BOD-Wader and BOD-Wader Pro: Provides real-time in situ assessment of Biological Oxygen Demand informing on impact of biodegradable substances

BOD-Wader and BOD-Wader Pro - Provides real-time in situ assessment of Biological Oxygen Demand within water systems, informing on impact of biodegradable substancesBOD-Wader and BOD-Wader Pro systems from Chelsea Technologies Group allows water process engineers to assess real-time, in situ levels of BOD in water systems. This is achieved by detecting UV Tryptophan fluorescence, which recent publications have shown correlates with the standard 5-day Biological Oxygen Demand (BOD) test.

 

BOD-Wader comprises a CTG UviLux fluorometer and a Hawk handheld display and logging unit. CTG’s UviLux fluorometers detect UV fluorescence with industry-leading sensitivity and selectivity and have been optimised for minimal interference from water turbidity. Data is displayed on the Hawk’s colour touchscreen and logged internally.

 

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Applications

  • BOD loading to Waste Water Treatment Works (WWTW)
  • Monitoring efficacy of separate processing tanks within WWTWs
  • Assessment of WWTW outflow compliance
  • BOD monitoring in the dairy industry 

Features

  • Real-time indication of BOD levels (in mg/l BOD)
  • User set Red, Amber, Green (RAG) data warning display
  • Simple, single touch data logging (2Gbyte storage capacity)
  • Position and time stamping of recorded data
  • Uses rechargeable or disposable batteries
  • High sensitivity

Introduction

BOD-Wader and BOD-Wader Pro systems allow water process engineers to assess real-time, in situ levels of BOD in water systems. This is achieved by detecting UV Tryptophan fluorescence, which recent publications have shown correlates with the standard 5-day Biological Oxygen Demand (BOD ) test.

 

The BOD-Wader comprises a CTG UviLux fluorometer and a Hawk handheld display and logging unit. CTG’s UviLux fluorometers detect UV fluorescence with industry-leading sensitivity and selectivity and have been optimised for minimal interference from water turbidity.

 

Data is displayed on the Hawk’s colour touchscreen and logged internally. If required, the Hawk can be programmed to apply a user calibration to the reported BOD values. The Hawk also incorporates a GPS receiver so that all logged data can be position and time stamped. 

What is the difference between BOD-Wader & BOD-Wader Pro?

BOD-Wader comprises a single CTG UviLux Tryptophan fluorometer and a Hawk handheld data logging unit. BOD-Wader Pro includes an additional UviLux sensor for discriminating Tryptophan fluorescence from Coloured Dissolved Organic Matter (CDOM). This is particularly useful when CDOM background levels are high or when correlating BOD levels across a wide range of locations where background CDOM levels may be variable.  CTG’s UviLux fluorometers detect UV fluorescence with industry-leading sensitivity and selectivity and have been optimised for minimal interference from water turbidity.

 

The UviLux BOD fluorometer is calibrated using standard solutions of Tryptophan. A conversion factor is then applied internally to the measured Tryptophan concentration to provide BOD  output in mg/l. The UviLux CDOM sensor reports concentration in units of µg/l and is calibrated using standard solutions of Pyrene (PTSA). 

How does it work?

BOD-Wader and BOD-Wader Pro detect UV fluorescence from dissolved organic compounds. These compounds absorb UV light and re-emit a fraction of this energy as fluorescence at longer wavelengths. Fluorescence intensity is directly proportional to Tryptophan concentration. The technique is widely recognised as one of themost sensitive detection methodsavailable.

 

What is Tryptophan?  Tryptophan is an essential amino acid in the human diet and is the main component of protein fluorescence. Recently published data demonstrates strong correlations between Tryptophan fluorescence and the standard BOD  water quality test. CTG have established a correlation factor that is used to convert Tryptophan concentrations to BOD5 values. This has been determined using environmental water samples, however, in conditions where there is a high BOD  contribution from suspended solids, a site dependent calibration may be required. This calibration can be programmed into the Hawk logger.

BOD Wader EEM

Fluorescence map of an environmental water sample spiked with
Tryptophan, indicating BOD-Wader measurement window

Configurations

  • BOD-Wader comprises a UviLux Tryptophan fluorometer, a 5-metre cable (longer cables are available) and the Hawk handheld display logging unit.
  • BOD-Wader Pro provides two UviLux fluorometers, configured for BOD and CDOM, securely mounted in a frame for ease of deployment. Data streams from both fluorometers are combined and reported in real-time on the Hawk data logger.
  • The Hawk incorporates a rechargeable battery pack, charged via the USB cable supplied. If required, the rechargeable battery pack can be replaced with standard disposable cells. User programmable thresholds allow data to be presented in a Red, Amber, Green (RAG) format, so that the operator is clearly notified when levels become significant. A plotting feature is also provided so that trends in the data can be clearly identified.

Specification

UviLux Fluorometer

Size

Ø70 x 150mm

Weight

800g

 

UviLux Performance

  BOD CDOM 
Sensitivity (QSU)

0.01

0.01

Calibrated range (QSU)

600

600

Example compound: sensitivity – range (ppb) BOD:
0.001 - 50mg/L
PTSA:*
0.02 – 900

 *PTSA is pyrene tetrasulphonic acid

 

Hawk handheld display and logging unit

Display

320 x 240 pixel qVGA backlit LCD 

Display size

70 x 50 mm

Size

210 x 110 x 45 mm 

Weight

500 g

Memory capacity

2 Gbyte

IP rating

IP67

Operating temperature

-2 °C to 40°C

Storage temperature

-40 °C to 70°C

 

BOD-Wader

Battery duration

4 hours continuous use

 

BOD-Wader Pro

Battery duration

2 hours continuous use

Overall size mm

200 x 200 x 100 mm

Weight

2.5 kg

In view of our continual improvement, the designs and specifications of our products may vary from those described.