Browsing by Author "Bhatnagar, Amit"

Now showing 1 - 6 of 6
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    Advancing the bioconversion process of food waste into methane: a systematic review
    (Elsevier, 2022-12-06) Workie, Endashaw; Kumar, Vinor; Bhatnagar, Amit; He, Yiliang; Dai, Yanjun; Tong, Yen Wah; Peng, Yinghong; Zhang, Jingxin; Fu, Cunbin
    With the continuous rise of food waste (FW) throughout the world, a research effort to reveal its potential for bioenergy production is surging. There is a lack of harmonized information and publications available that evaluate the state-of-advance for FW-derived methane production process, particularly from an engineering and sustainability point of view. Anaerobic digestion (AD) has shown remarkable efficiency in the bioconversion of FW to methane. This paper reviews the current research progress, gaps, and prospects in pre-AD, AD, and post-AD processes of FW-derived methane production. Briefly, the review highlights innovative FW collection and optimization routes such as AI that enable efficient FW valorization processes. As weather changes and the FW sources may affect the AD efficiency, it is important to assess the spatio-seasonal variations and microphysical properties of the FW to be valorized. In that case, developing weather-resistant bioreactors and cost-effective mechanisms to modify the raw substrate morphology is necessary. An AI-guided reactor could have high performance when the internal environment of the centralized operation is monitored in real-time and not susceptible to changes in FW variety. Monitoring solvent degradation and fugitive gases during biogas purification is a challenging task, especially for large-scale plants. Furthermore, this review links scientific evidence in the field with full-scale case studies from different countries. It also highlights the potential contribution of ADFW to carbon neutrality efforts. Regarding future research needs, in addition to the smart collection scheme, attention should be paid to the management and utilization of FW impurities, to ensure sustainable AD operations.
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    Bread waste – a potential feedstock for sustainable circular biorefineries
    (Elsevier, 2022-12-21) Kumar, Vinod; Brancoli, Pedro; Narisetty, Vivek; Wallace, Stephen; Charalampopoulos, Dimitris; Kumar Dubey, Brajesh; Kumar, Gopalakrishnan; Bhatnagar, Amit; Bhatia, Shashi Kant; Taherzadeh, Mohammad J.
    The management of staggering volume of food waste generated (∼1.3 billion tons) is a serious challenge. The readily available untapped food waste can be promising feedstock for setting up biorefineries and one good example is bread waste (BW). The current review emphasis on capability of BW as feedstock for sustainable production of platform and commercially important chemicals. It describes the availability of BW (>100 million tons) to serve as a feedstock for sustainable biorefineries followed by examples of platform chemicals which have been produced using BW including ethanol, lactic acid, succinic acid and 2,3-butanediol through biological route. The BW-based production of these metabolites is compared against 1G and 2G (lignocellulosic biomass) feedstocks. The review also discusses logistic and supply chain challenges associated with use of BW as feedstock. Towards the end, it is concluded with a discussion on life cycle analysis of BW-based production and comparison with other feedstocks.
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    Development of hypertolerant strain of Yarrowia lipolytica accumulating succinic acid using high levels of acetate
    (American Chemical Society, 2022-08-09) Narisetty, Vivek; Prabhu, Ashish A.; Bommareddy, Rajesh Reddy; Cox, Rylan; Agrawal, Deepti; Misra, Ashish; Ali Haider, M.; Bhatnagar, Amit; Pandey, Ashok; Kumar, Vinod
    Acetate is emerging as a promising feedstock for biorefineries as it can serve as an alternate carbon source for microbial cell factories. In this study, we expressed acetyl-CoA synthase in Yarrowia lipolytica PSA02004PP, and the recombinant strain grew on acetate as the sole carbon source and accumulated succinic acid or succinate (SA). Unlike traditional feedstocks, acetate is a toxic substrate for microorganisms; therefore, the recombinant strain was further subjected to adaptive laboratory evolution to alleviate toxicity and improve tolerance against acetate. At high acetate concentrations, the adapted strain Y. lipolytica ACS 5.0 grew rapidly and accumulated lipids and SA. Bioreactor cultivation of ACS 5.0 with 22.5 g/L acetate in a batch mode resulted in a maximum cell OD600 of 9.2, with lipid and SA accumulation being 0.84 and 5.1 g/L, respectively. However, its fed-batch cultivation yielded a cell OD600 of 23.5, SA titer of 6.5 g/L, and lipid production of 1.5 g/L with an acetate uptake rate of 0.2 g/L h, about 2.86 times higher than the parent strain. Cofermentation of acetate and glucose significantly enhanced the SA titer and lipid accumulation to 12.2 and 1.8 g/L, respectively, with marginal increment in cell growth (OD600: 26.7). Furthermore, metabolic flux analysis has drawn insights into utilizing acetate for the production of metabolites that are downstream to acetyl-CoA. To the best of our knowledge, this is the first report on SA production from acetate by Y. lipolytica and demonstrates a path for direct valorization of sugar-rich biomass hydrolysates with elevated acetate levels to SA.
