Water Testing

GRDL is equipped to evaluate ozone / AOP process reactions for an extremely broad range of water samples. Typically, most testing is done on sample volumes of 1 to 4 liters. However, the lab is also fully equipped to accommodate pilot testing of up to 3,000 gallons of artificially simulated water samples for specialty applications. All water testing begins with initial sample characterization tests to approximate the ozone demand of the sample and assist in determining the appropriate ozone dosing technique for the testing process. The bench-scale tests can all be performed with a jacketed reactor allowing us to control the sample temperature during testing to within ±0.2°C.

GRDL utilizes two different ozone dosing techniques for ozone demand testing, liquid ozone dosing or ozone gas injection. The appropriate technique is chosen based on the results of the initial characterization tests. If the ozone demand of the sample is estimated to be between 0.5 – 10 mg/L, the liquid ozone injection method will be employed. For this dosing method, a stock dissolved ozone solution with an ozone concentration of greater than 100 mg/L is created. The concentrated stock solution is then analytically transferred and injected into the representative sample. After dosing, the residual ozone concentration is monitored over time to calculate the ozone half-life and decay rate.

If the initial characterization tests determine the ozone demand of the sample to be greater than 10 mg/L, the lab will use a gaseous ozone injection technique. For this method, a representative sample will be dosed with 10-14%wt ozone gas using a full suite of precision monitoring equipment. This equipment includes but is not limited to the following: NIST calibrated mass flow meters and ozone analyzers; pH, temperature, ORP, and dissolved ozone probes; and GRDLs proprietary PLC-based testing system that continuously analyzes and records the data from all of the monitoring equipment.

Upon completion of the ozone demand testing, the treated samples are characterized again to quantify the changes to the specified target compounds. Our most common target compounds are total/dissolved organic carbon (TOC/DOC), color, iron, manganese, bromide/bromate, and phenols. We are also equipped to do ozone disinfection testing for heterotrophic plate count (HPC), E. coli, enterococci, fecal and total coliforms. Once the characterization has been completed, our scientists will analyze and interpret all of the data and compile it into a report with recommendations for your ozone project.

High Level Ozone Test Kit

Due to customer requests for the ability to measure dissolved ozone concentrations above 2 mg/L, GRDL has developed a high level ozone (HLO) test kit.

The kit comes complete with everything necessary to test dissolved ozone concentrations from 0.5 mg/L to 15 mg/L and is calibrated at Guardian’s Research and Development Lab based on the Indigo Colorimetric Method as outlined in Standard Methods 4500-O3.

The reliable ozone concentration readings are obtained from a HACH digital colorimeter that is custom programmed for each kit by a GRDL chemist. Every kit contains all of the necessary equipment for testing and detailed instructions on how to properly collect and test your sample.

PITS Solution for GRDL's HLO Kit

Time, heat, and light exposure cause the indigo in the PITS solution to break down. Since the HLO Kits are programmed to measure the direct reaction of residual ozone with the indigo, errors can arise from the natural indigo degradation. When planning to make critical dissolved ozone measurements using your HLO Kit, check the expiration date on your bottle of PITS solution. If it’s expired, it’s time to order a new bottle to get the most accurate readings!