Use of biopolymers as solid substrates for denitrification

The conventional process to remove nitrate from water, the biological denitrification, uses the addition of dissolved organic carbon that has the potential risk to further deteriorate water quality. Thus, this work aimed to evaluate the specific denitrification activity of a mixed microbial culture and a pure culture of Pseudomonas stutzeri with solid substrates such as polycaprolactone (PCL), polylactic acid (PLA), and starch. The highest nitrate reduction activity was obtained with a microbial mixed culture using starch, 104 mg N₂-N/(g VSS.d), and PCL, 97 mg N₂-N/(g VSS.d), followed by PLA, 53 mg N₂-N/(g VSS.d). A considerable advantage of using biopolymers in water denitrification is the reduced risk of contaminating the water with soluble biodegradable organic carbon.