Remediation of municipal wastewater sludge by electrokinetic geobox

摘要

ABSTRACT: A pilot-scale study was conducted on in situ decontamination of municipalnwastewater sludge containing relatively high concentrations of target metal contaminants such asncadmium (6.85 mg/kg), chromium (117.5 mg/kg), copper (335.7 mg/kg) and lead (64.1 mg/kg). Annew type of geosystem (a cellular geobox) composed of geocomposites (electrokinetic geosynthetic,nGEK) was developed for waste remediation. A low-level direct current results in physicochemicalnchanges in the applied media, leading to species transport by coupled mechanisms, such asnelectromigration, electro-osmosis, electrophoresis and electrolysis of water. The removal efficienciesnfor heavy metals were significantly dependent on their speciation in the sludge matrices and onnvarious geosynthetic properties. The modified geotextile and geocomposite with functions ofnfiltration, drainage, conduction, and ion exchange capacity accelerated the contaminant removalnrate. The electrokinetic removal efficiencies of abiotic heavy metals exceeded 85% for the mobilenand weakly bound fractions, such as the exchangeable and carbonate fractions, and were highernthan 69% for the strongly bound fractions, such as the organic/sulphide and residual fractions. Thenfinal product can be used as landfill material.