volume of Waste by Composting Vegetable Waste, Sewage Sludge and Sawdust

Abstract

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.

Recycling Biomass Waste to Compost

“…4a, b all the compost samples had good results for both radish and cabbage seeds. The best results were obtained using as biofertilizers the compost samples with biomass, sewage sludge and sawdust due to its enriched content in nutrients and biocatalysts enzymes [16,55,60]. From all the compost samples synthesized and characterized were selected 3 organic substrates with the best results regarding maturation and stability, established by literature [10,12,30,31,33,39] as optimum for a biofertilizer:…”

“…components of organic matter are hydrolyzed by enzymes to mono carbohydrates, which further are partially transformed into inorganic, volatile compound, carbon dioxide. The presence o sawdust and sewage sludge in compost samples promotes a slower biodegradation of poly carbohydrates due to inhibiting influence of sawdust over micro organisms' activity [11,55].…”

“…Biodegradation of poly carbohydrates is an oxidative process which generates energy by exothermic reactions. In the presence of biocatalyst enzymes, the poly carbohydrates are split into mono carbohydrates (glucose being the main component) which are decomposed into simpler compounds with lower molecular mass [55].…”

“…certifying both, the presence in all composts samples of complex, macro molecular compounds: poly carbohydrates, proteins, lignin, lipids etc., and their biodegradation process forming simpler products: mono carbohydrates, aldehydes, ketones, alcohols, amines, phenols, carboxylic acids and their derivatives (amides, esters, nitriles, etc.) [55,56,58].…”