For marshes, techniques such as vacuum and pumping, low-pressure flush, vegetation cutting, and bioremediation were used.
2.
Since the porcelain high-pressure flush toilet came into use about 100 years ago, thousands of inventors have tried to improve upon it.
3.
PATENTS ( Undated )-- Since the porcelain high-pressure flush toilet came into use about a hundred years ago, thousands of inventors have attempted to improve upon it.
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