The electrochemical activation phenomena were discovered by Russian engineer Bakhir in 1975. Then the electrochemical activation (ECA) technology has been widespreading in Russian Federation and many other countries in the world, including Vietnam. In Vietnam, since 2005 a researcher group of Institute of Environmental Technology, VAST, has began to study and fabricate the ECA divices by using imported from RF different electrochemical chambers suchs as FEM-3, FEM-7, MB-26, especially the latter model MB-11, which seemed to be the most suitable in work under tropical climate of Vietnam. However, after operating in real weather conditions our ECA device based on an electrolytical chamber MB-11 has exhibited some disadvantages such as ECA chamber’s temperature increasing, rapid deposition on the catode etc., resulting in worsening product’s quality as well as decreasing equipment’s lifespan. The need to improve the ECA solutions produced on the MB-11 – based ECA devices has become urgent since 2011. The research group of the Institute of Environmental Technology, among which author of this thesis has played an important role, have found out the solution to constrain the temperature increasing effect of the electrolytical process by changing the hydraulitic scheme of the device. The success of the improved designing of the ECA equipment using MB-11 module will open new possibilities to solve the problems of disinfection of hospital waste water which the Institute of Environmental Technology is dealing with for 15 years.