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    The effects of light regime on carbon cycling, nutrient removal, biomass yield, and polyhydroxybutyrate (PHB) production by a constructed photosynthetic consortium
    (Elsevier, 2022-09-12) Wicker, Rebecca J.; Autio, Heidi; Daneshvar, Ehsan; Sarkar, Binoy; Bolan, Nanthi; Kumar, Vinod; Bhatnagar, Amit
    Microalgae can add value to biological wastewater treatment processes by capturing carbon and nutrients and producing valuable biomass. Harvesting small cells from liquid media is a challenge easily addressed with biofilm cultivation. Three experimental photobioreactors were constructed from inexpensive materials (e.g. plexiglass, silicone) for hybrid liquid/biofilm cultivation of a microalgal-bacterial consortia in aquaculture effluent. Three light regimes (full-spectrum, blue-white, and red) were implemented to test light spectra as a process control. High-intensity full-spectrum light caused photoinhibition and low biomass yield, but produced the most polyhydroxybutyrate (PHB) (0.14 mg g−1); a renewable bioplastic polymer. Medium-intensity blue-white light was less effective for carbon capture, but removed up to 82 % of phosphorus. Low-intensity red light was the only net carbon-negative regime, but increased phosphorus (+4.98 mg/L) in the culture medium. Light spectra and intensity have potential as easily-implemented process controls for targeted wastewater treatment, biomass production, and PHB synthesis using photosynthetic consortia.
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    The potential of mixed-species biofilms to address remaining challenges for economically-feasible microalgal biorefineries: a review
    (Elsevier, 2022-08-10) Wicker, Rebecca J.; Kwon, Eilhann; Khan, Eakalak; Kumar, Vinod; Bhatnagar, Amit
    Several key challenges are hindering large-scale cultivation of microalgae for industrial purposes, including wastewater treatment, carbon capture, biomass production, and renewable energy production. These challenges are closely related to efficacy of 1) resource utilization, 2) biomass production, and 3) harvesting. This review describes how attached or biofilm cultivation of microalgae and/or cyanobacteria with heterotrophic bacteria in consortia could simultaneously resolve these technical obstacles, thereby reducing monetary and energetic costs of producing microalgal bioenergy. Symbiotic relationships between these organisms reduces the need for aeration or exogenous supplementation of nutrients. Additionally, this review details how increasing biodiversity correlates with diversity of functionality (carbon capture and nitrification) and how attached/biofilm cultivation can improve photosynthetic efficiency and water footprint. Mixed-species biofilms have persisted for billions of years across earth’s natural history because they are some of nature’s most highly efficient biosystems, and they deserve more dedicated study and broader application in bioenergy production. This review details the practical connections between microalgal-bacterial consortia, attached/biofilm cultivation, waste-to-value biorefining, and relevance to bioenergy production and value-added products (VAPs); four topics previously unconnected in a single review. As such this review aims to bridge current knowledge gaps across multiple research fields and industrial sectors, towards the goal of efficient, economical, and climate-forward microalgal bio-services and bioenergy production.
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    Process optimization for recycling of bread waste into bioethanol and biomethane: a circular economy approach
    (Elsevier, 2022-05-28) Narisetty, Vivek; Nagarajan, Sanjay; Gadkari, Siddharth; Ranade, Vivek V.; Zhang, Jingxin; Patchigolla, Kumar; Bhatnagar, Amit; Awasthi, Mukesh Kumar; Pandey, Ashok; Kumar, Vinod
    Bread is the second most wasted food in the UK with annual wastage of 292,000 tons. In the present work, bread waste (BW) was utilized for fermentative production of ethanol by Saccharomyces cerevisiae KL17. Acidic and enzymatic saccharification of BW was carried out resulting in the highest glucose release of 75 and 97.9 g/L which is 73.5 and 95.9% of theoretical yield, respectively. The obtained sugars were fermented into ethanol initially in shake flask followed by scale up in bioreactor in batch and fed-batch mode. In the fed-batch mode of cultivation, the maximum ethanol titers of 111.3, 106.9, and 114.9 g/L with conversion yield and productivity of 0.48, 0.47, and 0.49 g/g, and 3.1, 3.0, and 3.2 g/L.h was achieved from pure glucose, glucose-rich acidic and enzymatic hydrolysates, respectively. Further to improve the process economics, the solid residues after acidic (ABW) and enzymatic (EBW) hydrolysis of BW along with respective fermentation residues (FR) obtained after the ethanol production were pooled and subjected to anaerobic digestion. The solid residue from ABW + FR, and EBW + FR yielded a biochemical methanation potential (BMP) of 345 and 379 mL CH4/g VS, respectively. Life cycle assessment of the process showed that the total emissions for ethanol production from BW were comparable to the emissions from more established feedstocks such as sugarcane and maize grain and much lower when compared to wheat and sweet potato. The current work demonstrates BW as promising feedstock for sustainable biofuel production with the aid of circular biorefining strategy. To the authors knowledge, this is the first time, such a sequential system has been investigated with BW for ethanol and biomethane production. Further work will be aimed at ethanol production at pilot scale and BMP will be accessed in a commercial anaerobic digester.