Feasibility of the use of poultry waste as polymer additives and implications for energy, cost and carbon

https://doi.org/10.1016/j.jclepro.2021.125948Get rights and content

Highlights

  • Poultry bone, meal and feathers are ideal as feedstock for polymer materials.

  • Poultry waste streams contained high value minerals and materials.

  • Poultry waste incorporation significantly reduced polymer production costs.

  • Oil usage for polymer production also dropped through poultry waste addition.

  • Energy saving were higher compared to use for energy production.

Abstract

Increased poultry production worldwide has led to higher generation of poultry waste materials. To date, these materials have limited uses and often end up in landfill. Research has begun to investigate new applications for these waste materials, particularly as fillers and functional additives with a range of polymers. With oil supplies diminishing, use of an otherwise waste material to mitigate depletion rates represents a solution that will positively impact two global industries. This paper presents a technoeconomic analysis to determine the feasibility of using three abundant poultry waste materials, bone, meal and feathers, within the polymer industry, quantifying the energy, cost and carbon implications compared to conventional polymers and the potential oil savings compared to use as a bioenergy resource. Given the complexity of such an approach the assumptions involved have been detailed. Concurrently, compositional analysis yielded a detailed breakdown of each material (minerals and organic content), which was used to determine their potential as fillers in polymer processing. Calculations concluded that use as a polymer filler, in loadings up to 40% wt. for bone and meal and 60% wt. for feathers, provided high energy, carbon and cost savings to both the polymer and poultry industries. Crude oil savings were 5 times higher than use as a bioenergy source, showing the potential of poultry waste streams as polymer additives.

Introduction

Increasing population, greater purchasing power and urbanization continue to drive increases in global poultry production. In 2018, the FAO (Food and Agriculture Organization) estimated global chicken meat production at ∼124 million tonnes annually, contributing to 36.9% global meat production (Food and Agriculture Organization of the United Nations, 2019). Increased production has brought with it an increase in the volume of waste including litter, feathers, eggshell, carcass, blood, and wastewater. Currently 66 billion chickens (Compassion in World Farming, 2018), weighing 134 million tonnes are processed worldwide each year. Globally this results in 68 billion tonnes of waste per year, equivalent to the total annual domestic waste of 150 million people (Eurostat, 2015).

With this abundance of waste being generated, it must be ensured that these waste streams are sustainably managed. Nitrogen, phosphorous, heavy metals (particularly copper and zinc) and pathogenic microorganisms contained in the waste are of primary concern (Williams et al., 1999).

In the UK ∼1.1 billion birds (including 1.05 billion broiler birds and 59 million boiling fowl) are slaughtered annually (Department for Environment Food and Rural Affairs, 2020), each with an average mass of around 2.2 kg (Bain et al., 2018). These yield over 1 billion tonnes of bone, feather, offal, and blood (Table 1).

The poultry sector is also an emitter of greenhouse gas (GHG) emissions. Agriculture accounted for 9.9% of EU GHG emissions in 2014 (Eurostat, 2018), with poultry farming responsible for 8–9% of agricultural emissions (Leip et al., 2010). Research suggests that energy-related CO2 emissions are responsible for up to 30% of GHG emissions from poultry agriculture (Leip et al., 2010), and, of the energy embedded in the poultry production chain (agriculture, processing, packaging, consumption and end-of-life), almost 90% is from fossil sources (Monforti-Ferrario et al., 2015). While the GHG emissions associated with poultry agriculture are lower than those for ruminant and pig production (for total emissions and emissions per kg of product) (Leip et al., 2010), the trend for increased poultry consumption (Bolan et al., 2010) indicates that the associated share of emissions is likely to rise.

Increased consumption, coupled with: 1) increasingly stringent agri-environmental legislation targeting reduced GHG emissions and increased uptake of renewable energy and 2) waste-to-energy incentivization schemes, have led the poultry sector toward the implementation of anerobic digestion (biogas production) (Ma et al., 2019), direct combustion (heat/power generation) (Kantarli et al., 2016), and gasification (syngas production) (Stingone and Wing, 2011). The EU has set targets for a 20% renewable energy share of gross domestic energy consumption by 2020 (European Parliament, 2009a) and 20% reduction in GHG emissions on 1990 levels by the same year (European Parliament, 2009b). Such targets are supported in the agricultural sector by the EU’s Rural Development Policy. However, waste-to-energy is not the only option for agri-waste valorization and fossil fuel displacement. Legislation and societal pressures have urged changes to pathways further up the waste hierarchy pyramid outlined in Directive (2008)/98/EC (European Parliament, 2008). While energy recovery and disposal (landfill) are the least desirable (lowest tier) end of life pathways, reuse and recycling (i.e. the use of waste materials for secondary uses, possibly replacing virgin materials) are options further up the hierarchy and offer more desirable middle tier solutions (Quina et al., 2017).

Poultry wastes streams are currently reused as compost, fertilizer and pet food (Jayathilakan et al., 2012). Evidence in literature also suggests that poultry waste materials could be used for polymer production, but there has been limited research to date. This idea is not without merit: waste streams including agricultural and forestry (Treinyte et al., 2018), used tyres (Sienkiewicz et al., 2017), palm leaves (Binhussain and El-Tonsy, 2013) and plant-based materials (Shogren et al., 2019) have all be used as polymer filler in loadings up to 50% wt. Biomass or ash produced via processes such as incineration have been also used for as polymer additives (Igarza et al., 2014). Such use displaces petroleum-based polymers (plastics) with a sustainable resource. A key driver for this has been increasing global dependence on plastic culminating in levels of polymer production in the first decade of the twenty-first century exceeding that from the previous 100 years combined (Thompson et al., 2009). The move for bio-based polymers by these environmental concerns and those in society (Scherer et al., 2017), with the use of waste materials highlighted as one method to achieved this (Ng and Sadhukhan, 2017).

