United States Office Of EPA-832-R-01-004 Environmental Protection Water (4204) September 2001 Agency The Living Machine® Wastewater Treatment Technology An Evaluation of Performance And System Cost ------- THE LIVING MACHINE® WASTEWATER TREATMENT TECHNOLOGY An Evaluation of Performance and System Cost Prepared For. MUNICIPAL TECHNOLOGY BRANCH OFFICE OF WATER U.S. ENVIRONMENTAL PROTECTION AGENCY WASHINGTON, DC Prepared By: Parsons Engineering Science, Inc. and Environmental Engineering Consultants September 2001 ------- FOREWORD Providing effective and reliable wastewater treatment in a cost-effective manner continues to be a problem facing urbanizing areas across the country. In the future, add-on processes will be needed to upgrade many of the treatment facilities buUt over the past 25 years to meet the requirements of the Clean Water Act (PL92 5OO and its more recent amendments). In addition, more facilities will be needed to help deal with small volume municipal and industrial point sources of water pollution if thewaterquality objectives of the Clean WaterAct are everto be fully realized However, many of the treatment technologies currently available for use in meeting these future treatment requirements are expensive to build and operate, require extensive energy resources, and produce large volumes of sludges that are also expensive to manage properly Natural biological systems offer treatment and reuse alternatives that can often effectively overcome these problems For many years, there has been considerable interest in the use of “managed natural systems” such as ponds, land treatment (slow rate irrigation, overland flow, and rapid infiltration) systems, and wetlands for wastewater treatment and reuse. Over the years an extensive body of research results has been developed and planning, design, and O&M guidance materials published that provide information for those interested in considering the development of projects using these technologies. Recently, interest has been growing in the application of principles of “ecological engineering” to the development of sustained complex ecological systems for the processing of wastewater under controlled conditions to meet advanced treatment requirements (Mitsch and Jørgensen, 1989). These systems are developed in a manner to work in a symbiotic relationship with society, maximizing the use of solar power, natural ecological processes, and self-design to maintain diversity. Recent efforts to apply these concepts to the treatment of wastewater have resulted in the development of research facilities, demonstration projects, and a growing number of operational treatment systems in the United States and Europe Efforts to document the performance of these systems fully have been limited, as has the availability of published information on their design and performance There have been a number of conferences on this topic (e.g., Etnier and Guterstam, 1991) and there is now a journal, “Ecological Engineering; The Journal of Ecotechnology” that may help improve this situation After working with a number of small pilot-scale facilities employing his early proprietary designs (now referred to as “Solar Aquatics TM ”), Dr. John Todd, President of the non-profit organization Ocean Arks International, has developed a series of second generation design (non-proprietary) demonstration-scale projects he refers to as 0 Advanced Ecologically Engineered Systems” or Living Machines® A total of $7 8 million in federal funding has been provided by Congress in the form of special add-on appropriations to EPA’s budget (in Fiscal Years ‘92-98) to support these demonstration-scale Living Machine® projects. Most of these funds were awarded through a cooperative agreement to the Massachusetts Foundation for Excellence in Marine and ------- Polymer Sciences, a financial supporter of Dr. Todd’s earlier efforts to develop the original “Solar Aquatics TM1 ’ technology, to assist in the design, construction, operation and documentation of results associated with the demonstration-scale Living Machine® projects These demonstration projects have been implemented by the Massachusetts Foundation for Excellence in Marine and Polymer Sciences, in cooperation with Ocean Arks International and Living Technologies, Inc The “Advanced Ecologically Engineered Systems, or Living Machines®, have been promoted as a new, low cost, solar-powered, no chemical use alternative wastewater treatment technology capable of being constructed in modules as additional capacity is needed. These systems incorporate many of the same basic processes (e.g., sedimentation, filtration, clarification, adsorption, nitrification, denitrification, volatilization, anaerobic and aerobic decomposition) utilized in more conventional advanced biological treatment systems However, the Living Machines® try to simulate these processes as they occur in natural biological ecosystems (such as lakes, rivers and wetlands) and to operate them at optimal rates under cqntrolled conditions. The design and operation of these facilities has been approached from an ecological systems point-of-view and attempts to incorporate objectives well beyond just achieving the desired wastewater treatment goals into projects For example, Dr Todd has emphasized the importance of snails, freshwater clams, and other invertebrates in the ‘ecological fluidized beds,” as well as utilizing a variety of aquatic and wetland plants throughout the Living Machine® systems Todd also stresses the value of these systems as a potential opportunity to produce fish as well as aquatic and wetland horticultural plants that can be marketed locally, and for educating the public about the importance of natural bii logical systems in purifying and recycling wastewater Clearly these systems offer an aesthetically pleasing environment for treating and recycling wastewater while gaining strong public support This report represents EPA’s effort to summarize the data generated and experience gained during the operation of the four demonstration-scale Living Machine® wastewater treatment systems funded between 1993 and 1998. The experience gained at the initial demonstration system established at Frederick, MD, lead to modifications being incorporated into the final system at Burlington, VT. The Living Machine® wastewater treatment systems were found to reliably achieve very stringent limits for BOD 5 , TSS, and Ammonia Nitrogen (BOD 5 and TSS each <10 mgIL and NH 3 -N < 1 mg/L), respectable limits for Nitrate and Total Nitrogen (N0 2 -N <5 mg/L and TN < 1 mg/L), and about 50% Phosphorus removal The ecologically engineered Living Machines® incorporate variations of well established treatment technologies such as anaerobic bioreactors, complete mix aerated tanks, aerobic fluidized bed reactors, clarifiers, high-rate constructed wetlands, and plant-covered ponds The results of the EPA evaluations suggest that the excellent performance of the Living Machine® could be characterized in terms of these conventional technologies with minimal contributions from the “ecological” components. Robert K Bastian, September 2000 ------- FOREWORD TABLE OF CONTENTS PAGE TABLE OF CONTENTS EXECUTIVE SUMMARY ES-i CHAPTER 1 INTRODUCTION 1.1 Background 1.2 Living Machine® Technological Innovations 1 3 Scope and Purpose of This Report 1 4 Organization of This Report CHAPTER 2 THE FREDERICK, MARYLAND LIVING MACHINE® 2 1 Background . . .. . . . .. . 2 2 Process Description of the Frederick Living Machine® 2.3 Pr ocess Evaluation of the Frederick Living Machine® CHAPTER 3 THE BURL 1NGTON, VERMONT LIVING MACHINE® 3 1 Background . . . .. . . 3.2 Process Description of the Burlington Living Machine® 3 3 Evaluation of the South Burlington Living Machine®. CHAPTER 4 THE SAN FRANCISCO, CALIFORNIA LIVING MACHINE® 4.1 Background . .. . . . . .. . . . . . . 4.2 Process Description of the San Francisco Living Machine® 4 3 Evaluation of the San Francisco Living Machine® .. . CHAPTER 5 THE HARWICH, MASSACHUSETTS LIVING MACHINE® 5 1 Background 5 2 Process Description of the Harwich Living Machine® 5 3 Evaluation of the Narwich, MA Living Machine®. CHAPTER 6 PERFORMANCE COMPARISON THE BURLINGTON AND FREDERiCK LIVING MACHINES® 6.1 Introduction . . 6.2 Flow and Temperature 6 3 Biochemical Oxygen Demand (BOD) Removal 6.4 Chemical Oxygen Demand (COD) Removal 1-1 1-2 1-5 1-6 2-1 2-2 2-8 3-1 . 3-1 3-4 4-1 4-2 4-3 6-1 6-2 6-2 6-3 5-1 5-1 5-2 ------- TABLE OF CONTENTS (Continued) PAGE 6-6 6-6 6-7 7-1 7-3 7-6 7-10 • 8-1 • 8-7 • 8-8 • 8-8 9-1 10-1 CHAPTER 6 PERFORMANCE COMPARISON THE BURLINGTON AND FREDERICK SYSTEMS (Continued) 6 5 Total Suspended Solids (TSS) Removal.... . .. 6-4 6.6 Ammonia Nitrogen Removal . . ... • ..• •. .. 6-5 6 7 Nitrate Nitrogen Removal . ... . . 6-5 6.8 Total Nitrogen Removal 6 9 Phosphorus Removal . 6.10 Fecal Coliform Removal 6.11 Summary .... 6-7 CHAPTER 7 COST COMPARISON THE LIVING MACHINE® VS. CONVENTIONAL TECHNOLOGIES 7.1 Introduction . . . .. .. . . . . 7-1 7 2 Basis of Comparison . . 7 3 Conventional System Costs . .. 7 4 Living Machine® Costs . . . ... 7.5 Companson of Costs . . CHAPTER 8 EVALUATION OF THE LIVING MACHINE® TREATMENT PROCESS 8 1 The Frederick and Burlington Living Machines® . . 