# Biochar for Wastewater Treatment--Conversion Technologies and Applications
## 6 Future Perspectives and Environmental Concern of Biochar  
Biochar is a renewable resource that has significant potential to address several environmental issues in the field of wastewater depollution. Biochar is utilized as an adsorbent with high adsorbing capacity for a wide range of contaminants, however the detailed understanding of the different mechanisms governing the adsorption process are still lacking [201]. Since the efficient utilization of biochar for wastewater depollution depends on the biochar properties such as functional groups and surface area, on the availability and the nature of feedstock and on the conditions of thermal conversion method adopted for the biochar production, further studies are needed to center around \"tuning\" the biochar properties for tailored applications. Biochar modification is another important area that has to be exploited to enhance the biochar capacity for the removal of specific contaminants. Further research studies are needed to identify various modification methods and the different mechanisms involved according to the modification agents used. The understanding of the relationship between thermal conversion conditions, biochar properties, and biochar behavior toward wastewater contaminants can encourage its use for very complex compounds that hinder for example biological processes adopted for wastewater treatment. Thus, biochar could be incorporated in the pretreatment processes adopted to remove toxic compounds for subsequent biological treatment. Along with the wide application of biochar in the wastewater treatment field, scientists should pay attention to its potential negative effect on the environment. The stability of biochar is one of the most important properties that has to be taken into consideration when biochar is used. The stability of biochar refers generally to its aromaticity and degree of aromatic condensation [202]. When biochar is used for wastewater decontamination, the potential release of carbon from the biochar can increase the carbon content in the solution to be treated. In addition, a release of heavy metals could also occur, especially for biochar derived from sludge. [PERSON] et al. [203] showed that the dissolution of organic matter from biochar into the aqueous solution is due to the biochar instability. The stability of the biochar was also found usually decreased after several cycles when the biochar is used as a support for catalyst due to the variation in the carbon structure of the biochar. The stability of biochar generally depends on the nature of the startingfeedstock and on the experimental conditions used during its thermal conversion. Thus, it is necessary to identify the correlation between these two parameters and the biochar stability. Another important factor is the regeneration and the recovery of biochar after use. The adsorption process is generally consisting of the transformation of pollution from the liquid phase to the solid material/adsorbent. Thus, it is important to convert the toxic pollutants that are bound with the biochar into a non-toxic state for their efficient management [159; 204].