Sterols: a tracer of organic matter in combined sewers conferencePaper Zgheib, S. Gromaire, M.C. Lorgeoux, C. Saad, M. Chebbo, G. Van de Meulen, M. Ten Veldhuis, J.A.E. Schilperoort, R.P.S. International Water Organisation (IWA) 2007