8 2 The San Francisco, CA Living Machine® 8 3 The Har iich, MA Living Machine® 8.4 Other Applications of the Living Machine® .. CHAPTER 9 CONCLUSIONS AND RECOMMENDATIONS CHAPTER 10 REFERENCES II ------- Table 2 1 Table 2.2 Table 3 1 Table 3.2 Table 4.1 Table 4.2 Table 6.1 Table 7 1 Table 7.2 Table 7 3 Table 7 4 Table 7.5 Table 7 6 Table 7 7 Table 7 8 Table 7 9 Table 7 10 Table 7.11 Table 712 Table 8 1 Table 8 2 Figure Figure Figure Figure Figure Figure Figure Figure 2-1 2-2 2-3 2-4 2-5 2-6 2-7 3-1 TABLE OF CONTENTS (Continued) LIST OF TABLES PAGE 2-1 • 2-9 3-4 • 3-5 4-2 4-4 6-8 7-1 7-2 7-4 7-4 7-5 7-5 7-6 7-7 7-8 7-9 7-10 7-11 8-9 8-9 2-3 2-10 2-11 2-12 2-13 2-14 2-15 Treatment Goals for the Frederick County AEES . . .. EPA Water Quality Data Summary for Frederick, MD Living Machine® . Treatment Goals for the Burlington AEES . . Mean Wastewater Quality for the Burlington AEES Oceanside WPCP Effluent and San Francisco AEES Process Goals .. - San Francisco Living Machine® Performance Results for September 1996 Performance Summary Frederick, MD and Burlington, VT Living Machines®. lnfluent and Effluent Water Quality for Cost Comparison Cost Estirnate Assumptions, Inclusions and Exceptions Sludge Management for Conventional Treatment Systems . • Capital Costs for Conventional Treatment .. . . . Annual O&M Costs for Conventional Treatment Systems . . . . Cost Summary for Conventional Treatment Systems . . . . . Sludge Management for the Living Machines® . . . . . Capital Costs of the Living Machine® with Greenhouse . Capital Costs of the Living Machine® without Greenhouse . . Annual Operation and Maintenance Costs for the Living Machine® Cost Summary for the Living Machine® . .. . . . Present Worth Comparison of Living Machines® and Conventional Systems Some Other Applications of the Living Machine® Performance Summary of the Ethyl M Chocolates Living Machine® LIST OF FIGURES Process Flow Diagram of the 40 ,000gpd Living Machine® in Frederick, MD Frederick AEES BOD 5 Input Vs. Output . . .. Frederick, MD, COD Input Vs Output Frederick, MD, TSS Input Vs. Output . Frederick, MD, Ammonia Nitrogen Input Vs. Output . . Frederick, MD, Total Nitrogen, Input Vs. Output . .. . - Frederick, MD, Phosphorus Input Vs Output Process Flow Diagram of the 80,000gpd Living Machine® in South Burlington, Vermont .. . Influent and Effluent CBOD for the South Burlington Living Machine® Figure 3-2 3-2 3-7 iii ------- TABLE OF CONTENTS (Continued) PAGE LIST OF FiGURES (Continued) Figure 3-3 Percentage Removal of CBOD for the South Burlington Living Machine® . 3-8 Figure 3-4 Influent and Effluent COD for the South Burlington Living Machine® . . . 3-9 Figure 3-5 Influent and Effluent TSS for the South Burlington Living Machine® . . . 3-10 Figure 3-6 Influent and Effluent NH 3 for the South Burlington Living Machine® 3-12 Figure 3-7 Percentage Removal of NH 3 for the South Burlington Living Machine® . . 3-13 Figure 3-8 Influent and Effluent TKN for the South Burlington Living Machine® . . . 3-14 Figure 3-9 Percentage Removal of TKN for the South Burlington Living Machine®. 3-15 Figure 3-10 Influent and Effluent NO 3 for the South Burlington Living Machine® . . . 3-16 Figure 3-11 lnfluent and Effluent TN for the South Burlington Living Machine®. . . . 3-17 Figure 3-12 Influent and Effluent TP for the South Burlington Living Machine® . . . . 3-19 Figure 3-13 Influent and Effluent Fecal Coliform for the South Burlington Living - Machine® . . . . 3-20 Figure 7-1 Comparison of Present Worth Costs for the Living Machine® and Selected Conventional Technologies Over a Range of Flow Rates . 7-11 Figure 8-1 Process Schematic Diagram of the Burlington, VT Living Machine® with an Anoxic Reactor - - . . . . . 8-6 iv ------- EXECUTIVE SUMMARY This report describes the results of an evaluation carried out by the U S Environmental Protection Agency (EPA) that investigated a wastewater treatment technology named the Living Machine® The basic treatment system includes aerated tanks supporting vegetation at the water surface, a conventional clarifier, and gravel media filters (called “ecological fluidized beds” by the developers) In cooler climates, all of these components are typically enclosed within a greenhouse structure The basic Living Machine® concept with a greenhouse-enclosed system was demonstrated at a 40,000 gallons per day (gpd) flow rate at Frederick, MD, and at 80000 gpd in South Burlington, VT Variations, incorporating the “ecologicalfluidized bed” component, were also demonstrated at Harwich, MA, and at San Francisco, CA Federal funding for these demonstration projects, and the EPA evaluations, was provided by special appropriations by the U S Congress The Living Machine® was initially conceived and developed by Dr. John Todd of the non-profit organization Ocean Arks International (OAI), then was being designed and marketed by Living Technologies, Inc. (LTI) of Burlington, VT during the evaluation of the South Burlington facility The Living Machine® is now designed and marketed by Living Machines, Inc of Taos, New Mexico, whose w bsite can be found at www Irvingmachines corn . The EPA evaluations have included independent monitoring of flow and water quality, and tracer studies at the Frederick, MD facility Also included was assessment of data produced by others from all of the demonstration facilities, and development of cost estimates for conventional wastewater treatment technologies for comparison with Living Machine® costs Treatment goals for the basic process were established by the Living Machine® developers and these included: BOD < 10 mg/L; TSS < 10 mg/L, Ammonia Nitrogen < 1 mg/L; Nitrate Nitrogen <5 mg/L, Total Nitrogen < 10 mg/L; and Total Phosphorus <3 mgIL. The EPA evaluation found the currently designed process capable of meeting all of these goals (with municipal wastewater influents) except those for Total Phosphorus. The system was found to be capable of about 50% Phosphorus removal, which would not always be sufficient to meet the 3 mg/L goal when treating typical municipal wastewaters. The system also provided significant removal of fecal coliforms, primarily because of filtration in the “ecological fluidized beds;” at the South Burlington Living Machine®, the wastewater influent typically contained 8 x 106 MPN/1 00 mL while the final effluent averaged 1,200 MPN/100 mL. The proponents of the Living Machine® claim that the vegetation in the process units, and solar energy, play a significant role in the wastewater treatment within the system However, the deep (> 4m) tanks then in use, with their limited water surface area, limits the number of plants that can be used in the system. Consequently, the plant roots occupy a relatively small fraction of the total tank volume and, as a result, the plants and solar energy are believed to play a marginal role in providing treatment The system, as finally modified at Burlington VT (see Chapter 8 for details) can be characterized as an anoxic reactor followed by extended aeration activated sludge, followed ES-I ------- by clarification and filters for pathogen reduction and final polishing. Therefore? in effect, the system is a combination of conventional processes with plants floating on the water surfaces. However, these plants do provide very significant aesthetic benefits and serve to enhance public acceptance of the process. This system produces residuals in the form of plant materials and sludges. The evaluation showed that these combined residuals (depending on the type of plants grown) can be comparable in total volume to .the residuals produced by a conventional extended aeration activated sludge process. The EPA evaluation also compared costs of the Living Machine® at various design flow rates to costs of commercially available, conventional wastewater technologies capable of producing the same effluent quality. The cost comparison showed that the Living Machine® without a greenhouse was cost competitive with conventional technologies up to 1,000,000 gpd. A Living Machine® with a greenhouse structure is not cost competitive at the 1,000,000 gpd rate, but appears to be competitive up to about 600,000 gpd. These costs are only valid if the Living Machine® is operated as modified in 1999 and without the use of methanol for denitrification. The plants used in the Living Machine® process units provide very significant aesthetic benefits. ES-2 ------- CHAPTER 1 INTRODUCTION 1.1 Background The Advanced Ecologically Engineered System (AEES), or Living Machine® technology, is intended to provide water quality improvements for a variety of situations The concept is called a Living Machine® because of the ecologically based components that are incorporated within the treatment process The Living Machine®was conceived by Dr John Todd, the President of Ocean Arks International (OAI), a non-profit institution based in Falmouth, MA. The Living Machine® includes microorganisms, protozoa, higher animals, and plants in an “ecologically balanced” treatment system which has been claimed by its developers to be based on solar energy and “natural” treatment responses, as