Waste aroma profile in the framework of food waste management through household composting

Abstract

The aspect of backyard composting as element of sustainable development is examined and discussed. Towards this, the effect of various physicochemical parameters (temperature, humidity, organic content, pH, electric conductivity and seed germination index) with volatile organic compounds (VOCs) released during food waste composting is studied. Multivariate data analysis (MDA) was also applied to explore the potentials of using VOCs measurements in combination with various physicochemical parameters for monitoring the composting process in terms of compost maturity and biological activity. Therefore, composting bins filled with inedible food (95% v/v) and back yard (5% v/v) waste were sampled on a weekly base for a period of two months, in order to monitor the emitted odor compounds and the various physicochemical parameters of composting. The emitted VOCs were determined using the headspace solid-phase micro extraction gas chromatography/mass spectrometry (HS-SPME-GC/MS) method. The composting process resulted in the release of a variety of VOCs (terpenes, oxygenated compounds such as esters, acids, ketones and alcohols, sulfides, hydrocarbons), where terpenes played a dominant role. The most abundant VOC which was highly recognized during the process was limonene. The results of chemometric analysis revealed that high terpenes evolution is related with compost immaturity along with low seed germination index (phytotoxicity), whereas sulfides (i.e. dimethyl disulfide), temperature (Tin) and pH can be associated to compost biological activity. During maturation time, the emissions of terpenes and electronic conductivity were reduced, while the seed germination index increased. Thus, it is concluded that limonene can be related to the immature phase of compost and dimethyl disulfide with compost biological activity. These findings could be the basis for developing a future tool (e.g. special sensor combined with chemometrics) for monitoring purposes. The results of the current work are considered useful to any competent authority aiming to develop and apply a holistic strategy to treat organic waste (mainly food waste) using home composting as the best available technique, and at the same time to control the respective waste aroma.