Study on poly-hydroxyalkanoate (PHA) production in pilot scale continuous mode wastewater treatment system

Area of Science:

• Biotechnology
• Environmental Engineering
• Polymer Science

Background:

• Dairy processing generates significant wastewater rich in organic compounds.
• Poly-hydroxyalkanoates (PHAs) are biodegradable polyesters with diverse applications.
• Sustainable methods for PHA production and wastewater treatment are in demand.

Purpose of the Study:

• To investigate the pilot-scale generation of poly-hydroxyalkanoates (PHAs) from dairy processing wastewater.
• To evaluate an integrated reactor system for simultaneous wastewater treatment and PHA accumulation.
• To determine the kinetic parameters of the treatment and PHA synthesis processes.

Main Methods:

• Utilized a continuous-mode pilot-scale reactor system integrating an anaerobic acidogenic reactor (AAR), activated sludge production reactor (ASPR), and PHA synthesis reactor (PHAR).
• Treated raw dairy wastewater, inducing PHA accumulation in biomass.
• Harvested PHA-rich biomass while ensuring treated wastewater met disposal limits.

Main Results:

• Achieved approximately 43% PHA content in the PHA-rich biomass dry weight.
• The maximum PHA yield coefficient (Y(sp)(max)) was 0.25 kg PHA/kg COD degraded in the PHAR.
• Determined kinetic parameters for the ASPR: K(s) = 37.16 mg/l COD, µ(m) = 0.97 d⁻¹, Y(obs) = 0.51 mg MLSS/mg COD, and k(d) = 0.049 d⁻¹.

Conclusions:

• The integrated system effectively treats dairy wastewater, reducing disposable sludge.
• Significant PHA accumulation (43%) is achievable from dairy wastewater.
• The study provides crucial kinetic data for optimizing PHA production from industrial wastewater.