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

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