title: Characterisation of the impact of coagulation and anaerobic bio-treatment on the removal of chromophores from molasses wastewater.
abstract: The performance of a coagulation sequence using aluminium chlorohydrate (ACH) and a low MW polydiallyldimethylammonium chloride (polyDADMAC), and ferric chloride, for decolourising a high-strength industrial molasses wastewater was compared at bench scale. At their optimum dosages, ACH/polyDADMAC gave higher colour removal than FeCl(3) (45% cf. 28%), whereas COD reduction was similar (∼30%), indicating preferential removal of melanoidins (a major contributor to the colour) by ACH/polyDADMAC. Size exclusion chromatography and fluorescence excitation-emission matrix spectrometry suggested that chromophoric Fe-organic complexes were formed during FeCl(3) treatment of the molasses wastewater, which appeared to compromise decolourisation efficiency. Anaerobic bio-treatment of the wastewater enhanced the coagulation efficiency markedly, with FeCl(3) achieving 94% colour and 96% COD removal, while ACH/polyDADMAC gave 70% and 56% removal, respectively. The improved decolourisation was attributed to the decrease in low MW organics (<500 Da) and biopolymers by the biological treatment, leading to reduced competition with melanoidins for interaction with coagulant/flocculant. For both the wastewater and the biologically treated wastewater, ACH/polyDADMAC treatment gave flocs with markedly better settling properties compared with FeCl(3).
authors.affiliation: School of Civil, Environmental and Chemical Engineering, RMIT University, 124 La Trobe Street, Melbourne, Victoria 3001, Australia. linhua.fan@rmit.edu.au
authors.forename: Linhua
authors.initials: L
authors.lastname: Fan
authors.forename: Thang
authors.initials: T
authors.lastname: Nguyen
authors.forename: Felicity A
authors.initials: FA
authors.lastname: Roddick
mesh_terms: D000536:Aluminum Hydroxide / Q000737:chemistry; D000693:Anaerobiosis; D001673:Biodegradation, Environmental; D002712:Chlorides / Q000737:chemistry; D002850:Chromatography, Gel; D004396:Coloring Agents / Q000737:chemistry; D005290:Ferric Compounds / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D007220:Industrial Waste; D008965:Molasses; D011095:Polyethylenes / Q000737:chemistry; D011108:Polymers / Q000737:chemistry; D000644:Quaternary Ammonium Compounds / Q000737:chemistry; D014865:Waste Disposal, Fluid / Q000379:methods*
chemical_list: D002712:Chlorides; D004396:Coloring Agents; D005290:Ferric Compounds; D007220:Industrial Waste; D011095:Polyethylenes; D011108:Polymers; D000644:Quaternary Ammonium Compounds; C011908:melanoidin polymers; C041004:poly-N,N-dimethyl-N,N-diallylammonium chloride; D000536:Aluminum Hydroxide; C016976:aluminum chlorhydrate; C024555:ferric chloride