Assessment of dehydration as a commercial-scale food waste valorization strategy

Using a commercially available dehydration unit, this study aimed to valorize various food waste streams from different sources in the Rochester, New York area. Dehydration of the food waste collected for the study helped reduce the weight of the feedstock by 70–90%, as the incoming waste streams were relatively wet. The output was materially characterized against end uses such as cattle feed, fish feed, and compost. The results demonstrated that, other than fertilizer, the remaining five end uses (compost, fish feed, cattle feed, pyrolysis, and pelletized fuel) were potentially compatible with varying waste feedstocks based on the parameters analyzed. Fish feed in particular was found to be the most compatible end use, as a number of attributes, including protein, fell within the optimal range of values. Pelletized fuel was also determined to be a viable application, as six out of eight sources of dehydrated food waste had higher heating values above the minimum U.S. standard level of 18.61 MJ/kg. Ultimately, this analysis showed that the composition of the food waste needs to be matched to an end-use application and sale of the product for dehydration to be a worthwhile valorization strategy

Cell replacement strategies for lithium ion battery packs

The economic value of high-capacity battery systems, being used in a wide variety of automotive and energy storage applications, is strongly affected by the duration of their service lifetime. Because many battery systems now feature a very large number of individual cells, it is necessary to understand how cell-to-cell interactions can affect durability, and how to best replace poorly performing cells to extend the lifetime of the entire battery pack. This paper first examines the baseline results of aging individual cells, then aging of cells in a representative 3S3P battery pack, and compares them to the results of repaired packs. The baseline results indicate nearly the same rate of capacity fade for single cells and those aged in a pack; however, the capacity variation due to a few degrees changes in room temperature (\u27±3 ◦C) is significant (\u27±1.5% of capacity of new cell) compared to the percent change of capacity over the battery life cycle in primary applications (\u2720–30%). The cell replacement strategies investigation considers two scenarios: early life failure, where one cell in a pack fails prematurely, and building a pack from used cells for less demanding applications. Early life failure replacement found that, despite mismatches in impedance and capacity, a new cell can perform adequately within a pack of moderately aged cells. The second scenario for reuse of lithium ion battery packs examines the problem of assembling a pack for less-demanding applications from a set of aged cells, which exhibit more variation in capacity and impedance than their new counterparts. The cells used in the aging comparison part of the study were deeply discharged, recovered, assembled in a new pack, and cycled. We discuss the criteria for selecting the aged cells for building a secondary pack and compare the performance and coulombic efficiency of the secondary pack to the pack built from new cells and the repaired pack. The pack that employed aged cells performed well, but its efficiency was reduced

Thermoformed Containers Based on Starch and Starch/Coffee Waste Biochar Composites

Biodegradable containers support zero-waste initiatives when alternative end-of-life scenarios are available (e.g., composting, bio digestion). Thermoplastic starch (TPS) has emerged as a readily biodegradable and inexpensive biomaterial that can replace traditional plastics in applications such as food service ware and packaging. This study has two aims. First, demonstrate the thermoformability of starch/polycaprolactone (PCL) as a thermoplastic material with varying starch loadings. Second, incorporate biochar as a sustainable filler that can potentially lower the cost and enhance compostability. Biochar is a stable form of carbon produced by thermochemical conversion of organic biomass, such as food waste, and its incorporation into consumer products could promote a circular economy. Thermoformed samples were successfully made with starch contents from 40 to 60 wt.% without biochar. Increasing the amount of starch increased the viscosity of the material, which in turn affected the compression molding (sheet manufacturing) and thermoforming conditions. PCL content reduced the extent of biodegradation in soil burial experiments and increased the strength and elongation at break of the material. A blend of 50:50 starch:PCL was selected for incorporating biochar. Thermoformed containers were manufactured with 10, 20, and 30 wt.% biochar derived from waste coffee grounds. The addition of biochar decreased the elongation at break but did not significantly affect the modulus of elasticity or tensile strength. The results demonstrate the feasibility of using starch and biochar for the manufacturing of thermoformed containers

Anaerobic Digestion of Food Waste with Unconventional Co-Substrates for Stable Biogas Production at High Organic Loading Rates

Anaerobic digestion (AD) is widely considered a more sustainable food waste management method than conventional technologies, such as landfilling and incineration. To improve economic performance while maintaining AD system stability at commercial scale, food waste is often co-digested with animal manure, but there is increasing interest in food waste-only digestion. We investigated the stability of anaerobic digestion with mixed cafeteria food waste (CFW) as the main substrate, combined in a semi-continuous mode with acid whey, waste bread, waste energy drinks, and soiled paper napkins as co-substrates. During digestion of CFW without any co-substrates, the maximum specific methane yield (SMY) was 363 mL gVS−1d−1 at organic loading rate (OLR) of 2.8 gVSL−1d−1, and reactor failure occurred at OLR of 3.5 gVSL−1d−1. Co-substrates of acid whey, waste energy drinks, and waste bread resulted in maximum SMY of 455, 453, and 479 mL gVS−1d−1, respectively, and it was possible to achieve stable digestion at OLR as high as 4.4 gVSL−1d−1. These results offer a potential approach to high organic loading rate digestion of food waste without using animal manure. Process optimization for the use of unconventional co-substrates may help enable deployment of anaerobic digesters for food waste management in urban and institutional applications and enable increased diversion of food waste from landfills in heavily populated regions

Experiments and Modeling in Bubbly Flows at Elevated Pressures

Measurements of local void fraction, rise velocity, and bubble diameter have been obtained for cocurrent, wall-heated, upward bubbly flows in a pressurized refrigerant. The instrumentation used are the gamma densitometer and the hot-film anemometer. Departure bubble size is correlated in terms of liquid subcooling and bulk bubble size in terms of void fraction. Flow visualization techniques have also been used to understand the two-phase flow structure and the behavior of the bubbly flow for different bubble shapes and sizes, and to obtain the bubble diameter and rise velocity. The lift model is provided explicitly in terms of Eotvos number which is changed by changing the system pressure. In general, Eotvos number plays a strong role in determining both bubbly lift and drag. Such insight coupled with quantitative local and averaged data on void fraction and bubble size at different pressures has aided in developing bubbly flow models applicable to heated two-phase flows at high pressure

Experiments And Modeling In Bubbly Flows At Elevated Pressures

Measurements of local void fraction, rise velocity, and bubble diameter have been obtained for cocurrent, wall-heated, upward bubbly flows in a pressurized refrigerant. The instrumentation used are the gamma densitometer and the hot-film anemometer. Departure bubble size is correlated in terms of liquid subcooling and bulk bubble size in terms of void fraction. Flow visualization techniques have also been used to understand the two-phase flow structure and the behavior of the bubbly flow for different bubble shapes and sizes, and to obtain the bubble diameter and rise velocity. The lift model is provided explicitly in terms of Eotvos number which is changed by changing the system pressure. In general, Eotvos number plays a strong role in determining both bubbly lift and drag. Such insight coupled with quantitative local and averaged data on void fraction and bubble size at different pressures has aided in developing bubbly flow models applicable to heated two-phase flows at high pressure

Experiments and Modeling in Bubbly Flows at Elevated Pressures

Measurements of local void fractio