Potential lmnact of Background zyxwvu Metal Zinc Nickel Copper Lead Cadmium zyxwvu I A draft document, produced by the EuropeanCommission (EC), includes proposals to reduce the maximum permissible levels of a range of potentiallytoxic elements (PTEs) in (a) sewage sludge applied to agricultural land, and (b) the receiving soils after sludge appIication[l). Although these proposals have since been relaxed and explicit deadlines for meeting proposed limits on metal levels in sludge have been altered to medium- and long- re ive li I g term targetsc2), there are no plans to modifythe proposals for the D raft Proposa 1s to R ev i s e t h e E c EC Directive Proposed limits (current limits)* Initial Medium term Long term 2500-4000 2500 2000 1500 300-400 300 200 100 1000-1 750 1000 800 600 750-1200 750 500 200 20-40 10 5 2 Sewage-Sludge Applications to Land Metal W. Towers, BSc, E. Paterson, BSc, CChern, FRSC, and M. C. Coull, BSc* EC Directive (current limits)’ Abstract Zinc Nickel Copper Lead Cadmium The EC Directive which controls the application of sewage sludge to agricultural land, in particular, the reduction in permitted concentrations of heavy metals in sludge and sludge-amended soils, is being reviewed by the European Commission. The implications for sludge recycling in Scotland are examined, and it is estimated that the available land bank would be reduced to about 50% of its present area. In addition, the land area which is required would have to significantly increase because of the proposed lower application rates. These scenarios cast doubt on the long-term viability of the sludge- recycling option in Scotland. 150-300 30-75 50-1 40 50-300 1 -3 Key zyxwvutsrqponm words: Heavy metals; recycling; regulations; Scotland; sewage sludge. maximum permitted metal levels in sludge-amended soils. These proposals are summarised in Tables 1 and 2, and it is obvious that some of the changes represent considerable shifts in policy and reflectthe EC’s aim to reduce metal inputs at source. Obviously, it would be of considerable interest to a range of end-users within EC Member States to assess the impact that these changes could have on sludge-recycling strategies. The impact of these proposed changes on sludge recycling within Scotland has been carried out using the Scottish Soils Database which is held at the Macaulay Land Use Research Institute. zy Table 1. Proposed limit values for metals in sludge (mQ/kQ DS) Table 2. Proposed limit values for metals in sludge- amended soils (mg/kg DS) UK current limitsb 200 50-75 80-1 35 300 3 Proposed limits 20 70 0.5 1.5 ’Mandatory and recommended levels bFor soils with pH values between pH 5.0 and pH 7.0 Datasets and Modelling The Scottish Soils Databa~e(~8~1~) is held in a relational database with a ‘flagged’ subset, termed the Scottish Soil Inventory,taken on a 5 km grid across Scotland;this is often called the ‘national inventory point’ (NIP) dataset. Using archived samples from the NIP dataset, a geochemical dataset has been assembled using methods similar to those used by McGrath and Loveland@). With the exception of mercury, all the metals which feature in the EC and UK sludge regulations are in this dataset. ‘Sol1 Quality and Protection Programme, Macaulay Land Use Research Institute, Craigiebuckler, Aberdeen, Scotland, UK. 0 J.CIWEM 1 2002 1 16 I March 65