Anaerobic treatment of cane sugar effluent from Muhoroni sugar factory

Abstract

Cane sugar mill effluent is characterized by high COD, BOD and Suspended solids (SS) contents and its treatment by aerobic biological methods is usually difficult. Due to the high content of lignin-cellulose in the SS of the waste-water, its pH falls rapidly during treatment to low levels which is adverse to micro-organisms. This study, whose aim was to determine the anaerobic biodegradability of sugar mill effluent, presents a batch reactor experiment for anaerobic treatment of the waste. Three kinds of reactor were set out:- Case I with both pH correction and seeding; Case II with seeding and no pH correction; and Case III without both pH correction and seeding. After 30-days retention period the COD, BOD, and SS percentage reductions for the three cases were as follows: for Case I 81.5%, 14%, and 63% respectively; Case II 78%, 39%, and 67% respectively; and Case III 3%, 26%, and 37% respectively. Retention periods less than 10 days resulted in very little improvement in effluent quality. Biodegradability, as measured by the BOD/COD ratio, rose steadily during the reactor operation for cases I and II but remained relatively constant for case III. The findings of the study compared well with previous achievements by Hartman et al. (1984), Wheatley et al. (1984) and Rusten et al. (1990). It was therefore concluded that anaerobic treatment, particularly with pH control and seeding, shows potential in first stage management of sugar mill wastewater. Key Words: wastewater treatment, anaerobic treatment, cane-sugar effluent, , retention time, seeding, pH control, start-up process, batch reactor.