SBIR-STTR Award

We propose to determine optimal combinations of floating media sizes, shapes, and specific gravities to meet the deign criteria for treatment aquaculture backwash waters and effluents, aquacultural influent treatment systems, water pretreatment systems, nutrient harvesting systems and display aquaria applications. Specifically, we need to identify combinations that will achieve at least 90 percent removal efficiency on the 5-10 micron particle size category. APPROACH: The experiments will generate particle size capture data, turbidity and TSS measurements from six different media, three different media combinations and three different media bed depths using small-scale, single pass, up-flow floating media filter test chambers. Tests of influent and effluent water samples will be run to accurately determine the single pass capture efficiency of the test media. After analyzing the resulting particle size and frequency data, the two best performing media configurations will be re-tested using organically rich waters and propeller washing mechanisms to determine their resistance to biofouling. NON-TECHNICAL SUMMARY: There is an immediate demand for floating bead filters with improved single pass removal characteristics for wastewater treatment. AST has identified several potential areas of bead filter application that are inhibited by poor single pass removal of fine particles. These potential areas of application include treatment aquaculture backwash waters and effluents, aquacultural influent treatment systems, water pretreatment systems, nutrient harvesting systems and display aquaria. Successful completion of this research effort will facilitate rapid expansion into several new markets including agriculture and domestic wastewater treatment, potable water treatment, swimming pool filtration, industrial cooling water systems, and educational applications such as zoos and large public aquaria.

Keywords:
aquaculture; bead filters; clarification; filtration; effluent treatment

Commercial-scale marine aquaculture has the potential to balance the increasing demand for high-quality seafood products with the limited harvest capacity of our nations oceans. However, water reuse in recirculating aquaculture systems (RAS) is limited by the accumulation of nitrate, which can be toxic to many species, especially marine species. Thus, nitrate removal by denitrification presents a pressing need for the continued expansion of intensive recirculating aquaculture. In the waste treatment industry, denitrification has traditionally been achieved by adding methanol or a similar chemical to act as the necessary carbon source, which requires sophisticated computer monitoring and control systems. This project proposal will continue to investigate the potential for using Polyhydroxyalkanotes (PHAs), a biodegradable biopolymer produced from sugar fermentation, as an alternative carbon source for denitrification in aquaculture systems. Through a series of lab-scale denitrification bioreactor studies, the denitrification capabilities of PHA were quantified at more than 2.0 kg/m3-day using the effluent from a research production tank stocked with tilapia. The problems associated with clogging and short circuiting of the PHA filter bed were addressed by utilizing the PolyGeyser® bead filter technology which promoted a healthy thin biofilm due to its characteristic frequent and gentle backwashing. This Phase II project will cumulate with the development of a commercial PolyGeyser® Denitrification Filter employing PHAs as a simple, low-cost alternative to the relatively complex existing treatment methods. The final goal is to develop commercial systems to complement the exiting line of PolyGeyser® bead filter to provide both nitrification and denitrification in aquaculture systems.