**Author details**

*Environmental Issues and Sustainable Development*

microbial growth, biochar or biofuel production.

*valorisation*" (SUSTENVPRO), within PNCDI III.

**Acknowledgements**

column configuration.

**5. Conclusions**

model. The authors also tested an industrial wastewater containing lead ions in

Considering the adsorbent's life cycle, when its regeneration is not economical anymore or it's not possible due to a previous chemisorption mechanism, the sorbent must be disposed of in such a manner that secondary pollution is avoided. In this sense, several authors proposed that exhausted RS meal could be used as a substrate for microbial colonization [48, 61]. Other practices involved biochar production from dye-loaded rape straw (modified with oxalic acid) [73], soil fertilizer [76] and using depleted biochars as biofuel [106]. To avoid leaching, a metal contaminated CM biochar was stabilized using phosphate binders [115]. Recovery of heavy metals from RS biomass can be done by electrochemical methods [116].

The wastes derived from rapeseed cultivation and production of oil and biodiesel are of interest in the context of circular economy. According to the reviewed literature, there exists valorization options for each rapeseed waste (stems, stalks, leaves, hulls, meal/cake). Major applications of these wastes include the use as cover crop for agricultural residues (stems and leaves) and animal feed for rapeseed meal. Rapeseed wastes contain valuable constituents and nutrients, making them of relevant nutritional and economic importance. Protein, pectin and polyphenols can be extracted from stems, leaves and meal. Besides the use of animal feed, the RS meal has great potential for obtaining high-value products for human consumption. A less popular valorization option is the use of rapeseed waste as adsorbents for wastewater treatment. The literature survey presented in this chapter has revealed the existence of sufficient RS-derived adsorbents that have a stable structure and proved significant organic and inorganic removal efficiencies. However, many studies were done in batch operation, at laboratory scale. Very few researchers reported the use of fixed-bed column and/or real wastewater containing the target pollutants. Practical application of RS waste can sometimes be difficult. For example, RS meal forms a slurry when in sufficient contact time with water, which leads to difficult separation of phases or column clogging. This problem ca be tackled by mixing the biosorbent with some inert material (e.g., ceramic rings) or immobilization in a matrix (e.g. alginate). The use of stalks or husks is another solution, due to their lower protein content. In any case, chemical or thermal modification of natural RS waste can be also an alternative, especially when a higher sorption capacity is desired. Regeneration of the adsorbent and its subsequent use in a new sorption cycle is also possible. The exhausted adsorbent can be valorized as substrate for

This study was supported by a grant of the Romanian Ministry of Research and Innovation, CCCDI-UEFISCDI, project number 26PCCDI/01.03.2018, "*Integrated and sustainable processes for environmental clean-up, wastewater reuse and waste* 

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Irina Morosanu, Carmen Teodosiu\*, Lavinia Tofan, Daniela Fighir and Carmen Paduraru Department of Environmental Engineering and Management, "Cristofor Simionescu" Faculty of Chemical Engineering and Environmental Protection, "Gheorghe Asachi" Technical University of Iasi, Iasi, Romania

\*Address all correspondence to: cteo@ch.tuiasi.ro

© 2020 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
