Closing nutrient cycles with biochar- from filtration to fertilizer

Many food manufacturers in the U.S. are attempting to reduce the environmental footprint of their high biological oxygen demand (BOD) effluents due to increased risk of financial surcharges from publically owned treatment works, water scarcity issues and changes in societal opinions about large scale biodegradable waste releases. Managers at these firms are often reluctant to consider on-site processing due to their fear of committing to unfamiliar and complex wastewater treatment processes with excessive capital expenditures. While an abundance of research has been performed on the use of bio-char (i.e. charcoal intended to be used for agricultural purposes produced from organic waste feedstocks via pyrolysis) to mitigate the problem of heavy metal ions from traditional manufacturing effluents by filtration, little is known on biochar's potential to treat high BOD industrial aqueous food wastes. This paper attempts to fill this gap by gauging the environmental and financial sustainability of a vertically integrated biochar filtration system, wherein maple wood biochar is used to treat high BOD tofu whey effluent and subsequently re-utilize that material as an enriched value-added soil amendment to improve crop quality and yields in basil and lettuce. Results show whey filtered biochar significantly increased fresh weight in basil and lettuce above the no biochar and unfiltered biochar controls. This novel approach could potentially help food and beverage manufacturers sustainably reduce their carbon and water footprints by harvesting and monetizing the nutrients found in their wastewaters, while allowing farmers to close regional nutrient cycles by returning nutrient rich carbon to the soil and reduce the use of synthetic fertilizers or costly peat moss or perlite soil amendments in greenhouses. (C) 2018 Elsevier Ltd. All rights reserved.