Advances in Water Treatment and Enviromental Management

Chapter 20GROUNDWATER POLLUTION BYVOLATILE ORGANIC SOLVENTS:SOURCE IDENTIFICATION ANDWATER TREATMENTM Burley, B D Misstear and R P Ashley (Mott MacDonald Ltd,Cambridge, UK), J Ferry and P Banfield (Anglian Water Services Ltd,Cambridge, UK)SUMMARYGroundwater pollution by industrial solvents such as trichloroethene and tetrachloroetheneis of increasing concern internationally. These chemicals may break limits set in regulationsfor drinking water to protect consumer’s health. It is necessary in such cases to treat thewater to ensure that it is safe to drink. In this paper the authors describe some of their recentexperiences in the UK of identifying the sources of contamination and of designing and operatingsuitable water treatment plants.One case study has highlighted the necessity of detailed usage surveys of potentialcontaminants in siting exploration holes for the identification of pollution sources. A secondcase study has demonstrated the importance of comprehensive monitoring programmes, sincethe chlorinated solvents were only discovered as a result of another contamination.Two plants have been designed and constructed using air stripping for the removal of carbontetrachloride, trichloroethene and tetrachloroethene. The bases for design and operating resultsare discussed.NOMENCLATURE AND ABBREVIATIONSPCE = Perchloroethylene=tetrachloroetheneTCE = TrichloroetheneCTC = Carbon tetrachloride=tetrachloromethaneTCA = 1,1,1—trichloroethaneVOC = Volatile organic compoundPWS = Public water supplyµg/1 = micrograms per litreGC/MS = Gas chromatography/mass spectrometryx = Mole fraction of the organic in waterZ = height of packing (eg ft-m)© 1991 Elsevier Science Publishers Ltd, EnglandWater Treatment—Proceedings of the 1st International Conference, pp. 199–216199