Hydrothermal carbonization of microalgae for phosphorus recycling from wastewater to crop-soil systems as slow-release fertilizers

Chu, Q., Lyu, T., Xue, L., Yang, L., Feng, Y., Sha, Z., Yue, B., Mortimer, R.J.G. ORCID: 0000-0003-1292-8861, Cooper, M. ORCID: 0000-0002-1864-1434 and Pan, G. ORCID: 0000-0003-0920-3018, 2020. Hydrothermal carbonization of microalgae for phosphorus recycling from wastewater to crop-soil systems as slow-release fertilizers. Journal of Cleaner Production: 124627. ISSN 0959-6526

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Abstract

Due to the finite stocks of phosphate rock and low phosphorus (P) use efficiency (PUE) of traditional mineral P fertilizers, more sustainable alternatives are desirable. One possibility is to culture microalgae in wastewater to recover the P and then convert the microalgae biomass into slow-release fertilizers through hydrothermal carbonization (HTC). Therefore, this study aimed to recycle P from wastewater to agricultural field using microalgae and HTC technology. Chlorella vulgaris (CV) and Microcystis sp. (MS) were cultured in poultry farm wastewater with an initial concentration of 41.3 mg P kg-1 9 . MS removed 88.4% P from the wastewater, which was superior to CV. CV- and MS-derived hydrochars were produced at 200 or 260°C, in solutions using deionized water or 1wt% citric acid. The MS-derived hydrochar using 1 wt% citric acid solution at 260 °C (MSHCA260) recovered the highest amount of P (91.5%) after HTC. The charring promoted the transformation of soluble and exchangeable P into moderately available P (Fe/Al-bound P), and using citric acid solution as feedwater increased the P recovery rate and formation of Fe/Al-bound P. With the abundant moderately available P pool, hydrochar amendment released P more slowly and enhanced the soil P availability more persistently than chemical fertilizer did, which helped to improve PUE. In a wheat-cultivation pot experiment, MSHCA260 treatment improved wheat PUE by 34.4% and yield by 21.6% more than chemical fertilizer did. These results provide a novel sustainable strategy for recycling P from wastewater to crop-soil systems, substituting the mineral P fertilizer, and improving plant PUE.

Item Type: Journal article
Publication Title: Journal of Cleaner Production
Creators: Chu, Q., Lyu, T., Xue, L., Yang, L., Feng, Y., Sha, Z., Yue, B., Mortimer, R.J.G., Cooper, M. and Pan, G.
Publisher: Elsevier BV
Date: 12 October 2020
ISSN: 0959-6526
Identifiers:
NumberType
10.1016/j.jclepro.2020.124627DOI
S0959652620346710Publisher Item Identifier
1376815Other
Divisions: Schools > School of Animal, Rural and Environmental Sciences
Record created by: Jill Tomkinson
Date Added: 21 Oct 2020 15:12
Last Modified: 28 Oct 2020 09:47
URI: http://irep.ntu.ac.uk/id/eprint/41392

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