Identification and quantification of sulfur and nitrogen containing odorous compounds in wastewater

Sulfur and nitrogen containing malodorous compounds were identified and quantified in the samples taken from each step of sewage treatment employing aerated biofilters for advanced treatment. The sulfur compounds hydrogen sulfide, carbon disulfide, methyl mercaptan, dimethyl sulfide and dimethyl disulfide were detected by using GC-FPD with a headspace method and a modified purge and cold trap method. With a purge and cold trap method and a FPD system, the minimum detectable concentration of dissolved sulfur containing volatiles reached the ng l−1 level. As nitrogen containing compounds, indole, 3-methylindole, trimethylamine, dimethylamine and n-propylamine were present in the same wastewater samples. To determine indole and 3-methylindole, n-hexane extraction method was used, and for identifying and quantifying primary and secondary phase aliphatic amines, derivatization with o-phtalaldehyde (OPA) and N-succinimdyl-p-nitrophenylacetate (SNPA) was applied with HPLC. Trimethylamine was identified by directly injecting the filtered samples into GC-FTD. Detectable concentration of dissolved low aliphatic amines and indoles was about 10 μg l−1. Large amounts of nitrogen containing compounds remained after secondary treatment compared with sulfur containing compounds.