Biochar from co-pyrolysis of urban organic wastes-investigation of carbon sink potential using ATR-FTIR and TGA

authored by

Rahul Ramesh Nair, Moni M. Mondal, Dirk Weichgrebe

Abstract

Urban organic wastes (UOW) strain the infrastructures for solid waste treatment (SWT) in emerging economies. This study investigated biochar gained from three major UOW sources in India—banana peduncles (BP), a fibrous waste, from fruit markets; sewage sludge (SS) from wastewater treatment plants; and anaerobic digestate (AD) from food and market waste processing facilities—in terms of its potential to sequester and become long-term carbon sink in soils. Herein, the chemical properties (using ATR-FTIR) and thermal oxidative stability (using TGA) of biochars derived from these UOW and their three blends were examined. Biochar from SS and AD and the blends were found to possess more ash content, Cl, and alkali and alkaline earth metals (AAEM) than that from BP. The conventional recalcitrance index (R

₅₀) could not quantify and compare the stability of these mineral- and ash-rich biochars. Hence, a modified thermal oxidative recalcitrance index (TOR

_i) is proposed. All the biochar from blends prepared at highest treatment temperature of 650 °C shows similar aromaticity. However, biochar from blend of 50% SS, 30%BP, and 20% AD exhibits the highest recalcitrance (TOR

_i = 0.193) to become a long-term carbon sink in soil. More than aromaticity, the influence of Si, Fe, and AAEM on the biochar matrix affects its recalcitrance. Variations in the structural properties and recalcitrance of biochars from blends are attributable to the synergy among their constituents SS, AD, and BP. The determined TOR

_i confirms the potential of biochar from the blends of UOW as a long-term carbon sink.

Organisation(s)

Institute of Sanitary Engineering and Waste Management

Type

Article

Journal

BIOMASS CONVERSION AND BIOREFINERY

Volume

Pages

4729-4743

No. of pages

ISSN

2190-6815

Publication date

10.2022

Publication status

Published

Peer reviewed

Yes

ASJC Scopus subject areas

Renewable Energy, Sustainability and the Environment

Sustainable Development Goals

SDG 7 - Affordable and Clean Energy, SDG 11 - Sustainable Cities and Communities, SDG 12 - Responsible Consumption and Production

Electronic version(s)

https://doi.org/10.1007/s13399-020-01000-9 (Access: Open)