Systematic Review of Dairy Processing Sludge and Secondary STRUBIAS Products Used in Agriculture

Frontiers in Sustainable Food Systems

Mark G. Healy¹  Wenxuan Shi¹  Arezoo Taghizadeh-Toosi²  Peter Sørensen³  Sven G. Sommer⁴  Yihuai Hu⁴  J. J. Leahy⁵  Olha Khomenko⁵  Ángel Velasco-Sánchez⁶  Karen Daly⁷  Owen Fenton⁷  S. M. Ashekuzzaman⁷  Isabelle Trinsoutrot-Gattin⁸  Nadia Bennegadi-Laurent⁸ 

[1] College of Science and Engineering, Civil Engineering and Ryan Institute, National University of Ireland, Galway, Ireland;Danish Technological Institute, Taastrup, Denmark;Department of Agroecology, Aarhus University, Tjele, Denmark;Department of Biological and Chemical Engineering, Aarhus University, Aarhus, Denmark;Department of Chemical Sciences, School of Natural Sciences, University of Limerick, Limerick, Ireland;Soil Biology Group, Wageningen University and Research, Wageningen, Netherlands;Teagasc, Johnstown Castle, Environment Research Centre, Wexford, Ireland;UniLaSalle, Aghyle, Rouen, Rue du Tronquet, Mont-Saint-Aignan, France;

关键词: circular economy;    phosphorus;    environment–agriculture;    bio-fertilizer;    gaseous emissions (greenhouse gases and ammonia emissions);   

DOI  :  10.3389/fsufs.2021.763020

来源: DOAJ

【 摘 要 】

Worldwide dairy processing plants produce high volumes of dairy processing sludge (DPS), which can be converted into secondary derivatives such as struvite, biochar and ash (collectively termed STRUBIAS). All of these products have high fertilizer equivalent values (FEV), but future certification as phosphorus (P)-fertilizers in the European Union will mean they need to adhere to new technical regulations for fertilizing materials i.e., content limits pertaining to heavy metals (Cd, Cu, Hg, Ni, Pb, and Zn), synthetic organic compounds and pathogens. This systematic review presents the current state of knowledge about these bio-based fertilizers and identifies knowledge gaps. In addition, a review and calculation of greenhouse gas emissions from a range of concept dairy sludge management and production systems for STRUBIAS products [i.e., biochar from pyrolysis and hydrochar from hydrothermal carbonization (HTC)] is presented. Results from the initial review showed that DPS composition depends on product type and treatment processes at a given processing plant, which leads to varied nutrient, heavy metal and carbon contents. These products are all typically high in nutrients and carbon, but low in heavy metals. Further work needs to concentrate on examining their pathogenic microorganism and emerging contaminant contents, in addition to conducting an economic assessment of production and end-user costs related to chemical fertilizer equivalents. With respect to STRUBIAS products, contaminants not present in the raw DPS may need further treatment before being land applied in agriculture e.g., heated producing ashes, hydrochar, or biochar. An examination of these products from an environmental perspective shows that their water quality footprint could be minimized using application rates based on P incorporation of these products into nutrient management planning and application by incorporation into the soil. Results from the concept system showed that elimination of methane emissions was possible, along with a reduction in nitrous oxide. Less carbon (C) is transferred to agricultural fields where DPS is processed into biochar and hydrochar, but due to high recalcitrance, the C in this form is retained much longer in the soil, and therefore STRUBIAS products represent a more stable and long-term option to increase soil C stocks and sequestration.

【 授权许可】

Unknown