Drugs of abuse and tranquilizers in Dutch surface waters, drinking ...

RIVM Report 703719064At Weesperkarspel, water from the Bethune polder, an area where upwardseepage of groundwater (exfiltration) occurs, is abstracted for drinking waterproduction. Before water is transported to the storage reservoir, it hasundergone coagulation. In summer periods, water from the Amsterdam Rhinecanal can also be used but this was not the case in 2009. The detected DOA inthe raw water and finished drinking water (phenobarbital and barbital) show acomparable pattern with the Bethune polder water and not with the AmsterdamRhine canal water, where eight different DOA were detected (MDMA, BE,oxazepam, temazepam, codeine, methadone, pentobarbital and phenobarbital).The rapid sand filtration at Loenderveen and ozonation and softening,biologically activated carbon filtration and slow sand filtration employed atWeesperkarspel do not completely remove all barbiturates: althoughphenobarbital is removed, barbital is still present in the finished drinking water.Barbital, a tranquilizer that is no longer available as a prescription drug, was theonly compound that was detected at the drinking water production site De Punt(Groningen), which uses surface water from the river Drentsche Aa as sourcewater. This compound was observed to be present in the river Drentsche Aa (7ng/L) and in the raw water (8 ng/L). In the finished drinking water barbital wasdetected but in a concentration too low to quantify (LOD). Theactivated carbon filtration that is performed apparently does not completelyremove this compound 2 .Drinking water production sites using surface water and soil aquiferrechargeFigures 3.6 to 3.10 show the results for the drinking water production sites thatproduce drinking water from surface water using soil aquifer recharge. It has tobe stressed that these figures are based on only one sampling point in time, theresults should therefore be regarded as indicative. Except for the production siteof Heel, where water from the Lateraalkanaal (river Meuse) is temporarily storedin a reservoir then bank filtrated and finally re-abstracted, the infiltration areasinvolved are located along the coastline (dunes). The pretreated river water istransported to these dune areas, where it is infiltrated after pre-treatment andre-abstracted. After subsoil passage, the re-abstracted water is treated mostlyby ozone (except at Ouddorp and Scheveningen), followed by activated carbon.When comparing the monitoring results of the raw water and finished drinkingwater, the only compound that was detected in the finished drinking water isphenobarbital at Scheveningen. Apparently, the activated carbon filtration at thissite is not effective in completely removing this compound. Besidesphenobarbital, all raw waters of Leiduin, Haamstede, Ouddorp and Scheveningencontain detectable levels of the benzodiazepines oxazepam and temazepam, butthe benzodiazepines are not present in the finished drinking water.2 An additional sampling was performed by order of waterbedrijf Groningen at the drinking water productionsite De Punt on January 17 th , 2011. Water samples from the river Drentsche Aa, raw water and finisheddrinking were analysed for 6 barbiturates, none of which could be quantified (all concentrations