Identification and photocatalytic destruction of malodorous compounds in sewage.

Malodorous compounds were identified in sewage samples using two different types of pre-concentration procedures: (a) pre-concentration onto adsorbent column (Tenax), (b) liquid-liquid extraction, in conjunction with sensory analysis. Sulphur and nitrogen containing compounds, hydrocarbons, substituted benzenes and components of essential oils and aldehydes were identified. These compounds were considered to be responsible for the septic and grassy/earthy odour described by sensory panellists. Studies on photodestruction of malodorous compounds present in the sewage samples showed that the main compounds were destroyed. This destruction was confirmed by both sensory analysis and gas chromatography through abatement in the intensity of odour as well as chromatogram peak areas. Comparing odour destruction using two processes, photocatalysis and loss due to mass transfer, the conversion rate was 71% at the beginning, later reaching a plateau of about 65%. Thus photocatalysis seems to be a promising technology in the degradation of malodorous compounds stripped to the atmosphere from sewage, especially when they are present at low concentrations.