Waste water, especially industrial waste water, is the most challenging water for instrumentation. Mostly, this water is characterized by highly fluctuating loads, very high salt concentrations as well as a high particle density. Hence, the accurancy and speed of measurements depends on the measurement system itself and the oxidation technique used. Obviously, application-specific analyzers provide huge advantages against standard analyzers that are used for all applications.
Water Influent / Water Effluent / Discharge Control
Depending on the industry, different demands are made on the quality of water regarding the water influent, water effluent and discharge control. Limits are prescribed by law or defined by industry-specific associations.
Water that is supplied to an existing system, e.g. cooling water circuit, an industrial plant or waste water treatment plant (WWTP) is described as the water influent. Depending on the application, it may be necessary that this water be treated before use.
Water that is derived from a water system is known as the water effluent. Depending on the application, the water matrix may comprise a wide variety of characteristics, one of which being that the process water has a high particle density. To the contrary, process water of a cooling water system is characterized by low particle density, however, it is mixed with chemicals.
Discharge control is the monitoring of the water effluent being released into a river or waste water treatment plant. Local law defines the limits for the effluent in public waters.
In the winter months aeroplanes, runways and landing strips are de-iced with the help of chemicals resulting in the pollution of storm water. Consequently, its disposal may have an extreme impact on waste water treatment plants or public water. Hence, the continuous monitoring of this storm water is of special importance.
Due to the large sealed surfaces at an airport, there is enormous amount of storm water when it rains. To ensure a fluent operating procedure this amount of water has to be discharged in the fastest possible way. During the summer months the water is usually treated with an oil extractor and discharged into the nearest discharge system or partially sprayed on green areas.
During the winter months aeroplanes, runways and landingstrips are de-iced with special de-icing agents which deposit on sealed surfaces, which through precipitation leads on to the contamination of storm water. The disposal of such surface water, especially de-icing waste water, challenges not only airport operators but also planners and equipment suppliers. TOC (Total Organic Carbon) and COD (Chemical Oxygen Demand) are used as parameters in order to monitor for contamination.
Because of its adhesive characteristics de-icing water causes huge memory and carry-over effects with online monitoring systems. Hereby, residual traces of previous measurements falsify the results of the current measurement. Furthermore, due to this characteristic neither filtration nor transportation through thin tubing is recommended.
Another challenge is the strongly fluctuating loads. On the one hand, the critical values for public discharge are very low, the discharge regulation for the river Rhein for example stipulates 150 mg/l O2. On the other hand, the provision to accurately measure high concentrations of up to 50,000 mg/l C must be made. Therefore, a very fast and precise measurement technique is required in order to discharge most of the water into the discharge system in a cost efficient way. Depending on its concentration / load the water can then be discharged in a WWTP or storage basin.
In cooperation with airport operators LAR has developed an online TOC analyzer that meets the high requirements of this application: LAR's QuickTOCairport.
Surface water is water which is located above ground such as rivers and lakes. Precipitation water that has not seeped away also belongs to surface water.
As nowadays fresh water resources are limited, surface water is increasingly used in industry. Most surface water is polluted by various substances such as algae, bacteria, organic matter and suspended solids. In order to use this water for further purposes it must be pre-treated at first. Treatment to water for drinking water or service water is usually done by clarification, sedimentation, sand filtration, activated carbon adsorption and disinfection.
Industrial Waste Water
Usually, waste water is characterized by suspended and dissolved pollutantsand has a significantly more complex water composition than municipal waste water.
Industrial waste water may involve toxic chemicals. This water needs more intensive treatment than municipal waste water. Hence, the requirements on the measurements taken are enormous. Whether adhesive properties, high and fluctuating loads or a wide variety of water compositions, industrial waste water treatment plants are specialized to specific waste water to perform an optimal cleaning process.
Accuracy in the online analysis of industrial waste water allows conclusions about the functionality and effectiveness of a production facility to be drawn. The right measurement technique enables the fast detection of product spills and provides the opportunity to take countermeasures.
For the toughest applications, LAR Process Analysers AG presents its Ultra-series. The analyzers QuickTOCultra, QuickCODultra or QuickTONultra provide reliable measurements of TOC, COD and TNb. Combinations of these parameters are possible. For a safe monitoring of toxicity LAR offers its NitriTox. This online toximeter protects the biology of a waste water treatment plant against toxic loads.