Kinetics of Biotic and Abiotic CO Production during the Initial Phase of Biowaste Composting

Sylwia Stegenta-Dąbrowska,Karolina Sobieraj,Jacek A Koziel,Jerzy Bieniek,Andrzej Białowiec

doi:10.3390/en13205451

Sylwia Stegenta-Dąbrowska, Karolina Sobieraj + Show 3 more

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https://doi.org/10.3390/en13205451

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Abstract

Knowledge of kinetic parameters of CO production during biowaste composting is significantly important for the prediction of its course and estimation of total gas quantity. This allows increasing the control of the process, to minimize its negative impact on the environment and to protect the occupational safety of employees exposed to CO in the biowaste composting plant. For the first time, a full study of the influence of temperature and biowaste sterilization on the kinetics of CO production is presented. The lab-scale experiments used a mixture of green waste, dairy cattle manure, and sawdust in two variants: sterilized and non-sterilized samples. The process was carried out in controlled temperature reactors with measuring the concentrations of CO, O2, and CO2 every 12 h.CO production and k value increased with temperature. However, higher CO production was observed in biotic conditions between 10~50 °C, suggesting the biotic CO formation and 1st-order kinetics. The abiotic (thermochemical) process was more efficiently generating CO above 50 °C, described with a 0-order kinetic model. Additionally, the rate constant (k) value of CO production under biotic conditions was increasing up to a temperature of 60 °C, above which a slight decrease in CO production rate was observed at 70 °C. The presented results are the basis for further studies focused on the feasibility of (1) the mitigation and (2) valorization of CO production during the biowaste biostabilization are warranted.

Highlights

Carbon monoxide (CO) is an odorless gas, without color or taste, with a strong toxic effect on living organisms
For 25 ◦ C, the moisture content decreased in the abiotic variant to 58%, while it increased to almost 62% for the biotic variant
In the case of abiotic variant, the significant (p < 0.05) drop of the water content compared to the abiotic conditions at 25, 60, and 70 ◦ C (Figure 2a), but less significant than at 30 ◦ C

Summary

Introduction

Carbon monoxide (CO) is an odorless gas, without color or taste, with a strong toxic effect on living organisms. It is toxic to many microorganisms due to its ability to inhibit electron transport [1]. Composting and aerobic biostabilization processes of biowaste are sources of CO production, besides major ones such as natural forest fires and incomplete fuel combustion and through biochar production [2]. CO emissions have been observed during the composting of green waste [4], green waste with manure [5], organic waste [2], and aerobic biostabilization of the municipal waste [6]. The detection of CO during the pioneering experiments was a surprise due to the widespread belief in its primary production by incomplete combustion [7]

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