Complete In-situ Ammonia Analyser and Sample Prep System

The PBS1, from Envitech (UK), is a complete wet chemical ammonia analyser + sample preparation system in a single housing. This reduces installation and running costs by removing the need for pumps, pipes, sample preparation and GRP housings.

It is the only self-calibrating ammonia monitor which uses a gas sensing electrode. The design uses gravity to introduce the sample into the measurement system thereby avoiding any need for liquid pumps. The settlement of the sample is used to create a smaller volume for analysis. Sodium Hydroxide is added taking the pH to above 11 which drives all the ammonium in the sample to ammonia gas. The gas sensing electrode measures the ammonia and calculates the result. Calibration is 24 hourly and based on the standard addition principle. Two different known volumes of a standard are added to the sample. The movement of all the various liquids is driven by air pressure created within the instrument by a small compressor.

The ingenious use of settlement for sample clarification results from the design criteria of measurement in activated sludge. The design has been so successful that the PBS is in use for measuring ammonia in activated sludge and final effluent in several Water Utilities across the UK. Envitech Ltd is now manufacturing the PBS Ammonia Monitor in Cardiff and using its wide experience of measurement in waste water combined with electronics skills to build the PBS and develop new versions for the future.