CICEET Progress Report for the period 3/16/06 Through 9/15/06

Project Title: Integrated Biofilm Reactor for Nitrogen Removal from Wastewater
Principal Investigator(s): Robert Nerenberg
Project Start Date: 9/01/05 (funded as of 11/20/05)

Figures

Figure 1

Figure 2

Tasks to meet objectives
Task 2 ­ Construct Bench-Scale Systems
Task 3 ­ Develop Analytical Methods
Task 4 ­ Continuous Literature Review
Task 5 ­ Performance Screening Tests
Task 6 ­ Microbial Structure and Function Tests
Task 8 ­ Pilot Scale Design and Testing Plan

Progress on Tasks
Task 2 ­ Construct Bench-Scale Systems. Second and third-generation MBfP configurations were developed and tested. The second generation reactor increased the membrane packing density from 43 m²/m³ (see Progress Report 1) to 90 m²/m³, and periodic N₂ sparging was used to improve mixing. Specific removal rates were initially similar to those of the first generation, but biofilm accumulation eventually filled the spaces between the membranes and led to lower specific removal rates.

In the third generation configuration, bundles of 32 membranes were grouped into manifolds, and eight of these manifolds connected in a row. Eight rows were used for the membrane bank. This configuration allows the packing density to be modified by changing the row spacing. It also allows ready access to membranes for thickness measurements and biofilm sampling. The reactor is being operated with a 10-hour hydraulic retention time (HRT), a 2-day SRT, and a 5 psi(g) air in the membranes. Currently, the reactor is being operated with ammonium and no BOD to establish a nitrifying biofilm.

Task 3 ­ Develop Analytical Methods. A large effort was made to develop methods for constructing liquid ion exchange (LIX) microsensors, which are not commercially available and needed to measure nitrate, nitrite, and ammonia gradients within the biofilm. Preliminary work was also carried our on several microbial ecology techniques, including DNA extraction and amplification by PCR, cloning and sequencing of PCR products, denaturing gradient gel electrophoresis (DGGE), quantitative PCR (qPCR), and fluorescence in situ hybridization (FISH).

Task 4 ­ Continuous Literature Review. We continue compiling and reviewing literature related to our research topic. This information will be added to a literature review section in our final report.

Task 5 ­ Performance Screening Tests. The second generation MBfP was operated with an influent of 20 mg/L NH₃-N and 120 mgBOD/L of acetate. This reactor was operated for only 50 days, and was ineffective for the last two weeks. Excessive biomass accumulated in the densely packed membrane bank due to insufficient hydraulic shear, resulting in reduced nitrification rates. Initial removal rates were similar to those reported in Progress Report 1 (See Figure 1). Periodic sparging of the tank with nitrogen gas proved to be an effective means of mixing the bulk liquid surrounding the membrane bank. Sparging 30 seconds every 2 minutes at a pressure of 10 psi(g) proved to be the most effective pattern, as flocs of suspended solids were prevented from settling, and the bulk liquid had a homogeneous level of suspended solids content. Periodic sparging will be used in future prototypes.

Tests with the third generation reactor were recently started. Results will be provided in the next progress report.

Task 6 ­ Microbial Structure and Function Tests. A preliminary investigation of the microbial ecology of the biofilm and suspended biomass for the first generation reactor was conducted using DGGE. DGGE indicated significant differences between the biomass attached to the membrane surface and the suspended solids (See Figure 2). It appears that both nitrifying and heterotrophic biomass was attached to the membrane, however nitrifying bacteria were only present in the biofilm and not in the suspended biomass. Currently, steps are being taken to quantify the difference between the suspended and attached biomass in the MBfP during TN removal. We currently are developing a clone library from the biofilm and suspended biomass to help identify the species in the DGGE bands.

A new “column reactor” configuration is being used to study of the microbial structure and function on a biofilm under varying BOD:NH₃ conditions. The column reactors include a single membrane in side a glass tube. The membrane is inoculated with activated sludge, and a biofilm develops under different BOD:NH₃ conditions that may be present in the full scale MBfP reactor. Sampling ports have been included to allow easy access for microsensor measurements. A cryosectioning technique has been developed to section the membrane for microbial ecology analysis by FISH.

Task 8 ­ Pilot Scale Design and Testing Plan

We are awaiting the results of the third generation reactor before beginning the pilot scale design. This may delay the pilot-scale tests.

Have the results/data gathered during this reporting period changed the project objectives when compared to your original proposal?

Data Generated to date
Please see Figures 1 and 2, as referenced above.

Project Objectives for Next Reporting Period

Objectives
The objectives for the next reporting period are: (1) continue bench scale screening tests to determine an effective fiber configuration and mixing approach, and to determine necessary operational parameters; (2) investigate the MBfP biofilm’s microbial function and structure; and (3) begin design and construction of the pilot scale MBfP reactor.

Tasks to Meet Objectives
The third generation MBfP prototype has been constructed and is currently being operated. The third prototype is similar in design to the anticipated pilot scale reactor. A simplified column reactor has been designed to examine the microbial structure and function of a biofilm grown under varying conditions that the MBfP reactor may be exposed to. Development of a pilot scale design and testing plan will continue.

Work Plan for Next Reporting Period
Bench scale work will continue at the University of Notre Dame. Design and construction of the pilot scale reactor will begin as a joint effort between APT, Metcalf & Eddy, and the University of Notre Dame.

Dissemination Objectives for next reporting period
Workshops: None

Conferences:
(1) “Concurrent Nitrification, Denitrification, and BOD Removal in a Hybrid Membrane Biofilm Reactor” was presented at the IWA World Water Congress in Beijing, September 11, 2006;
(2) "Performance and microbial ecology of the hybrid membrane biofilm process (HMBP) for concurrent nitrification and denitrification” was accepted for platform presentation at the IWA Biofilms VI Conference in Amsterdam, September 25, 2006.
(3) “Concurrent Nitrification, Denitrification, and BOD Removal in a Hybrid Membrane-Biofilm Reactor,” was accepted for presentation at the Indiana Water Environment Association Annual Conference, Indianapolis, November 18, 2006.
(4) “The Hybrid Membrane Biofilm Process (HMBP): A Novel Technology for Upgrading Activated Sludge Plants to Achieve Biological Nitrogen Removal” was submitted to the IWA/WEF conference Nutrient Removal 2007: The State of the Art, Baltimore, March 2007.

Manuals, Protocols: None

Outreach Activities: None

Contact with End Users: None, other than for End User Report

Patent, Copyright, Invention Disclosure Activity: IP Disclosure submitted to ND Technology Transfer Office for MBfP.

Overall Project Timeline Update
The project is currently on track within the proposed schedule. However, the pilot-scale work may need to be deferred until a bench-scale prototype is selected.

Expenditures
Expenditures were in the range anticipated for the work accomplished to date.