PLA (Polylactic Acid)

PLA (Polylactic Acid) is a biodegradable, bio-based thermoplastic polyester produced by ring-opening polymerisation of lactide, which is derived from the fermentation of corn starch, sugarcane, or cassava. Its density is 1.21–1.25 g/cm³, glass transition temperature ~55–60°C, and melting point 150–160°C. PLA is used in single-use cups, cutlery, food packaging film, and 3D printing filament, primarily marketed as a sustainable alternative to petroleum-based plastics because its carbon is biogenic (atmospheric CO₂ captured by the source plant). Major global producers include NatureWorks (USA, under the Ingeo brand) and TotalEnergies Corbion (Netherlands, Luminy brand). PLA is not currently produced at scale in India.

The critical misunderstanding around PLA in India is the distinction between industrial composting and real-world disposal conditions. PLA is certified compostable under EN 13432 or ASTM D6400 standards, which require hydrolysis and microbial breakdown within 12 weeks at >58°C, >50% humidity, with aeration — conditions found only in industrial composting facilities operating at those temperatures. At ambient temperatures (15–35°C, typical of Indian landfills or open dumps), PLA does not meaningfully break down within decades and behaves identically to conventional plastics from an environmental impact perspective. India has fewer than 200 operational industrial composting facilities nationally, most in the CBG/biogas sector or food-processing clusters — far from adequate for the volume of PLA packaging entering the market.

From a recycling perspective, PLA is problematic when mixed with conventional plastics. Its density (1.21–1.25 g/cm³) places it in the same float-sink fraction as PET (1.38–1.40 g/cm³) — above 1.0 — so PLA bottles look identical to PET in the sink fraction. PLA melts at 150–160°C, dramatically lower than PET (250°C); even 0.5% PLA contamination in a PET stream causes processing problems (bubble formation, reduced IV, visual defects). NIR spectroscopy can distinguish PLA from PET but requires specific sensor calibration. The CPCB is yet to issue definitive guidance on PLA disposal routing in India — whether it should go to composting, mechanical recycling, or landfill.

For Indian recyclers, PLA represents a risk more than an opportunity at present. Flag PLA packaging at intake (typically labelled 'compostable' or 'bio-based'), segregate it from PET and other recyclates to avoid contamination, and hold it separately pending guidance. Do not process PLA through a PET recycling line without NIR sorting upstream. As compostable packaging volumes grow under EPR-driven brand owner adoption, recyclers should begin planning for a dedicated PLA handling stream — whether composting offtake or a dedicated low-temperature processing line.