Elimination of sulfur(IV) interference in five-day biochemical oxygen demand determinations
Abstract
Sulfur dioxide is a reduced species [SIV] that may exert a positive interference in carbonaceous biochemical oxygen demand (BOD) determination when present in municipal and industrial waste waters. The addition of 0.1 mg dm–3 of Co2+ after pH adjustment to 7.8, followed by agitation for 16 h at 4 °C, resulted in oxidation of the SIV. The procedure was used on waste-water samples containing 500 mg dm–3 of SIV, which were subsequently analysed for five-day BOD (BOD5). The results were not significantly different from data obtained for control samples. The elimination procedure provided a statistically valid means of removing SIV interference in BOD determination. The method may provide an efficient procedure for the determination of the carbonaceous BOD of water containing SIV.