Development of 3D-printed surfaces for ultra-high surface area biofilters for water pollution remediation

EPA Grant Number: SV836951
Title: Development of 3D-printed surfaces for ultra-high surface area biofilters for water pollution remediation
Investigators: Blersch, David , Carrano, Andres
Institution: Auburn University Main Campus
EPA Project Officer: Shapiro, Paul
Phase: II
Project Period: February 1, 2017 through January 31, 2019
Project Amount: $74,310
RFA: P3 Awards: A National Student Design Competition for Sustainability Focusing on People, Prosperity and the Planet - Phase 2 (2016) Recipients Lists
Research Category: Sustainability , P3 Awards , P3 Challenge Area - Water

Description:

Water pollution is a global problem and exists wherever there is human activity. Every 20 seconds a child dies from a preventable illness caused by unsafe drinking water, poor hygiene and inadequate sanitation [1]. Although the United Nations Millennium Development Goals (MDGs) for water access have been met ahead of schedule, the world is not on track to meet goals for access to sanitation by 2015 [2]. Nearly half of the people living in developing regions still lack improved sanitation [3]. In addition, the Natural Resources Defense Council states that dirty water is the world’s biggest health risk and threatens quality of life as well as public health [4]. Water is considered polluted when impaired by anthropogenic contaminants and thereby rendered unusable as drinking water. Wastewater typically contains a combination of organic and inorganic substances, and different remediation methods exist for various pollutants. One method that addresses water pollution recovery is through biofilters that involve the cultivation of complex microbial biofilms that can grow rapidly and with high metabolic rates. Biofilms colonize a surface substratum and captures pollutants that are subsequently removed from the water by harvesting or sloughing processes. While reliably high metabolism of biofilms in these systems has been proven in many applications related to pollution remediation, the efficiency of the operation is currently limited by design of the effective colonization surface (i.e. biofilter media). Recent advances in 3D printing technologies allow for a precise fabrication of complex shapes that can provide ultra‐high surface area for a complex of bacteria and algae to colonize thus potentially increasing the pollution recovery rate of the biofilter. The goal of this Phase I project is to design, develop and evaluate new media for biofiltration of water by using complex shapes and geometries achieved with 3D printing.

Objective:

As mentioned before, preliminary mathematical refinement of the media design has shown that this area can be modulated and further improved significantly. Improvements in the order of 20‐200% additional surface area for biofilm and bacteria attachment have been achieved in the design space. A student‐designed media (called “spidosphere”) boasts an specific surface area between 1559 m2/m3 and 2000 m2/m3 which is a very promising improvement in this field; only possible because 3D printing removes all manufacturing complexity.

The specific goal of this Phase II proposal is to improve efficiency of biofiltration by advanced media design. This will be accomplished by achieving the following objectives:

  1. Optimization of biofilter media topology with multiple objectives (e.g. maximize the specific surface area or void ratio)
  2. Characterization of geometric conditions that promote mixed aerobic‐anaerobic microbial biofilm colonies;
  3. Life Cycle Assessment of high‐efficiency moving bed and trickling biofilters.

Approach:

Most commercial biofilter media provide a specific surface area that is less than 1000 m2/m3 (with the most popular media ranging between 200‐500 m2/m3). The findings in Phase I produced a spherical Gyroid media design that achieved 1168 m2/m3, almost a 12% improvement over standard commercial media. This was proved feasible via fabrication and testing in bioreactors with wastewater from agricultural (fisheries) effluents. The new designs outperform existing commercial media not only in specific surface area but also on sinking velocity as well as other factors. Furthermore, preliminary mathematical refinement of the media design has shown that this area can be modulated and further improved significantly.

Expected Results:

This phase I effort successfully challenged the existing paradigms in media design for biofilters. It proved the concept that ultra‐high surface area media designs can be realized and produced with advanced manufacturing approaches such as 3D printing. This effort also aimed at fabricating and testing these design in pilot‐scale bioreactors on agricultural wastewaters and compared them to commercially available media. This novel idea opens a wide array of possibilities that point towards a significant increase in efficiency in next‐generation biofilter technologies. These novel ideas have generated IP/invention disclosures and may likely produce patent application to lead the way towards product commercialization.

Expected outputs:

  • A set of ultra‐high surface area designs of filtration media that is shown to improve each of the three objectives: maximize specific surface area, maximize void ratio and facilitate mixed biofilm colonization.
  • A set of “green guidelines” for advance media design based on life cycle assessment.

Expected outcomes:

  • Increase on the efficiency of biofilter systems on nitrogen removal from wastewaters
  • Increased capacity of wastewater treatment systems

Supplemental Keywords:

biofilm, biofilters, Moving Bed biofilter, 3D printing, additive manufacturing.


P3 Phase I:

Development of 3D-printed surfaces for ultra-high surface area trickling biofilters for water pollution remediation