compared to the use of mechanical energy and chemicals in conventional wastewater treatment processes - The Living Machine® is similar in some respects to the commercially available Solar Aquatics TM .technology. Both concepts utilize aerated tanks, which support floating or rafted vegetation, within a greenhouse for the treatment of wastewater. In fact, both systems derive conceptually from early developmental work by Dr. Todd in treating domestic wastewater in Vermont and septage wastes at Harwich, MA (Reed, 1992; Nolte & Assoc, 1989). Ecological Engineering Associates (EEA) of Marion, MA, the firm responsible for the SolarAquatics TM system, was offered the opportunity to participate in this evaluation but declined to do so. The Living Machine® is also commercially available and is currently operational at a number of industrial operations, treating food processing and similar wastewaters, as well as domestic wastewater applications, some of these other applications are described in Chapter 8 These commercial applications proceed concurrently with the continued U S. Government funding of the AEES demonstration program. The AEES pilot demonstration systems were located in Frederick County, MD, South Burlington, VT, Harwich, MA, and San Francisco, CA. The Frederick facility (decommissioned in June 1996) was intended to provide advanced levels of treatment for untreated municipal sewage. The South Burlington project uses essentially the same basic technorogy, and has the same purpose as the Frederick facility but is designed to operate at a higher flow rate and in a colder climate The project in Harwich, MA uses a floating raft incorporating a portion of the AEES technology to provide h-situ water quality improvements for a pond. The project in San Francisco (inactivated in December 1996) also used part of the AEES technology to provide final high flow rate polishing of municipal secondary effluent, the objective being to produce a water quality which would allow unrestricted irrigation reuse of the effluent in accordance with State of California Title 22 requirements Process details on each of these systems can be found in subsequent 1-1 ------- chapters. These Living Machine® facilities were designed and constructed by Living Technologies, Inc. (LTI) of Burlington, VT, and were operated by either LTI or OAI staff The Living Machine® is now designed and marketed by Living Machines, Inc. of Taos, New Mexico These four AEES demonstration projects were funded, in part, with special appropriations from the U.S. Congress. The funding was awarded by the U S Environmental Protection Agency (EPA) to the Massachusetts Foundation for Excellence in Marine and Polymer Sciences (MFEMPS) through a cooperative agreement (grant). The demonstration facilities were designed and operated by either OAl or LTI under contract to MFEMPS, and these operating personnel routinely collected performance data. The grantee, MFEMPS decided that an independent evaluation by EPA would be desirable and funds were made available for that purpose from the special Congressional appropriations While all of the AEES facilities have been included in the evaluation, an independent EPA data collection effort was undertaken at only the Frederick, MD system The results of this detailed evaluation of the AEES facility at Frederick, MD were presented in a separate report (EPA, 1996). The independent test results obtained by the EPA study at Frederick were compared to those produced by OAI staff and were found to be equivalent As a result, it was considered unnecessary to undertake further independent sampling at the South Burlington, VT facility for the purposes of preparing this report Parsons Engineering Science, Inc. (Parsons) was selected by EPA, under Contract No. 68-C6-0001, to perform the evaluations of the AEES treatment concept and to assist in the preparation of this report. Mr. Sherwood Reed, of Environmental Engineering Consultants (EEC), Norwich, VT, was retained under the same contract as Technical Director for these efforts. 1.2 Living Machine® Technological Innovations The Living Machine® incorporates several apparent technological innovations which alone, or in combination, are used to provide the expected treatment via “natural” processes. Two of the major components include: aerated tanks supporting floating or rafted vegetation on the water surface, and “ecological fluidized beds” (EFBs) which also have plants on some of their water surfaces These two components are generally used in full-scale AEES applications. The system at Frederick, MD also included a high-rate, gravel bed marsh with emergent vegetation that was located inside the greenhouse. Additionally, at Frederick, MD, and in some other cases, an anaerobic bio-reactor was used for preliminary treatment of the high strength wastewater influent. A brief description and discussion of the aerated tanks and EFBs can be found below A more detailed evaluation of all system components can be found in the later chapters of this report. 1-2 ------- An aerated tank at the South Burlington, Vermont Living Machine®. 1.2.1 Aerated, Vegetated Tanks The aeration provided (small bubble, submerged diffusers) is intended to mix the contents of the tank and to bring them into contact with the plant roots which are suspended in the liquid. This aeration can be considered to be “complete mix” intensity. Although the plants do take up some nutrients, metals, and other substances, it is their physical presence in the system, particularly the root mass, which is their most important contribution to treatment. The major treatment pathway in these units appears to be microbial and is a result of the microorganisms suspended in the water and attached to the surfaces of the plant roots. Surface area for microbial attachment is considered to be the major reason, other than aesthetics, for the plants on these units. - - - - 1-3 ------- 1.2.2 “ Eco!o iical Fluidized Beds ” Some variation of these units were used in all of the AEES demonstration projects. At Frederick, MD and Burlington, VT the units were contained in tanks. The outer container of these tanks was the same size and constructed of the same materials used for the aerated tanks. The EFBs also include an inner tank which contained the gravel (volcanic stone) which was the media used in these beds. Flow enters the EFB in the annular space between the inner and outer tanks and is lifted by air lift pipes to the top of the inner ring containing the media. The bottom of the inner tank is not sealed so the downward flowing liquid returns to the outer annular space and is again circulated on to the top of the gravel bed. These air lifts not only move the liquid but the air bubbles provide the oxygen source to maintain aerobic conditions in the circulating liquid. When the unit is in operation, it serves as a fixed bed, downflow, granular media filter. Particulate matter in the water is effectively separated and since the granular media surfaces are occupied by microorganisms the initially necessary nitrification reactions were completed under the prevailing aerobic conditions. Subsequent process modifications, described in Chapter 8 allowed An “ecological Iluidized bed” at the South Burlington Living Machine®. 1-4 ------- completion of nitnfication reactions in the aeration tanks which reduced the function of the EFBs to filtration As sludge is separated from the fluid stream in the EFB bed the hydraulic capacity in the forward flow direction is impeded, if accumulation were allowed to continue the bed would eventually become completely clogged To correct this potential problem the unit was designed with additional aeration diffusers beneath the gravel bed When these aerators are on, the whole inner tank acts as an upflow airlift so the flow direction is reversed This aeration may “fluidize” the bed and release the trapped sludge which is washed over into, and settled at the bottom of, the outer annular space. The choice of “ecological flu idized bed” as the name for this unit is somewhat misleading. It is normal practice to define the function of a treatment unit while operating in the forward flow direction In this case, when the bed is in the treatment mode the gravel is not fluidized and the bed acts as a downflow, coarse media, contact filter unit. It is only during the backwash cleaning operations that the gravel may be partly fluidized At both Frederick, MD and Burlington, VT some of the EFBs were operated as anoxic units to provide a capability for denitrification. This was accomplished without major physical changes in the unit. The airlift delivery pipes were turned off and a recirculating pump located at the top of the central tank This induced an upflow direction in the pumice bed and the pump delivered the fluid to the bottom of the annular space. The lack of aeration and the resulting low oxygen levels created anoxic conditions in the media which established an environment suitable for denitrification The modified unit is still backflushed in the same manner as previously described. Since the 1999 process modifications at the Burlington facility denitnfication is accomplished elsewhere in the system, so all of the EFBs only serve a filtration function Denitrification requires a carbon source for the reaction to function. The available carbon (BOlD 5 ) in the wastewater is, by design, very low, at this point in the system, and it is insufficient to support denitrification. As a result, with the original process configuration it was necessary to add a carbon source to the water prior to the denitrification process Methanol became the standard carbon source in the AEES process, as it is in conventional wastewater treatment systems. However, process modifications in 1999 at the Burlington Living Machine® facility (see Chapter 8 for description) provided for denitrification elsewhere in the system and eliminated the need for methanol additions. 