| Calcium carbonate is one of the most common scales found in valves, pipes, and heat exchanger surfaces. Calcium-binding proteins have received much attention by scientists due to the important biological function of calcium ions as, among others, an intracellular messenger in many eukaryotic signal-transducing pathways, such as vision, the phosphoinositide cascade and the regulation of muscle contraction.;This work proposes an innovative method of fouling mitigation by protein and genetic engineering. It makes use of the strong affinity of proteins in binding and removing the key dissolved metal ion (in the fluid) that triggers scale formation on heat exchanger surfaces. It shows that by raising temperature to its melting temperature, a metal-binding protein with chelated metal ions can change its native (folded) conformational state to its denatured random-coiled polypeptide (unfolded) state, and that by raising a temperature higher than the melting temperature, the protein will release the chelated ions. It is further proven that by repeating the heating and cooling cycle, the protein can chelate and release the scale inducing metal ions, thus establishing the feasibility of developing a new class of effective biodegradable anti-foulants that are thermally regenerative and friendly to the environment.;Furthermore, with the new expression system constructed and the simplified purification procedure developed, an industrial process by fermentation for the mass production of calmodulin was successfully developed through genetic engineering. By the proposed process, a massive amount of genetically engineered calmodulin was produced for a series of essential experimental investigations, including (1) behavior of calmodulin column for pretreatment of a working fluid containing calcium ions, (2) immobilization of calmodulin on an inorganic support (SiO2) for high temperature application, and (3) inhibition of calmodulin for calcium carbonate scale formation on heat transfer surfaces.;The experimental results show (1) that calmodulin column does have the ability to remove calcium ions from a working fluid containing low level of calcium ions and (2) that calmodulin inhibitor does have the ability to mitigate calcium carbonate scale formation on heat transfer surfaces. |
