ANALYSIS OF EMISSIONS FROM LAB-SCALE COMPOSTING EQUIPMENT: DATA FOR A SUSTAINABILITY CHALLENGE

The increase of global environmental consciousness is pushing more and more towards sustainable systems for the management of cities and agricultural area. Organic waste can be converted into good soil amendments by composting, which is therefore recognized as an ecofriendly process. Recently, CNR-ISAFOM developed a simplified static composting method easy to be carried out at farm level for olive mill waste recycling; in order to analyze and model the impacts of such a method, a highly air-forced automated apparatus including two 35-liters bioreactors has been designed and developed. The system is able to analyze in real time the emissions derived from the respiration activity of the in situ microbiota. The air flow is managed by means of mass flow controller able to keep the oxygen concentration in the exhausted air within a pre-fixed optimal aerobic value. An accurate monitoring of temperature in the biomass, as well as in the inlet and outlet airflow, is carried out all along the composting trials. In addition, the apparatus records the progressive weight loss of the two bio-reactors while the concentrations of oxygen, carbon dioxide, ammonia and hydrogen sulfide are gathered in the exhausted air by means of separate specific detectors. The equipment is managed by custom NI LabVIEW software: parameters under control are recorded every fifteen minutes and promptly displayed in tables, graphs and spreadsheets. The apparatus has been tested by composting olive mill waste with hygroscopic additives, such as straw and waste wool. Monitoring at a Lab-scale the amount of emissions from composting may led to optimize those parameters which influence the release of greenhouse gases (GHG) emissions. This may help composting companies in comply the even more restrictive rules imposed by Regulators for reducing its environmental impacts.