CICEET Progress Report for the period 1/9/04 Through 3/15/05

Project Title: Evaluation of Leachfield Aeration Technology for Improvement of Water Quality and Hydraulic Functions in Onsite Wastewater Treatment Systems
Principal Investigator(s): Jose A. Amador
Additional Investigator(s): David A. Potts, Josef H. Gorres, George W. Loomis , Erika L. Nicosia
Project Start Date:1 September 2004

Figures

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5a

Figure 5b

Tasks to meet objectives
Pilot Scale Experiments: Switch from Anaerobic to Aerobic:
1. Baseline data collection
2. Switch aeration
3. Post-disturbance data collection
4. Monitoring for new equilibrium

Field Scale Experiments: Planning and Protocol Development:
1. Meet to familiarize all PIs with project goals, methods and schedule

Progress on Tasks
Pilot Scale Experiments: Switch from Anaerobic to Aerobic:
1. Baseline data (quality of water draining from lysimeters, headspace gas composition, removal efficiencies) were collected every 2 to 4 weeks for 492 days prior to the first pilot scale experiment (Figure 1). Four replicate lysimeters (filled with soil, 30-cm deep) were analyzed for each of two treatments: aerated headspace (AIR) and headspace vented to a leachfield (LEACH).

2. On December 15, 2004 we switched LEACH lysimeters from a headspace atmosphere consisting of leachfield gases (low O₂, high in CH₄, H₂S and CO₂) to an atmosphere with an O₂ concentration identical to ambient air and low concentrations of CH₄, H2₂ and CO₂. This treatment is referred as L->A. In addition, the headspace of lysimeters in the aerated treatment was switched to vent to the leachfield. This treatment is referred to as A->L.

The purpose of this experiment was to measure changes in the quality of water draining from lysimeters, as well as headspace gases and removal efficiencies for lysimeters when (1) conventional septic system leachfields are aerated by simulating the effects of SoilAir Technology (L->A) and (2) aeration is interrupted for a long period of time (A->L). Data from the latter treatment will be useful in devising a sampling schedule for our second disturbance experiment, which involves a 48-h interruption of aeration due to an accidental power loss.

3. Post-switch water quality, headspace gas composition, and removal efficiencies in the two treatments have been monitored for the past two months. Samples were collected on the day of the switch and 1, 5 12, 28, 47 and 63 days after the switch. These data are discussed in the Preliminary Data section (below).

4. Monitoring indicates that the treatments may have reached a new equilibrium, as suggested by a trend towards removal rates for N, BOD5, and fecal coliform bacteria that are similar to those observed prior to the switch. In other words, the L->A treatment behaves like the AIR treatment prior to the switch, whereas the A->L treatment behaves like the LEACH treatment did prior to the switch.

Field Scale Experiments: Planning and Protocol Development:
1. A meeting of the PIs and the End-User (RIDEM Individual Sewage Disposal Section) was held, with part of the agenda involving a discussion of the site selection criteria for field experiments, as well as potential problems and solutions associated with these experiments.

Difficulties
No technical difficulties have been encountered. However, an unnecessary delay in processing the grant paperwork at the University of Rhode Island did result in issues with personnel and purchasing that have been resolved by the PI.

Project Objectives for Next Reporting Period

Objectives
Objective A: Pilot Scale Experiments - “Accidental” Loss of Aeration
Objective B: Pilot Scale Experiments - Increase Wastewater Hydraulic Loading
Objective C: Field Scale Experiments - Protocol Development and Site Identification

Tasks to Meet Objectives
Tasks to Meet Objective A:
1. Baseline data collection to confirm equilibrium
2. Switch off aeration to the L->A lysimeters for 48 h
3. Restore aeration to the L->A lysimeters
4. Post-disturbance data collection
5. Monitor for new equilibrium

Tasks to Meet Objective B:
1. Baseline data collection to confirm equilibrium
2. Double wastewater hydraulic loading to the L->A lysimeters for 48 h
3. Restore previous wastewater hydraulic loading to the L->A lysimeters
4. Post-disturbance data collection
5. Monitor for new equilibrium

