viii Water/Wastewater Making the Correct Water Quality Instrument Selection


With increasing legislation, performance related targeting and the need for continual improvement, no one can dispute the continued need to automate waste-water treatment processes and monitor final effluent quality.


However, the correct instrument selection is absolutely vital to optimise treatment, reduce energy usage, minimise chemical consumption and make treatment processes more efficient. Whilst correct process control is crucial, the ability to monitor final effluent quality, to demonstrate compliance to imposed consents, is also extremely important. When OFWAT negotiates pricing in the UK, past performance is critical thus impacting upon the future funding and indeed the profitability of any given Water Company. Consequently, the data generated by on-line water quality analysers for critical parameters can have a very significant impact. After all, mis- information is probably worse than none at all. One of the most important water quality measurements is ammonia. The biological treatment process known as nitrification, is used to remove harmful ammonia from sewage which is toxic to fish and can harm aquatic environments. Continuous on-line measurement of ammoniacal-nitrogen allows site operators to assess the treatment process and take proactive decisions to maintain compliance, to site specific consent concentrations.


The Proam ammonia monitor, manufactured by Pollution & Process Monitoring, is a proven design and has many advantages over contemporary instruments. The instrument self-validates the reported data against known calibration standards and produces diagnostic information including outputs to telemetry. Diagnostic information is vitally important if users are to have confidence in the reported data. Historically, too many false negative alarms from analytical instruments that were not fit for purpose, have caused operators to ignore real positive events, to their own detriment. Good advice should therefore stress the need, to select analysers that are obviously designed for the intended application; with a proven track record and of a design which incorporates a number of key features.


For example, remote telemetry monitoring and reliable process automation require on-line instrumentation to identify when a sensor failure occurs. Instruments should not fail without diagnostic indication and certainly not when the device fails low i.e. under-reports concentration. Consideration must also be given to the complete installation, which may include sample delivery, preparation, and the correct instrument installation. Too many occurrences of poor installation have undermined the correct instrument selection. With increasing pressures to reduce the cost of making the installation of these assets, the trick will be to assess how best to complete a cost effective installation without compromising quality. Once again this is where a proven track record, knowledge and experience, can pay dividends.


Reader Reply Card No. 157


New Spectrophotometer to Revolutionise Water Analysis


Hach Lange announces the launch of a major new spectrophotometer, the DR 3900. The DR 3900 employs the latest RFID (Radio Frequency Identification) technology to ensure that an accurate, reliable, traceable record is created for every sample. However, as Sarah Blayds explains: "Improved traceability is not the only benefit of the technology; users are now able to define their own ’set points’ for specific sampling locations, so that any results falling outside of these points will be flagged immediately. This facility will be of great benefit to staff such as application scientists who may wish to be alerted to specific conditions such as deviation from normal C:N:P ratios."


In order to establish a fully traceable system, users will undertake the following procedure: 1. Place RFID tags in


monitoring locations, 2. Provide sampling staff with personal RFID keyring fobs, 3. Utilise a portable, pocket-sized RFID Locator to assign location and sampler ID data to the sample bottle RFID label and 4. Utilise cuvettes with new 2D Barcode.


The DR3900 will then read sample RFIDs and assign traceability data to the analytical result – date, time, sampler, location and test method. The DR3900 will also read the sample barcode to determine the batch number and expiry date, and this data will also be assigned to the analytical result.


Small changes are sometimes made to analytical methods and these represent an opportunity for test errors to occur. However, the introduction of the advanced Barcode 2 and RFID can prevent such errors because the DR3900 will issue a warning if a test requires an update.


By simply holding the cuvette box RFID label in front of the DR3900, the user is then able to update the test methodology in the spectrophotometer. The new barcodes also contribute to accuracy by alerting the user if reagents have expired.


A further benefit of the DR3900 is made possible when the device is networked via Ethernet to facilitate the automatic calibration of Hach Lange online process monitoring instruments.


Reader Reply Card No. 158


Isodaq’s Frog RX GPRS data logger is proving a major industry success, with over 1500 units already installed in the water and environmental monitoring sector, both in the UK and overseas, in organisations including local drainage authorities, water companies, government organisations such as the Environment Agency, monitoring contractors, consultants and universities.


The Frog’s innovative design ensures ease of installation, due to its in-built GSM antennae, which enables it to be hung inside a 100mm diameter tube, for example a borehole or riverside stilling-pipe.


Is Testing Your Water Quality Costing You Too Much?


Do you want to make testing waste water easy and cost effective? You now can by bringing your testing in-house.


Mettler Toledo offers reliable, cost effective solutions to help ensure you have the right instrumentation to control the physical, chemical and biological processes involved in wastewater.


Whether you test ground water, solids in sludge or drinking water quality, it’s vital to ensure quality measurements. With accurate control of water quality testing you can be sure that you meet standards and avoid environmental damage.


Choose from a selection of analytical instrumentation including titrators for dissolved oxygen measurement and permanganate index, pH and conductivity meters, ion selective electrodes for nitrate and ammonia measurements, moisture analysers for testing total solids and much more.


Reader Reply Card No. 159


This flexibility, together with the extensive range of possible inputs from a wide variety of battery-powered sensors - with both analogue and digital sensors, including multi-channel SDI-12 sensors - makes the Frog ideally suited to a wide range of applications, including the monitoring of tipping bucket rain-gauges, river-level early warning stations, borehole level logging and groundwater monitoring.


The lower cost of ownership and ease of installation of Frog RX has won it several prestigious European framework contracts with government organisations including the UK Environment Agency, Ireland’s Environmental Protection Agency, NVE Norway and the Danish Meteorological Institute.


Hydro-Logic MD, Rod Hawnt, comments; “Each of these organisations recognised Frog’s potential for significant cost savings when operating large networks of battery-powered GPRS loggers by using long-life lithium batteries to reduce the frequency and cost of site visits combined with much lower communications costs of annual GPRS service charges”.


Reader Reply Card No. 160


Over 1500 “Frog” GPRS Data Loggers Installed


IET November / December 2011 www.envirotech-online.com


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