Poultry wastes, or their constituent elements/compounds have huge potential to be utilized as polymer fillers or functional additives. However, composition varies with different production practices and across different geographical locations (Medugu et al., 2010). Characterisation is needed to gain accurate compositional breakdown for broiler chickens produced according to typical EU production practices. Their potential as an additive then depends on several factors: chemistry, ability to retrieve, particle size and morphology (Xanthos, 2010).

To date, the use of poultry waste streams as polymer additives has been limited to eggshell (McGauran et al., 2020), blood (Piazza et al., 2011) and feathers (Reddy, 2015). Eggshell is the most commonly used having been incorporated into polymers in loading up to 40% wt. to provide better improvements in tensile properties (McGauran et al., 2020). However poultry waste streams such as bone, meal and feathers are available in much higher quantities (Table 1), yet have not been investigated to similar levels.

To date, there has been no research on the use of poultry bones (or a derived powder) in polymers. Research has, however, developed composites incorporating 5–15% wt. bovine bone with polypropylene (Asuke et al., 2012), where increases in tensile and flexural properties were observed. Likewise hydroxyapatite (the predominant mineral found in bone) is regularly used as a functional additive in polymers utilized in biomedical applications. Research has demonstrated the potential for successful integration of bone particulates (or its facsimiles) into a range of polymer matrices (Xanthos, 2010). The use of poultry meal for polymer applications has also not yet been investigated. While no previous work has looked exclusively at poultry meal, films have been produced using mixed-meat and bone meal (in loadings up to 60%) blended with low-low density polyethylene (LLDPE) (Lukubira and Ogale, 2014). Due to the differences in protein structure between poultry meal and meat and bone meal, it is unknown whether this process could be recreated using poultry meal as the base material. Feather, utilized for fibre reinforcement, have been commonly used in a range of polymers (Reddy, 2015). The branched, fibrous nature of feathers were shown in literature to have good mechanical properties itself including tensile strength of 206 MPa, modulus of 3.6 GPa and elongation of 6.9% (Zhan and Wool, 2011). Research found increases in tensile and flexural properties with feather loading over 50% wt. (Reddy and Yang, 2010).

Ultimately the use of poultry wastes in polymer production would replace fossil oil-based feedstock, bring sustainability benefits, potentially both in terms of cost savings and displacement of fossil fuels. With 1.92 kg of crude oil needed (44% as a feedstock, 56% for processing energy) on average to produce 1 kg of plastics (Hammond and Jones, 2011), the industry uses 6.9 billion barrels of oil per year, yielding ∼359 million tonnes of polymer (Plastics Europe, 2019). This paper focuses on the three most plentiful poultry wastes, bone, meal and feathers, and seeks to answer the following questions: 1) Are poultry wastes suitable for polymer production as fillers, functional additives or polymer precursors? and 2) What are the energy, cost and carbon savings compared to conventional polymers and the oil savings compared to use as a bioenergy source?

Section snippets

Overview

The aim of this paper was to investigate the suitability of poultry wastes (bone, meal and feathers) for polymer production, both in terms of material characterisation and the energy, carbon and cost implications. The energy, cost and carbon impacts associated with biopolymer use were compared with those from conventional polymers, while the impact on resource utilization (i.e. oil feedstock) was also considered through a comparison of use of the wastes for biopolymers versus use as a bioenergy

Particle size analysis

Particle size distribution for each waste stream ranged from a consistent powder for bone and meal to fibres of varying length for feathers. D50 values were recorded at 46.0, 44.0 and 218.2 μm for bone, meal and feather fibres respectively.

Loss on ignition

The mass of samples before and after each heating stage was recorded (Table 2). These values were used to calculate the percentage of moisture, organics, carbonate and inorganics present in each material using equations 1–4:

X-ray diffraction

XRD with the addition of Rietveld

Conclusions

This paper sought to investigate alternative uses for poultry waste, which due to an expanding industry has now reached 68 million tonnes per year worldwide. In the past, the waste-to-bioenergy route has often been favoured for agricultural wastes, but these wastes can also be used for production of novel biomaterials. All three of the wastes investigated (bone, meal and feathers) hold considerable potential for the polymer industry, with characterisation testing showing the presence of organic

Credit author statement

Thomas McGauran: Data curation, Methodology, Formal analysis, Writing – original draft, Writing – review & editing Beatrice Smyth: Methodology, Formal analysis, Supervision, Resources, Writing – original draft, Writing – review & editing, Project administration Nicholas Dunne: Funding acquisition, Supervision, Resources, Writing – original draft Eoin Cunningham: Conceptualization, Funding acquisition, Methodology, Formal analysis, Supervision, Resources, Writing – original draft, Writing –

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgments

The authors would like to acknowledge financial backing from the Department for the Economy (DFE) and Moy Park (Armagh, UK) for their contribution of material supplies. The authors would also like to thank Rawan Hakawati for preliminary work on energy conversion.

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