Good for sewage treatment and good for agriculture: algal based compost and biochar

Cole, Andrew J., Paul, Nicholas, De Nys, Rocky, and Roberts, David A. (2017) Good for sewage treatment and good for agriculture: algal based compost and biochar. Journal of Environmental Management, 200. pp. 105-113.

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Abstract

In this study we test a novel approach to closing the anthropogenic nutrient cycle, by using the freshwater macroalga, Oedogonium intermedium, to recover dissolved nitrogen (N) and phosphorous (P) from municipal wastewater. We then convert this cultivated algae into two types of soil ameliorant; compost and biochar. To produce compost, algae was combined with sugarcane bagasse and left to mature for 10 weeks, and to produce biochar, algae was processed through slow pyrolysis at 450 degrees C. The mature compost had a total N and P content of 2.5% and 0.6%, which was 2- to 4-times lower than the algal biochar, which had a total N and P content of 5.5% and 2.5% respectively. Composting stabilized the N and P recovered from wastewater, with 80% of the initial N and >99% of the initial P retained in the mature compost. In contrast, only 29% of the initial N and 62% of the initial P was retained in the biochar. When the mature compost was added to a low fertility soil it significantly increased the production of sweet corn (Zea mays). Treatments receiving 50 and 100% compost produced 4-9 times more corn biomass than when synthetic fertilizer alone was added to the low fertility soil. When biochar was applied in conjunction with compost there was an additional 15% increase in corn productivity, most likely due to the ability of the biochar to bind labile N and P and prevent its loss from the soil. This study demonstrates a unique model for recovering N and P from municipal wastewater and recycling these nutrients into the agricultural industry. This could be an ideal model for regional areas where agriculture and water treatment facilities are co-located and could ultimately reduce the reliance of agriculture on finite mineral sources of P.

Item ID: 50528
Item Type: Article (Refereed Research - C1)
Keywords: broad-acre agriculture, soil carbon, aquaculture, nutrients, pyrolysis, sewage treatment
ISSN: 1095-8630
Funders: Australian Renewable Energy Agency (ARENA), Australian Government's Cooperative Research Centre Scheme (CRCS)
Projects and Grants: ARENA 002369, CRCS DP109602
Date Deposited: 20 Sep 2017 09:56
FoR Codes: 07 AGRICULTURAL AND VETERINARY SCIENCES > 0704 Fisheries Sciences > 070401 Aquaculture @ 25%
10 TECHNOLOGY > 1002 Environmental Biotechnology > 100203 Bioremediation @ 25%
10 TECHNOLOGY > 1003 Industrial Biotechnology > 100302 Bioprocessing, Bioproduction and Bioproducts @ 50%
SEO Codes: 82 PLANT PRODUCTION AND PLANT PRIMARY PRODUCTS > 8203 Industrial Crops > 820399 Industrial Crops not elsewhere classified @ 50%
96 ENVIRONMENT > 9609 Land and Water Management > 960912 Urban and Industrial Water Management @ 50%
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