## 4 Conclusions  
CRDF production from RDF is a novel method of MSW fuel valorization and production of the new type of carbonized fuel. The presented preliminary research on the influence of pelletization on VOCs emission from CRDF show that:  
* VOCs are emitted from CRDF during storage.
* Pelletization reduced the VOCs emissions potential during storage by \(\sim\)86%, in comparison with ground CRDF.
* Due to pelletization, it was possible to reduce the emission of 10 highly toxic compounds, 50 highly flammable compounds, and 35 potentially explosive VOCs.
* CRDF pellets can be classified as a less hazardous material than bulky and powdery CRDF.
* CRDF pelletization reduces the risk of exceeding health standard threshold values for occupational inhalation exposure and influences on technical requirements of forced ventilation of CRDF storage bins or a production facility.  
Mitigation of VOC emissions from densified CRDF is confirmed, and research is warranted to understand the influence of structural modification on VOCs emission kinetics, as well as possibilities of implementing of this solution into the practice of cleaner production of pellets, volume reduction, storage, transportation, and utilization logistics of CRDF. Further research on the mechanism and kinetics of VOCs emission from CRDF and other biochar types is recommended. Emissions during pelletization should also be investigated on an industrial scale.  
**Supplementary Materials:** The following are available online at [[http://www.mdpi.com/1996-1944/12/10/1692/s1](http://www.mdpi.com/1996-1944/12/10/1692/s1)]([http://www.mdpi.com/1996-1944/12/10/1692/s1](http://www.mdpi.com/1996-1944/12/10/1692/s1)), The model and data used for simulations are available in 'Model of VOC emissions from CRDF during storage.xlsx.' The file contains: 'Readme' spreadsheet with paper title and Authors names, 'Ground CRDF' spreadsheet with Table S1, Table S1: Simulation of VOCs concentration in the headspace of the storage hall after 4 days of emission from ground CRDF; 'Pelletized CRDF' spreadsheet with Table S2, Table S2: Simulation of VOCs concentration in the headspace of the storage hall after 4 days of emission from pelletized CRDF. The results from the blank sample (SMS format) are available in 'blank biochar [2017-12-05].SMS'.  
**Author Contributions:** Conceptualization, A.B. and A.S.; methodology, A.B., M.M., A.S. and J.L.; formal analysis, A.B., M.M. and J.L.; validation, A.B., M.M., A.S. and J.A.K.; investigation, M.M. and J.L.; resources, A.B. and A.S.; data curation, M.M., J.L., A.S. and A.B.; writing--original draft preparation, A.B. and M.M.; writing--review and editing, A.B., J.A.K., A.S. and J.L.; visualization, A.B. and J.A.K.; supervision, A.B., A.S. and J.A.K.  
**Funding:** Authors would like to thank the Fulbright Foundation for funding the project titled \"Research on pollutants emission from Carbonized Refuse Derived Fuel into the environment,\" completed at the Iowa State University. In addition, this project was partially supported by the Iowa Agriculture and Home Economics Experiment Station, Ames, Iowa. Project No. IOW05556 (Future Challenges in Animal Production Systems: Seeking Solutions through Focused Facilitation) sponsored by Hatch Act and State of Iowa funds.  
**Conflicts of Interest:** The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript; or in the decision to publish the results.