Mineral　scaling　and　scaling　induced　wetting　remain　the　primary　bottlenecks　for　membrane　distillation　(MD)　during　saline　wastewater　treatment.　The　in-line　granular　filtration　using　modified　activated　alumina　(MAA)　was　effective　in　mitigating　MD　scaling,　while　the　accurate　design　of　filter　media　properties　would　benefit　this　technology　in　long-term　operation.　This　study　focused　on　the　mechanism　of　mitigation　of　gypsum-organic　combined　fouling　in　MD　by　mixed　filter　media　(MAA　and　granular　activated　carbon,　sand,　zeolite　or　fiber).　The　normalized　MD　flux　was　＜0.20　using　single　MAA　within　3-cycle,　while　superior　performance　was　observed　for　the　mixture　of　MAA　and　fiber,　with　a　final　normalized　flux　of　0.80　and　conductivity　of　1.20　mu　S/cm　over　4　cycles.　In　the　MAA-fiber　mixed　filter　media,　humic　acid　removal　increased　from　81　%　(1.87　mg/L)　to　＞93　%　(0.63　mg/L),　and　the　captured　foulant　weight　reached　204　%　from　962.2　mg,　with　turbidity　＜10　NTU,　compared　to　single　MAA.　These　optimized　media　resulted　in　the　lowest　membrane　foulant　weight　(5.3　mg),　the　highest　liquid　entry　pressure　(164　kPa)　and　the　best　hydrophobicity　(contact　angle　=118.5　degrees).　Adsorption,　interception　and　crystallization　occurred　in　MAA-fiber　mixed　media,　and　superior　anti-scaling　performance　during　long-term　operation　in　MD　was　obtained,　paving　the　way　for　saline　wastewater　desalination.