1.3 Scope and Purpose of This Report The intent of this report is to describe the various AEES pilot facility configurations, their purpose, and their documented performance Where possible, the functional aspects óftheAEES technologies and their performance are corn pared to available conventional technologies. The cost of the AEES technology is aLso compared to conventional technologies providing the same level 1-5 ------- of treatment The overall purpose of this report is to provide information on the status of this technology and present recommendations regarding the Living Machine’s® future applications. 1.4 Organization of This Report. Chapters 2 through 5 present an evaluative description of the process components of the several Living Machine® demonstrations Chapter 6 provides a comparative evaluation between the Frederick, MD and Burlington, VT systems since they were similar facilities with comparable treatment goals Chapter 7 compares the cost of the AEES process to conventional wastewater treatment systems capable of producing the same effluent quality Chapter 8 is a general evaluation of the AEES process, and Chapter 9 contains the conclusions and recommendations of this report 1-6 ------- CHAPTER 2 THE FREDERICK, MARYLAND LIVING MACHINE® 2.1 Background The City of Frederick is located in central Maryland at about latitude 39 25 and an elevation of 300 feet. The mean annual air temperature in the Frederick area is about 11°C (52°F) and the minimum winter temperatures can be less than -1°C (30°F) For this reason, a greenhouse structure was required to protect the process components of the Living Machine® The Frederick Living Machine® was located adjacent to the Ballenger Creek municipal wastewater treatment plant (WWTP). The Living Machine® in Frederick was constructed in 1993 and remained in continuous operation until it was decommissioned in June 1996 The design flow at this AEES was 40,000 gpd and the influent was taken from the Ballenger Creek WWTP after its screening and grit removal unit The final effluent from the Frederick AEES, and any sludge residuals, were returned to the VVVVTP for further treatment and disposal. The treatment goals established by OAl for this facility are shown in Table 2 1 Table 2.1 - Treatment Goals for the Frederick County AEES Parameter Goal All units in mg/L Biochemical Oxygen Demand (BOD 5 ) <10 Total Suspended Solids (TSS) <10 Ammonium/Ammonia Nitrogen (NH 3 /NH 4 ) <1 Nitrate Nitrogen (NO 3 ) <5 Total Nitrogen (TN) <10 Total Phosphorus (TP) <3 2-1 ------- An independent EPA performance evaluation was performed during the spring and summer of 1995 (EPA, 1996) It was intended that the system would be in “steady state” operation during the study but that proved not to be the case, as discussed later in this Chapter. 2.2 Process Description of the Frederick Living Machine® A schematic of the AEES process at Frederick, MD, is shown in Figure 2 -1 All of the components except the anaerobic bio-reactor were housed in a greenhouse with plastic glazing (Nexus design steel frame, Serac glazing) The anaerobic bio-reactor was situated outside the greenhouse and was partially buried with an exposed, insulated, floating cover The greenhouse structure enclosed three sets of the components shown in Figure 2-1. Two of these process “trains” were used to demonstrate the capability to treat the design flow rate under steady state conditions The third train was used for testing and experimentation but typically received one third of the 40,000 gpd design flow. The pumice stone filters are termed “ecological fluidized beds” by the system developers. The conceptual design and structural details of the anaerobic bio-reactor were developed by Sunwater Systems, Inc. located in Solano Beach, CA The Living Machine® concept, and the conceptual design of the AEES facilities were developed by OAl. The engineering and structural details for tbe greenhouse and enclosed components were provided by LTI. The computer controls for the greenhouse units were provided by Q-Com Environmental Control of Irvine, CA 2 2.1 Anaerobic Bio-reactor The first treatment unit at the Frederick facility was the partially buried anaerobic bio-reactor, orABR. This unit had a concrete floor and concrete block side walls and was lined with 30 mm thick, high density polyethylene. The floating plastic membrane cover contained a layer of insulation for thermal protection. The reactor was 15 feet wide and 28 feet long, and maintained a water depth of 9 feet. As represented in Figure 2-1, an internal dam about 6 feet tall retained a permanent sludge blanket in the first compartment of the ABR. The untreated wastewater entered this zone via diffuser pipes on the bottom of the tank, flowed upward through the sludge blanket and then entered the second compartment A unique aspect of the second compartment were the strips of polypropylene mesh netting which were suspended from the reactor cover and spanned the full width of the tank. This mesh assisted in trapping and settling solids, as well as providing significant surface area for colonization by attached growth microorganisms. The settled sludge in this compartment underwent some anaerobic digestion. Sludge was removed from this compartment on a weekly schedule via perforated pipes on the bottom of the reactor. At a flow rate of 37,000 gpd, the theoretical hydraulic residence time (HRT) in this ABR was 18% hours. 2-2 ------- Figure 2-1 Process Flow Diagram of the 40,000gpd Living Machine® in Frederick, Maryland to Trains A and C (identical to Train B) Raw Influent Treated Effluent I __ 4 ,..•• •‘%•••‘ . .4 ‘ _____ Anaerobic Bio-reactor (outside greenhouse) High-rate Marsh Train B (Sampled Train) Aerated Tanks Final Cia r fier Clar fler Pumice Stone Filters (“Ecological Fluidized Beds’) ------- Untreated wastewater was pumped to the ABR at a constant rate from the Ballenger WWTP screening and grit removal unit. A depth of about two feet of settled sludge from the Ballenger facility was added to thefirst compartment at start-up to serve as the initial sludge blanket. The ABR was similar in concept and configuration to another commercially available unit called a “Bulk Volume Fermenter” (BVF) offered by ADI, Ltd (Malina & Pohland, 1992; Landine et al, 1992) Both units have an initial upflow sludge blanket zone followed by a second zone for clarification. As described previously, the Sunwater Systems ABR utilizes strips of polypropylene mesh in the second compartment to assist in treatment and solids removal. The BVF unit offered by AD! uses mixers in the first and second compartments to enhance contact and treatment A typical HRT in the ADI-BVF is six to eight days whereas the HRT in the Sunwater Systems ABR at Frederick was less than one day. Except for these differences, the physical configuration of the two systems are very similar, so the concept does not represent a unique advance in the state-of-the-art for wastewater treatment In order to reduce odors in the greenhouse and in the surrounding area, the effluent from the ABR was piped to small, covered aerated tanks with a detention time of about 20 minutes at design flow. Consequently, the effluent leaving this unit was aerobic and odor-free, and ready for treatment in the greenhouse The exhaust gasses from this aeration unit were routed to an underground earth filter for odor control. The basic purpose of the ABR was to reduce significantly the concentrations of BOD 5 and solids (TSS) in the wastewater prior to treatment in the greenhouse Supplemental heat was not added to this reactor so a relatively warm climate and a longer HRT would be required for significant sludge solids digestion The designers have replaced the anaerobic bio-reactor with an aerated aerobic unit in the 80,000 gpd Living Machine® that is in operation at South Burlington, VT. The wastewater at South Burlington has lower concentrations of organics and solids so the use of a preliminary ABR is less critical Also, the very low winter temperatures in Vermont would limit the potential for microbial activity in an unprotected and unheated unit. 2 2 2 Aerated Tanks As shown in Figure 2-1, the aerated effluent from the anaerobic bio-reactor flowed to the first of two aerated tanks in series at the head of each of the process trains. At the Frederick AEES, each tank was 10 feet in diameter and 9 feet deep; the top 4 feet of