ABSTRACT
Cross-flow microfiltration is an important step in separating Baker's yeast (Saccharomyces cerevisiae) from aqueous suspension in many processes. However the permeate flux often declines rapidly due to colloidal fouling of membranes and concentration polarisation. The present work explores the possibility of maintaining acceptable permeate flux by co-current sparging of gas along with the feed, which would scour away colloidal deposits and reduce concentration polarisation of membranes. In this work, both washed and unwashed yeast were used to study the effect of washing to reduce protein fouling of membranes. It was found that permeate flux increased by 45% for liquid throughput of 75 kg/h for a feed concentration of 2.0 kg/m3 of washed yeast as compared with unwashed yeast suspension without gas sparging. For washed yeast suspension, the increase in gas flow rate from 0.5 lpm to 1.5 lpm (30 l/h to 90 l/h) had beneficial effect on permeate flux. It is concluded that in the present case, the gas flow rate should be less than or equal to the liquid flow rate for enhancement of permeates flux.
Subject(s)
Cell Separation/instrumentation , Colloids/isolation & purification , Microfluidics/instrumentation , Saccharomyces cerevisiae/isolation & purification , Ultrafiltration/instrumentation , Cell Separation/methods , Colloids/chemistry , Equipment Design , Equipment Failure Analysis , Gases/chemistry , Microfluidics/methods , Pilot Projects , Ultrafiltration/methodsABSTRACT
Biosorption of copper by inactivated biomass of the brown marine alga Sargassum baccularia immobilized in polyvinyl alcohol (PVA) beads was investigated. PVA-immobilized biomass beads were packed in a laboratory-scale fixed-bed column and subjected to three consecutive cycles of copper loading and elution. Bound copper was eluted with solutions containing a range of ethylenediaminetetraacetic acid (EDTA) concentrations. Up to 100% of the bound copper was consistently recovered from immobilized biomass using an aqueous solution containing 4mM EDTA in repeated loading/elution cycles. The PVA-immobilized biomass beads were shown to be robust and stable with little decrease in the copper uptake capacity under dynamic flow conditions. The excellent reusability of the new biosorbent could lead to the development of a viable metal removal technology.
