Arthrospira (Spirulina) in tannery wastewaters. Part 1: The microbial ecology of tannery waste stabilisation ponds and the management of noxious odour emissions using microalgal capping

Abstract

We investigated the problem of noxious gas and odour emissions in zero-discharge evaporative tannery waste stabilisa tion ponds. These have been little-studied systems although they present one of few options for the management of tannery wastewaters in highly water-stressed areas. A three-year study of the microbial ecology of an evaporative waste stabilisation ponding cascade was undertaken and a descriptive account of the biology and the physico-chemical parameters related to odiferous gas release is reported. Large populations of Arthrospira (Spirulina) dominated the latter facultative ponds in the cascade where odour emission was substantially reduced compared to initial anaerobic ponds. Photosynthetic productivity maxima of up to 9 000 mg∙m-2∙day-1 carbon fixation were measured in bloom conditions. Arthrospira production was associated with an oxygenated, alkaline layer established on the surface of facultative ponds (0.35 min depth) in which oxidation of sulphide and ammonia, and the trapping of other odour-causing compounds was observed.

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