Co-digestion of the mechanically recovered organic fraction of municipal solid waste with slaughterhouse wastes


Zhang, Y. and Banks, C.J. (2012) Co-digestion of the mechanically recovered organic fraction of municipal solid waste with slaughterhouse wastes. Biochemical Engineering Journal, 68, (15), 129-137. (doi:10.1016/j.bej.2012.07.017).

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Description/Abstract

The current work aimed to resolve some long-standing questions about the potential benefits and limitations of co-digestion of slaughterhouse wastes. To achieve this, a laboratory-scale trial was carried out using the mechanically recovered organic fraction of municipal solid waste mixed with either sheep blood or a mixture of pig intestines with flotation fat. Both of these co-substrates are difficult to digest in isolation because of their high nitrogen and lipid concentrations, and are regulated as Category 3 materials under the Animal By-Products Regulations (EC 1069/2009). The results showed that at an organic loading rate of 2 kg VS m−3 day−1 with the slaughterhouse material making up 20% of the load on a volatile solids basis the process could operate successfully. As the loading was increased to 4 kg VS m−3 day−1 signs of inhibition appeared with both co-substrates, however, and volumetric methane production was reduced to a point where co-digestion gave no process advantage. The main operational problem encountered was an increase in the concentration of volatile fatty acids in the digestate, particularly propionic acid: this was thought to be a result of ammonia toxicity. The concentration of potentially toxic elements in the digestate made it unsuitable for agricultural application for food production, although the increased nitrogen content made it more valuable as a fertiliser for non-food crop use.

Item Type: Article
ISSNs: 1369-703X (print)
Keywords: naerobic processes, biodegradation, waste treatment, slaughterhouse waste, product inhibition, potentially toxic element
Subjects: Q Science > QH Natural history > QH301 Biology
T Technology > TD Environmental technology. Sanitary engineering
Divisions: Faculty of Engineering and the Environment > Civil, Maritime and Environmental Engineering and Science > Centre for Environmental Science
ePrint ID: 342078
Date Deposited: 13 Aug 2012 09:19
Last Modified: 27 Mar 2014 20:24
URI: http://eprints.soton.ac.uk/id/eprint/342078

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