Paper details

Title:

Hemp Residues Valorization Through a Co-Composting Biochar Process: a Pilot Case Study

Author(s):

Ottani, F., Pedrazzi, S., Paris, R., Montanari, M., Allesina, G.

Document(s):

Abstract:

Composting, to date, is one of the most used methods for the recovery of waste organic matter. Many are the organic wastes, sent to composting industrial plants, which come from municipal solid wastes (MSW), but many are also waste from the agri-food sector. Hemp industry has grown rapidly in recent years, both in terms of fiber and seeds production and inflorescences production for the pharmaceutical sector. The necessity of high crop productivity and high final product quality has led to the birth of many farms specialized in intensive field or greenhouses indoor hemp cultivation in which unsustainable and non-reusable substrates are used. Furthermore, hemp farms produce a lot of waste since part of the cultivated plants are not used for the market-ready products. Aim of this work is to explore the reuse of the hemp industry residues (from in field or indoor cultivation) to produce a soil conditioner that can be applied to the soil or mixed with the standard substrate to improve agronomic characteristics. In this case study, leaves and flowers from a hemp fiber cultivation are used. This work investigates the addition of biochar at the beginning of the decomposition process to study how biochar can improve both the decomposition process and the final product. An "aerated static pile" system has been simulated since this is one of the most used and easier-to-manage composting methods. Two compost bins of 1.3 m3 were built and a controlled aeration system was set up. Two tests were performed. The first test was necessary to regulate the air insufflation periods to obtain an excellent composting process. During the second test, instead, two different theses were tested to study the behavior of two different organic mixes. Thesis 1: leaves and flowers (LF); Thesis 2: leaves and flowers with the addition of 10% biochar v/v (LFB). Each bin was instrumented with 9 thermocouples through which the temperatures were logged throughout the composting cycle. The results showed that the system can produce a final quality product despite the small size of the compost bin. Temperatures remained high throughout the duration of the process and the trend was in line with the standard curves of the decomposition processes. During the tests, moisture content measurements were made and showed that the biochar was able to keep the mass wetter than the thesis without biochar, facilitating the proliferation of bacterial families. Furthermore, the LFB thesis has reached higher temperatures and kept them high for longer, which ensures the sterilization of the biomass (e.g. elimination of pathogens or fungi). It can therefore be concluded that composting hemp residues in small compost bins can be a valid alternative to the disposal of residues and the final compost biochar aided, called COMBI, can be used as improver in field or as substrate during the cultivation of potted plants

Keywords:

agricultural residues, CO₂ capture, composting, biochar, circular economy

Topic:

Sustainable Resources for Decarbonising the Economy

Subtopic:

Innovative biomass production for energy integrated into traditional agri-forestry systems

Event:

30th European Biomass Conference and Exhibition

Session:

1AV.4.17

Pages:

161 - 169

ISBN:

978-88-89407-22-6

Paper DOI:

10.5071/30thEUBCE2022-1AV.4.17

Price:

FREE