Rapid method for different types of biocide residual with analysis procedure

A method for controlling biocide concentration in biocide treated water, the method comprising:

• transporting a water stream comprising water and a biocide from an upstream location to a downstream location;
• intermediate an upstream location and a downstream location, withdrawing a sample of the water stream to a sample collection and analyses system;
• in the sample collection and analyses system:
• preconditioning the sample, wherein preconditioning of the sample comprises heating the sample to produce a preconditioned sample;
• injecting the preconditioned sample into an online gas chromatography analyzer;
• measuring a concentration of the biocide in the sample via the online gas chromatography analyzer to obtain a measurement result;
• transmitting the measurement result to a control system, wherein the control system calculates a biocide dosage requirement;
• and
• either on a batch or a semi-batch basis, adjusting by the control system, automatically injecting an amount of biocide into the water stream at the upstream location based on the biocide dosage requirement;
• or
• on a continuous basis, adjusting by the control system, automatically injecting a rate of biocide injection into the water stream at the upstream location based on the biocide dosage requirement.