1. The amount of energy trapped in it. One can use the anaerobic digestion to recover it in the form of methane. Simple digesters like a modified biogas plant sometimes work
2. The color of the spent wash(due to Malliard reaction during molasses formation in the sucrose recovery process) is due to melanoidins, another ecotoxic substance, Normally it gets reduced during the anaerobic digestion. Activated charcoal adsorption can help to some extent.
From your question, I can identify colour, acidity level and BOD/COD as major concern. A good adsorbent(activated charcoal) will take care of that once.