1. THE REMOVAL OF VOLATILE AND NON-VOLATILE ORGANIC COMPOUNDS FROM SMALL WATER SUPPLIES. 2. REVIEW OF EUROPEAN EXPERIENCE AND ATTITUDES TO GROUNDWATER CONTAMINATION BY ORGANIC COMPOUNDS. FINAL REPORT 91330/RD9/10.87 CONTRACT PECD 7/7/204
Report No DWI0002

NOV 1987

SUMMARY

The extent of organic contamination of private groundwater-derived water supplies in the UK has been evaluated. Little information was found to exist with regard to specific organic compounds, other than that obtained as a result of investigations relating to complaints or serious contamination incidents caused by spillage or improper disposal of chemicals. Where monitoring of private supplies is carried out by local Authorities, emphasis is, for reasons of limited resources, placed upon bacteriological quality and basic inorganic chemical parameters. One particular incident of aquifer contamination by chlorinated solvents in the Midlands was discovered, where supply to a factory had to be discontinued.

Treatment processes for the removal of volatile and non-volatile organic compounds have been identified and the performance characteristics have been assessed. Counter-current aeration towers are most efficient for volatile organics removal, whilst granular activated carbon filters are more suitable for reduction of non-volatile organic compounds.

Cost assessments of both aeration and granular activated carbon treatments revealed that for volatile contaminants counter-current aeration would be the preferred treatment method to granular activated carbon on cost grounds and that treatment by both methods was financially advantageous when compared with the alternative of resorting to a municipal water supply.

An assessment of the effects of aeration upon downstream water quality indicated that no significant changes would occur, but it is considered that disinfection should be carried out before aeration in order to preclude the possibility of bacterial growth in the aeration tower packing.

The extent of groundwater contamination by organic compounds in other European countries has been assessed, with particular emphasis on water quality standards and attitudes to public health, in the light of the current UK position.

Volatile chlorinated solvents were found to be the most common and widespread contaminants of aquifers, although there is increasing concern over the occurrence of agriculturally-applied pesticides in groundwater beneath intensive arable farming areas. Water quality standards have been established for chlorinated solvents by the Netherlands and West Germany, although in the latter country there is some dispute both over the relevance of the standard and the apparent politicisation of drinking water quality issues.

Public concern over the contamination of drinking water is well-developed in European countries, and particularly so in the Netherlands and West Germany, and concern is growing in the UK. This concern may not be valid scientifically or medically, given the low levels of contamination found at present. It is concluded that in the UK, with an increasing trend in groundwater contamination, there is a need to assist water undertakers, local authorities and industry in decisions over when to undertake or require treatment of water through national interim guideline standards for chlorinated solvents in potable water.

Some other European countries appear to be more advanced in groundwater protection and treatment with respect to chlorinated solvents, than the UK. There is scope for economic application of remedial measures for treatment in some situations and to return use of sources which might otherwise be abandoned.

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