Mineral　scaling　and　scaling-induced　wetting　are　major　challenges　for　the　widespread　application　of　membrane　distillation　(MD)　in　saline　wastewater　treatment.　For　the　first　time,　an　in-line　modified　activated　alumina　(AA)　granular　filtration　coupled　with　MD　process　was　proposed　to　achieve　effective　control　of　gypsum　scaling.　Firstly,　the　AA　modified　by　NaOH　impregnation　with　tuned　pore　structure　and　surface　characteristics　were　supplied　as　the　filter　media.　The　optimized　MD　performance　was　obtained　using　in-line　filtration　with　modified　AA　(MAA)　with　20　g/L　NaOH　and　the　ratio　of　AA　and　NaOH　solution　of　1:3　for　the　duration　of　24　h.　Compared　with　severe　scaling　without　granular　filter,　the　optimized　performance　with　a　final　normalized　flux　higher　than　0.7　and　a　permeate　conductivity　less　than　5　μS/cm　at　70　%　water　recovery　was　observed.　The　MAA　with　rich　pore,　scale-like　structures　and　high　Na　loading　showed　a　superior　ability　in　capturing　gypsum　scaling　due　to　the　enhanced　heterogeneous　scaling　and　the　retention　of　scaling.　In-line　granular　filtration-MD　was　also　effective　in　mitigating　gypsum　scaling　and　scaling-induced　wetting　in　saline　solutions　(e.g.,　7–12　g/L　NaCl).　Our　findings　provide　guidance　for　surface　design　of　granular　filter　media　and　scaling　control　in　membrane　desalination　technology.　©　2024　Elsevier　B.V.