A Review of the Feasibility of Producing Polylactic Acid (PLA) Polymers Using Spent Coffee Ground

Abstract

Coffee is one of the most popular beverages in the world. Annual coffee consumption continues to increase, but at the same time, it generates a large amount of spent coffee grounds from the brewing process that give rise to environmental problems. An appropriate solution to manage these spent coffee grounds (SCGs) becomes crucial. Our project aims at discussing the feasibility of utilizing SCGs to synthesize polylactic acid (PLA) as a recycling application for SCGs. Producing PLA from SCGs offers the opportunity to contribute to the circular economy and sustainability due to the significant volume of coffee consumption. This approach reduces waste, provides environmental benefits, and promotes the use of renewable resources. Through repurposing SCGs into PLA, we can close the loop, minimize environmental impact, and create a more sustainable alternative to fossil-fuel-based plastics. This paper first discusses the properties and potential recycling applications of spent coffee grounds. The production of PLA from lactic acid and the potential processes for converting SCGs to lactic acid are then briefly discussed. From our review, it is feasible to utilize SCGs as the primary source for lactic acid production via bacteria fermentation and, further, to produce PLA via ring-opening polymerization. Possible ways to improve the yield and a corresponding cost analysis are also discussed.

The Effect of Size on the Mechanical Properties of 3D-Printed Polymers

“…PLA is a solution to replacing fossil plastics [46]. Reviews have indicated that using spent coffee grounds as the main source for bacterial fermentation to produce lactic acid and ring-opening polymerization to produce PLA are both possible [47]. Meanwhile, the unparalleled fatigue performance exhibited by nylon renders it indispensable in manufacturing components that are subjected to rigorous wear and tear, such as high-performance gears [48,49], among various other applications.…”

The Effect of Recycled Spent Coffee Grounds Fertilizer, Vermicompost, and Chemical Fertilizers on the Growth and Soil Quality of Red Radish (Raphanus sativus) in the United Arab Emirates: A Sustainability Perspective

“…Adding SCGs to the soil enhances its chemical and physical properties, increasing the levels of nitrogen (N), phosphorus (P), and potassium (K). It also enhances the structural stability of the soil aggregates, water-holding capacity, and soil hydrophobicity, improving the soil organic matter content, decreasing the soil bulk density, and increasing the soil microbial diversity [1][2][3][4]. This feature makes SCGs an effective solution for various soil types that frequently exhibit a significant deficiency of organic matter, rendering them highly vulnerable to erosion, such as in the United Arab Emirates (UAE) [5][6][7].…”

“…This creates a sense of urgency and becomes a crucial obstacle for sustainable management, necessitating inventive solutions that address environmental issues and enhance crop production quality and quantity [9,10]. This issue can be resolved by implementing a promising and encouraging strategy that focuses on repurposing different food waste materials, including SCGs, to produce organic fertilizers with fewer chemical side effects [1,2,4,6,11]. Several studies have explored this approach [11][12][13][14][15][16], demonstrating its potential to mitigate environmental impacts while improving soil health and crop yields [12,14,16].…”

Utilization of Spent Coffee Grounds as a Sustainable Resource for the Synthesis of Bioplastic Composites with Polylactic Acid, Starch, and Sucrose

“…According to Karmee et al [14], one ton of green coffee beans can produce approximately 650 kg of SCG. It has become a significant environmental problem because coffee grounds are dumped in landfills, but SCG can also be found in streets, pavements, and riverbeds [16,17]. The huge amounts of SCG generated each year from coffee production require efficient waste management in line with stricter environmental legislative regulations.…”