Successful removal of lead from drinking water

For some time now, there have been chal­lenges with the qual­i­ty of the ground­wa­ter in a water­works in the town of Mech­er­nich, Norde­ifel. In par­tic­u­lar, lead is a major prob­lem that is found in the ground­wa­ter. For this rea­son, the use of gran­u­lat­ed iron hydrox­ide, GEH 102, for the elim­i­na­tion of lead from drink­ing water has been test­ed since sum­mer 2021. While pre­vi­ous tri­als with oth­er approach­es showed only lim­it­ed effec­tive­ness in remov­ing lead, the iron hydrox­ide 102 from GEH Wasserchemie was ful­ly con­vinc­ing. Thus, the high lead con­cen­tra­tion of 100 μg/L in the raw water could be safe­ly removed to below the lim­it of determination.

“Lead in drink­ing water” — This already very old top­ic is usu­al­ly asso­ci­at­ed with old lead pip­ing in domes­tic instal­la­tions. Lead pipes have not been allowed to be used since as ear­ly as the 1970s. In recent decades, the pipes have there­fore been replaced by oth­er mate­ri­als in the ren­o­va­tion of old build­ings. At the same time, the lim­it val­ue for lead in drink­ing water was low­ered in sev­er­al stages and has been at a val­ue of 10 μg/L since 2013.

How­ev­er, lead does not only occur through lead pip­ing. It can also occur in nat­ur­al ground­wa­ter. The rea­son for this is nat­u­ral­ly occur­ring rock lay­ers con­tain­ing lead. For affect­ed water util­i­ties, which rely on clean raw water in drink­ing water pro­duc­tion, lead removal is a chal­lenge. If they can­not reli­ably remove the lead on a per­ma­nent basis, the ground­wa­ter can­not be used for drink­ing water supplies.

Lead removal is usu­al­ly achieved by chem­i­cal­ly deacid­i­fy­ing the raw water: this involves pass­ing the water over cal­ci­um car­bon­ate gran­ules or dolomitic fil­ter mate­r­i­al to bind the free car­bon­ic acid. At high­er pH val­ues, the dis­solved lead pre­cip­i­tates as insol­u­ble lead hydrox­ide or lead car­bon­ate and is fil­tered off. Although this process has proven suc­cess­ful in the past, it has its lim­i­ta­tions when very low lead con­cen­tra­tions are to be achieved and the pH val­ue can­not be raised too much. In this case, it is a good idea to specif­i­cal­ly remove the lead with a dif­fer­ent approach in the form of using an iron hydrox­ide adsorber.

Since July 2021, gran­u­lat­ed iron hydrox­ide under the brand name GEH® 102 of the com­pa­ny GEH Wasserchemie has been used for this pur­pose in a water­works of the city of Mech­er­nich (North Eifel) in sup­ply-effec­tive oper­a­tion. With­in the frame­work of the so-called Extend­ed Effec­tive­ness Test (EWP), which takes place under the aus­pices of the Fed­er­al Envi­ron­ment Agency, the effec­tive lead removal is proven and eval­u­at­ed by an expert.

After 6 months of oper­a­tion, a first con­clu­sion could be drawn: The GEH has suc­cess­ful­ly demon­strat­ed its per­for­mance and achieved excel­lent lead reten­tion. Lead was removed to below the ana­lyt­i­cal deter­mi­na­tion lim­it of < 1 μg/L. It should be empha­sized that in this first test phase, the adsor­ber was fed with raw water with a par­tic­u­lar­ly high lead con­tent of 100 μg/L and a pH of 5.7 in order to test its effec­tive­ness under the most unfa­vor­able con­di­tions pos­si­ble. The sec­ond test phase, sched­uled for sum­mer 2022, will then test actu­al oper­a­tion as a “police fil­ter” after the deacid­i­fi­ca­tion stage. It remains to be seen what the results will be in the sec­ond test phase. How­ev­er, it can be assumed that GEH 102 will also be con­vinc­ing in this case after the suc­cess­ful first test phase.