Simultaneous Removal of Soluble Metal Species and Nitrate from Acidic and Saline Industrial Wastewater in a Pilot-Scale Biofilm Reactor

The hydrometallurgical treatment of waste printed circuit boards for the recovery precious metals generates acidic wastewater containing nitrate, chloride and residual base metals. scope this work is study a biological process concurrent metal sequestering, nitrate reduction neutralization. A pilot-scale packed-bed biofilm reactor was set up, inoculated with strain H. denitrificans experimentally monitored. range operating parameters examined included: (a) concentration 750–5750 mg/L NO3−; (b) pH 3–8; (c) Cu, Ni, Zn Fe at 50 100 mg/L; (d) 5%–10% as NaCl. presence did not affect denitrification concentrations examined. completely reduced intermediately produced nitrite elevated levels. Denitrification shifted towards circumneutral to alkaline values, where iron, zinc, copper nickel were sequestered quantitatively from solution via bioprecipitation. proposed simple, robust low-cost unit advantageous compared conventional treatment, precipitation based on chemical neutralization problem removal remains unresolved.