the tank being above the concrete greenhouse floor while the remainder was below ground. The cylindrical tank walls were corrugated steel, of the type commonly used for culvert pipe The interior of the tank was lined with a 20 mm thick plastic membrane container to insure complete fluid retention Both aerated tanks were operated in the complete-mix aeration mode to keep all solids in suspension and to insure rapid circulation and contact with the submerged roots of the plants floating on the water surface of these tanks Wifley Weber circular diffusers were used as the aeration source in 2-4 ------- these tanks and the other process units. Air was supplied for the entire system with three Roots blowers (1-1 hp, 1-1 5 hp, 1-2 hp) which operated continuously. The aeration intensity in these tanks can be considered a “complete mix” system. The plants used on these tanks were floating macrophytes; the first tank usually was covered with water hyacinth (Eichhornia crass ipes), the second with pennywort (Hydrocofyle umbellata) About 1 hour per week of operator time was required for the care of these plants Plant material removed from these tanks was corn posted The theoretical HRT in each tank was 8% hours at design flow (13,300 gpd/train). A variety of biological, bacterial, and mineral additives were applied to the wastewater prior to the aerated tanks in order to enhance treatment responses and maintain the health of the plants. Bacterial additions included Bactapure N for nitrification, and XL to assist in breakdown of grease and sludges Mineral additions consisted of Manah powderwhich was intended to improve mineral content and the health of the plants The biological additive was Kelp meal to supplement the potassium content in the wastewater Additions of this type are not routinely used in conventional wastewater treatment, except for during upsets and emergencies The basic purpose of these aerated tanks was to reduce the dissolved wastewater BOD 5 to low levels and to commence nitrification of ammonia The roots of the floating plants were intended to serve as a substrate for the support of attached growth nitrifying organisms. In the original design and layout of units in the Frederick greenhouse, the flow from the second aerated tank passed directly to the next treatment component which was the first “ecological fluidized bed.” Sludge accumulation in these beds required very frequent cleaning so a small clarifier was added to the process train after the second aerated tank, as shown in Figure 2-1. Most of the sludge removed from this clarifier was wasted to the anaerobic bio-reactor, however, a small percentage was recycled to the first aerated tank. The mixed liquor suspended solids in these tanks was typically less than 150 mg/L In a complete mix activated sludge process the mixed liquor solids might range from 3,500 to 4,000 mgiL depending on the purpose of the aerated reactor 2 2 3 Ecological Fluidized Beds As shown in Figure 2-1, there were three “ecological fluidized beds” in each process train. The outer container of these tanks was the same size and constructed of the same materials used for the aerated tanks. These units also included an inner tank which contained the pumice gravel which was the media used in these beds. Flow entered in the annular space between the inner and outer tanks and was lifted by air lift pipes to the top of the inner ring containing the pumice media The bottom of the inner tank was not sealed so the down flowing liquid returned to the outer annular space and was again circulated onto the top of the pumice gravel. The air lifts not only 2-5 ------- moved the liquid but the air bubbles provided the oxygen source to maintain aerobic conditions in the circulating liquid. The depth of pumice in the inner tank was about 8 feet and the pumice gravel had a median size of about 1/2 inch This size media was selected to provide a high surface to volume ratio for the attachment of the microbial organisms for effective nitrification in the bed Pumice was selected as the material because of its low density which renders it nearly buoyant and this feature was believed to be important to the successful operation of the unit As sludge was separated from the fluid stream in the bed, the hydraulic capacity in the forward flow direction was impeded and, if accumulation were allowed to continue, the bed would eventually become completely clogged. To correct this potential problem the unit was designed with additional aeration diffusers beneath the pumice bed When these aerators were on, the whole inner tank acted as an upf low airlift so the flow direction was reversed; this aeration “fluidized” the pumice bed and suspended the buoyant pumice gravel n the liquid. This also released the trapped sludge which was washed over into, and settled at the bottom of, the outer annular space Most of this sludge was removed manually from this space and was returned to the anaerobic bio-reactor The choice of ‘ecological fluidized bed” as the name for this unit is somewhat misleading since it is normal practice to define the function of a treatment unit while operating i the forward flow direction. In this case, when the bed is in the treatment mode, the pumice is not fluidized and the bed acts as a downflow, coarse media, contact filter unit. It was only during the backwash cleaning op erations that the pumice was fluidized Both contact filters and truly fluidized media beds have been available for some time as components in conventional treatment processes The three EFBs were originally designed and operated as three aerobic units in series but operational experience soon indicated that nitrificatton was essentially complete after the second unit. Consequently, the third tank was converted to an anoxic unit to provide additional capacity for denitrification. This was accomplished without major physical changes in the unit the airlift delivery pipes were turned off and a 1 5 hp recirculating pump was located at the top of the central tank. This induced an upflow direction in the pumice bed and delivered the fluid to the bottom of the annular space. The lack of aeration and the resulting low oxygen levels created anoxic conditions in the pumice, creating an environment suitable for denitrification This modified unit was still backflushed in the same manner described previously Denitrification requires a carbon source for the reaction to function. The available carbon (BOD 5 ) in the wastewater was, by design, very low at this point in the system and, consequently, was insufficient to support denitrification. As a result it was necessary to add a carbon source to the water prior to the denitrification process A variety of carbon sources were tried, including sugar and acetate, but ultimately methanol became the standard addition for the AEES process, as it is in conventional wastewater treatment processes The theoretical HRT in each of the EFBs was about 7 hours at design flow. It was the basic purpose of the first two units essentially to complete the removal of BOD 5 , and to nitrify the ammonia contained in the wastewater. The third unit was then used for denitrification of that — 2-6 ------- nitrified ammonia. The water surface of the annular space in these tanks was used to support the hydroponic growth of tree seedlings and other plants suspended in pots around the penmeter of the tank The plants probably removed some nutrients and micronutrients from the water but their contribution to the treatment function of the system appeared to be minimal However, these plants can provide a beneficial return since they can be sold. It was estimated that an annual revenue of about $1,200 could be achieved from sale of these plants during the spring/summer gardening season in Maryland 2 2 4 Final Clarifier The three EFBs were followed by a hopper-bottomed clarifier for final separation of most of the remaining sludge prior to the final marsh component in the system. The tank for this clarifier and the materials used were the same as previously described for the aerated tanks The settled sludge was periodically removed from this tank and discharged to the Ballenger Creek WWTP. The water surface on this tank was covered with duckweed (Lemna sp) and other small floating plants but it is not believed that these plants contributed significantly to the treatment in these tanks, owing to their very small root structure and the relatively short detention time in this unit The theoretical HRT in the final clarifier was calculated to be 81/2 hours at design flow. 2.2.5 High-rate Marsh The high-rate marsh was the final component in the process train It was similar in concept to the subsurface flow (SF) constructed wetland, widely used for treatment of municipal and domestic wastewaters. This high-rate marsh consisted of a lined excavation in the floor of the greenhouse. The excavation was filled with clean selected gravel and planted at the top with a variety of plant species. The rectangular bed was about 13 feet wide and 30 feet long, and contained a 3½ feet depth of gravel. The top foot of gravel was sniall %“ stone while the remaining depth comprised 1W stone. The theoretical HRT in this unit was about 9 hours at design flow The high-rate marsh was operated and maintained in a different manner to conventional SF treatment wetlands n the latter case, the depLh of the SF wetland bed typically does not exceed 2 feet to allow the roots of the vegetation to interact with a l of the wastewater flowing through the bed. Deeply rooted emergent vegetation such as bulrush (Scirpus) or common reeds (Phragmites) are typically used (Reed et al., 1995, EPA, 1993). The plant litter is allowed to accumulate on top of the bed and the decomposition of this materia’ provides some of the carbon source needed for denitrification. The SF wetland bed is sized to accomplish the limiting treatment response. One of these SF wetland units, depending on only the plant litter as a carbon source for denitrification, would have to be much larger than the high-rate marsh in the Living ’Machine®. 