Tasks to Meet Objective C:
1. Develop protocol for field site selection
2. Develop list of potential sites
3. Perform on-site evaluation and final selection
4. Install systems, instrument sites

Work Plan for Next Reporting Period
Pilot-Scale Experiments
We will continue to monitor the quality of water draining from lysimeters, as well as efficiency and headspace gases to ensure a new equilibrium has been reached. At that point we will proceed with the second pilot scale experiment, which involves an “accidental”, short-term loss of aeration. Once the lysimeters have attained a new equilibrium condition, the last of the pilot scale experiments - doubling the wastewater load - will be conducted. We anticipate that data collection for the two remaining pilot-scale experiment will be finished by July of 2005. The data collection, analysis and interpretation will be carried out by Nicosia, Potts, Amador, and Gorres.

Field Scale Experiments
A meeting of the PIs and the End User (RIDEM) will be held in March/early April to develop a protocol for field site selection. A list of potential field sites will be developed by End-User in consultation with PIs Potts, Loomis, Gorres, and Amador by mid-April. Visits to sites for the purposes of evaluating site suitability will take place in late April/early May. Following final site selection, we will start to do the necessary site preparations, installation of instruments and of SoilAir systems as soon as the weather and soil conditions permit. Site preparation will be carried out by Potts, Gorres, Amador, and Nicosia, with Loomis and End User participation.

Anticipated Success in Meeting Project Objectives
We do not anticipate problems in meeting the project objectives for the next six months. Factors beyond our control - poor weather and soil conditions for field experiments, long equilibration times post-disturbance for the pilot-scale experiment - could put us behind schedule, but we have tried to plan for these eventualities.

Overall Project Timeline Update
At this point we are on track to finish our pilot-scale experiments on time and begin the field-scale experiments in mid-summer, as expected.

Preliminary Data
LEACH to AIR (L -> A) Treatment
Within 63 days of the switch, the L -> A treatment is behaving like the AIR treatment prior to the switch: the water quality parameters, removal efficiency for N, P, BOD and fecal coliforms, and the composition and concentration of headspace gases are similar to those for the previously aerated treatment.

In terms of water quality, the pH of effluent from the lysimeters has become increasingly acidic (indicative of nitrification and supported by nitrate data) and DO levels are at or near saturation (Figure 2). In addition, the speciation of inorganic N is close to that for aerated lysimeters prior to the switch, with nitrate accounting for more than 90% of this pool (Figure 2). Reduced iron has disappeared from the effluent water, whereas sulfate concentrations are close to those prior to the switch, after a very large increase immediately after the switch (Figure 2). The time required for these parameters to meet or exceed levels observed prior to the switch follows the order: Fe (1 d), DO (5d), SO₄ (47 d), NH₄ (63 d), NO₃ (63 d), pH (>63 d).

L -> A lysimeters are removing over 50% of the total N inputs, greater than 80% of the total P, and more than 99% of BOD₅ and fecal coliform bacteria 63 days after the switch (Figure 3). These values are either identical or higher than the average values observed for aerated lysimeters prior to the switch (dash line). The time required for these values to meet or exceed expected average levels of contaminant removal for aerated lysimeters prior to the switch (dashed line) follows the order: total P (1 d), fecal coliforms (5 d), BOD₅ (47 d), and total N (63 d).

The composition and concentration of headspace gases in the L‡A treatment reached levels observed for aerated lysimeters prior to the switch 1 d after the switch for O₂, CO₂, H₂S and CH₄ (Figure 4).

Ponding, which had been prevalent in LEACH lysimeters (Figure 5a, disappeared within 5 days of the switch to aerated conditions in L -> A lysimeters (Figure 5b).

AIR to LEACH (A -> L) Treatment
Previously aerated lysimeters have responded to the change in headspace gas composition to leachfield gases by behaving - for the most part - like lysimeters that were unaerated prior to the switch.

