Dairy processing sludge and co-products: A review of present and future re-use pathways in agriculture

Shi, Wenxuan; Healy, Mark G.; Ashekuzzaman, S.M.; Daly, Karen; Leahy, James J.; Fenton, Owen

doi:10.1016/j.jclepro.2021.128035

Cited by 63 publications

(37 citation statements)

References 95 publications

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“…The amount and composition of DPS is determined by the composition of milk and use of additives, the dairy production line and cleaning and disinfectant products used for cleaning. In addition, wastewater treatment, varies between plants (Figure 2), and depends on the type of dairy processing involved (Rico Gutiérrez et al, 1991;Karadag et al, 2015;Ahmad et al, 2019;Shi et al, 2021a). Recently, physical and chemical characteristics of 63 DPS samples (9 dairy processing plants in Ireland) were reported (Ashekuzzaman et al, 2019a).…”

Section: Wastewater Volumes and Contentsmentioning

confidence: 99%

“…Dairy processing wastes (even after treatment at source) may contain harmful substances, which need testing and quantification across all the DPS and STRUBIAS types. The substances in focus should be antimicrobial drugs, hormones, pesticides, emerging contaminants, pathogens, disinfectants, persistent organic pollutant residues, microplastics, and nanoparticles in DPS or DPS-derived STRUBIAS (Shi et al, 2021a).…”

Section: Wastewater Volumes and Contentsmentioning

confidence: 99%

“…DPS and DPS-derived STRUBIAS products are used or research is underway to ascertain their potential as bio-based fertilizers in agriculture (Shi et al, 2021a). DPS is typically stored off site until applied to land in spring, whereas STRUBIAS products can be processed and stored until needed.…”

Section: Dps and Dps-derived Strubias As Fertilizersmentioning

confidence: 99%

“…Storage and land application of DPS is a source of the greenhouses gases (GHGs), methane Abbreviations: NH 3 , Ammonia; AD, Anaerobic digesters; BOD, Biological oxygen demand; C, Carbon; CO 2 , Carbon dioxide; CWW, Cheese whey wastewater; COD, Chemical oxygen demand; CFU, Colony forming units; CLPP, Communitylevel physiological profiling; CSTR, Completely stirred tank reactor; DPS, Dairy processing sludge; DAF, Dissolved air floatation; DM, Dry matter; EU, European union; FEV, Fertilizer equivalent value; GHG, Greenhouse gas; HTC, Hydrothermal carbonification; IFSM, Integrated farm systems model; MRT, Mean residence time; MARS, Membrane Anaerobic reactor system; MBR, Membrane reactor; CH 4 , Methane; MFE, Mineral fertilizer equivalence; MFRV, Mineral fertilizer replacement value; N, Nitrogen; N 2 O, Nitrous oxide; OM, Organic matter; OTCs, Organic trace compounds; O 2 , Oxygen; P, Phosphorus; PLFAs, Phospholipid fatty acid assays; PCBs, PolyChloroBiphenyls; PAHs, Polycyclic aromatic hydrocarbons; PSM, P solubilising microorganisms; PC, Pyrolysis; RBC, Rotating biological contractors; SBR, Sequencing batch reactor; STRUBIAS, struvite, biochar, ashes; TAN, Total ammonium nitrogen; UASB, Up-flow anaerobic sludge blanket; VS, Volatile solids. (CH 4 ) and nitrous oxide (N 2 O) (Smith et al, preparation) 1 , and when applied to soil may result in incidental losses of nutrients along surface or near surface pathways (Fenton et al, 2017;Shi et al, 2021a). As production becomes more centralized on a smaller number of larger farms in some EU member states (e.g., Denmark or France), the land bank opportunities for DPS application may become limited depending on the land use change and farmer willingness to accept DPS.…”

Section: Introductionmentioning

confidence: 99%

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

Khomenko

Shi

et al. 2021

Front. Sustain. Food Syst.

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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.

