Bio-SAP Caught Up. PHA Did Not.

India generates 12.3 billion disposable sanitary napkins each year, adding 113,000 tonnes of menstrual waste to landfills, per Toxics Link's 2021 estimate — the most recent national figure available, now dated.¹ A single conventional pad is approximately 90 per cent plastic by composition — the equivalent of four plastic bags — and takes 250 to 800 years to degrade.¹ Of the country's 355 million menstruating women, only 36 per cent currently use sanitary pads, and that share is climbing.² The waste problem will compound before it plateaus.

The response from the market has been biodegradable pads. In India, the biodegradable segment already represents 16.3 per cent of the approximately ₹7,400 crore (USD 894.49 million) sanitary napkin market, growing at 10.8 per cent CAGR against 8.04 per cent for the category overall.³ Globally, the biodegradable sanitary napkin market reached USD 2,972.5 million in 2025 and is projected at USD 12,700.1 million by 2034, a 17 per cent CAGR.⁴ Capital is flowing. But "biodegradable" is not "compostable," and almost none of these products can claim to be fully compostable across every layer. The reason is not what most observers expect.

Bamboo Fibre Foam Absorbs 22.5 g/g, 36 Per Cent Above Commercial Pads

The standard argument against compostable menstrual products has been performance: bio-based absorbent cores cannot match sodium polyacrylate, the petroleum-derived superabsorbent polymer (SAP) used in virtually every conventional pad. That argument is now dated.

Deville et al. (2024) demonstrated that bamboo fibre foam achieved a liquid absorbency of 22.5 g/g, exceeding a commercial reference pad's 16.6 g/g by 36 per cent.⁵ This was accomplished through structural porosity — engineered air pockets in lignocellulosic foam — rather than chemical superabsorbency. Retention under compression remains a constraint: unrefined bamboo fibre retains only 50 per cent of absorbed liquid at 5 kPa pressure, though refined variants reach 73 per cent.⁵ That gap is an engineering problem, not a materials dead end.

Separately, Ismaeilimoghadam et al. (2025) published direct evidence that polysaccharide-based hydrogels — derived from cellulose, starch, and alginate — can replace acrylic acid superabsorbent polymers in sanitary napkins with comparable absorption performance.⁶ A parallel line of work on sodium alginate and konjac glucomannan hydrogels, published in the International Journal of Biological Macromolecules in 2025, confirms this direction is widening, not narrowing.⁷

The absorbent core, in short, is no longer the constraint. Alginate-chitosan hydrogels, bamboo viscose, and banana fibre (used commercially by Saathi in Ahmedabad since 2018⁸) all offer viable absorption at scale. The constraint has moved downstream — to the backsheet.

PHA Costs 3–10× More Than Polyethylene, and Its Largest Producer Sold for USD 19 Million

A fully compostable pad requires every layer to biodegrade: the top sheet, absorbent core, adhesive, and the backsheet that prevents leakage. Conventional pads use polyethylene or polypropylene backsheets — materials that will persist in a landfill for centuries. The only credible compostable alternative for this barrier layer is polyhydroxyalkanoate (PHA), a bioplastic produced through bacterial fermentation.

PHA's problem is not technical. It biodegrades in soil, marine, and home-composting conditions. Its problem is economic and industrial.

Current PHA resin prices range from USD 4 to USD 16 per kilogramme, against USD 1 to USD 1.74 for conventional polyethylene — a 3× to 10× premium at the resin level.⁹ Global PHA production capacity stood at approximately 70,000 metric tonnes in 2024.⁹ To reach cost parity with commodity plastics, analysts estimate the industry needs to exceed 500,000 tonnes annually, a figure the market does not project before 2028 at the earliest.

The supply picture worsened materially in early 2025. Danimer Scientific, the most prominent PHA producer globally and the company behind the Nodax brand, filed for Chapter 11 bankruptcy on 18 March 2025 with USD 402 million in funded debt and USD 189.5 million invested in a paused manufacturing expansion.¹⁰ Its assets — including approximately 125 patents — were acquired by Teknor Apex for USD 19 million, roughly 4.7 per cent of funded debt.¹⁰ The company had never commercialised its PHA biopolymer technology at profitable scale.

