Staged methods and systems for the valorization of sludge and biosolids

A method for pre-treatment of sludge and biosolids in preparation for electrochemical valorization, comprising:

• (a) selecting a sludge source;
• (b) preparing a slurry, wherein the slurry comprises the sludge source and an electrolyte;
• (c) adjusting a pH of the slurry to a range between approximately 8 and approximately 13;
• (d) flowing the slurry through a first electrochemical cell, wherein the first electrochemical cell enables partial oxidation of the sludge via hydroxyl radicals, wherein the first electrochemical cell comprises:
• (i) a first-cell anode,
• (ii) a first-cell cathode,
• (iii) a membrane, and
• (iv) an electrolyte;
• and
• (e) flowing the partially oxidized slurry from the first electrochemical cell to a second electrochemical cell for selective conversion, wherein the second electrochemical cell comprises:
• (i) a second-cell anode,
• (ii) a second-cell cathode, and
• (iii) a second-cell catalyst.