INDRODUCTION
Mr. Richard Vanderwal of Hydroclave Systems Inc. approached the University of Ottawa regarding testing of the machine (Hydroclave) which Hydroclave Systems Inc. had developed for the treatment of biomedical waste. A protocol for such testing was submitted to the Ontario Ministry of Health on September 27, 1995. Subsequent to verbal approval of this protocol given to Mr. Vanderwal, and authorization for him to conduct the testing using normal hospital waste, testing was conducted by the University of Ottawa on a prototype machine installed at Kingston General Hospital between October 4, 1995 and November 11, 1995. This report describes these tests in detail.

METHODOLOGY
As noted above, the protocol for testing this machine was submitted to the Ontario Ministry of Health for approval in September 1995. Tests were conducted according to the submitted protocol. The tests were conducted in two stages. The first tests to determine cycle time (Runs 1-6) and one additional run at 121°C (Run 8) and one run at 132°C (Run 7) were conducted using all of the biological indicators originally described. All biological indicators were held in a specially constructed container in order to hold them away from the rotating blades of the Hydroclave and to prevent them from damage during the operation of the unit.

As described in the original protocol, measurements of temperature and pressure during the runs were taken manually during this initial testing of the prototype. The timing for the run was started only after the proper temperature was reached. Subsequently, automated instrumentation will be installed for this purpose. At that time, the cycle time will start only after the thermocouple indicates the proper preset temperature. The thermocouple will be located at the coolest part of the unit, which will be where any water in the load accumulates at the base of the machine.

RESULTS & DISCUSSION
Specifications for the Bacillus stearothermophilus spores in the biological indicators used are shown in Table 1; all BI's were stored according to the manufacturer's recommendations. Populations were determined for all the biological indicators according to USP procedures.

Table 2 shows a summary of all 16 runs performed:

• Runs 1-6 determined the cycle time at 121ºC to be 30 min.
• Run 7 confirmed that an equivalent result could be obtained at 132ºC in only 15 min.
• Run 8 repeated the 30 min. run at 121ºC.
• Runs 12-14 repeated the 15-minute cycle at 132ºC, which equally was shown to be effective at inactivating the biological indicators.
• Runs 15 and 16 were selected because they were comprised entirely of garburator waste and were very heavy wet loads. The biological indicators included in these runs at 132ºC for 15 min. at temperature showed no growth.

Weight reductions in the waste load during operation of the Hydroclave were determined on only runs 1 and 2; these showed reductions of 32.6% and 38.4%, respectively. However, the weight reductions achievable will be a function of the percentage of water in the load.

CONCLUDING REMARKS
The Hydroclave appears to be highly suitable for the treatment of biomedical waste and can achieve an inactivation of microbial load of >106 equivalent of B. stearothermophilus within 30 minutes at 121ºC or within 15 minutes at 132ºC. Although the cycle time may be able to be shortened even further at 132ºC, 15 minutes is a relatively practical period and a shorter exposure may be unnecessary.

Table 1     Specifications of Bacillus stearothermophilus in Biological Indicators used

Biological Indicator	Manufacturer	Lot #	ATCC Strain #	D121[D132] (min)	Expiry date	Nominal population per strip/ampoule	Mean Titre per strip/ampoule
Attest 1262/1262P	3M	282	7953	1.8[n/a]	July 97	4.60E+05	7.10E+05
Kilit	BBL	L5GMOD	7953	1.8[n/a]	June 96	4.40E+04	2.04E+04
Sportrol STS-05	NAMSA Inc.	S49503	7953	1.9[0.12]	Dec.96	1.90E+05	1.30E+05
Biosign	MDT	181195B	7953	2.78[0.44]	Aug. 96	1.00E+04	2.86E+04
In house BI	Univ. of Ottawa	n/a	12980	n/a	not available, freshly prepared	not available	6.00E+05
In house BI	Univ. of Ottawa	n/a	12980	n/a	not available, freshly prepared	not available	6.00E+04
In house BI	Univ. of Ottawa	n/a	12980	n/a	not available, freshly prepared	not available	6.00E+03
In house BI	Univ. of Ottawa	n/a	12980	n/a	not available, freshly prepared	not available	6.00E+02
Sportrol STS-06	NAMSA Inc.	S48403	7953	2.1[0.1]	Feb. 97	1.7 X 106	6.00E+06

n/a = not available