Forming Solid, Adhesive-Free Composite of Membrane Filters and Cellulosic Cardboard

1. The method of forming a solid, adhesive-free, layered composite material composed of two clearly defined layers consisting of a membrane filter layer and a porous backing layer, comprising the steps of depositing on cellulosic cardboard a layer of a gelatinized polymeric membrane-forming substance between onset of synerisis and final solidification thereof, and allowing said membrane-forming substance to solidify on said cellulosic cardboard.

2. The method of claim 1, where said polymeric membrane-forming substance is cellulose nitrite, cellulose acetate, gelatin, polyvinylchloride, polyvinylacetate, a polyamide or an alginate.

3. The method of claim 1, where said cellulosic cardboard is impregnated with a nutrient solution for microorganisms.

4. The method of claim 3, where said impregnated cellulosic cardboard is dried.

5. The method of claim 3, where said nutrient solution is an aqueous solution which contains about 0.25 to 1 gm of L-arginine, 0.5 to 2 gm of L-asparginic acid, 0.25 to 1 gm of L-crysteine, 1 to 4 gm of L-glutaminic acid, 0.1 to 0.4 gm glycocoll, 0.15 to 0.6 gm of L-histidine, 0.4 to 1.6 gm of L-leucine, 0.25 to 1 gm of L-isoleucine, 0.3 to 1.2 gm of L-lysine, 0.15 to 0.6 gm of L-methionine, 0.15 to 0.6 gm of L-phenylalanine, 0.2 to 0.8 gm of L-proline, 0.2 to 0.8 gm of L-threonine, 0.05 to 0.2 gm of tryptophane, 0.2 to 0.8 gm of L-tyrosine, 0.5 to 2 gm of L-valine, 1.5 to 6 gm of sodium chloride, 0.15 to 0.6 gm of potassium chloride, 0.5 to 2 gm of anhydrous sodium acetate, 0.5 to 2 gm of sodium pyruvate, 3 to 12 gm of sodium glycerophosphate pentahydrate, 0.025 to 0.1 gm of magnesium sulfate heptahydrate, 0.005 to 0.02 gm of adenine, 0.005 to 0.02 gm of guanine, 0.005 to 0.02 gm of uracil, 1 to 4 gm of D-glucose, 0.005 to 0.02 gm of inosite, 0.005 to 0.02 gm of choline chloride, 0.005 to 0.02 gm of nicotinic acid, 0.005 to 0.02 gm of thiamine hydrochloride, 0.0005 to 0.0002 gm of riboflavin, 0.003 to 0.012 gm of pyridoxin hydrochloride, 0.005 to 0.02 gm of calcium pantothenate, 0.005 to 0.02 gm of folic acid, 0.0001 0.0004 gm of biotin, 0.0025 to 0.01 gm of p-nitrophenylpropanetriol, 0.05 to 0.4 gm of pimaricin per liter of water, as well as the required quantity of sodium hydroxide in dilute aqueous solution for adjustment of the pH to 7.2.