Patent ID: 7491325

Claim:
An assembly for supporting biomass for treating sludge or wastewater, the assembly comprising: a plurality of first and second corrugated sheets and an intermediate member having openings therein, the intermediate member being mounted between at least one of the plurality of first corrugated sheets and at least one of the plurality of second corrugated sheets; each of the first corrugated sheets having crests and valleys, the crests having peak surfaces and the valleys having trough surfaces, each of the first corrugated sheets having a plurality of projections extending outward from the peak surfaces of the crests, and a plurality of depressions formed in the trough surfaces of the valleys, the first corrugated sheets having a first longitudinal axis and a first transverse axis; each of the second corrugated sheets having crests and valleys, the crests having peak surfaces and the valleys having trough surfaces, each of the plurality of second corrugated sheets having a plurality of projections extending outward from the peak surfaces of the crests, and a plurality of depressions formed in the trough surfaces of the valleys, the second corrugated sheets having a second longitudinal axis and a second transverse axis; and the projections of the second corrugated sheets being disposed within the openings in the intermediate member and extending into mating depressions of the first corrugated sheets to retain the intermediate member between the first and second corrugated sheets and to generally define a rigid structure that supports the intermediate member.