Odstranjevanje potencialno strupenih kovin iz odpadnega blata iz cistilne naprave z uporabo EDTA

摘要

Sewage sludge has the potential to be used as a fertilizer in agriculture because of its high nutritional value, but it is often contaminated with toxic metals (TM). This study investigated whether ReSoil~R technology, based on the use of EDTA (50, 70, and 100 mmol l~(-1)), efficiently removes TM from sewage sludge collected after aerobic (blato1) and anaerobic (blato2) treatment. The highest removal efficiency of Pb was achieved in blato1 (up to 60 ) and of Zn and Cu in blato2 (up to 55 and 29 , respectively). The content of nutrients did not change significantly after remediation, only available phosphorus decreased up to 1.7-times in blato2, but its content remained high (489-510 mg 100~(-1) g~(-1)). After remediation, the concentration of allmetals, except Zn, in the leachates was below the limit for non-hazardous substances. To demonstrate the possibility of recycling process solutions and EDTA, blato2 was washed in 5 consecutive batches with 50 mmol l~(-1) washing solution, removing on average 28 Pb, 48 Zn, 35 Cu, 30 Mn, and 10 Fe. ReSoil~R technology removes metals from sludge and preserves its nutritional value. However, the efficiency of the technology depends on the treatment process used in the wastewater treatment plant.