BOD-Station and BOD-Station Pro: Provides real-time assessment of Biological Oxygen Demand within water systems, informing on the impact of biodegradable substances

BOD-Station and BOD-Station Pro - provides real-time assessment of Biological Oxygen Demand within water systems, informing on the impact of biodegradable substancesThe Chelsea Technologies Group's BOD-Station and BOD-Station Pro systems allow water process engineers to assess real-time 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-Station comprises a CTG UviLux fluorometer and a Watchkeeper wall mounted data display and logger. CTG’s UviLux fluorometers detect UV fluorescence with industry-leading sensitivity and selectivity and have been optimized for minimal interference from water turbidity.

 

 

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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
  • Monitoring industrial effluent discharge into surface waters

Features

  • Real-time indication of BOD levels (in mg/l BOD)
  • Automated data logging (2Gbyte storage capacity)
  • 4 – 20mA output for data export in real-time
  • Relay for audible alarm or control valve
  • In-line flow-through operation with standard pipe fittings
  • High sensitivity

Introduction

BOD-Station and BOD-Station Pro systems allow water process engineers to assess real-time 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-Station comprises a CTG UviLux fluorometer and a Watchkeeper wall mounted data display and logger. CTG’s UviLux fluorometers detect UV fluorescence with industry-leading sensitivity and selectivity and have been optimized for minimal interference from water turbidity.

What is the difference between BOD-Station and BOD-Station Pro?

 

BOD-Station comprises a single CTG UviLux Tryptophan fluorometer and a Watchkeeper wall mounted data display and logger. The BOD-Station 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 are varying.

 

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 BOD5 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-Station and BOD-Station 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 concentration. The technique is widely recognised as one of the most sensitive detection methods available.

 

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 has established a correlation factor that is used to convert Tryptophan concentrations to BOD 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.

BOD Station EEM

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

Configuration

BOD-Station and BOD-Station Pro have been designed for outdoor operation, where the UviLux fluorometers can be deployed within a water trough or mounted in flow-through manifolds for in-line operation. A single cable connects the UviLux fluorometers to the Watchkeeper display and logger unit, which is powered from a 24Vdc supply.

 

Signal inputs are presented on the screen and up to three 4 – 20 mA signals can be accessed for data system networking. Audible alarms or control valves can be fitted and programmed to alert or activate when signals exceed user-set thresholds. Data is recorded onto a 2 Gbyte memory card. Data can be by download via a USB cable, or by removal of the memory card.

Specification

UviLux Fluorometer

Size Ø70 x 150mm
Weight 800 g
Pressure rating 60 bar

 

 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

 

BOD-Station, single UviLux fluorometer with Flow Manifold

Size Ø130 x 200 mm
Weight 5 kg
Fluid Connections Union, 20mm, PN16
Pressure Rating 4 bar
Max operating temp. 55ºC

 

BOD-Station Pro, two UviLux fluorometers with Flow Manifolds

Size 265 x 200 x 200 mm
Weight 5 kg
Fluid connections Union, 20mm, PN16
Pressure rating 4 bar
Max operating temp. 55ºC

 

Watchkeeper display and logger

Display 320 x 240 pixel qVGA backlit LCD
Display size 70 x 50 mm
Size 200 x 110 x 60 mm
Weight 900 g
Memory capacity 2 Gbyte
IP rating IP67
Voltage input 24 Vdc
Power

2.8 W @ 24 Vdc

4.6 W @ 24 Vdc (Pro)

Temperature range -20 ºC to 55ºC

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