That leaves Kaneka Corporation of Japan as the only major PHA producer with active, expanding capacity. Kaneka operates a 5,000-tonne-per-year PHBH plant at Takasago and invested approximately €114 million to expand to 20,000 tonnes per year, with the new line starting operations in early 2024.¹¹ Twenty thousand tonnes is not trivial, but it serves a global market. The menstrual pad application alone — even at modest penetration — would require thousands of tonnes of thin-film PHA backsheet annually.

Ningbo Tianan Biologic Materials in China produces PHA at smaller scale, and several startups (PHAXTEC, COFCO subsidiary operations) hold pre-commercial capacity.⁹ The overall PHA market is projected at USD 265.2 million by 2030, with production capacity potentially reaching 974,000 tonnes by 2029.⁹ But projections compiled before Danimer's collapse assumed a supply base that no longer exists in its projected form.

The Price Gap Survives at the Pad Level: ₹22 Versus ₹12

The unit economics of a compostable pad reflect PHA's premium directly. Whisper Ultra Clean XL, the market leader from Procter & Gamble, retails at an MRP of approximately ₹350 for a 30-pack — roughly ₹11.67 per pad.¹² Biodegradable alternatives from Carmesi, Saathi, and Heyday cluster between ₹15 and ₹25 per pad, depending on the channel.

A fully compostable pad using bamboo viscose, alginate-chitosan bio-SAP, and a PHA backsheet — the architecture behind products like Alvera — carries a bill of materials around ₹7.45 per pad at the XL size, with a target MRP of ₹22 and a gross margin of 43.7 per cent.¹³ That ₹22 price point is nearly double Whisper's per-pad cost. In a market where Procter & Gamble, Unicharm (Sofy), and RSPL Group (Pro-Ease) compete aggressively on price, and where 48 per cent of rural Indian women have only recently adopted pads at all,³ a 2× premium constrains the addressable market to urban consumers with demonstrated willingness to pay for sustainability.

Breakeven for a product at this price requires approximately 9,500 pads per month¹³ — achievable for a direct-to-consumer brand in a single city but demanding for a distributed retail operation.

No Indian Municipality Operates Menstrual Pad Composting Infrastructure

Even where a pad is certifiably compostable, the composting infrastructure to process it does not exist in India. Natracare, the European market leader, certifies its pads to EN 13432 (European industrial composting) and ASTM D6400 (American equivalent).¹⁴ Under industrial composting conditions — sustained temperatures above 58°C, controlled moisture, active aeration — these pads decompose within the certification window of 12 weeks.

Home composting is a different matter. Natracare's own guidance estimates 18 to 24 months for cold-bin decomposition.¹⁴ TÜV Austria's OK Compost HOME standard, the most rigorous home-composting certification available, requires 90 per cent biodegradation within 12 months at ambient temperature.¹⁵ No menstrual pad on the Indian market currently carries this certification.

Saathi claims degradation within six months for its banana fibre pads,⁸ but that claim is for the biopolymer content under favourable conditions — it is not a third-party composting certification, and the adhesive strip on any pad is typically degradable rather than biodegradable.¹⁴

India's Solid Waste Management Rules (2016) classify menstrual waste as sanitary waste requiring separate collection, but 100 per cent of menstrual waste in Delhi reaches municipal systems unsegregated.¹ The gap between a compostable product and a composted product is, in India, an infrastructure gap that no single brand can close.

What Would Falsify This Argument

Three developments would materially change the picture. First, a PHA producer — Kaneka, Teknor Apex (now holding Danimer's patents), or a Chinese entrant — achieving a price below USD 3 per kilogramme at volumes above 50,000 tonnes annually would bring backsheet costs into range of conventional materials. Second, a non-PHA compostable barrier film — PLA blends, thermoplastic starch composites, or wax-coated cellulose — passing the TÜV OK Compost HOME certification for thin-film hygiene applications would bypass the PHA bottleneck entirely. Third, a state or municipal government in India mandating composting infrastructure for sanitary waste, as Kerala has piloted for general organic waste, would create the demand signal that makes compostable pads rational at the system level rather than the product level.

None of these three is implausible. None is current.

For the 128 million Indian women who adopted pads in the last decade,² the immediate reality is that the pad they throw away will outlast them, their children, and the landfill it sits in. A fully compostable alternative exists in the laboratory and in small-batch production. Scaling it requires not a better pad but a cheaper bioplastic and a composting bin at the ward level — one industrial, one municipal, neither glamorous, both absent.