def frac_vol_floc_initial(ConcAluminum, ConcClay, coag, material):
    """Return the volume fraction of flocs initially present, accounting for both suspended particles and coagulant precipitates.

    :param ConcAluminum: Concentration of aluminum in solution
    :type ConcAluminum: float
    :param ConcClay: Concentration of particle in suspension
    :type ConcClay: float
    :param coag: Type of coagulant in solution
    :type coag: float
    :param material: Type of particles in suspension, e.g. floc_model.Clay
    :type material: floc_model.Material

    :return: Volume fraction of particles initially present
    :rtype: float
    """
    return ((conc_precipitate(ConcAluminum, coag).magnitude/coag.PrecipDensity)
            + (ConcClay / material.Density))
Return the volume fraction of flocs initially present, accounting for both suspended particles and coagulant precipitates.

    :param ConcAluminum: Concentration of aluminum in solution
    :type ConcAluminum: float
    :param ConcClay: Concentration of particle in suspension
    :type ConcClay: float
    :param coag: Type of coagulant in solution
    :type coag: float
    :param material: Type of particles in suspension, e.g. floc_model.Clay
    :type material: floc_model.Material

    :return: Volume fraction of particles initially present
    :rtype: float