Compost leachate treatment using polyaluminium chloride and nanofiltration

Laboratory scale filtration tests utilizing leachate were conducted to investigate fouling and filtration performance of nanofiltration membranes. The work presented in this study is conducted on real samples rather than model water. Physico-chemical analyses showed that the leachate contained a lot of organic substances, exceeding 20000 mg/L O2 expressed as chemical oxygen demand. Proper pre-treatment method must be chosen in order to reduce fouling index. Coagulation pre-treatment using poly-aluminium chloride was chosen. Two thin film polysulfone membranes were used, purchased by Osmonic Desal. The focus of this research is to assess the influence of the particle size and zeta-potential of the colloidal fraction in leachate on nanofiltration performance. The isoelectric point of both membranes was 4.7 and 4.3, respectively. The fouled membranes were negatively charged over the pH range with isoelectric point shifting to the left (lower pH) indicating the foulant material mainly not charged. It was confirmed by its zeta-potential, measured at -2 mV