Recycling Aquacultural Waste through Horticultural Greenhouse Production as a Resource Recovery Approach

For intensive production systems like the Blue Ridge Aquaculture (BRA), based in Martinsville, VA, there are significant economic incentives to reuse the waste by diverting it into a cropping system that would increase the total productivity and total resource-reuse efficiency, and decrease the environmental, ecological, and financial costs of aquacultural waste disposal. In order to facilitate the reuse of effluent from the tilapia production at the BRA, a green house was developed. On this site, sludge waste from recirculating aquaculture was separated and composted using a vermicomposting technique and the resulting compost was utilized as an amendment to conventional greenhouse potting mixes. These aquacultural waste products were compared to conventional greenhouse culture of a common ornamental annual plant. It was hypothesized that (1) vermicomposted aquaculture sludge would increase the growth of plants over conventional greenhouse potting mixes, and (2) recycled aquacultural wastewater can serve as a quality source of irrigation water, and plant response would differ with irrigation method. Plant growth and 11 out of 12 plant tissue nutrients were greater when compost was increased in the substrate. Plant root growth and 3 out of 12 tissue nutrients were increased when irrigated with wastewater. Plant shoot mass and total mass was greater when irrigated by ebb and flow irrigation compared to overhead mist irrigation, and 4 out of 12 tissue nutrients were greater when irrigated with mist irrigation. Overall plant performance was greatest with 15% vermicomposted sludge in the substrate and watered with wastewater by ebb and flow irrigation.