Browsing by Author "Mailaram, Swarnalatha"

Now showing 1 - 2 of 2
  • Thumbnail Image
    ItemOpen Access
    Lactic acid and biomethane production from bread waste: a techno-economic and profitability analysis using pinch technology
    (Royal Society of Chemistry, 2023-06-07) Mailaram, Swarnalatha; Narisetty, Vivek; Maity, Sunil K.; Gadkari, Siddharth; Thakur, Vijay Kumar; Russelle, Stephen; Kumar, Vinod
    Lactic acid (LA) is a vital platform chemical with diverse applications, especially for biodegradable polylactic acid. Bread waste (BW) is sugar-rich waste biomass generated in large quantities in residential and commercial operations. Recently, we evaluated the potential of BW for LA production by Bacillus coagulans under non-sterile conditions. This work presents a techno-economic and profitability analysis for valorizing 100 metric tons of BW per day to alleviate environmental pollution with concurrent production of LA and biomethane. We compared two fermentation approaches: acid-neutral (Scenario I) and low pH (Scenario II). Traditional esterification with methanol, followed by hydrolysis of methyl lactate, was employed for downstream separation to obtain polymer-grade LA. High-pressure steam was generated from solid debris via anaerobic digestion to complement energy demands partly. Energy consumption was further attenuated by process integration using pinch technology, with around 15% and 11% utility cost savings for Scenario I and II, respectively. These processes were capital-intensive, with 42–46% of LA production cost stemming from direct and indirect costs. Utilities were the major cost-contributing factor (19–21%) due to energy-intensive water evaporation from dilute fermentation broth. Due to additional processing steps, capital investment and operating costs were slightly higher in Scenario I than in Scenario II. LA manufacturing cost was thus more for Scenario I ($2.07 per kg) than Scenario II ($1.82 per kg). The minimum LA selling price for Scenario I and II were $3.52 and $3.22 per kg, respectively, with five-year payback periods and 8.5% internal rates of return. LA was slightly more expensive for decentralized BW processing than the market price.
  • Thumbnail Image
    ItemOpen Access
    Techno-economic analysis for the production of 2,3-butanediol from brewers’ spent grain using pinch technology
    (American Chemical Society, 2022-12-31) Mailaram, Swarnalatha; Narisetty, Vivek; Ranade, Vivek V.; Kumar, Vinod; Maity, Sunil K.
    2,3-Butanediol (BDO) is a versatile platform chemical with great potential as the precursor for various value-added derivatives across different industrial sectors. This work thus presents a techno-economic feasibility study for microbial BDO production from C5 and C6 sugars derived from brewers’ spent grain (BSG). Water-soluble carbohydrates obtained from pretreatment were further utilized for the biogas generation. Besides, the solid residue generated after fermentation and biogas were used to generate high-pressure steam and electricity. The process integration was carried out using pinch technology for various BDO titers and plant capacities. The pinch analysis helped in the reduction of hot and cold utility consumption by about 34 and 18%, respectively. The minimum hot and cold utility consumption was 4.59 and 10.97 MW for 100 MT BSG per day with 100 g/L BDO titer, respectively. The cooling water consumption was decreased, and electricity generation was increased with the increase in BDO titer, while the BDO production cost reduced marginally. For 100 MT BSG per day, the BDO production cost was US$1.84, US$1.76, and US$1.74/kg for BDO titers of 80, 100, and 120 g/L, respectively. However, the unitary BDO production cost was only US$1.07 for 2000 MT BSG per day. For 100 g/L BDO titer, the minimum BDO selling price was US$3.63 and US$2.00/kg for 100 and 2000 MT BSG per day, respectively, with 8.5% return on investment and 5 years as the payback period.