2-7 ------- Conversely, the Living Machine® high-rate marsh did not have to provide significant nitrification since the ecological fluidized beds were intended for that purpose. Since methanol was used as a process addition, plant litter was not necessary as a carbon source and was regularly cleared from the surface of the gravel be-d. In addition, as deeply rooted plants were not really needed, a variety of plants could be grown for aesthetic and commercial horticultural purposes. These plant roots were in contact with the flowing wastewater, and certainly provide some uptake of nutrients and micro nutrients, but they were not one of the major components responsible for treatment as they are in a true SF wetland system. In essence, this final high-rate marsh acted as a final polishing filter with the upper surface maintained as a commercial horticultural operation. Seedlings were planted and raised to marketable size and then replaced with new plant material. Using data provided by OAl, the authors of this report estimated that a revenue of about $3,600 per year could be achieved from sale of these plants during the summer gardening season in Maryland 2.3 Process Evaluation of the Frederick Living Machine® The independent EPA evaluation of this facility was conducted during the spring and early summer of 1995. The study included flow measurement; tracer studies to determine the actual HRTs in each of the process units, regular composite water quality sampling to determine performanQe of the major process units, and a special study to evaluate the contribution of the plants to the treatment occurring in the system. The study report (EPA, 1996) describes all of these efforts in detail 2 3.1 EPA Water Quality Data A summary of average water quality data over the 11 week EPA study period is given in Table 2.2. Based on the EPA test data shown in Table 2 2, it would appear that the Living Machine® at Frederick, MD did not meet any of its treatment goals during the study period, with the exception of TSS. However, it became obvious during the study period that the system was not yet in true “steady state” operation. For example, the utilization of methanol as the denitrification carbon source began during the early stages of the testing program Inexperience with methanol dosages on the part of the AEES operators resulted in unusually high values for BOD 5 , COD, and NO 3 Consequently, it can be concluded that the data collected during the 11 week test period was not truly representative of the “steady state” capabilities of the process 2-8 ------- Table 2.2 - EPA Water Quality Data Summary for Frederick, Maryland Living Machine® (March-June 1995) Raw Parameter Sewage lnfiuent Anaerobic Bio-reactor Effluent Aerated Tank Effluent First EFB Eff Third EFB Eff. High-raLe Marsh (Final) Effluent Treatment Goals Mean Water Quality, mg/L Tota’ 1307 445 399 150 73 53 -- COD Sol COD 158 216 64 51 43 38 -- Total BOO 469 160 106 49 18 12 <10 Sol.BOD 70 108 10 6 11 10 -- TSS 470 78 148 43 10 4 <10 VSS 364 64 122 34 6 2 -- TKN 56 43 46 30 10 8 -- Ammonia 26 34 28 23 8 6 <1 NO 3 02 02 04 2 10 5 <5 TP 14 8 8 8 7 7 <3 TN 562 432 464 32 20 13 <10 FecalC5li 8x10 6 l7Qcful lOO -- cfu/100 ml ml The flow monitoring and lithium chloride tracer study carried out during the course of the EPA evaluation did confirm that Train B of the Frederick Living Machine® was treating its intended design flow of 13,300 gpd, and that the actual HRTs of the process units were within ito 3 hours of the theoretical retention times The actual HRT of the whole Frederick AEES was calculated to be approximately 3% days at the design flow rate, whereas the theoretical total HRT was closer to 3 days Two further studies were carried out as part of the EPA evaluation. The first was an analysis of process residuals which was intended to examine how suitable the biosolids and plants generated by the process were for land application or composting. The second additional study was designed to assess the contribution of the floating macrophyte plants to the treatment performed by the AEES. Both of these studies are described later in this chapter. 2.3 2 Additional Water Quality Data Another purpose of the independent EPA data collection program described above was to compare test results with similar data collected by the AEES staff. As described in the study report 2-9 ------- (EPA, 1996), this comparison indicated a reasonable correlation between the two data sets. Such a correlation should be expected since many of the AEES samples were tested in the certified laboratory at the Ballenger Creek VVWTP. This correlation allowed an extension of the evaluation to include data collected after the EPA test period. The performance data shown in Figures 2-2 to 2-7 cover the period from March 1995 through March 1996. These provide data on a full annual cycle of system operation and may suggest seasonal influences because of low winter temperatures. Figures 2-2 to 2-7 present these data in graphical form. AU six figures are constructed in a similar manner and show the treatment goal, the concentration in the raw wastewater influent, in the final effluent (both EPA and OAI test data), and in the case of BaD 5 , COD, TSS, and TP the concentration of the influent entering the greenhouse after anaerobic pretreatment (denoted as UGH Input” in the figures). The graphs for BOD 5 , COD, and TSS are plotted to a logarithmic scale because of the broad range of concentrations observed. Sampling and testing occurred on a weekly basis (for both EPA and OAI data) but are shown on the graphs as monthly averages for clarity. The EPA study also included additional sampling and testing between the major system components in the greenhouse to define the role of these units. These data and the related discussion can be found in EPA, 1996 and Reed et a!., 1996. 400 100 -j 0, E 0 0 10 MAR 95 APR MAY JUN JUL AUG SEP OCT NOV DEC JAN 96 FEB MAR MONTH —•-— flaw In —&-- Effluent — — Goal —0—— GH Input —A-— EPA Figure 2-2 Frederick AEES BOD 5 Input Versus Output, March 1995 - March 1996 2-10 ------- The annual average concentration of BOD 5 in the raw sewage was 230 mg/L which is within the range normally expected for municipal wastewaters. The influent to the greenhouse (effluent from the preliminary anaerobic treatment) was measured during the EPA study period and averaged 156 mg/L so the anaerobic reactor removed about 68 percent of the .incoming BOD 5 during the study period. During April and May the final effluent BOD 5 exceeded the 10 mg/L project goal but this was probably a result of the introduction of methanol as a carbon source for denitrification. Once experience was gained in the management of this methanol addition, the effluent BOD dropped to about 4 mg/L. The annual average BOD 5 , including the higher values, was 7 mg/L which is still significantly below the process goal. Consequently, it can be concluded that the Living Machine® at Frederick, MD displayed a reliable capability to remove BOD 5 to below the 10 mg/L target. Most of that removal occurred in the anaerobic bio-reactor and the aerated 2000 “Mean - 377 mgJL w a 1oo iII II jIiIIiiIiiIi ______ EPASTUDY > j -MEAN- 3Omg 1. I 10 I I I I I I I MAR 95 APR MAY JUN JUL AUG SEP OCT NOV DEC JAN 96 FEB MAR MONTH —+ Raw mu —h— Effluent — —- Goal —+--— GH Input —A— EPA Figure 2-3 Frederick, MD, COD Input Versus Output, March 1995 - March 1996 tanks, both of which are comparable to conventional wastew ter treatment processes. The chemical oxygen demand (COD) performance shown on Figure 2-3 is similar to that shown previously for BOD 5 . The majority of this component (60%) was removed in the anaerobic bio-reactor, and the elevated values during April and May 1995 are again probably a result of the introduction of methanol as a new carbon source. The annual average effluent COD was 30 mg/L 2-11 ------- o EAN—7Om9 t. -J 0 (I ) 0 U 0 MEAN-2mgJL ___ EPASTUDY >‘T” A MAR95 APR MAY JUN JUL AUG SEP OCT NOV DEC JAN96 FEB MAR MONTH —1—— Raw in —z — EllIuent —-— Goal —* GH Input —A--— EPA Figure 2-4 Frederick, MD, TSS Input Vs. Output, March 1995 - March 1996 which is well below the target performance goal, indicating that the Living Machine® at Frederick, MD could provide