:: Chlorine Dioxide Generator Comparisons ::

B : Chlorine / Chlorite System.

This method can use either a) chlorine gas or b) hydrochloric acid and sodium hypochlorite together with the sodium chlorite. The net result is the same ie.

2 NaClO2 + Cl2 ® 2ClO2 + 2 NaCl.

The yield is 100% and typically these units run at 95 - 99% yield.

(i) Chlorine Gas -
The disadvantage of this system is based on having to use Chlorine gas cylinders, chlorinators and the safety issues related to the handling of chlorine. These units produce a reaction product that has the following characteristics:

		::	A pH under 2;
		::	It is highly corrosive
		::	Typically they run with higher than stoichiometric levels of chlorine resulting in high free chlorine levels

(ii) Hydrochloric Acid and Hypo -
This is the alternative method of using "Chlorine Gas" to derive the benefits of nearly 100% yield since the action of acid on hypochlorite will produce chlorine gas. These systems can be designed to use either an eductor to produce a vacuum in order to meter the three chemicals or they can use electronic dosing pumps. Eductor Sysytems

The major advantage of the eductor system is as follows:

		::	Extremely safe to use because the motive water used to operate the eductor is used for instantaneous dilution of the resultant solution
		::	The motive water controls the suction of chemicals hence no water means no chemical flow
		::	The pH runs from 4.5 to 7 in these systems
		::	The reaction time is instantaneous
		::	Concentrated chemicals are used and capacity of 2 tons per hour of chlorine dioxide is feasible
		::	The unit can be designed to be portable giving much greater flexibility in treating systems from low water volumes to extremely high flow rates

Dosing Pump System
The major disadvantages are the need for 4 dosing pumps ( including one for dilution water), the cost, the problems with safety inherent in having to monitor 4 pumps.