Comparison of Heavy Metal Limits Allowed for Reuse of Sewage Sludge In Turkey and EU Countries

Sewage sludge has the possibility of providing organic matter and nutrients for the soil

reduces the need for fertilizer and provides beneficial usage. One of the most limiting factors for its reuse

is heavy metal contamination of sewage sludge. Since heavy metals in high amounts in sludge will cause

toxic effects on soil, limits have been determined by governments regulations. Limit values for the use of

domestic or urban sewage sludge on land in Turkey were determined as Pb(750), Cd(10), Cr(1000),

Cu(1000), Ni(300), Zn(2500), and Hg(10) mg/kg dry matter. According to the European Union requirements

to apply treated sewage sludge on land were set as Pb(750-1200), Cd(20-40), Cu(1000-1750), Ni(400),

Zn(4000), Hg(16-25) mg/kg dry matter. However, some of the EU Member States have reduced these limits

to more stringent limits. According to the implementation reports, the strictest limit values applied by

different member states were Pb(100), Cd(10), Cr(75), Cu(75), Ni(30), Zn(300), and Hg(2.5). The heavy

metal annual limits allowed for use on land were set to Pb(225), Cd(3), Cr(300), Cu(300), Ni(90), Zn(750),

Hg(3) g/da/year dry matter in Turkey. On the other hand, the 86/278/EEC set the annual limits as Pb(1500),

Cd(15), Cu(1200), Ni(300), Zn(3000), Hg(10) g/da/year. But much more stringent limits were reported by

different national regulations in the implementation report which are Pb(0.025), Cd(0-0.15), Cr(0.04),

Cu(0.2), Ni(0.025), Zn(0.6), Hg(0) mg/kg dry matter. Other member states will also change the regulatory

requirements in a similar way over time the prevention of the annual accumulation of heavy metals resulting

of land application of sewage sludge. Although there are similarities between Turkey and EU regulations

in terms of Cd and Hg values for the use of sewage sludge on land, EU requirements are becoming much

more stringent than Turkey for Pb, Cr, Ni, Cu, Zn values.