Fwd: sustainable biofloc auaculture

---------- Forwarded message ----------
From: Pannirselvam P.V <pannirbr@gmail.com>
Date: Sat, Jun 18, 2011 at 11:33 AM
Subject: sustainable biofloc auaculture
To: Mário Cardoso <mcardosozoot@gmail.com>, ecobusinessnetwork@grouplygroups.com, "pannirbr.biomassenergybr" <pannirbr.biomassenergybr@blogger.com>, GPECBIOMASS <biomasstech@googlegroups.com>, 

Aquaculture 2010 - Meeting Abstract

801

SUSTAINABLE BIOFLOC TECHNOLOGY: USING BIOREACTORS TO TREAT AQUACULTURAL EFFLUENTS WHILE PRODUCING BIOFLOCS FOR SHRIMP FEED

David Kuhn*, Addison Lawrence, Gregory Boardman, Susmita Patnaik, Lori Marsh, George Flick

*Department of Food Science and Technology 
Virginia Polytechnic Institute and State University (Virginia Tech)
FST Building (0418), Blacksburg, VA 24061
davekuhn@vt.edu

Seafood is the only protein source in the human diet that is still dependent on wild stocks, whether it comes from direct harvests or use of marine meals/oils in aquaculture diets. Experts agree that overexploitation of wild fisheries is becoming more common. Aquaculture has the potential to reduce pressure on wild populations and meet the world demand for seafood. However, significant challenges still remain and need to be overcome before aquaculture becomes more sustainable. This work addresses two problems facing the aquaculture industry, the reliance on large quantities of fresh water and the need to use unsustainable ingredients in aquaculture feeds. Specifically, researchers have investigated the feasibility of recovering and processing bioflocs generated from wastewater treatment devices used in recirculating aquaculture and using this processed biofloc as a protein-rich component for aquaculture feeds. This biofloc technology consists of two major processes: (1) biologically removing pollutants from fish effluent, which increases the feasibility of water reuse, and (2) using the resulting biofloc as a protein-rich ingredient in shrimp feed, thereby reducing other protein requirements (e.g. fishmeal). 

Pilot-scale, sequencing batch reactors (SBRs) and membrane biological reactors (MBRs) were successfully used in this study to remove pollutants in fish effluent from a farm that uses recirculating aquaculture systems (RAS). Removals (> 85%) of ammonia, nitrite, nitrate, organic carbon, and suspended solids exceeded 85% for each parameter. Bioflocs harvested from both of these reactor types proved to be a suitable and often superior ingredient, to soybean protein and fishmeal in lab-scale feeding trials with the marine shrimp, Litopenaeus vannamei. High quality control diets were compared against experimental diets in 35-day feeding trials. Experimental diets were varied greatly and notable independent variables included complete replacement of soybean protein, two-thirds replacement of fishmeal, and no fish oil. Biofloc inclusion always increased growth rates and ranged from a low average increase of 4% to a high average of 67% over the control diets; the latter percent increase was significant at P < 0.01. Based on the results of our studies, it seems that biofloc technology represents a promising option for sustainability of the aquaculture industry.