Grantee Research Project Results

2013 Progress Report: An On-Site Biological Graywater Treatment System Suitable for a Small Business

EPA Grant Number: SU835330
Title: An On-Site Biological Graywater Treatment System Suitable for a Small Business
Investigators: Swinson, Bobbie Jo , Houser, James , Hambourger, Mike , Martin, Jack , Gamble, Kevin , Davis, Joe , Johnson, Jennifer , Barlow, Jacob , Carter, Daniela , Dipple, Kathleen , Downey, Erin , Gropper, Alexis , Kenny, Jillian , McCachren, Ross , Poston, Elizabeth , Roark, Stephanie , Stell, Ryan , Wallach, Hannah , Williams, Megan
Current Investigators: Martin, Jack , Houser, James , Hambourger, Michael , Bandala, Erick R. , Swinson, Bobbie Jo , Davis, Joseph , Edge, Chase , Martin, Benjamin , Neff, Eric , Johnson, Jennifer , Willett, Howard , Roden, Elizabeth , Bethman, Travis , deJong, Emil , Homes, Anna Maria
Institution: Appalachian State University
EPA Project Officer: Hahn, Intaek
Phase: II
Project Period: August 15, 2012 through August 14, 2014 (Extended to August 14, 2016)
Project Period Covered by this Report: August 15, 2012 through August 14,2013
Project Amount: $89,708
RFA: P3 Awards: A National Student Design Competition for Sustainability Focusing on People, Prosperity and the Planet - Phase 2 (2012) Recipients Lists
Research Category: Pollution Prevention/Sustainable Development , P3 Awards , P3 Challenge Area - Safe and Sustainable Water Resources , P3 Challenge Area - Sustainable and Healthy Communities , Sustainable and Healthy Communities

Objective:

Throughout the Phase II research period, students will be involved in creating a website for the project, as well as holding educational seminars, giving class presentations relating to the project and proposed design, and present papers at conferences while preparing a paper for journal submission. The salon setting also provides an ideal setting for educating the community about ecological design concepts, specifically grey water filtration scenarios.

Figure 1. Original trough design and alternative 'garden wall' design (front and back) by Stephanie Roark

The objectives for Phase II were the following:

• Objective A: Continue characterization of removal efficiencies of pilot-scale system.
• Objective B: Finish and test prototype design through consultation with salon owner.
• Objective C: Install and monitor a prototype system on-site in the salon.
• Objective D: Conduct outreach activities to reach the local and University community
• Objective E: Integrate process into University curriculum.

Progress Summary:

Prototype Development and Construction

Students in the Department of Technology and Environmental Design designed a number of potential systems upon which our first small full-scale prototype was built. The prototype was a two trough system with a 20 gallon storage reservoir. Water is pumped from the storage reservoir to the top trough through 1/2" PEX tubing where the water then flows by gravity through the top trough, through 3/4 inch PEX tubing to the lower trough and back to the storage reservoir through 3/4 inch PEX tubing. It is a continuous flow system with a flow meter and control valve above the pump and another flow meter where water returns to the storage reservoir. Three Matala® filters in series (low, medium and high density) are used in the storage reservoir. The open flow configuration of these filters allows high volumes of dirty water with very high biological oxygen demand to pass through without clogging. The bacteria growing on these strands form thick biofilms in an oxygenated environment with even flow distribution, which we have found reduces suspended solids and color in the salon grey water. Without the Matala® filters color reduction in the salon grey water is problematic.

A frame was attached to the prototype to hang fluorescent lights. Currently there are two four-foot bulbs hanging roughly one foot above each trough. A timer has them on for 18 hours and off for 6 hours.

A number of different pumps were tested for reliability, noise level and affordability. Inexpensive submersible pond pumps were tested first and found to be inadequate to overcome the potential head of the final proposed system (over 10 feet) and to be of inferior reliability for long-term maintenance-free operation. A Little Giant magnetic drive pump (model 2-MDQ-SC) was tested and found to meet head and flow requirements but was determined to be too noisy. Ultimately a TACO 008-SF6 cartridge circulator pump was determined to be the best fit for the prototype and, ultimately, the final installed system. The TACO pump is completely silent and a pump routinely used in solar domestic hot water systems which require long-term continuous operation. The pump is more expensive than the others but reliability and performance of the pump is a major key component of the system.

Trial runs were performed to check the hydraulic performance of the system and to determine an equilibrium flow rate. Ultimately, using in-line control valves, a final flow rate of 0.7 gallons/minute was found to be the optimum flow rate to balance the hydraulics of the system, which was similar to the flow rate of the Phase I living system (0.5 gallons/minute). A dye study was conducted to ensure that flow through the system was consistent and that there were no "dead-zones" or eddies were flow did not occur or that flow did not "short-circuit" through the trough. The dye study revealed that flow was uniform and diffuse. The entire system holds about 34 gallons, so at a flow rate of 0.7 gallons/min, water passes through the system about 30 times per day.

Building codes for grey water systems in North Carolina require that there be no exposed open water, so the prototype has covered troughs with holes cut in them for potted plants to fit in so that their roots sit in the grey water. Different configurations for pot placement were investigated to maximize the number of plants while not impinging on flow inlets and outlets.

