Calcium carbonate hardness removal by a novel electrochemical seeds system

Scale prevention is widely encountered in cooling water systems and is one of the main difficulties in both thermal and membrane water desalination processes. The usual scale control method applied in water desalination systems is based on the dosage of inhibiting compounds which are able to suppress scale precipitation up to a certain degree. Electrochemical scale control systems are beneficially used for hardness abatement of cooling tower waters. The main drawback hindering their use in desalination applications is the very high electrode area requirement. The novel electrochemical system developed in this study enables drastic reduction in the electrode area requirement. This is achieved by directing the precipitation to occur in a seeds crystallization vessel rather than on the cathode. Results obtained in preliminary experiments have already yielded a reduction in the specific cathode area by a factor exceeding 10 without altering the specific energy requirement. Furthermore, the seeds systemappears to be free fromthe restriction of an asymptotic precipitation rate limit. The outstanding advantages of the low electrode area seeds system opens possibilities for widespread applications of electrochemical hardness removal in diverse processes requiring scale prevention measures.