The Helios Ammonium Process Buoy measures ammonia through direct immersion in aeration basins or final effluent. The buoy is filled by the hydrostatic pressure of the water, and emptied by air pressure. This eliminates the need for pumps in the wastewater. Valves contact only air, reagents, and calibration standards, assuring a high level of reliability.

The ammonia Buoy is equipped with a filtration cell, in which wastewater is separated from sludge and solids before it is fed into the reaction cell. During the ammonia measurement, a low volume of reagent is accurately regulated to assure high measuring accuracy with low reagent consumption. The buoy automatically calibrates itself daily using the standard addition method, and at the same time compensates for variability in the wastewater.

The Helios probes operate in-situ, directly in the wastewater or activated sludge. Helios has an integrated filtration unit and does therefore not require external pumps and waterlines. The system operates self-sufficiently and can easily be installed at the measuring point. As the analyzer has a modular design sample preparation, sample transport, electronics unit, photometer and reagent tanks are located in different modules. The simple and user-friendly design guarantees operational safety and saves money.

Measurement
In order to measure ammonium or ortho-phosphate in the wastewater a small amount of wastewater is filtered and transported to the photometer. Reagents are added to the wastewater sample. The nutrient ions produce a color complex according to DIN- and EPA-methods which is measured at two different wavelengths. The analyzer automatically calibrates itself daily and consumes very little reagents.

Photometer Module
The measurement of the nutrient and color complex takes place in the compact photometer module. The module contains two light sources and two photodiodes with different wavelengths. The absorbance of the color complex is measured with both wavelengths. Using two wavelengths allows compensation for matrix effects (such as intense coloring) and measurements within a wide range. This is possible due to an automatic transition between linear and non-linear measurement algorithms.

Integrated Filtration
The in-situ sample preparation takes place in an integrated filtration cell, which eliminates the need for external, expensive sample preparation such as plate or ultra-filtration systems. The sample is prepared by filtering the wastewater through special filtration mats with a nominal mesh size of 2µ. The filtrate is then mixed with reagents and measured in the photometer.

Helios Wall Mount
In addition to the installation directly in the basin, Helios is available as a wall-mounted unit when sampling and sample preparation systems are already installed. The easy handling and low reagent consumption match the Helios probe system.