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Uhlemann JPR, Oude Lansink A, Leahy JJ, Dalhaus T. Do investments in phosphorus recovery from dairy processing wastewater pay off? JOURNAL OF ENVIRONMENTAL MANAGEMENT 2024; 357:120606. [PMID: 38583387 DOI: 10.1016/j.jenvman.2024.120606] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2023] [Revised: 02/14/2024] [Accepted: 03/10/2024] [Indexed: 04/09/2024]
Abstract
While phosphorus fertilizers contribute to food security, part of the introduced phosphorus dissipates into water bodies leading to eutrophication. At the same time, conventional mineral phosphorus sources are increasingly scarce. Therefore, closing phosphorus cycles reduces pollution while decreasing trade dependence and increasing food security. A major part of the phosphorus loss occurs during food processing. In this article, we combine a systematic literature review with investment and efficiency analysis to investigate the financial feasibility of recovering phosphorus from dairy processing wastewater. This wastewater is particularly rich in phosphorus, but while recovery technologies are readily available, they are rarely adopted. We calculate the Net Present Value (NPV) of investing in phosphorus recycling technology for a representative European dairy processing company producing 100,000 tonnes of milk per year. We develop sensitivity scenarios and adjust the parameters accordingly. Applying struvite precipitation, the NPV can be positive in two scenarios. First, if the phosphorus price is high (1.51 million EUR) or second if phosphorus recovery is a substitute for mandatory waste disposal (1.48 million EUR). However, for a variety of methodological specifications, the NPV is negative, mainly because of high input costs for chemicals and energy. These trade-offs between off-setting pollution and reducing energy consumption imply, that policy makers and investors should consider the energy source for phosphorus recovery carefully.
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Affiliation(s)
- Jan-Philip R Uhlemann
- Business Economics Group, Wageningen University and Research, Wageningen, the Netherlands.
| | - Alfons Oude Lansink
- Business Economics Group, Wageningen University and Research, Wageningen, the Netherlands
| | - James J Leahy
- Department of Chemical Science, University of Limerick, Limerick, Ireland
| | - Tobias Dalhaus
- Business Economics Group, Wageningen University and Research, Wageningen, the Netherlands
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Kwapinska M, Pisano I, Leahy JJ. Hydrothermal carbonization of milk/dairy processing sludge: Fate of plant nutrients. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2023; 345:118931. [PMID: 37688960 DOI: 10.1016/j.jenvman.2023.118931] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2023] [Revised: 08/24/2023] [Accepted: 09/02/2023] [Indexed: 09/11/2023]
Abstract
Dairy processing sludge (DPS) is a byproduct generated in wastewater treatment plants located in dairy (milk) processing companies (waste activated sludge). DPS presents challenges in terms of its management (as biosolids) due to its high moisture content, prolonged storage required, uncontrolled nutrient loss and accumulation of certain substances in soil in the proximity of dairy companies. This study investigates the potential of hydrothermal carbonization (HTC) for recovery of nutrients in the form of solid hydrochar (biochar) produced from DPS originating from four different dairy processing companies. The HTC tests were carried out at 160 °C, 180 °C, 200 °C and 220 °C, and a residence time of 1h. The elemental properties of hydrochars (biochars), the content of primary and secondary nutrients, as well as contaminants were examined. The transformation of phosphorus in DPS during HTC was investigated. The fraction of plant available phosphorus was determined. The properties of hydrochar (biochar) were compared against the European Union Fertilizing Products Regulation. The findings of this study demonstrate that the content of nutrient in hydrochars (biochars) meet the requirements for organo-mineral fertilizer with nitrogen and phosphorus as the declared nutrients (13.9-26.7%). Further research on plant growth and field tests are needed to fully assess the agronomic potential of HTC hydrochar (biochar).
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Affiliation(s)
- Marzena Kwapinska
- Dairy Processing Technology Centre, University of Limerick, Limerick, V94 T9PX, Ireland.
| | - Italo Pisano
- Department of Chemical Sciences, University of Limerick, Limerick, V94 T9PX, Ireland.
| | - James J Leahy
- Department of Chemical Sciences, Bernal Institute, University of Limerick, Limerick, V94 T9PX, Ireland.