Plants and Growing Medium

Shade tolerant, wetland plants that have a short stature have been investigated. We are currently using dwarf horsetail (Equisetum scirpoides), elephant ear (Colocasia sp.), and ferns from Edenspace Systems Corporation. The edenfern ^TM is specifically bred for phytoremediation in partial shade. We experimented with using rock wool as the growing medium but had a problem with grey water wicking to the surface, so we are using hydroponic Growstones®.

A control test with uncovered troughs, no plants and salon water was performed. Then a test with covered trough and no plants was performed and lastly trials have been performed with plants in place. Batch trials were run up to 12 days with continual recirculation.

Water passed through artificial wetland beds was tested for contaminant removal by GC-MS (primary test method), liquid chromatography (UV-vis detection), and by colorimetric assay. This was a continuation of the methods used during Phase I funding. However, during the Phase II funding period, the decision was made to transition to alternative methods for water analysis. This change was undertaken to better align our measurements with the recent NSF/ANSI 350-2011 standard "Onsite residential and commercial water reuse treatment systems." Following this standard, the following parameters were chosen for analysis - temperature, pH, turbidity, total suspended solids (TSS), biochemical oxygen demand (BOD₅), and total coliform bacteria. These tests were taken as a reasonable subset of the specifications listed in the NSF/ANSI 350-2011 standard. These tests are expected to report on water quality (temperature and pH), particulate matter (turbidity and TSS), chemical contamination (BOD₅), and bacterial contamination (coloform bacteria).

For each test, Standard Methods (Standard Methods for the Examination of Water and Wastewater, 20^th ed, 1998, Washington DC. Clesceri, Greenberg, and Eaton editors) were followed - temperature (SM 2550 B); pH, electrometric (SM 4500-H⁺ B); nephelometric turbidity (SM 2130B); total suspended solids (SM 2540 D); 5-day biochemical oxygen demand (BOD₅), (SM 5210 B); and total coliform bacteria (SM 9221 B)

Meters were obtained and calibrated for measurement of temperature, pH, and nephelometric turbidity. Standard solutions were used as quality controls to ensure appropriate measurement of total suspended solids and biochemical oxygen demand. Coliform bacteria counts have not yet been undertaken. However, arrangements have been made to use equipment in the Department of Biology for these measurements after a UV-sterilization unit is installed on the prototype 'living system'. These new analytical methods offer a straightforward method to reproducibly assess water quality before and after filtration through the prototype model. Sample results are shown in Figures 3 and 4 for turbidity reduction and pH.

Dissolved oxygen (DO) measurements were also taken of grey water in the system and was found to be low, about 50% of saturation. Aerators were added to increase DO saturation, but this motivated us to reincorporate cascades into our final design.

During the funding period, abiotic water filtration media (sand, 'biochar', and a combination of the two) were tested for contaminant removal.  Water samples before and after filtration were analyzed by GC-MS, liquid chromatography, and UV-vis light scattering.  These results showed that both sand and 'biochar' filters removed scattering particles (note that these measurements were performed prior to obtaining a nephelometric turbidity meter). Key components observed by GC-MS analysis were readily removed by filtration through 'biochar'. As a control, filtration of grey water samples through a 0.45 micron PTFE filter did not show removal of contaminants in GC-MS analysis.  Parabens were also shown to be removed following 'biochar' filtration (as analyzed by liquid chromatography).

Figure 2. Turbidity change in salon grey water  after circulation through prototype with plants                         

Figure 3. pH change in salon grey water aftercirculation through protoype with plants

Future Activities:

The prototype is performing well, operating continuously without problems and improving the quality of grey water within a few days (Figure 2). However, DO has been a problem and aesthetically we wanted to incorporate more of a water feature into the wall, while maintaining the building code requirement of no exposed open water in a grey water treatment system. Figure 4 shows our current proposed design. In the design the troughs pass water through the wall where it cascades to the next lower trough behind a transparent shield. It still needs to be modified to include the coffee bar and incorporate sink locations and towel racks etc. Our next task is to, in consultation with the salon owner, design and build a full scale version of this system so that thorough testing of hydraulics, removal efficiencies and automated systems for delivering treated grey water to the toilets can be completed before installation of the system in the actual salon. We have some concerns about the time it will take to actually finish the final installation in the salon as bidding and inspections often take a long time, and we do not expect to complete construction and testing of the full-scale prototype until the end of the Spring 2014 semester. However, there is the possibility that the full-scale system may be able to be dismantled and reassembled in the salon, greatly facilitating the final construction process.

Figure 4. Preliminary final design for salon grey water system.

Journal Articles:

No journal articles submitted with this report: View all 5 publications for this project

Supplemental Keywords:

Living system, grey water treatment, sustainable water management, water purification technologies, sustainable development, ecological water purification, pharmaceuticals in water, treatment technologies, sustainable urban planning, environmental planning, bioengineering, biofiltration technology.

Progress and Final Reports:

Original Abstract

2014 Progress Report

2015

Final Report

P3 Phase I:

An On-Site Biological Graywater Treatment System Suitable for a Small Business  | Final Report