Levels of DO and pH values in effluent water from A -> L lysimeters are similar to those for unaerated lysimeters prior to the switch (Figure 2). The inorganic N pool is dominated by NH4, with NO3 completely absent (Figure 2). The concentration of sulfate is similar to that for LEACH lysimeters prior to the switch, whereas reduced iron levels are considerably higher than for unaerated lysimeters prior to the switch (Figure 2). The time required for these parameters to meet or exceed levels prior to the switch follows the order: NO₃ (5 d), DO (28 d), NH₄ (28 d), pH (47 d), SO₄ (63 d), Fe (>63 d).

A‡L lysimeters showed a net loss of total N for part of the experiment, but appear to be close to zero net loss 63 d after the switch (Figure 3). In contrast, total P removal is on the order of 80% and the reduction in BOD₅ is nearing that for LEACH lysimeters prior to the switch (Figure 3). Removal of fecal coliforms has reached prior levels (Figure 3). The time required to meet or exceed average values for unaerated lysimeters prior to the switch (dashed line) follows the order: total P (1 d), fecal coliforms (12 d), BOD₅ (>63 d), total N (>63 d).

The concentration and composition of headspace gases has reached pre-switch values for all four gases (Figure 4). The time required for headspace gas concentrations to meet or exceed levels observed prior to the switch follows the order: H₂S (12 d), CO₂ (12 d), CH₄ (63 d), O₂ (63 d).

AIR lysimeters did not exhibit ponding prior to the switch. Once aeration was suspended, the A -> L lysimeters became ponded 12 days after the switch.

Dissemination
Publications:
Amador, J. A., J. H. Görres, E. L. Nicosia, and D. A. Potts. 2004 Microbiological and chemical properties of aerated and conventional leachfield soil. Abstracts of the Annual Meeting of the Soil Science Society of America, Seattle, WA.

Potts, D. A., M. C. Savin, P. Tomlinson, and J. A. Amador. 2004. Leachfield bacterial community structure as affected by aeration in septic tank effluent treatment. Abstracts of the Annual Meeting of the Soil Science Society of America, Seattle, WA.

Workshops:
Amador will be giving a talk on 15 March 2005 at a workshop for coastal decision makers entitled “Denitrification Systems: New Technologies and Alternatives to Traditional Septic Systems”. The workshop is co-sponsored by the Massachusetts Coastal Training Program and the Waquoit Bay Estuarine Research Reserve in East Falmouth, MA.

Conferences:
Potts and Amador gave an invited presentation on the SoilAir system at the annual meeting of the Pennsylvania On-Site Wastewater Recycling Association in Harrisburg, PA on 13 December, 2004.

Manuals, Protocols: None

Outreach Activities:
On 31 March, 2005 Potts, Loomis, and Amador will be hosting a site visit by participants attending the upcoming 2nd Northeast Onsite Wastewater Treatment Short Course in Mystic, CT. Participants will get a tour of the Geomatrix pilot research facility in Westbrook, CT and of currently operating SoilAir systems in Southeastern CT. In addition, we hope to get some feedback from the participants with respect to future experiments that form part of our CICEET project.

Contact with End Users:
A meeting of PIs (Loomis, Nicosia, Gorres, Amador) and End-User (Moore) was held on 29 November, 2004 at the University of Rhode Island to familiarize the End User with the project objectives, tasks, and schedule and to get his input on field site identification and implementation of field experiments.

Patent, Copyright, Invention Disclosure Activity: None

Expenditures
Expenditures are lower than anticipated as a result of the unnecessary delay in processing of the grant by URI administrative personnel.

End User Advisor Feedback
Name: Brian M. Moore
Organization: RI DEM
Location: 235 Promenade Street, Providence, RI 02908
Phone number: (401) 222-4700 Ext. 7713
E-mail: brian.moore@dem.ri.gov

1) At this stage, what are the potential applications for this research? Please discuss how you and others could potentially use the technology.
Renovate existing failed drainfields.

2) What, if anything, has changed about this project's potential applicability since the last reporting period (not applicable to the first Progress Report)?
N/A

3) Do you see any key challenges that the researchers may want to address or keep in mind?
Identifying useful, appropriate sites for field testing.

4) Does this report offer you enough information to adequately address the above questions?
Yes

5) Other feedback?
No