DISCUSSION TODAY: Waste Water Ponds and Nutrient Reduction (Algae Friend or Foe?) (What happens to carbon, ammonia, nitrogen & phosphorous?

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Merilyn Pope
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1 By Michael Christensen, Regional Manager SolarBee Inc., Telephone: SolarBee USA Regional Offices: California Colorado Florida Minnesota North Dakota (Factory) Pennsylvania Washington SolarBee International Regional Offices: Africa Asia Canada China Europe Middle East South America South East Asia SolarBee is a unique floating solar powered high flow circulator Applications are numerous and depending on the model the SolarBee draws up to 10,000 gpm. FRESHWATER -Lakes - Reservoirs -Ponds POTABLE WATER - Raw water storage reservoirs - Finished potable water tanks/towers - Blending tanks / Clear wells WASTEWATER - Municipal (reuse, sludge storage) - Industrial -Agricultural STORMWATER SolarBee Impact on Surface Water Tension and Removing Biofilm The two photos below of wastewater lagoons show how SolarBee circulation reduces surface water tension (in both photos, SolarBees are in the right-hand basin only). Soledad, California Ripley, West Virginia DISCUSSION TODAY: Waste Water Ponds and Nutrient Reduction (Algae Friend or Foe?) (What happens to carbon, ammonia, nitrogen & phosphorous?) Short Circuiting Aeration Equipment (aeration -vs. - mixing H.P.) How the energy efficient LDC mixing fits into wastewater pond systems Case Histories Alum application for P removal Radial - Long-Distance Circulation (radial LDC) Technology Question and Answer

2 Handout, Page 2 -- The Company UNDERSTANDING AND IMPROVING NUTRIENT REDUCTION IN WASTEWATER LAGOONS: LEVELS OF TREATMENT, SUMMARIZED PRIMARY TREATMENT: REMOVE SETTLABLES AND SOLIDS SECONDARY TREATMENT: REMOVE THE BOD AND TSS TERTIARY TREATMENT: NUTRIENT REDUCTION (N AND P) PART 1: N & P REMOVAL THROUGH CONTROLLED ALGAE GROWTH IN THE FIRST CELLS FOR N REDUCTION THERE ARE ONLY 2 MAIN MECHANISMS FOR P REDUCTION THERE ARE ALSO 2 MAIN MECHANISMS Algae: A GOOD STRONG ALGAE CROP IN THE FRONT END PONDS TO RAISE THE ph IS THE KEY TO ACHIEVING BETTER N AND P REDUCTION IN WASTEWATER LAGOONS. BUT ALGAE IN THE FINAL POND CAN CAUSE BOD, TSS, AND ph VIOLATIONS. IF (TSS X 0.5)+7 = BOD, ALL TSS IS ALGAE Algae is perhaps the most important organism in the world. Algae is found in almost all types of water. Algae is at the bottom of many food chains, a primary producer that can transform sun s energy to usable forms. Algae in the ocean is responsible for producing most of the oxygen in our atmosphere (21%). There are over 25,000 species of algae. Algae growth is governed by the Limiting Nutrient either C, N, or P. (Light can also be limiting). To control algae, identify the limiting nutrient and reduce the amount available. In most wastewater ponds, Carbon is the limiting nutrient. In most receiving streams, Phosphorus or Nitrogen are the limiting nutrient. Without algae, BOD reduction produces carbon dioxide that drives the PH down. Summary: Effects of BOD reduction without algae. The ph remains the same or is lower than when the water came in. Consequently: Less Nitrogen (Ammonia) is gassed off. Less Phosphorus is precipitated The anaerobic zone can develop the stuck digester syndrome by having too low of PH. So if there is limited or no algae growth in the first cells, algae growth can really take off in the last cell and cause the effluent to exceed the limit on BOD, TSS, N and P. Algae in the front-end ponds or cells can change this outcome. To see how, we have to understand: (1) algae s two body nature, (2) how algae raises the PH, and (3) the effect of higher PH on pond nutrients (carbon, N and P) and on anaerobic digestion. Algae has 2 parts: During the day algae is a net DO producer At night, algae becomes a net DO consumer Algae s Role in Aerobic Digestion

