Report No DWI0149

SURVEY ON OCCURRENCE OF TECNAZENE AND ITS BREAKDOWN PRODUCTS INEFFLUENT FROM POTATO PROCESSING PLANTS AND RELEVANT WATER RECLAMATION WORKS. FINAL REPORT

DWI0149

March 1991

SUMMARY

This report has been prepared by Severn Trent Laboratories under contract to the Department of the Environment, Water Directorate.

Samples of effluents from potato-processing plants, water reclamation works and receiving waters have been analysed for the anti-sprouting agent tecnazene and its two metabolites tetrachloroaniline and tetrachlorothioanisole.

Use of tecnazene is allowed to commence in January and the highest concentrations in process waters might be expected thereafter. It would be anticipated that its use would diminish by June/July and also that the compound may have volatilised following earlier useage. However, high levels of the compounds, particularly tetrachloroaniline have been found in process streams.

The levels found have been very variable. A summary of the range and mean for the different types of sample is set out below. All results are g/l.

 

T

TCA

TCTA

Crisp Manufacture Effluent (10)      

range

0.006-121

0.29-2200

0.10-138

mean

40

274

21.7

Potato Washing Effluent (32)      

range

<0.006-261

0.06-510

<0.006-9.4

mean

19.7

38.7

1.6

WRW Effluent (18)      

range

<0.006-1.16

0.12-23.0

0.008-5.3

mean

0.11

3.17

0.64

Rivers Upstream (27)      

range

<0.006-1.5

<0.01-15.5

<0.006-0.52

mean

0.12

0.81

0.06

River Downstream (47)      

range

<0.006-458

<0.01-547

<0.006-18.3

mean<

13.0

22.4

0.79

T = Tecnazene

TCA = Tetrachloraniline

TCTA= Tetrachlorothioanisole

The use of mass spectrometry has confirmed the findings obtained by gas chromatography for the metabolite-tetrachlorothioanisole.

The main finding is that even in June/July the levels of target compounds can reach high levels. This would suggest that further surveys be carried out earlier in the year when the use of tecnazene may be more widespread.

Copies of this report may be available as an Acrobat pdf download under the 'Pre 2000 Reports' heading on the DWI website.