Biodigestor

Journal of Hazardous Materials 203–204 (2012) 38–45

Contents lists available at SciVerse ScienceDirect

Journal of Hazardous Materials
journal homepage: www.elsevier.com/locate/jhazmat

Performance of in-vessel composting of food waste in the presence of coal ash
and uric acid
Chun-Jiang An a , Guo-He Huang a,∗ , Yao Yao a , Wei Sun a , Kai An b
a
b

Faculty of Engineering andApplied Science, University of Regina, Regina, Saskatchewan, S4S 0A2, Canada
MOE Key Laboratory of Regional Energy Systems Optimization, S&C Academy of Energy and Environmental Research, North China Electric Power University, Beijing 102206, China

article

info

Article history:
Received 14 July 2011
Received in revised form 24 October 2011
Accepted 20 November 2011
Available online 28November 2011
Keywords:
Composting
Food waste
Coal ash
Uric acid
In-vessel system

abstract
Massive quantities of food waste often coexist with other agroindustrial and industrial waste, which
might contain coal ash (CA) and uric acid (UA). This study investigated the influence of CA and UA on
the composting of food waste in the in-vessel system. The patterns of food waste composting werecompared among various combinations. The results showed that the temperature level was enhanced in
the presence of CA and UA during the first 8 days. The significant drop in pH was observed in the treatment
without any amendment. But the presence of CA could alleviate the drop of pH. More intensive organic
mass reduction took place in the treatments with amended CA and UA in the first half ofprocess. The
O2 uptake rate in the reactor with CA and UA was higher than that with only CA in the early stage.
Both thermophilic and mesophilic microorganisms were present throughout the composting period. The
populations of both thermophilic and mesophilic microorganisms were influenced when amended with
CA and UA. The decreasing trend in C/N ratio was shown in all the reactors, while a relativelylower C/N
ratio was obtained in the series with both CA and UA.
© 2011 Elsevier B.V. All rights reserved.

1. Introduction
With the rapid development of economy and population, a large
amount of solid waste has been generated from domestic, industrial and agricultural activities over the last few decades [1,2]. Food
waste, which can be from various sources such as restaurants, markets,residents and many other food-processing facilities, is one of
the most general forms of organic solid waste [3]. In some areas
of China and Korea, it can account for approximately more than
one quarter of the total solid waste generation [4,5]. Food waste
has been demonstrated to be a threat to human health due to the
potentially releasing of nuisance odors and leachate. Inappropriate
disposalpractice has often resulted in various economic, environmental and biological losses across the world.
Composting has been developed as one of the most promising
solid waste disposal methods for safe treatment strategies [6–8].
During the composting process, the microorganisms decompose
the substrate through breaking it down from complex to simpler
compounds under aerobic conditions [9,10].Composting can significantly reduce waste volume within various composting systems,
such as non-reactor, enclosed reactor and in-vessel systems [11].
The produced product with humus-like property can be used for

∗ Corresponding author. Tel.: +1 306 585 4095; fax: +1 306 585 4855.
E-mail address: huang@iseis.org (G.H. Huang).
0304-3894/$ – see front matter © 2011 Elsevier B.V. All rightsreserved.
doi:10.1016/j.jhazmat.2011.11.066

stimulating microbial activities and plant growth in various field
applications. From the viewpoint of green-recycling in the ecosystem, composting is an environmentally and economically sound
manner.
The properties of different solid wastes can be quite variable
and this variability could play an important role in the effectiveness
of composting....