Evaluating the sustainability of AnMBR for domestic greywater treatment in small islands

Greywater management on small, highly populated islands is becoming increasingly important due to environmental degradation and limited freshwater resources. The purpose of this study is to assess AnMBR technology's potential for sustainability as a greywater wastewater management solution on small islands. This research used a case study method with two major stages: the development of a laboratory-scale AnMBR design and a sustainability evaluation with 13 key informants chosen by snowball sampling and in-depth interviews. The Multi-Dimensional Scaling (MDS) RAPFISH technique was used to assess sustainability, with six essential dimensions considered as technical, environmental, economic, socio-cultural, public health, and institutional framework. Key findings of this research are (1) AnMBR technology is technically quite sustainable for treating household greywater on densely populated small islands; (2) the sustainability aspects of AnMBR are multidimensional and interrelated; (3) long-term sustainability depends on the capacity of local institutions, regulatory support, and the availability of resources for operation and maintenance; (4) social acceptance among the community is still limited but can be improved through a participatory approach, and (5) the development of AnMBR by-product utilization has the potential to be integrated with aspects of the circular economy. The implications of this research are that it has greater development potential, particularly in an industrial context, to lay the groundwork for building modular, low-power wastewater treatment technologies suitable to decentralized settings and small geographic areas. Future research should focus on pilot-scale implementation, cost-benefit analysis, and long-term performance monitoring in real-world conditions to validate the overall scalability and sustainability of AnMBR technology, resulting in an integrated wastewater management system that incorporates the circular economy concept for environmental sustainability on small islands. © 2025 The Author(s)