Advancing decentralized water reuse: pilot-scale testing of a membrane bioreactor – air gap membrane distillation system

Figure showing side of shipping container and a schematic of the treatment system Mobile water reuse units can be used in off-grid communities or conflict zones to provide sanitation and drinking water during times of need. In this study, a pilot-scale membrane bioreactor (MBR) – air gap membrane distillation (AGMD) system was installed in a CONEX shipping container, tested at one water reclamation facility, and subsequently transported to a second facility with different infrastructure and water quality. The MBR-AGMD treated approximately 1,000 L/day of municipal wastewater and consistently produced high-quality water with low total dissolved solids and only trace levels of organic contaminants. Non-volatile species were reduced by over 99% (2-log10). Total coliforms, Escherichia coli, somatic coliphages, and male-specific (F+) coliphages were reduced to levels below the limit of detection (1 Most Probable Number/100 mL) before reaching the MD system, representing reduction values of approximately 6-log10 and 5-log10 for bacteria and viruses, respectively. A co-spike test into the MD system was performed with >4-log10 removals for each virus tested. At the second site, pretreatment requirements were identified, as clogging from high levels of wastewater solids challenged the MBR unit. Additional components, including an external pre-filter tank, were added to increase flexibility for wastewater streams lacking treatment by screens or primary clarification.