Polyhydroxyalkanoates (PHA) production using wastewater as carbon source and activated sludge as microorganisms

Area of Science:

• Environmental Microbiology
• Biotechnology
• Polymer Science

Background:

• Activated sludge from wastewater treatment plants harbors diverse microbial communities.
• Microorganisms can synthesize intracellular biopolymers like polyhydroxy alkanoates (PHA) under specific conditions.
• PHA are biodegradable plastics with potential applications in sustainable materials.

Purpose of the Study:

• To investigate the potential of activated sludge from various industrial sources for PHA production.
• To evaluate different carbon sources, including industrial wastewaters, for optimizing PHA accumulation.
• To identify optimal conditions for maximizing PHA yields from microbial sources.

Main Methods:

• Activated sludge from municipal, pulp/paper, starch, and cheese manufacturing plants was used.
• Shake flask experiments were conducted to cultivate microorganisms.
• Acetate, glucose, and various industrial wastewaters served as carbon sources.
• Polyhydroxy alkanoate (PHA) accumulation was quantified as a percentage of dry weight.

Main Results:

• Pulp and paper industry wastewater sludge achieved the highest PHA accumulation (43% of dry weight) when acetate was the carbon source.
• Pulp and paper and starch industry wastewaters were the most effective carbon sources for PHA production using pulp and paper activated sludge.
• High concentrations of volatile fatty acids in these wastewaters are suggested as the reason for enhanced PHA accumulation.

Conclusions:

• Activated sludge from industrial wastewater treatment plants is a viable source for PHA-producing microorganisms.
• Industrial wastewaters, particularly those rich in volatile fatty acids, can be effectively utilized as carbon sources for bioplastic production.
• This study highlights the potential for sustainable bioplastic manufacturing using waste streams.