Spirulina cultivation in digested sago starch factory wastewater

Wastewater arising from the production of sago starch has a high carbon to nitrogen ratio, which is improved with anaerobic fermentation in an upflow packed bed digester. The digested effluent with an average C: N: P ratio of 24: 0.14: 1 supported growth of Spirulina platensis (Arthrospira) with an average specific growth rate (mu) of 0.51 day(-1) compared with the average mu of 0.54 day(-1) in the inorganic Kosaric Medium in a high rate algal pond. Supplementation with 6 mM urea and 2.1 mM K2HPO4 produced gross biomass productivity of 14.4 g m(-2) day(-1). A flow-rate of 24 cm s(-1) increased the mu and gross biomass productivity (18 g m(-2) day(-1)). The highest crude protein, carbohydrate and lipid contents of the biomass were 68%, 23% and 11%, respectively. Percentage reductions in chemical oxygen demand, ammoniacal-nitrogen and phosphate levels of the digested effluent reached 98.0%, 99.9% and 99.4% respectively. The HRAP offers a good treatment system for sago starch factory wastewater.