## 6 Digital Technologies Enabling the CE Transition: Discussion and Open Issues
In particular, a holistic investigation on the following points is advised, understanding their role in the different phases of the adoption process of CE practices, and how they could change according to the action of different DTs:  
* Barriers to CE transition: identification and evaluation of the inhibitors of the adoption process [9; 17];
* Drivers for CE transition: identification and evaluation of the fostering factors for the adoption process [17; 66];
* Performance measurement: identification and evaluation of the performance reached after the adoption; fundamental for this aspect would be the identification of how the performance could be gauged [17; 59]. Another important aspect to consider is the evaluation of performance beyond the ones strictly related to CE. As introduced in the previous section, some authors started investigating the performance related to the overall sustainability derived from the adoption of CE practices supported by the DTs, see for example [54; 98; 134]. However, despite the common agreement, additional research seems to be necessary to better determine the relationship between DTs and industrial sustainability [135; 136];
* Contextual factors: identification of those contextual factors, as geographical area, sector or firm's size that could influence the adoption process [137] and that so far appear still limitedly investigated (see Section 4.4. ); previous research showed a pivotal role of the firm's size, particularly when SMEs and LEs are confronted [138; 139; 140];
* Digital maturity level: evaluation of the impact of the digital maturity of the firm on the outcomes, as it might represent a quite important influence [98; 141];
* CE management: evaluation of the impact of how CE is managed within the firm, as it might influence the outcomes [137]. For example, the presence of an environmental management system demonstrated to strongly support the CE transition [142]; as a clear predominance for a heterarchical control for DTs has been underlined [143; 144], the debate on whether a centralized or decentralized system would be better for environmental-related aspects is still open [145; 146]. _Empirical research._ As abovementioned and shown in the descriptive results (Figures 11 and 12) and highlighted by the in-depth analysis of the content (Table 3), the largest share of the published contributions employs a theoretical approach. This urges for more empirical research, which is also highlighted in previous literature [15; 77; 87; 110]. Although an increase in empirical studies can be appreciated in the latest years (Table 2) [82], there is still ample room for providing practical demonstrations of the impact of DTs on the CE transition. To deepen the understanding of the relationships, the adoption of the case study methodology is suggested, providing more qualitative than quantitative evidence, but allowing a deeper analysis of the context under investigation [101; 147] (see also Table 3). As some contributions employed the case study methodology, the investigations present less than five case studies, with the largest share of contributions focusing on one case study (Table 2; Figure 12). To confront an already existing theory toward an empirical application and structuring the theory in light of the observed results, a larger number of case studies is therefore suggested [148; 149]. _The role of industrial systems and stakeholders_. Moving from a micro to a meso-level of analysis, DTs have been proven to facilitate the cooperation and connection of firms, foster industrial symbiosis and help build a collaborative environment to promote the CE [104]. Regardless of the provided insights on the possible influence of DTs on SCM, it is suggested to conduct specific studies investigating industrial systems from the perspective of all the involved firms, not only a focal/single one [131; 150] (see also Table 3).