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Ebrahimi M, Friedl J, Vahidi M, Rowlings DW, Bai Z, Dunn K, O'Hara IM, Zhang Z. Effects of hydrochar derived from hydrothermal treatment of sludge and lignocellulose mixtures on soil properties, nitrogen transformation, and greenhouse gases emissions. CHEMOSPHERE 2022; 307:135792. [PMID: 35872065 DOI: 10.1016/j.chemosphere.2022.135792] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2022] [Revised: 07/17/2022] [Accepted: 07/18/2022] [Indexed: 06/15/2023]
Abstract
In this study, hydrochar samples derived from hydrothermal treatment (HTT) of sludge and sludge-biomass mixtures were applied to a sandy soil and their effects on soil properties, soil nutrients, greenhouse gas (GHG) emissions, and soluble heavy metals were investigated. The application of untreated sludge and hydrochar derived from HTT of sludge at 180 °C led to the highest soluble nitrate, CO2 and N2O emissions, followed by the application of hydrochar samples derived from HTT of sludge-biomass mixtures at 180 °C. Although the application of hydrochar samples derived from HTT of sludge alone and sludge-biomass mixtures at 240 °C in sandy soil led to the lowest emissions of CO2 and N2O, it resulted in lower levels of soil electrical conductivity (EC), cation exchange capacity (CEC) and soluble phosphorus. The application of hydrochar samples derived from HTT at 240 °C led to the production of CH4 and lower nitrate-N contents than hydrochar samples derived from HTT at 180 °C. These results indicated that the soils containing hydrochar samples from HTT at 240 °C were anaerobic, which might inhibit the growth of plants. The application of hydrochar samples derived from HTT of sludge-biomass at 180 °C led to significantly improved contents of soil soluble phosphorus (2.56 and 2.84 g kg-1 soil) and soil nitrate-N (160.2 and 263.2 mg kg-1 soil) at the end of 60 days of incubation. However, these contents were lower than the contents of soluble phosphorus (3.71 and 4.45 g kg-1 soil) and nitrate-N (528.3 and 583.2 mg kg-1 soil) with the application of untreated sludge and sludge derived from HTT of sludge alone at 180 °C. Although more studies are needed to understand the mechanisms and effects on different soils, this study provides useful insights into the application of hydrochar derived from sludge-biomass mixture in soil.
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Affiliation(s)
- Majid Ebrahimi
- Centre for Agriculture and the Bioeconomy, Faculty of Science, Queensland University of Technology, Brisbane, Queensland 4000, Australia; School of Mechanical, Medical and Process Engineering, Faculty of Engineering, Queensland University of Technology, Brisbane, Queensland 4000, Australia.
| | - Johannes Friedl
- Centre for Agriculture and the Bioeconomy, Faculty of Science, Queensland University of Technology, Brisbane, Queensland 4000, Australia; School of Biology and Environmental Science, Faculty of Science, Queensland University of Technology, Brisbane, Queensland 4000, Australia
| | - Mohammadjavad Vahidi
- Department of Soil Science, Faculty of Agriculture, University of Birjand, Birjand, Iran
| | - David W Rowlings
- Centre for Agriculture and the Bioeconomy, Faculty of Science, Queensland University of Technology, Brisbane, Queensland 4000, Australia; School of Biology and Environmental Science, Faculty of Science, Queensland University of Technology, Brisbane, Queensland 4000, Australia
| | - Zhihui Bai
- Key Laboratory of Environmental Biotechnology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China; College of Resources and Environment, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Kameron Dunn
- Centre for Agriculture and the Bioeconomy, Faculty of Science, Queensland University of Technology, Brisbane, Queensland 4000, Australia; School of Mechanical, Medical and Process Engineering, Faculty of Engineering, Queensland University of Technology, Brisbane, Queensland 4000, Australia
| | - Ian M O'Hara
- Centre for Agriculture and the Bioeconomy, Faculty of Science, Queensland University of Technology, Brisbane, Queensland 4000, Australia; School of Mechanical, Medical and Process Engineering, Faculty of Engineering, Queensland University of Technology, Brisbane, Queensland 4000, Australia
| | - Zhanying Zhang
- Centre for Agriculture and the Bioeconomy, Faculty of Science, Queensland University of Technology, Brisbane, Queensland 4000, Australia; School of Mechanical, Medical and Process Engineering, Faculty of Engineering, Queensland University of Technology, Brisbane, Queensland 4000, Australia.
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