Activated　sludge　(AS)　offers　great　potential　for　resource　recovery　considering　its　high　organic　and　nutrient　content.　However,　low　recovery　efficiency　and　high　costs　are　directing　the　focus　toward　the　high-valuable　resource　recovery.　This　study　extracted　71.5　±　5.9　mg/g　VSS　of　alginate-like　exopolysaccharides　from　AS　(ALE/AS)　and　applied　it　to　mortar　as　a　novel　biopolymer　agent　for　crack　self-healing.　With　a　mortar　crack　of　120　μm,　addition　of　0.5　wt%　ALE/AS　yielded　a　high　crack　closure　ratio　of　86.5　%　within　28　days.　In　comparison　to　commercial　healing　agents,　marginal　flexural　strength　reduction　with　ALE/AS　addition　(17.9　%　vs　30.2–50.5　%)　was　demonstrated.　The　abundance　of　COO−　group　in　GG　blocks　of　ALE/AS　resulted　in　a　higher　cross-link　capacity　with　Ca2+,　while　the　reduction　of　hydrophilic　residues　(e.g.,　COO−　and　O–H)　after　complexation　engendered　a　lower　swelling　capacity,　which　facilitated　self-healing　and　flexural　strength　maintenance.　Molecular　dynamics　(MD)　revealed　that　lower　Ca2+　diffusivity,　arising　from　the　stronger　electrostatic　interactions　between　the　COO−　groups　and　Ca2+,　resulted　in　a　high　Ca2+　concentration　around　the　cracks,　leading　to　CaCO3　deposition　and　healed　cracks.　The　outcomes　of　this　study　provided　light　on　ALE-based　mortar　crack　healing　and　presented　a　possibility　for　multi-level　AS　resource　recovery.　©　2022　Elsevier　B.V.