From Science & Research
From Science & Research The United States generates a colossal seven million tonnes of sewage sludge annually, enough to fill 2,500 Olympic-sized swimming pools. While a portion of this waste is repurposed for manure and other land applications, a substantial amount is still disposed of in landfills. In a new study, Texas A&M University researchers have uncovered an efficient way to use leftover sludge to make biodegradable plastics. In last years September issue of the journal American Chemical Society (ACS) Omega, the researchers have shown that the bacterium Zobellella denitrificans ZD1, found in mangroves, can consume sludge and wastewater to produce polyhydroxybutyrate (PHB). In addition to reducing the burden on landfills and the environment, the researchers said Zobellella denitrificans ZD1 offers a way to cut down upstream costs for bioplastics manufacturing, a step toward making them more competitively priced against regular plastics. “The price of raw materials to cultivate biopolymerproducing bacteria accounts for 25–45% of the total production cost of manufacturing bioplastics. Certainly, this cost can be greatly reduced if we can tap into an alternate “There is a multitude of bacterial species that make polyhydroxybutyrate, but only a few that can survive in highsalt environments and even fewer among those strains can produce polyhydroxybutyrate from pure glycerol,” said Chu. “We looked at the possibility of whether these salt-tolerating strains can also grow on crude glycerol and wastewater.” For their study, Chu and her team chose the Zobellella denitrificans ZD1, whose natural habitat is the salt waters of the mangroves. They then tested the growth and the ability of this bacteria to produce polyhydroxybutyrate in pure glycerol. The researchers also repeated the same experiments with other bacterial strains that are known producers of polyhydroxybutyrate. They found that Zobellella denitrificans ZD1 was able to thrive in pure glycerol and produced the maximum amount of polyhydroxybutyrate in proportion to its dry weight, that is, its weight without water. Next, they tested the growth and ability of Zobellella denitrificans ZD1 to produce polyhydroxybutyrate in glycerol containing salt and fatty acids and found that even in these conditions, it produced polyhydroxybutyrate efficiently, even under balanced nutrient conditions. When they repeated the experiments in samples of high-strength synthetic New strain of bacteria could make PHB more affordable resource that is cheaper and readily obtainable,” said Dr Kung-Hui (Bella) Chu, professor in the Zachry Department of Civil and Environmental Engineering at A&M. “We have demonstrated a potential way to use municipal wastewateractivated sludge and agri- and aqua-culture industrial wastewater to make biodegradable plastics. Furthermore, the bacterial strain does not require elaborate sterilization processes to prevent contamination from other microbes, further cutting down operating and production costs of bioplastics.” PHBs are produced by several bacterial species when they experience an imbalance of nutrients in their environment. This group of polymers acts as the bacteria’s supplemental energy reserves, similar to fat deposits in animals. In particular, an abundance of carbon sources and a depletion of either nitrogen, phosphorous or oxygen, cause bacteria to erratically consume their carbon sources and produce PHB as a stress response. One such medium that can force bacteria to make polyhydroxybutyrate is crude glycerol, a by-product of biodiesel manufacturing. Crude glycerol is rich in carbon and has no nitrogen, making it a suitable raw material for making bioplastics. However, crude glycerol contains impurities such as fatty acids, salts, and methanol, which can prohibit bacterial growth. Like crude glycerol, sludge from wastewater also has many of the same fatty acids and salts. Chu said that the effects of these fatty acids on bacterial growth and, consequently, polyhydroxybutyrate production had not yet been examined. wastewater and wastewater-activated sludge, they found the bacteria was still able to make polyhydroxybutyrate, although at lower quantities compared to crude glycerol. Chu noted that by leveraging Zobellella denitrificans ZD1 tolerance for salty environments, expensive sterilization processes that are normally needed when working with other strains of bacteria could be avoided. “Zobellella denitrificans ZD1 natural preference for salinity is fantastic because we can, if needed, tweak the chemical composition of the waste by just adding common salts. This environment would be toxic for other strains of bacteria,” she said. “So, we are offering a low cost, a sustainable method to make bioplastics, and another way to repurpose biowastes that are costly to dispose of.” Other contributors to this research include Fahad Asiri, Chih-Hung Chen, Myung Hwangbo, and Yiru Shao from the civil and environmental engineering department at Texas A&M. This research is supported by the Kuwait Institute for Scientific Research, the Ministry of Higher Education of Kuwait Fellowship, and the fellowship from the Ministry of Science and Technology of Taiwan. AT Based on an article by Vandana Suresh, Texas A&M University College of Engineering, published December, 2020, which originally appeared on the College of Engineering website. https://engineering.tamu.edu/ 14 bioplastics MAGAZINE [01/21] Vol. 16