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Section: Wastewater Volumes and Contentsmentioning

confidence: 99%

Section: Wastewater Volumes and Contentsmentioning

confidence: 99%

Section: Dps and Dps-derived Strubias As Fertilizersmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

Khomenko

Shi

et al. 2021

Front. Sustain. Food Syst.

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“…The high organic load of waste whey causes numerous operational problems for treatment systems [18]. Another technological hurdle lies in the high seasonal variance in waste output, which correlates with the volume of milk supply for processing (much higher in summer than winter) [19]. Aerobic processes have proven to be inefficient owing to sludge bulking and excessive biomass growth [20].…”

Section: Introductionmentioning

confidence: 99%

Microwave Radiation Influence on Dairy Waste Anaerobic Digestion in a Multi-Section Hybrid Anaerobic Reactor (M-SHAR)

2021

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Whey is a primary by-product of dairy plants, and one that is often difficult to manage. As whey processing units are costly and complicated, only 15–20% of whey is recycled for use in the food industry. The difficulties in managing waste whey are particularly pronounced for small, local dairy plants. One possible solution to this problem is to use advanced and efficient digesters. The aim of this study was to present an innovative multi-section hybrid anaerobic bioreactor (M-SHAR) design and to identify how microwave radiation heating (MRH) affects methane fermentation of liquid dairy waste (LDW) primarily composed of acid whey. The MRH reactor was found to perform better in terms of COD removal and biogas production compared with the convection-heated reactor. The heating method had a significant differentiating effect at higher organic load rates (OLRs). With OLRs ranging from 15 to 25 kgCOD∙m−3∙d−1, the M-SHAR with MRH ensured a 5% higher COD removal efficiency and 12–20% higher biogas yields.

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Phosphorus fertiliser equivalent value of dairy processing sludge‐derived STRUBIAS products using ryegrass (Lolium perenne L.) and spring wheat (Triticum aestivum)

Shi,

Fenton,

Ashekuzzaman

et al. 2023

J. Plant Nutr. Soil Sci.

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BackgroundStruvite, biochar and ash products (collectively known as STRUBIAS) derived from different waste streams are used as fertilisers in agriculture. Raw dairy processing sludge (DPS) shows promise as bio‐based fertilisers, but secondary STRUBIAS‐derived products need further testing as fertilisers.AimsThe objective of this study was to calculate the phosphorus mineral fertiliser equivalency (P‐MFE) for some STRUBIAS products derived from DPS.MethodsRyegrass (Lolium perenne L.) and wheat (Triticum aestivum) pot trials were used to determine the P‐MFE using the apparent P recovery (APR) method for Fe‐DPS and DPS‐derived struvites (Struvite 1–4), hydrochars (HC1–3) and ash.ResultsThe tested STRUBIAS products can be divided into two groups: (1) a range of products that can (i.e. Struvite 1–3) and (2) cannot (i.e. Struvite 4, HC1–3, ash and Fe‐DPS) be considered fertilisers. In the first group, the P‐MFE ranged from 66.8% to 76.7% for ryegrass and from 77.9% to 93.5% for spring wheat grain. In the second group, the P‐MFE ranged from 7.8% to 58.3% for ryegrass and from −34.5% to −151.3% for spring wheat grain. The negative agronomic effects of some products for wheat grain (struvite and HC) in this study were mainly caused by high Fe content, which could be overcome by improved treatment processes.ConclusionsFuture policy and research must be aware that not all the DPS‐derived STRUBIAS products are suitable as fertilisers and therefore need to be tested individually.

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Dairy processing sludge and co-products: A review of present and future re-use pathways in agriculture

Cited by 63 publications

References 95 publications

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

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

Microwave Radiation Influence on Dairy Waste Anaerobic Digestion in a Multi-Section Hybrid Anaerobic Reactor (M-SHAR)

Phosphorus fertiliser equivalent value of dairy processing sludge‐derived STRUBIAS products using ryegrass (Lolium perenne L.) and spring wheat (Triticum aestivum)

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