reliable and consistent COD removal. The removal of total suspended solids (TSS) is shown on Figure 2-4 and, in this case, 82% of the TSS was removed in the anaerobic bio-reactor. Slightly elevated effluent values were experienced during the spring and early summer but, with improved solids management procedures, the effluent values were consistently at or near 1 mg/L. The annual average effluent value was 2 mg/L which is significantly below the 10 mg/L target goal, indicating that the Living Machine® at Frederick could provide reliable and consistent removal of TSS. The EFBs which serve as filter beds are extremely effective in reducing TSS concentrations to very low levels. The removal of ammonia nitrogen (NH 3 /NH 4 ) is shown on Figure 2-5. In this case, ammonia concentrations were only measured in the greenhouse influént and averaged 22 mg/L which is within the typical range for municipal wastewaters. The effluent showed some elevated values during the spring and early summer and this may also be a result of inexperience with the methanol additions. The mean annual effluent value was 3 mg/L which is relatively low but was still above the target performance goal of I mg/L that was established for this process. If the higher values that occurred during the spring of 1995 are not included, the average for the remainder of the year 2-12 ------- 30 - 25 C) E z w C, 0 i.- 15 z z 10 0 5 0 MAR 95 APR MAY JUN JUL AUG SEP OCT NOV DEC JAN 96 FEB MAR MONTH —1--— GH Input —h—— Eflluent 1 rng/L Goal —A--- EPA Figure 2-5 Frederick, MD, Ammonia Nitrogen Input Vs. Output, March 1995 - March 1996 would still exceed the 1 mg/L project goal. Therefore, the Living Machine® in Frederick, MD did not meet its intended goal for ammonia removal. However, it is believed that the ammonia target could be achieved with improved operation and management procedures, and this has been demonstrated with the results from the 80,000 gpd system in South Burlington, VT (see Chapter 3). Figure 2-6 presents influent versus effluent data for total nitrogen, at the Frederick, MD Living Machine®. Data for this parameter are only shown for the influent to the greenhouse and the final effluent. It is again likely that the higher effluent values during the spring of 1995 were a direct result of inefficient denitrification owing to inexperienced management of the newly introduced methanol carbon source. The divergence during the winter of 1995-96 is believed to be a result of other causes, such as the low winter temperatures inside the greenhouse. The mean annual effluent TN concentration was 11 mg/L which exceeds the 10 mg/L target goal. If the divergence in the spring of 1995 were ignored, the average effluent value would still exceed the target goal. Figure 2-7 compares influent versus effluent data for total phosphorus at the Frederick, MD Living Machine®. In this case, the concentration in the raw sewage, the greenhouse influent and the final effluent were all measured. The mean annual phosphorus concentration in the effluent was 6 mg/L which is twice the design goal of 3 mg/L. At the Frederick facility, most of the 2-13 ------- 50 -J 40 z H ;3 0 w 0 ‘I I.- z -J 10 F- 0 MAR 95 APR MAY MONTH —4— GH Input —a-— Etituent ——- Goal —A-— EPA Figure 2-6 Frederick, MD, Total Nitrogen, Input Vs. Output, March 1995 - March 1996 phosphorus (30%) was removed in the anaerobic bio-reactor, probably as a result of the settling of suspended solids in this unit. The biological components in the greenhouse accounted for a further 15% of the removal. None of the biological pathways available in the current AEES process can be expected to remove large quantities of phosphorus, however, biological phosphorus removal is possible in specially designed and operated treatment plants. Several commercially available processes induce biological uptake of phosphorus by the activated sludge microorganisms and result in the production of significant quantities of sludge. The other commonly used phosphorus removal method in wastewater treatment is the use of chemical additions to precipitate the phosphorus but these typically also result in the production of large quantities of sludge. It is also possible to remove phosphorus via plant uptake and harvest. However, the plant density and the harvesting program at the Living Machines® are not sufficient to account for significant amounts of phosphorus removal. Based on the data presented in the study report (EPA, 1996), it can be calculated that about 751 kg/yr of phosphorus enters the AEES with incoming wastewater, at a flow rate of 40,000 gpd. Approximately 0.44 kg/yr of phosphorus would leave the JUN JUL AUG SEP OCT NOV DEC JAN 96 FEB MAR 2-14 ------- 18 -J C) E 15 0 . (I, o g I 0 C l , 0 6 -J 0 MAR 95 APR MAY JUN JUL AUG SEP OCT NOV DEC JAN 96 FEB MAR MONTH —1-—— Raw Inp — — Efflueni ——- Goal +- GH Input —A—- EPA Figure 2-7 Frederick, MD, Phosphorus Input Versus Output, March 1995 - March 1996 facility with the routinely harvested and composted plant material. Additional phosphorus is removed during the horticultural operations but it is unlikely that the total annual phosphorus for all plants leaving the greenhouse exceeds 1 kg/yr. Consequently, it can be estimated that the plants in the Frederick Living Machine® could account for the removal of about 0.1% of the phosphorus entering the system. Based on this estimate, either significant phosphorus removal should be dropped as an AEES performance goal or additional processes for phosphorus removal should be incorporated into the system. 2.3.3 Process Residuals The residuals leaving the Frederick, MD Living Machine® process include biosolids from the anaerobic bio-reactor and biosolids from the clarifiers and the plants removed from the water surfaces on the various tanks. The plants removed during the horticultural operations are not included in this residuals estimate since they are intended for replanting rather than disposal. The sludge removed from the EFBs at Frederick, MD was returned to the anaerobic bio-reactor and was accounted for in the sludge wasted from that unit. 2-15 ------- Samples of sludge and plant material were collected on several occasions during the EPA study at Frederick, MD and tested for nitrogen, phosphorus, fecal coliforms, and the metals of concern for land application of sludge (under the 40 CFR, Part 503 regulations) These results can be found in the study report (EPA, 1996). The plant material showed no unusual concentrations of any material and it was concluded that the final compost could be used for any agricultural or horticultural purposes The sludges from the system met all of the 503 limits for High Quality sludge, except those for fecal coliforms The fecal coliform limits could be satisfied with additional stabilization and treatment of the sludges The total amount of residual materials removed from the AEES facility in Frederick can be estimated from the data in EPA, 1996. Based on these data an average of 4,434 gallons of sludge per week were wasted from the anaerobic bio-reactor; at 2 8 percent solids; that is about 472 kg/wk of dry solids, the final clarifier would contribute about 2 kg/wk, and the plant residuals about 1 kg/wk of dry material. On an annual basis, the residuals production would be about 12 dry tons (metric) per year A comparable 40,000 gpd extended aeration package plant, with a final denitrification filter, would waste about 1,000 gallons of sludge per day with about 2% solids, this would equal 76 kg/d of dry solids or 14 dry tons (metric) of sludge per year The AEES appears to produce slightly less sludge than a conventional extençied aeration treatment process, which also includes final filtration, when effluent characteristics are comparable for the two systems. This should not be surprising since the process functions in each system are also similar The difference in residuals production between the two systems is probably a result of the estimated 20% solids reduction achieved in the AEES anaerobic bio-reactor 2 3.4 The Role of Plants in the Frederick Living Machine® Plants are included in almost every unit in the AEES system and their contribution has been claimed to be essential to the performance of the process (Todd & Josephson, 1996) Having committed to plants and solar energy, the design logic then requires the use of a greenhouse when colder seasonal climates prevail, for protection and continued year-round growth of the plants The commitment to the greenhouse then causes a design dilemma since the high cost of the space enclosed by a greenhouse then requires deep high-rate treatment units for cost effective use of that space. Such high-rate units consequently minimize the surface areas available for utilization of plants, so the role of the plants is diminished along with the original and highly desirable intent to utilize plants and solar energy as major components in the system A treatment system based on the use of plants and solar energy as major components must provide sufficient surface area so that the plants are in fact a major physical presence in the system. However, this does not appear to be the case at the Frederick Living