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DE2904658A1
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Activation process for biological purificn. of sewage - using tank filled with stubs of roughened corrugated PVC piping
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DE2847229B1
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Drip heads for biological treatment plants
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Slotting plastic land drainage pipe
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Plastic packing or filler element for trick- - ling beds
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Plastics drainage pipes with helical capill - ary wick and reinforcing ribs
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Producing foamed plastic spheres in large - numbers
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Flexible plastic porous drain pipes are mass - produced by alternating absorbent strips
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Flexible drainage pipes
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Hollow plastic bodies
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Formation of porous plastic draining hose - pipe
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