Water/Wastewater 35
two sets of data comparing the hexane/infrared method to the hexane/gravimetric method. One data set is from a meat packing plant and the other from tests done on a grease trap from a restaurant. While taking into account that it is difficult to get two identical grab samples from a waste stream, the two methods correlate very closely.
Sample # 1 2
Meat Packing Plant Infrared 67 ppm
1990
2 3 4
423 332 103 157
inverted container such as a separatory funnel or a jar with a septum to remove the solvent.
For the hexane method, the extract is placed on the ATR crystal and after evaporation (about 3 minutes) the result is displayed. For the ASTM method D7066, the cuvette is filled with the S-316 or perchloroethylene extract and placed in the analyser. After 30 seconds, the result is displayed. The analysis from sample collection to final result takes less than 10 minutes.
Gravimetric 70 ppm 2020
After Grease Trap at a Restaurant 1
415 300 130 170
Table 1: Comparison of the Hexane/infrared Method to the Hexane/gravimetric Method
Photo 1: Wilks InfraCal Analyser Infrared Oil and Grease Measurement Procedure
An advantage of infrared analysis over the gravimetric method is the ease of use and the quick analysis time. Portable, relatively inexpensive fixed-filter infrared analysers, such as the Wilks InfraCal TOG/TPH Analyser (photo 1), are currently employed by regulators and industrial pretreatment personnel worldwide for on-site testing. The extraction and measurement procedure involves several simple steps allowing an operator with minimal training to do the analysis.
The sample is collected in a container. The solvent, hexane,
perchloroethylene or S-316, is added at a ratio of one part solvent to ten parts sample. After shaking for 2 minutes the hexane, which is lighter than water, will rise to the top carrying dissolved oil and grease with it. The S-316 and perchloroethylene are heavier than water and require an
Conclusion
Using portable infrared analysers with a simple and quick infrared procedure enables operators of a pretreatment system to easily assess their system’s efficiency and ensure their part in protecting the quality of water resources. On-site analysis gives plant operators the advantage of taking samples before and after treatment to see how a system functions under different operating conditions. Pretreatment system parameters can be immediately adjusted and the results of the changes tested without waiting a week or more for an off-site laboratory result. Regulators also have the advantage of immediately knowing if the FOG levels at an industrial outflow are above the regulatory limits. Most importantly, high FOG levels can be stopped before it stops the flow of the sewer lines and impacts water quality.
Successful Final Effluent Monitoring Trial
Engineers at Intellitect Water (UK) have developed a version of the company’s innovative multiparameter water quality monitoring sonde, the ’Intellisonde FE™’ that can continuously monitor final effluent without the need for chemicals or frequent maintenance and calibration.
A unit has been installed on the final effluent of Wessex Water’s Holdenhurst wastewater treatment plant in Bournemouth since January 2010 and initial results indicate that this new technology could bring the advantages of online monitoring to a much larger proportion of wastewater treatment plants.
The Intellisonde FE™ is a very small multiparameter monitor that is able to run unattended for weeks. Low capital and operational costs will mean that it will become possible to install continuous monitors at plants for which the costs were previously considered prohibitive.
The Bournemouth trial was conducted adjacent to traditional online monitoring instruments and Wessex Water’s Regional Waste Scientist Mike Robinson, says: "The trial is proceeding very well, with the Intellisonde FE™ producing measurements that closely mirror data from our other monitors and from manual tests. For example, we employ traditional online single parameter monitoring instruments at the outfall and we also utilise portable instruments to measure parameters such as clarity and ammonium."
The Intellisonde FE™ is located in a flow-through chamber which is fed by a submerged sampling pump located in a sump. A level gauge ensures that the sump does not pump dry. The trial unit has been fitted with a small strainer to prevent any possible accumulation of dirt in the measurement chamber. However, it has only been necessary to occasionally remove small stones and snails, although these did not have any effect on the measurements.
Inside the sonde head, tiny solid-state sensors continuously monitor conductivity, pH, temperature, turbidity and ammonium. The unit can log at intervals between one minute and one hour on all parameters simultaneously. Measurements are retained on an internal datalogger, however data is transmitted via GPRS to a dedicated server which feeds a web site to enable 24/7 access to (almost) live water quality information. The units are also able to provide an analogue output that could interface with a water company’s regional telemetry system, providing a closed-loop system for data protection.
Reader Reply Card no 122
Simultaneous Determination of Anions and Cations in Saline and Drinking Water Matrices
Dionex (USA) announces a new method that easily resolves common anions and cations present in saline and drinking water in 20 min. Application Note 260: Monitoring Inorganic Anions and Cations During Desalination demonstrates that the IonPac®
AS18 and CS12A columns allow
sample analysis with minimal sample pretreatment and maintenance during operation. This new method also generates less waste and uses less eluent, thus saving both time and money. This approach provides good resolution between sodium and ammonium, the two analytes that can be challenging to resolve. This method supports a varying range of matrices from seawater to drinking water and is shown to be robust for all ion monitoring needs of a typical desalination facility.
With the growing demand for water and the limited supply of fresh water, desalination is increasingly being used to produce potable and irrigation water from salty or brackish water. The global market for desalination is projected to grow at an annual rate of 10% over the next 10 years. To optimise processing efficiency and meet regulatory requirements, it is critical to monitor anions and cations at all stages of desalination.
Reader Reply Card no 123
TOC TN NO3 TKN TP
COD BOD TC TIC VOC
AUTHOR DETAILS
Sandra Rintoul President
Wilks Enterprise, Inc. 25 Van Zant Street, Suite 8F Norwalk, CT 06855 USA Tel: 203-855-9136 Email:
srintoul@wilksir.com
are specifically developed for continuous analysis in the harsh on-line environment
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• Low Maintenance – 6 month service intervals • High Reliability – 99.7% uptime & up to 86,000 measurements per year
• Self-Cleaning Technology – prevents clogging & sample contamination
• No Filtering requirements • Dramatic Payback on product loss, treatment costs & maintenance costs
• Guaranteed to handle the most demanding applications
www.biotector.com
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Email:
info@biotector.com Tel: +353 21 4374237
Reader Reply Card no 124
November/December 2010
IET
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