JOURNAL OF FERMENT&TION AND BIOENGINEERING Vol. 75, No. 6, 438-442. 1993 Decolorization of Molasses Wastewater Using an Inorganic Flocculant VERONICA P. MIGO, 1 MASATOSHI MATSUMURA, 3. ERNESTO J. DEL ROSARIO, 2 AND HIROSHI KATAOKA 3 National Institutes of Biotechnology and Applied Microbiology, l Institute of Chemistry, 2 University of the Philippines at Los Banos, College, Laguna, Philippines; and Institute of Applied Biochemistry, University of Tsukuba, Tsukuba-shi, Ibaraki-ken 305, Japan 3 Received 18 January 1993/Accepted 3 March 1993 The removal of molasses-derived melanoidin in alcohol distillery wastes was studied using a commercial in- organic flocculant with a chemical formula of [Fe2(OH)°(SO4)3.n/2]m. Decolorization yields of 32, 87 and 94% were obtained for fresh slops and for biodigester and lagooned effluents, respectively, at a flocculant dosage of 4~ v/v. The reduction in total organic carbon (TOC) was 21~ for fresh slops and averaged to more than 73°~ for the biodigester and lagooned effluents. The presence of relatively high amounts of fluoride ions affected the decolorization of fresh slops; supplementing CaO at a rate of 30 g/l improved the decolorization of the distillery slops, resulting to 93~ color removal. Molasses, a waste product of the sugar industry, is a cheap raw material used in fermentation industries be- cause of its relatively high sugar content, ranging from 48-58% (So, R. et al., Intl. Symp. Adv. Technol., Japan, 1991). In alcohol distillation, ethanol ranges from 5-12% by volume, hence it follows that the amount of wastes varies from 88-95% by volume of the alcohol distilled (1). The large volume of wastewater generated has a high latent biological oxygen demand (BOD) and contains a dark brown pigment called "melanoidin" which can hardly be decomposed by the usual biological treatments such as the activated sludge process and methane fermentation (2). Melanoidin is a product of the non enzymatic reaction between sugars and amino compounds (3), also called the "Maillard Reaction". Studies on its chemical properties (4, 5) and possible molecular structure (6) have been con- ducted and preliminary experiments using electropho- resis revealed that melanoidin is negatively-charged. De- colorization by microbial methods includes the enzy- matic breakdown of melanoidin and flocculation by micro- bially secreted substances. Microbial decolorization has been investigated by many workers using bacteria (7-9) MOLASSES ~ Yeas t ALCOHOL FERMENTATION 'DISTILLATION and several classes of fungi (10-12). However, the technol- ogy has not yet been developed for practical applications. A chemical method of decolorizing molasses wastewater is oxidation by ozone (personal communication, Kirin Brewery, Co. Ltd., Yokohama); however, ozonation is at present very limited, mainly for economic reasons as well as the efficiency of ozone generation equipment. Also, the feasibility of ozone injection methods is not ideally suited to conventional wastewater treatment plants, the majority of which employ open-channel flow systems (13). Physico-chemical methods of decolorizing molasses wastewater include flocculation using either inorganic or organic compounds. Previous results (14) on the floccu- lation of metanoidin using aluminum and iron salts re- vealed that molasses distillery slops were difficult to decol- orize. In this regard, our aim was focused on the treatment of molasses slops. In this study, a physico-chemical me- thod of decolorization was employed using commercial inorganic flocculant, a polymer of ferrichydroxysulfate (PFS) with the chemical formula [Fe2(OH)n(SO4)3.n/2] m. The method is rapid, and significant reductions in tur- bidity and total organic carbon (TOC) were obtained. Methane Ethanol (Biodigester) T ~ [METHANE FER,ENTATION -~ LAGOON l Fresh Biodigester slops effluent FIG. 1. Three types of molasses wastewater. - ~ RIVER Lagooned effluent * Corresponding author. 438