3 Handout, Page 3 Benefits of Algae in Primary Pond Algae can provide free DO, up to 300 lbs per acre in satisfactory conditions in facultative ponds. (Wm. Oswalt, 1960, Research and Experience in California) Algae, in front-end ponds, ties up carbon so it doesn t get to the final pond. Algae raises the PH of the water. for increased N(ammonia) gas off for increased P precipitation for increased anaerobic sludge digestion How does algae tie up carbon and raise the PH? During photosynthetic activity, algae can pull CO2 from carbonic acid, and drain down the entire carbonate alkalinity pool. Further CO2 reduction raises the PH. What does algae do with the carbon? The carbon is assimilated into new algae cells. When the carbon alkalinity pool is empty, the algae bloom crashes and the algae dies because no more CO2 is available. The algae falls to the bottom of the pond. The dead algae is digested anaerobically and about 2/3 of the carbon is gassed off as CH4 (methane), a non-nutrient. How does the higher ph caused by algae affect N (ammonia)? At ph over 9.3, almost all ammonia is in the form of NH3(-) ammonia gas, easily stripped by mixing. At ph under 9.3, most ammonia is in the form of NH4(--) liquid ammonium ion, which can t be stripped. Every push upward in the ph results in more ammonia gas being present and stripped out of the water. How does the higher ph caused by algae affect Phosphorus (P) At ph over 8.5, most phosphates can be precipitated out as crystalline solid compounds that fall to the bottom of the pond and do not very easily go back into solution. Every push upward in the ph results in more phosphorus being removed by precipitation. How does the higher PH caused by algae affect anaerobic digestion? If the higher PH water is mixed (by wind or otherwise) to lower depths, it can prevent the stuck digester syndrome where the acid formers get ahead of the methane producers and make the ph too low for methane production. A healthy anaerobic layer can process up to 2000 lbs of BOD per acre, with no cost for adding DO. Anaerobic digestion reduces carbon nutrients in the pond by using carbon to produce CH4 (methane), a non-nutrient. Algae Levels Depend on Pond Type. Facultative ponds have high algae in the upper 16, with the highest concentration usually at Without any mixing, the effects of algae are only at the top of the pond. Partial-Mix ponds have some algae, but only enough for slight diurnal (daily) ph cycles. Total-Mix ponds have virtually no algae due to turbulence and turbidity of the mixing. Algae Considerations: Facultative Systems They were designed for your climate. Hopefully the wind blows just right to: Mix the top zone (with its high algae, high PH, high DO) throughout the depths of the pond, but not so far down that the DO stops the anaerobic digestion or that odors are released. Consider a mixing system to remove the uncertainty of relying on the wind, with a good mixer you get consistently good results.

4 Handout, Page 4 Algae Considerations: Partial-Mix Systems Grow all the algae you can in the front-end ponds by turning off the aeration system during part of the day: Save some energy, get valuable DO for free. Reduce the Carbon, N, and P in the top 16. Don t let the pond go anaerobic! It will kill algae and cause odor problems. The result will be better water quality in the final pond. Less nutrient Carbon, N, and P, and therefore less algae, less BOD, and TSS. Algae Considerations: Total-Mix Systems The ph will be low, so Carbon, N and P will be available in high quantities in the settling pond. So have a short retention time (5-10 days?) in the settling pond and release the water with high carbon nutrients into the receiving stream. Otherwise the algae will proliferate and cause the BOD and TSS to increase in the settling pond to high levels. Carbon is already in abundance in the receiving stream. Rely on various means other than a high ph for getting needed reductions for N and P. Reference Oswald s AIPS system, or Richard s variations in Colorado, or Rich s high performance aerated systems.) Short-Circuiting in Wastewater Ponds Grid-Powered Turbulent Flow Aeration / Mixing Equipment Surface Aerators Aspirators Diffused Air Systems Mixers Splashers Aspirators Mixers SolarBee Approach in Wastewater SB is a circulator, not an aerator. Two mechanisms to elevate the DO, with SolarBees: surface reaeration and photosynthetic oxygenation. Do not take credit for DO enhancement. The SolarBee unit is a very efficient long-distance mixing device. In aerated ponds, usually the need for mixing energy is much greater than the need for oxygen production energy, so each SolarBee can typically displace hp of mixing energy. Leave the aerators in place, run them less hours, often just at night. Wastewater Benefits Reduces Energy Consumption Improves Secondary Treatment BOD / TSS / Algae Reduction Improves Tertiary Treatment Ammonia (NH 3 ) and Phosphorous (P) Reduction Odor Control Improves Sludge Digestion Reduce / Eliminate Desludging Reduces Short Circuiting Improves DO and ph Levels Facultative Ponds Improve Circulation Reduce Short Circuiting Better Effluent BOD,TSS, N and P Odor Control Sludge Digestion, avoid dredging Avoid the need to install high hp grid-powered turbulent flow aeration/mixing

5 Handout, Page 5 Partial Mix Aerated Ponds Complete Mix Ponds Effluent Storage Ponds SolarBee circulation & mixing: Near-laminar, non turbulent, high flows -- up to 10,000 gpm SolarBee circulation & mixing: Near-laminar, non turbulent, high flows - J-hook intake design High-Flow - Radial Long-Distance Circulation SolarBee v12 Key Features SolarBee Company Manufacturing SolarBee Wastewater Case Studies OTHER WASTEWATER PONDS ANAEROBIC PONDS: SLUDGE STORAGE PONDS: TOTAL EVAPORATION PONDS STORM WATER RESERVOIRS GREAT APPLICATION FOR COMBINED ODOR CONTROL AND BOD REDUCTION Independent Research on SolarBee Wastewater Benefits Summary SolarBees can: Reduce Energy Consumption Improve Secondary Treatment Improve Tertiary Treatment Provide Odor Control Improve Sludge Digestion Reduce Short Circuiting Improve DO and ph Levels Reduce phosphorous Questions on Wastewater Section?

WASTEWATER TREATMENT OBJECTIVES

WASTEWATER TREATMENT OBJECTIVES The student will do the following: 1. Define wastewater and list components of wastewater. 2. Describe the function of a wastewater treatment plant. 3. Create a wastewater