prov:value
| - Examples of such covers include those found in U.S. Pat. Nos. 3,991,900, 4,438,863, 5,265,976, 6,136,194, 4,294,589, 5,400,549, and 5,562,759.Despite their utility in certain areas, current covers do not offer a simple, inexpensive way to address issues such as odor control or algae control while providing the ability to release gas at the same time.
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