Meat waste as feedstock for home composting: Effects on the process and quality of compost

Abstract

Home composting is a powerful tool, which is spreading in different parts of the world, to reduce the generation of municipal waste. However, there is debate concerning the appropriateness, in terms of domestic hygiene and safety, of keeping a composter bin in the household deputed to kitchen waste of animal origin, such as meat or fish scraps and pet droppings. The purpose of our work was to study how the addition of meat scraps to household waste influences the composting process and the quality of the final compost obtained. We compared four raw material mixtures, characterized by a different combination of vegetable and meat waste and different ratios of woody bulking agent. Changes in temperature, mass and volume, phenotypic microbial diversity (by Biolog™) and organic matter humification were determined during the process. At the end of the experiment, the four composts were weighed and characterized by physicochemical analysis. In addition, the presence of viable weed seeds was investigated and a germination bioassay was carried out to determine the level of phytotoxicity. Finally, the levels of pathogens (Escherichia coli and Salmonella spp.) were also determined in the final compost. Here we show that the presence of meat waste as raw feedstock for composting in bins can improve the activity of the process, the physicochemical characteristics and maturity of the compost obtained, without significantly affecting its salinity, pH and phytotoxicity. Pathogen levels were low, showing that they can be controlled by an intensive management and proper handling of the composter bins.

Inside the small-scale composting of kitchen and garden wastes: Thermal performance and stratification effect in vertical compost bins

“…Considering that WSC values decreased at the end of the process (see Fig. 5a), pine wood shavings in unsieved samples could have contributed to compost C total content, as it was stated before and observed by Storino et al (2016a and2016b). Thus, it could be assumed that final compost TOC was mainly composed of this more stable C source.…”

“…The C: N ratio (TOC: TKN ratio, in this study) has also been considered as a reference to assess compost stability, and it could be relevant to understand changes in the composting process. However, it is currently a controversial parameter and requires being complemented with other variables and indicators in order to evaluate the stability of a compost, as it is done in this study (Adhikari et al, 2012c;Karnchanawong and Suriyanon, 2011;Storino et al, 2016aStorino et al, , 2016b. Despite this considerations, other authors and environmental authorities have suggested a C: N ratio between 10 and 20 for defining compost stabilization (Mazzarino et al, 2012;Papadopoulos et al, 2009).…”

“…This suggests the need to carefully consider temperature average values (i.e. instead of the absolute minimum ones) as a reliable parameter to predict pathogen eradication in these systems, since sanitization requirements could not be reached in every sector of the composting mass, as it was previously observed in other decentralized composting experiences (Abdullah et al, 2013;Adhikari et al, 2012aAdhikari et al, , 2012bBarrena et al, 2014;Storino et al, 2016aStorino et al, , 2016b.…”

“…For example, as an alternative to this standard, Storino et al (2016a and2016b), recalculated the number of thermophilic days (NTD) to consider the days that the temperature of the compost was higher than 45°C. Also, these authors calculated the thermophilic heat sum (THS) as the sum of the daily differences between the temperature reached by the compost and the thermophilic threshold temperature (45°C).…”

“…However, these parameters behaviour could be quite different in small-scale composting, and it has not been fully understood yet. Compost bins without a homogenization mechanism are the simplest, common and more promoted small-scale composting devices (Smith and Jasim, 2009;Storino et al, 2016aStorino et al, , 2016b. In these composters, the process usually starts when the first of various batches of organic waste is incorporated through an opening at top of the device, and it would end when the final product can be collected from a door usually placed in the bottom part of the composter.…”