Conference Papers | 2010 Conference Papers

CHALLENGE TESTING WATER RECYCLING PLANTS – MAKING SURE WE GET THE BUGS OUT

Christopher Pipe-Martin, Principal Water Quality Consultant, ALS Water Sciences

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KEY WORDS

Water Recycling, validation, membrane, UV.

1.0 INTRODUCTION

Regulators require recycled water treatment processes to be validated to ensure they meet the water quality requirements for the intended water use. Validation will often require challenge testing of processes such as membrane filtration and UV disinfection to demonstrate the ability of the process to remove specific target organisms. Challenge testing is expected to confirm the maximum removal credit that a process is eligible to receive from the appropriate regulatory body. This is achieved by dosing challenge organisms into the feed of a process and measuring their removal by testing the feed and product water. The USEPA has published a Membrane Filtration Guidance Manual (2005) and an Ultraviolet Disinfection Guidance Manual (2006). These manuals are commonly used by Australian regulators to set conditions for validation and challenge testing.

UV disinfection systems are subjected to validation testing by their manufacturers. Australian regulators will generally accept the manufacturer’s validation providing the operating conditions are within the validated range. Consequently it is not common for UV systems to require on site validation challenge testing although performance verification testing may be required. Membrane filtration is more likely to be affected by site specific installation and operation and as a result some regulators require site challenge tests to confirm membrane performance of the unit installed.