Biorock

Biorock, also known as Seacrete or Seament, is a trademark name used by Biorock, Inc. to refer to the substance formed by electro-accumulation of minerals dissolved in seawater. Prof. Wolf Hilbertz developed the process and patented it in 1979. The building process, popularly called , is not to be confused with Biorock sewage treatment. The biorock building process grows cement-like engineering structures and marine ecosystems, often for mariculture of corals, oysters, clams, lobsters and fish in salt water. It works by passing a small electric current through electrodes in the water. The structure grows more or less without limit as long as current flows.

In an attempt to slow the damage done to the world’s coral, artificial reefs have been built since the 1950s out of materials ranging from concrete blocks to discarded tires. However, most of these plans have failed to provide a new coral habitat. Most notoriously, the attempt using tires off the shore of Fort Lauderdale has become an environmental disaster. There have been some successes with artificial reefs, but most remain relatively barren compared with natural reefs. The one notable exception is the work of architect/marine scientist Prof. Wolf Hilbertz (born 1938, died 2007) and marine biologist Dr. Thomas J. Goreau (born 1950).

Biorock technology arose from experiments in the 1970s when Hilbertz was studying how seashells and reefs grow, by passing electric currents through salt water. In 1974, he found that as the salt water electrolyzes, calcium carbonate (aragonite) combines with magnesium, chloride and hydroxyl ions to slowly form around the cathode, eventually coating the electrode with a material similar in composition to complex magnesium oxychloride cements and as strong as concrete. Over time cathodic protection replaces the negative chloride (Cl-)ion with dissolved bicarbonate (HCO3-) to harden the coating to a hydromagnesite-aragonite mixture with gaseous oxygen being evolved through the porous structure. Later experiments showed that the coatings can thicken at the rate of 5 cm per year. As long as current flows, the structure continues to get larger and stronger. It can also heal itself if damaged, making it particularly useful as a replacement for concrete in hard-to-access locations. High levels of dissolved oxygen make it particularly attractive to marine organisms, particularly fin fish.

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