The information required to develop design criteria for ozone facilities includes ozone demand, ozone decay, and screening of ozone application points. Traditionally, this information has been developed using pilot-scale facilities, semi-batch bench-scale testing units, or modeling techniques. The major drawbacks of ozonation pilot studies include the tendency to overestimate the hydraulic efficiency and the high cost and time commitment required to mobilize the equipment. Semi-batch reactors and the use of mathematical models do not provide sufficiently reliable data for extrapolation to full-scale design. To address these drawbacks, Carollo has developed a continuous-flow bench-scale ozone testing unit which combines the reliability of pilot-scale testing and cost-effectiveness of bench-scale methods.

Carollo’s benchscale unit consists of a six-stage ozone contactor with three chambers operating in counter-current flow for ozone transfer and three chambers operating without gas transfer for ozone contacting. The volume of each chamber available for ozone contacting is adjustable to achieve detention times ranging from 3 to 40 minutes. The ozone concentration in the feed gas is monitored by an ultraviolet (UV) light absorption spectrophotometer. Ozone residuals in the liquid phase are analyzed by collecting grab samples at the effluent of each of the columns.
In order to ensure the applicability of the results, we have designed this system so that the hydraulics are characterized with a T10/T ratio of 0.6 to 0.7. This hydraulic behavior is modeled by seven to nine completely stirred tank reactors (CSTR) in series, corresponding to Peclet numbers of 12 to 16, respectively. This hydraulic characteristic is maintained in Carollo’s pilot-scale ozone systems.
The ozone system resides in a shipping container for easy transport to various sites for ozone testing. Associated equipment includes ozone contactors, rotameters for measuring liquid and gas flow rates, valves and tubing, and sample taps. This unit also includes a 0.08 lb/day ozone generator. Other equipment required to perform ozone evaluations, such as a feed water pump, UV spectrophotometer, and ozone residual measurement kit, is shipped with the system.

Mobilization and testing can begin within a half-day of arrival on-site. Only a small sample volume (approximately 5 gallons) is required in order to develop key design data such as ozone demand and decay relationships, by-product formation, and ozone quenching alternatives.