Strategic partnership leverages sustainable solutions for automotive sector By: Chris Scarazzo Automotive Segment Market Manager Eastman, Kingsport, Tennessee, USA Automotive The global pandemic that defined 2020 triggered a reduction in greenhouse gas emissions due to lockdowns and stayat-home measures which dramatically, albeit temporarily, decreased the use of automobiles. This is noteworthy because 2020 was also the year that the Paris Agreement went into effect. Adopted in 2015 in accord with the United Nations Framework on Climate Change (UNFCC), the Paris Agreement addresses the mitigation of greenhouse gas emissions in response to global climate change. China and India – the countries with the most and third most CO 2 emissions, respectively – are among UNFCC members that have ratified or acceded to the agreement. China is the largest producer of automobiles, followed by Japan, Germany, India and South Korea. In a year when everyone’s focus was on surviving a health crisis, the world’s most sweeping regulations on climate change quietly took effect. Governments, NGOs and corporations released their own goals, pledges and targets to drive down emissions on the road to mid-century carbon neutrality. Crisis creates opportunity Against this backdrop of sustainability aspirations and COVIDrelated chaos, global materials provider Eastman (Kingsport, Tennessee, USA) and Gruppo Maip (Settimo Torinese, Italy), a leading international plastics formulator and compound producer, announced a strategic partnership to positively impact the environment. Together, the venerable industry leaders are creating new sustainable polymer solutions for automotive interior applications. These new polymers will enable automotive OEMs to meet aggressive targets for sustainable content and replace petroleum-based materials. It’s a win-win at a time when the COVID-19 crisis has led to cost-cutting measures which don’t allow for investments in new products and technology. Technological breakthroughs lead to innovative products Fortunately for OEMs, in 2019, Eastman became the first company to begin commercial-scale molecular recycling for a broad set of mixed-waste plastics that would otherwise be landfilled or, worse, wind up in the environment. Eastman Advanced Circular Recycling technologies offer a range of both biobased and molecular-recycled content solutions, including Tritan Renew copolyester and Trēva Renew engineering bioplastic. Tritan Renew is powered by Eastman’s polyester renewal technology and delivers up to 50% certified recycled content diverted from post-consumer and postindustrial waste streams. Tritan Renew is enabled through Eastman’s carbon renewal technology, a unique process that breaks down waste plastic back into its basic chemical building blocks. Unlike traditionally recycled plastics, Tritan Renew offers the same high performance as virgin plastics. Trēva Renew is a mix of cellulose esters, the cellulose of which is derived from sustainably harvested trees. Trēva Renew offers up to 48% biobased content which is certified by the USDA’s BioPreferred ® program. In addition, Trēva Renew benefits from carbon renewal technology that uses mixed waste plastic, providing an additional 23% certified recycled content as an alternative to polycarbonate, ABS and PC-ABS and other materials typically used for interior and exterior applications. Via its Advanced Circular Recycling technologies, Eastman produces circular products that are certified by the International Sustainability and Carbon Certification (ISCC) by mass balance allocation. For more details about Trēva Renew and Eastman’s carbon renewal technology in automotive applications see bM 01/2020) Gruppo Maip develops a wide range of high-tech engineered thermoplastic materials with a focus on specialty colors and technical solutions that require filled and reinforced custom formulation development. In partnership with Eastman, MAIP is now developing specialty compounds using Tritan Renew and Trēva Renew to create new sustainable formulations for a variety of interior applications, including accent trim, both molded in color and decorated, speaker grills, center console trim, door handles, knobs, pillars, overhead consoles and lighting, both ambient and diffusive. Through Eastman’s circular recycling technologies and Gruppo Maip’s formulations, OEMs will now be able to specify content and recycled-content plastics in critical interior Class A components, such as molded-in-color interior trim, bringing a new level of sustainability to the automotive industry. The road to net zero calls for collaboration The automotive industry is at a watershed moment. Electrification, autonomous technologies and shared mobility are just a few of the challenges facing automotive OEMs and suppliers. According to a study by McKinsey & Company, the top 20 OEMs in the global auto sector saw profits plummet by USD100 billion in 2020 due to repercussions of the COVID-19 crisis. This is generational disruption. How it all plays out is still to be determined. However, one thing is certain: transformation is essential to survival. Government regulation, consumer preferences and investor demands are forcing companies in carbon-intensive sectors to align with the sustainability goals of the Paris Agreement. Automotive industry players must work together to reduce fossil carbon in transportation. www.eastman.com | www.maipsrl.com bioplastics MAGAZINE [01/21] Vol. 16 15
