Electrochemical heavy metal removal from organic wastes

The EU as well as LT renewable organic waste on-land disposal regulations are rather stringent. To a large extent their stringency is based on the heavy metal content in wastes and the possibility of those metals to become solubilised and migrate into the groundwater and surface water bodies, or to accumulate in plant tissue. Aim of this work was to investigate the possibility of electrochemical heavy metal removal from semi-liquid organic wastes, namely sewage sludge. Results with mono-component model solutions showed 60-90% efficiency after 10 h of electrochemical treatment, while in multi-component systems and natural liquid sludge the removal percentage appeared to be lower - 40-80% after 120h. According to removal efficiency heavy metals ranked in the following order: Cu > Cd > Pb. Both - total and mobile forms have been investigated during sewage sludge cleaning procedure. EDTA extraction showed rather effective decrease of HM mobility after electrochemical SS treatment, especially for such non-biogenic elements as Cd and Pb. Acidification of the media has also been applied - removal percentage of the acidified sludge samples is higher than that of initial pH.