NOVELTY - Modular support system comprises multiplicity of polygonal bed platform modules (12a) to form raised bed platform covering selected area; multiplicity of bed support legs having length sufficient to support and elevate bed platform modules above base surface; corner pedestals (62) having portions positioned to engage with bottom side of bed platform modules; and large threaded fastener positioned centrally of each corner pedestal, securing corners of adjacent bed platform modules down against corner pedestal by acting downwardly against adjacent bed platform modules.    USE - The modular support system useful for organic filter material.    ADVANTAGE - The modular support system supports very heavy loads such as earth-moving equipment used to move and spread filter bed or compost material. The modular support system provides improved strength integrity for biofiltration or compost materials, in efficient manner.    DETAILED DESCRIPTION - A modular support system comprises a multiplicity of polygonal bed platform modules (12a) having generally planar top surfaces and shaped to be arranged side-by-side contiguously to form a raised bed platform covering a selected area; a multiplicity of bed support legs having upper ends engaged with bottom sides of the bed platform modules, and of length sufficient to support and elevate the bed platform modules above a base surface on which the support system rests; corner pedestals (62) in positions where several of corners of the polygonal bed platform modules come together in the assembly, each corner pedestal having several of portions positioned to engage with a bottom side of one of the bed platform modules, such that the corner pedestal supports all adjacent bed platform modules at the corners and retains the bed platform modules together at corners; and a large threaded fastener positioned centrally of each corner pedestal, securing the corners of the adjacent bed platform modules down against the corner pedestal by acting downwardly against the adjacent bed platform modules such that the bed platform modules adjacent to each corner pedestal are drawn more closely laterally together on assembly as the fastener pulls the platform modules down against the corner pedestal, where the bed platform modules are securely held together and to the corner pedestal at corners of the platform modules, and where the assembled modular support system can support a relatively heavy load in a secure and stable manner. The bed platform modules are compression molded of low-density polyethylene. The bolt is formed of compression molded plastic. The bed platform modules, bed support legs and corner pedestals are all formed of recycled plastic material.    DESCRIPTION OF DRAWING(S) - The figure shows perspective view alternative form of corner connection for platform modules and inter-fitting of adjacent platform modules.    Bed platform module (12a)    Stud (60)    Pedestal (62)    Base (62b)    Holes (72)