Valorization of Swine Manure into Hydrochars

Abstract

There is a significant interest in valorizing swine manure that is produced in enormous quantities. Therefore, considering the high moisture content in swine manure, the objective of this research was to convert manure slurry into hydrochars via hydrothermal carbonization and analyze the yields, pH, energy contents, and thermal and oxidation kinetic parameters. Experiments were performed in triplicate in 250 mL kettle reactors lined with polypropylene at 180 °C, 200 °C, 240 °C, 220 °C, and 260 °C for 24 h. Analyses of the results indicated that the process temperature affected the hydrochar yields, with yield generally decreasing with increasing temperature, but it had little effect on the composition of the hydrochar. The hydrochars were found to have higher volatile contents and H/C and O/C ratios and about 85% of the energy compared to coal. However, the presence of high fraction (35–38%) of ash in hydrochars is a serious concern and needs to be addressed before the complete utilization of hydrochars as fuels. The surface characterization of hydrochars coupled with wet chemistry experiments indicated that hydrochars were equipped with nitrogen functional groups with points of zero charges between 6.76 and 7.85, making them suitable as adsorbents and soil remediation agents and energy storage devices.

Organic waste valorisation towards circular and sustainable biocomposites

“…It is also used for active air and water filtration given its effective binding to heavy metals. [90][91][92] The abundant nutrients in manure ( phosphorus, nitrogen, potassium, sulphur) 93 make this biowaste a water and solid contaminant when inappropriately managed. Therefore, it is necessary to provide efficient recycling or upcycling approaches to profit from the 73 million tons of manure produced each year in the United States alone.…”

“…94 Swine manure has potential for hydrochars via hydrothermal carbonization. 93 These carbon structures are used for energy storage or soil/water remediation purposes. The high cellulose content of (elephant) manure could be exploited to obtain nanocellulose through an energy-efficient approach profiting from the cellulose already attacked by animal acid and enzymes.…”

Modeling of thermochemical conversion of waste biomass – a comprehensive review

“…Similar to pyrolysis, the carbon content of biomass is increased while oxygen and hydrogen contents are decreased, thus resulting in a higher energy-dense hydrochar. The produced hydrochar has improved fuel properties such as high calorific value, high carbon content, high degree of homogeneity, low degradability, hydrophobicity, better self-binding properties, etc., and it is comparable to bituminous or lignite coal (Baratieri et al, 2015;Lentz et al, 2019). However, the distribution, composition, and structure of HTC products, including the properties of hydrochar (HHV, porosity, moisture content, etc.…”

“…Moreover, HTC allows recovering valuable chemicals and nutrients from waste biomass. Some studies (Liu et al, 2017b;Lentz et al, 2019) claim hydrochar has more developed porosity than biochar, making it more suitable for soil remediation, enrichment, and carbon sequestration. Further, Gascó et al (2018) reported that HTC could concentrate phosphorus and heavy metals in hydrochar.…”

Integration of Hydrothermal Carbonization and Anaerobic Digestion for Energy Recovery of Biomass Waste: An Overview

“…HTC was first studied by Nobel laureate Friedrich Bergius (1913), who described the process of carbonization in a few hours by means of high temperature and self-generated pressure . In recent years, HTC technology has received growing attention at lab and pilot-plant scale, and a number of full-scale projects have been developed with different biomass wastes, such as sewage sludge, − animal manure, ,, biowaste, , lignocellulosic biomass − and mixed residues. − Some pilot-scale HTC plants have been constructed (Ingelia, HTCycle, Terranova Energy, Ava CO 2 ), but thus far, the detailed structure of such plants and their efficiencies are still unknown to most researchers involved in HTC.…”