Simple, low cost air ...

Simple, low cost air oxidation will do the job, ranging from various simple outdoor spraying/fountain/cascading methods  to fully enclosed stripping towers filled with raschid-type packing rings.  Air-oxidation techniques will, as ever, depend on volumes, concentrations and money (and Capex v Opex budgets),  and the release of bad-smelly, poisonous hydrogen sulphide gas into the atmosphere . Small volumes maybe environmentally dispersable/allowable, whilst larger volumes will require alkali absorption, and then correct disposal.

PH is critical. Fortunately you already have acid-pH, so simple air oxidation is cheap and acceptable - although you will need to adjust pH very carefully around 4.5-ish. Too low (~4.0) speeds up the oxidation reaction but is in danger of producing a sticky ppt of sulphur, whilst too high (~5.0) avoids the sulphur danger , but slows the reaction. ! A careful balance is required.

Basic thermodynamics using Pourbaix Diagrams (Eh v pH) will give you the answers.

I hope this helps you to understand the problem and its various solutions.