Chitosan-filled filter media from lignocelulosic biomass

Abstract

The aim of this research is to evaluate the feasibility of the fibrous media for removal of total suspended solid and oil grease from palm oil mill effluent (POME). The first part of the research deals with the fabrication and characterization of the non-woven filter media. Wet lay-up method was adopted for filter fabrication where empty fruit bunches (EFB) were matted together with chitosan polymer in nonwoven manner. The percentage of water sorption is significantly lower for chitosanfilled filter media as compared to binder-less filter media and the percentage decreases as the chitosan concentration increases. The increase of tensile strength of the chitosan-filled filter media could be attributed to the presence of the hydrogen bond between cellulose fibre and chitosan molecules as indicated in Fourier transform infrared spectroscopy spectra and good dispersion of chitosan solution onto the surface of filter media as suggested by the optical images. The Taguchi method revealed that the amount of chitosan loading had the most significant effect on filter media permeability compared to chitosan concentration, filter thickness, fabrication method and the fibre size. The filter with alkali-treated fibre showed a tighter network structure compared to the filter prepared from untreated EFB. The second part of the research studied the performance of the newly developed nonwoven filter media. Filtration flow-rate, filter depth, amount of chitosan loading in fibres and influent concentration were studied using the Response Surface Methodology. Filtration results indicated that chitosan-filled filter media filtration only removed up to 28.14% of total suspended solid, 29.86% of oil and grease, and 8.13% of chemical oxygen demand. Chitosan loading in the fibres was the most significant factor affecting the treatment of POME by chitosan-filled filter media filtration. The filter with a lower depth was able to remove particulates quickly but due to its thinness could not remove substantial quantities of the particulates over a long period of time. POME with a higher influent concentration led to a more rapid pressure drop during filtration process. In addition, all filter media suffered permeability loss and were easily clogged, which renders it unusable for long term filtration.