SUSTAINABLE PRODUCTION OF INDUSTRIALLY IMPORTANT CHEMICALS FROM AGRO-INDUSTRIAL WASTE

Abstract

The aim of the research is to provide a comprehensive study on potato peel waste, an agro - industrial waste. Thesis consists of three major parts, which distinguish detailed discussion of composition analysis and pretreatment, PHA production from extracted sugar from potato peel waste by two different bacterial species and characterization of extracted PHA biopolymer. Thesis summarizes the mass balance study of PHA from the both the species of bacteria which emphasizes the circular economy of a sustainable integrated waste management. Agro-Industrial waste is a source of renewable energy which comes from agricultural and industrial residues such as peels, husk, etc. and Chemical composition shows, these waste biomasses contain significant amounts of sugars, proteins, fats, minerals and complex nutrients. From different agro-industrial waste potato peel waste was selected for biopolymer (PHA) production due generation in huge amount, high amount of starch and low lignin content and wheat straw was selected for enzyme production due to easy availability. According to the world bank report, annually 2.01 billion tons of waste is generated as only industrial waste and by 2050 it will increase by 3.40 billion tons. According to “Food and Agricultural Organization of the United Nations,” globally, annual potato peel waste production exceeds 40 million tons, resulting in substantial quantities of potato peel waste. Approximately 40% of which is generated as byproducts in the food processing industry, including products such as fries, chips, and other packaged food. Commonly potato peel waste is utilized for generating low-value animal fodder, compost, or raw substrate for biogas production, resulting in the squandering of valuable nutritional resources within it. vii Potato peel waste possess antioxidant, antibacterial, and anti-inflammatory and further more properties. However, the fundamental principle of the current study remains the efficient disposal of waste with the economic viability of processing advancement. After generation waste biomass is generally disposed of by landfilling, dumping and burning without any proper treatment that causes harmful impacts on the environment including emission of greenhouse gases, accumulation of plastic in the ocean, pollution caused by toxic gases. That is why it is essential to build up a sustainable management strategy for them. Utilization of renewable resources for bioenergy production can be a promising step towards waste management which fulfills the concept of biorefinery. PHAs also known as carbonosomes, are polymers synthesized by a variety of bacteria inside their cell in the form of inclusion bodies and utilized as energy source in adverse condition. PHA are of three types on the basis of carbon chain length that are short chain length (3-5), medium chain length (6-10) and long chain length (10-16). PHA possess variety of industrial and medical applications such as packaging material, drug delivery and dental implantation etc. Bioplastics are gaining attention due to sustainability, biodegradability, biocompatibility, and lower carbon footprint. Nevertheless, the commercialization of PHA is predominantly hindered by the elevated production expenses arising primarily from the use of a pure sugar substrate. Our study has established a feasible method for bioplastic formation applying Pseudomonas putida MTCC (2475) and Bacillus circulans MTCC (8167), and potato peel waste as a carbon source. To optimize the sugar yield response surface methodology was used, which released 69.34 ± 0.25% reducing sugar. PHA production experiments using Pseudomonas putida were performed in hydrolysate containing media as well as commercial sugar containing mineral salt media. After 48 hours of fermentation of using this sugar, a biomass concentration of 2.19 g/L-1 , with a PHA production of 0.60 g/L (28.71 ± 0.55%) was obtained which was comparatively similar with synthetic media (2.56 g/L cell dry weight and 29.97 ± 0.45% PHA). Furthermore, the monomers of PHA produced by hydrolysate were characterized using Gas chromatography-mass spectrometry, Fourier transform infrared spectroscopy, differential scanning calorimetry, and nuclear magnetic resonance. This investigation has identified three distinct viii monomers of medium-chain PHAs, namely, methyl 3-Hydroxydodecanoate, 3- Hydroxytetradecanoate, and Hexadecenoic acid 3-Hydroxy methyl esters. However, Bacillus circulans MTCC 8167 deposited hexadecenoic acid 3-hydroxy, methyl esters, pentadecanoic acid 14 methyl esters, and tetra decanoic acid 12- methyl esters. Crotonic acid assay was used for quantification of PHA and it was found highest (0.232 ± 0.04 g/L) at 37 °C and 36 h of incubation. Hence this study concludes a sustainable production of bioplastics from potato peel waste.