The potential of dairy manure and sewage management pathways towards a circular economy: A meta-analysis from the life cycle perspective

Junyan Zhang; Mengmeng Wang; Changbin Yin; Thomas Dogot

doi:10.1016/j.scitotenv.2021.146396

The potential of dairy manure and sewage management pathways towards a circular economy: A meta-analysis from the life cycle perspective

Sci Total Environ. 2021 Jul 20:779:146396. doi: 10.1016/j.scitotenv.2021.146396. Epub 2021 Mar 12.

Authors

Junyan Zhang¹, Mengmeng Wang², Changbin Yin³, Thomas Dogot⁴

Affiliations

¹ Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing 100081, China; Economics and Rural Development Laboratory, TERRA Teaching and Research Centre, Gembloux Agro-Bio Tech, University of Liège, Gembloux B-5030, Belgium.
² Agricultural Information Institute, Chinese Academy of Agricultural Sciences, Beijing 100081, China.
³ Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing 100081, China; Research Center for Agricultural Green Development in China, Beijing 100081, China. Electronic address: yinchangbin@caas.cn.
⁴ Economics and Rural Development Laboratory, TERRA Teaching and Research Centre, Gembloux Agro-Bio Tech, University of Liège, Gembloux B-5030, Belgium.

PMID: 33740556
DOI: 10.1016/j.scitotenv.2021.146396

Abstract

The global dairy farming sector has markedly expanded and intensified over the past decades due to the growing demand for milk and dairy products. The interest in implementing life cycle assessments of various manure and sewage management (MSM) strategies is increasing on a global scale, which is motivated by the concerns of environmental degradation caused by unsustainable MSM and growing awareness of circular economy. Life cycle thinking concept has been widely introduced to favor the comparative studies of different MSM strategies, with the aim of identifying suitable MSM strategies and formulating related policies. This meta-analysis presented comparative results of publicly available dairy MSM pathways, including waste-to-energy, composting, recycling, and other management pathways, aiming to explore potential benefits towards a circular economy. Results showed a consensus that waste-to-energy pathway significantly reduced global warming, eutrophication, and ecotoxicity potential. More specifically, the comparative performances of various detailed technologies belonging to a specified pathway were analyzed. Results indicated that anaerobic mono-digestion decreased global warming and eutrophication remarkably; its integrated management technologies reduced global warming considerably and an obvious decrease in eutrophication potential was observed. It revealed that most of current MSM strategies had limited potential and uncertain consequences to reduce environmental impacts and costs. In terms of influence factors, besides the intrinsic factor (pathway type), key extrinsic determinants including location, country income level, and farm scale were proved to affect mitigation potential of some specific impacts. Overall, it is necessary for the scientific community and policy-makers to focus on more possible trade-offs of different life cycle performances towards sustainability and circularity.

Keywords: Bioenergy; Dairy farming; Life cycle assessment; Meta-analysis; On-farm waste management; Sustainability.