Water/Wastewater
Plumb-and-Play Chlorine Dioxide Analyser For Raw Water Treatment Reduces Maintenance Costs
The low maintenance, economical CDA-22 Chlorine Dioxide Analyser from Electro-Chemical Devices (USA) is ideal for supporting raw water treatment filtration systems. Featuring a panel mounted plumb-and-play design and automatic flow control, the user-friendly CDA-22 is a complete Chlorine Dioxide (ClO2) measurement system.
Treating raw water with ClO2 is an important part of the water purification process. ClO2 is used at very low concentrations (<1 ppm) in filtration systems to precipitate manganese, iron and other minerals in raw water and to break up tannins, which discolour the water often giving it a red hue. Inaccurate ClO2 monitoring may allow levels to exceed acceptable limits, leading to the generation of toxic chlorates.
Raw water sources vary in quality depending on their geographic location, the source type such as natural lake or reservoir, river or canal, etc. Depending on many factors, the level of manganese, iron and tannins
varies from source to source. Removing the manganese, iron and tannins helps clarify the water. The CDA-22 Chlorine Dioxide Analyser ensures that ClO2 levels are properly maintained as part of the water source filtration system, preserving safety and water quality.
Easy to install and maintain, the CDA-22 Chlorine Dioxide Analyser can run for up to one year between electrolyte/membrane changes. It incorporates a CIO2 sensor, automated flow control device and analyser/controller mounted on a PVC panel. Installation is complete after connecting the sample and drain lines, power and outputs, and calibration is accomplished with DPD comparison.
The CDA-22 features a polarographic gold/silver PTFE membrane amperometric CIO2 sensor. While these types of sensors are flow sensitive, the CDA-22’s output is virtually flow independent at values greater than 0.5 ft/sec. The CDA-22’s “constant head” flow control device maintains the sensor’s optimum flow over a wide range of incoming sample flow rates, from 10-80 gal/hr.
The CDA-22’s sensor operates at a wide temperature range of 0 to 100ºC (32 to 212ºF). Because temperature affects the CIO2 permeability of the PTFE membrane, increasing the temperature increases the output of the sensor about 4% per Cº. The chlorine flow cell includes a temperature sensor that allows the C22 analyser to perform automatic temperature compensation of the measurement.
The CDA-22 features a 2.5-x1.75-inch backlit LCD display, with 4 lines for text and graphics. It requires no expensive reagents and eliminates pressure regulators and rotometers. The CDA-22 offers dual measurements, an XY graphical plot and an optional PID Control Output. The analyser provides a 4-20 mA output proportional to the Chlorine Dioxide measured and two alarm relays SPDT 230 VAC/5A or 30 VDC/5A resistive max. It features the options to include additional 4-20 mA outputs for pH or temperature and up to 6 additional relays.
Reader Reply Card No. 106
New Tadpole GPRS Data Logger Launched
With the costs of mobile communications falling and the costs of site visits rising, now is the time to switch from data loggers to wireless telemetry for routine data collection.
Isodaq Technology (UK) has launched Tadpole, which sets new standards for ease of deployment in tight spaces and harsh environments. Tadpole is a fully-fledged GPRS RTU outstation
water-proofed to IP68 standards with the main board sealed for life, but with SIM cards and batteries field exchangeable, making Tadpole ideal for rapid deployment on short-term surveys.
Two models are available with application-specific battery packs to suit - model S hangs on a special bracket inside 50mm piezometer tubes for logging water level and quality measurements, whilst Model D is designed to fit inside automatic rain-gauges including the popular Casella tipping- bucket gauge.
Data is delivered to your desktop PC via either telemetry server software or web-site at whatever interval you choose e.g daily or hourly. Alarm messages can also be set to warn of key events. Tadpole enables you to reduce the long-term cost of monitoring—lower installation costs, fewer site visits and less carbon footprint, with data delivered to your desktop whenever needed. Enquiries from international distributors are welcomed.
Reader Reply Card No. Two Stage Advanced Oxidation
The BioTector (Ireland) patented oxidation method is a powerful and robust technology. By exposing high pH reagents to a concentration of ozone, unstable and highly corrosive hydroxyl radicals are created. These hydroxyl radicals are the ‘workhorse’ of the analyser. The result is a very aggressive oxidation process – Two Stage Advanced Oxidation (TSAO) – which dispenses with the restrictive norms of TOC measurement.
TSAO eliminates build up problems from salts (up to 30%), calcium sludge (up to 12% w/w), particulates, sludge and FOGS that lead to drift. Greater accuracy is achieved as no filtration is required, the typical industry sampling tube is ≤ 0.8mm ID, the BioTector sampling tube is 3.2mm ID. This powerful oxidation method allows particulates of up to 2mm, more representative samples and
up to 1,000 times the sample size used for measurement by some technologies. BioTector analysers can also monitor TOC & TN, TOC TN & TP.
BioTector analysers automatically self-clean all parts of the analyser which have come into contact with the sample, during every measurement cycle and without the need for an external cleaning agent thus preventing clogging, sample contamination and inaccurate results. The BioTector analyser only requires calibration at six-monthly service intervals. TSAO technology is used in a range of applications including dirty and difficult industrial, clean condensate and potable water, process wastewater and surface water.
This technology operates beyond conventional oxidation methods of UV Persulphate and Thermal Oxidation. Both methods are less expensive but less effective than TSAO in the harsh sampling and measurement environment of a Dairy Processing Plant. They are prone to clogging, subsequent downtime, higher maintenance efforts, frequent recalibration and require filtration which dilutes accuracy – all of which have served to erode the perception of the reliability of TOC analysers.
BioTector Online TOC Analysers have delivered a consistently high performance across many industries with harsh sampling environments including Dairy Processing, Soft Drinks & Brewery, Food Processing, PetroChemical and Pharmaceutical. With MCERT certified uptime of 99.86% and typical accuracy and repeatability better than ±3% of reading, clients use BioTector measurements with confidence.....
Reader Reply Card No. 108 Reader Reply Card No. 109
www.envirotech-online.com IET November / December 2012 107
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