Recipient Organization
Wastewater Compliance Systems, Inc.
150 First Avenue # 607
Salt Lake City,UT 84103
Performing Department
(N/A)
Non Technical Summary
Shallow lagoon systems are the most common form of engineered domestic wastewater treatment in the United States and the world. Municipalities, particularly smaller rural communities, use this low cost treatment method. These lagoon systems are generally effective at reducing biochemical oxygen demand (BOD) to acceptable levels prior to discharge. They are generally ineffective at nutrient removal, specifically nitrogen and phosphorous compounds dissolved in the discharge water. The biological removal of nitrogen compounds takes place in two stages when naturally occurring nitrifying, then denitrifying bacteria consume them. Biological removal of dissolved phosphorous compounds occurs through uptake by a class of bacteria known as polyphosphate accumulating organisms (PAOs). In open lagoon systems, these nutrient consuming bacteria are generally out-competed by the more robust bacteria that consume the carbonaceous BOD, and do not proliferate. Because of this, municipalities using lagoon systems often have difficulties meeting nutrient discharge requirements. To promote the proliferation of nitrifying and denitrifying bacteria and PAOs in shallow lagoon systems, specially designed aerated dome structures (Poo-Gloos) have been developed. These dome structures are nested hemispheres made out of ABS black plastic. Fine-bubble diffuser hose is attached in the gap between the inner and outer annulus around the bottom of each dome. Nested dome structures are mounted on a sturdy base and rest on the bottom of a lagoon so they are fully submerged. The space between the dome shells is filled with a high surface area to volume packing material made out of polypropylene plastic. Low-pressure air is supplied to the diffusers and the released bubbles travel up the inside of each dome. The dome structures retard the upward movement of the aeration bubbles, forcing the bubbles against naturally occurring bio-film colonizing the surfaces, promoting oxygen transfer. The rising air bubbles also drag the wastewater up from near the bottom of the lagoon, along through the insides of the dome structures, and out the top. This promotes micro-mixing of nutrients into the bio-film. By providing surface area, oxygen, mixing, and blocking of sunlight, these dome structures greatly enhance the growth and metabolism of nitrifying bacteria. In addition, denitrifying bacteria proliferate in the deeper portions of the inside bio-film surfaces as well as the non-aerated backside surfaces of the domes and during times the aeration bubbles are cycled off. The performance of PAOs is also enhanced by aeration cycling. This cycling should provide the necessary aerobic/anoxic/ anerobic phases for these bacteria. The benefit to rural communities will be a low-cost technology that can be manufactured in rural areas, and can be easily added to existing lagoon systems. The installed dome structures will increase lagoon performance, allowing the communities to meet increasingly stringent nutrient level discharge requirements while retaining existing lagoon systems.
Animal Health Component
100%
Research Effort Categories
Basic
(N/A)
Applied
100%
Developmental
(N/A)
Goals / Objectives
Technical Objectives Funds are sought for the period 1 May, 2010 to 31 December, 2010 to accomplish the following goals: 1. Upgrade pilot plant with 6 new scale Poo-Gloos (outer domes 1.6' radius) and parallel paths for simultaneous control runs. 2. Verify previous work for CBOD and NH4+ removal rates while establishing biofilm on new Poo-Gloos. 3. Begin a series of controlled runs that vary air cycling times, organic and hydraulic loading rates, and temperature. 4. Analyze results and modify factors to optimize N removal through nitrification and de-nitrification. 5. Analyze results and modify factors to optimize P uptake and release. 6. Perform statistical analysis on all results to show significant results. 7. Write report, and develop preliminary Operations Manual for full-scale applications. 8. Begin preliminary monitoring of full scale application (35 Poo-Gloos, each 6' diameter at base and 4' high dome) in Wellsville, Utah. Expected Outputs Lab analysis of each experimental run will produce the following factors: Temp, HRT, organic loading, COD/CBOD5, NH4+, NO3-/NO2-, TN, PO43-, TP, ORP, DO, Air Flow Rate, Air Flow On/Off Cycling. In addition, pH, TDS and ALK will be monitored to ensure that conditions are favorable for biological growth. Adjustments to the controllable factors (HRT, Air Flow Rate and Air Flow On/Off Cycling) will be made based on results as the experimental runs progress. All factors will be input into the software program STAT-EASE DX7.1 for statistical analysis. The product of this will be a data set, along with figures that will show the effect of air cycling on effluent NO3-/NO2-, as well as PO43- uptake and release at different loading rates. Based on HRT, loading rates for CBOD, N and P compounds will be analyzed. Mass balances will be calculated for N and P compounds. Finally, the cost/benefit ratios for the BOD removal rate (g BOD/m2/d), nitrogen compound (g N/m2/d), and phosphorus removal rate (g P/m2/d) will be calculated and compared to the typical values in the industry. The system costs (capital and O&M) will be estimated and defined in terms of $/lb BOD, $/lb N, and $/lb P removed.
Project Methods
1. Modify pilot plant currently located at CVWRF to divide lengthwise into two parallel paths, each approximately 3'6" wide, 22' long, with a water depth of 2'6". 2. Assemble six prototype pilot scale dome structures and install them in one side of the pilot plant. Assemble six bubble release tube sets in identical configuration and install in the other side of the pilot plant. 3. Operate pilot plant in batch mode in May 2010 to establish bio-film and determine the typical times required for organic carbon removal and nitrification. Pilot tank and control tank will be operated simultaneously to eliminate the effects of some factors such as temperature and initial loadings, as well as bio-film accumulation on the sides of the tank. Starting June 2010, the pilot plant will convert to a punctuated influent modified plug flow reactor which means wastewater will be periodically introduced into the first three Poo-Gloos. This initial configuration may be modified to include 4, 5 or all 6 Poo-Gloos to receive influent. During the wastewater pumping in time, air would be turned off and will be kept off until anaerobic conditions are created and de-nitrification and phosphorus release are observed. Vary wastewater flow and air cycling regiments to maximize nitrogen, then phosphorus reduction. This operation will be conducted through the temperature ranges of June to mid-December of 2010. In the past, we have noted a water temperature range in the tank from 28 degrees C in August to 1 degree C in December. 4. Monitor the water quality of the influent and effluent of the pilot plant. The water quality includes COD, BOD5, CBOD, TSS, NH4+, NO3-, NO2-, total nitrogen (TN), reactive ortho-P, total phosphorous (TP), alkalinity. Horiba W-23XD probe will be set in the bulk solution between Poo-Gloo # 3 and # 4 to continuously monitoring temperature, pH, TDS, Turbidity, DO, and ORP. Samples will be taken in triplicate for the influent and effluent as experimental conditions dictate. Typically this has been from one to three times per day (24 to 8 hour intervals). Samples will be analyzed at the U of U Civil & Environmental Engineering Lab. Results will be cross-checked with CVWRF lab data for accuracy. CVWRF measures ammonia, TP, COD and BOD5 for the influent to our pilot plant, which is the transfer ditch from their primary clarifiers to their trickling filters. 5. Determine the Oxygen Transfer Efficiency (OTE) and ammonia air-stripping for the dome structures and controls with off-gas methods. 6. To improve the performance of P uptake, one possible modification could be a pre-fermentation tank on the influent. This tank would hold the influent water in an anaerobic, mixed environment to increase the concentration of VFAs. Organic strength could be increased by allowing a settling period prior to pumping off the bottom into the test tank, then decanting the supernatant. Based on P uptake and release results, this modification may be added.