Machine®. During the first eleven weeks of the EPA study period at the Frederick Living Machine®, macrophyte plants were present and completely covered the water surfaces in the aerated tanks. As a result, their contribution to treatment was included in the performance data collected during that time but it could not be separately defined At the suggestion of the EPA study team and with 2-16 ------- the concurrence of the grantee, MFEMPS, all of the floating macrophyte plants were removed from the aerated tanks in the tested treatment train for a second phase of the study, which included three additional weeks of data collection A comparison of the data collected during these two periods of the study indicated that there was no significant difference, with or without the floating rnacrophyte plants, for removal of COD, BOD 5 , TSS, VSS and phosphorus, for either the final system effluent or for the effluent from the aerated tanks (EPA, 1996) There were very small but significant dtfferences for the nitrogen forms The TKN and ammonia were lower and the nitrate levels were higher when the aerated tanks contained plants Since the nitrate concentrations leaving the aerated tanks were somewhat higher with plants on the tanks, this suggested that the microbial activity on the plant roots does contribute to nitr fication However, this slightly diminished nitrification capacity without the plants could apparently be compensated for by nitrification in the EFBs, so there was no major difference in performance of the overall system with or Without plants in the aerated tanks. This observation was confirmed by continued operation without the plants after the EPA study period ended and, consequently, it was concluded that the floating macrophytes used in the aerated tanks at the Frederick Living Machine® did not contribute significantly to the treatment of the influent wastewater The potential exists for the plants to contribute more but the water surface area available on the deep AEES tanks was limited which suggested that there were not enough plants available to make a significant difference in treatment performance In other “natural” systems, t e plant roots and the associated microbes have been shown to provide the major source of treatment However, these other natural systems have a very large water surface area and a relatively shallow water depth so the use of protective greenhouses may not be economical under most circumstances. 2-17 ------- CHAPTER 3 THE BURLINGTON, VERMONT LIVING MACHINE® 3.1 Background The Living Machine® at this location is situated on the grounds of the South Burlington wastewate? r treatment plant (VVWTP) in Chittenden Co , VT, at a latitude of 44.28 and an elevation of 330 feet The mean annual temperature at this site is 7°C (450 F) with minimum temperatures of -22°C (-8° F) occurring in January The extended periods of sub-freezing temperatures require a greenhouse structure at this location to protect the treatment components of the Living Machine® These periods of low temperature were also considered by the system designers to limit the anaerobic reactions in the preliminary bio-reactor, so the unit was replaced in the design with additional aeration units located inside the greenhouse The design flow at this system is 80,000 gpd of raw wastewater which is received, after screening and grit removal, from the South Burlington WWTP The treated AEES effluent and sludge residuals are all returned to the WWTP for further treatment and disposal. The treatment goals established for this AEES facility are the same as the 40,000 gpd system in Frederick, MD (see Chapter 2), however, the influent wastewater at Burlington is not as strong as that received by the Frederick Living Machine®. Nevertheless, the water temperatures are much lower at the Burlington system: influent temperatures in the range of 4° to 7°C (39° to 45° F) were expected during the winter months Start-up of this Living Machine® occurred in October 1995 and the facility was in continuous operation through March 2000. 3.2 Process Description of the Burlington Living Machine® The greenhouse that encloses the South Burlington facility covers an area of 8,000 square feet, and the 80,000 gpd design flow is split equally between two 40,000 gpd process trains. A third train of much smaller tanks has also been included for research purposes The hydraulic residence time in the South Burlington facility is estimated to be about three days at design flow. The total HRT under design flow conditions at the Frederick AEES was measured at 3.6 days; 2.4 days of that time were in the aeration tanks and ecological fluidized beds which are the only biological components to be used at South Burlington. A process flow diagram of the South Burlington Living Machine® is shown in ‘Figure 3-1 This process train was later modified, as shown in Figure 8-1. 3-1 ------- Figure 3 -1 Process Flow Diagram of the 8O,000gpd Living Machine® to Test Trains Vermont Raw Influent to Train B (identical to Train A) Train A in South Burlington, Aerated Tanks Pumice Stone Filters (“Ecological FluidizedBeds “) Treated Effluent Cia r fier ------- 3 2.1 Aerated Tanks There are five aerated tanks in series at the Burlington AEES as compared to two at the Frederick facility A clarifier follows the last aerated tank and effluent from this clarifier flows to three EFBs in series Sludge separated by the clarifier flows to a holding tank and is then returned to the South Burlington WVVTP There is a recycle line for return of liquid from the fifth aerated tank to the first The use of five aerated tanks at this location was considered necessary by the designer because of the lower temperature sewage during the winter months and because there is no preliminary anaerobic treatment provided. These aerated tanks are larger and constructed differently than those that were at the Freder;ck Living Machine At Burlington, each tank is 14 feet in diameter (10 feet at Frederick) and 13 feet deep (9 feet at Frederick) They are glass lined, bolted steel tanks manufactured by Aquacare Inc of Seattle, WA This new tank composition is expected to eliminate the potential maintenance problems with the plastic membrane lined tanks that were used at the Frederick location. The aeration equipment used is similar to that used in Frederick. The process design anticipated at least partial nitrification of the wastewater ammonia by the fifth aerated tank. The total HRT in the aerated tanks is estimated to be about two days at design flow. Fixed racks on the water surface of these tanks support a wide variety of plant species, ranging from grasses to tree seedlings. 3 2 2 Ecological Fluidized Beds The EFBs are functionally the same as the units that were in place at the Frederick facility. However, a higher density, harder volcanic stone is used at South Burlington instead of the softer pumice used at Frederick. The pumice suffered significant abrasion losses during the “fluidizing” portion of the operational cycle and the fine particles can also create maintenance problems. The EFBs at South Burlington contain about 0.1 cubic feet of media per gpd of process flow which is a slightly higher ratio than used at Frederick, MD. The process design at Burlington anticipates complete nitrification in the first EFB. Methanol was added as a carbon source of the influent of the second EFB, which is operated as an upflow anoxic reactor in the treatment mode. The third EFB is intended for final effluent polishing Backflushing these filter beds uses the same general procedure for the Frederick AEES, as described in Chapter 2 The backflushed sludge accumulates in the outer annular space in these tanks and is then pumped to the clarifier located after the fifth aerated tank. The third EFB is the final unit at the South Burlington Living Machine®. The final clarifier and high-rate marsh used at the Frederick facility were eliminated in this system, based on their marginal contribution to treatment observed at Frederick and because of space limitations in the South Burlington greenhouse 3-3 ------- Steady state operations were achieved in May 1996 and continued through August 1999 with actual flows at or near the 80,000 gpd design flow Since natural carbon sources are not present in sufficient quantities in the anoxic EFB to support denitrification, methanol was used routinely for this purpose, as it was at Frederick Kowev r, process changes in 1999 at this Burlington facility (See Chapter 8 for description) eliminated the need for methanol additions 3.3 Evaluation of the South Burlington Living Machine® The target performance goals are similar to the previously specified for Frederick, MD and are summarized in Table 3 1. Independent testing of this facility by EPA was not deemed to be necessary, based upon the experience established from the previous study of the Frederick Living Machine®. Consequently, for the purposes of this report it was assumed that the test data collected by the AEES operating staff, much of which was analyzed at a certified laboratory, would provide a reliable basis for the evaluation Data summaries and discussions in this report are based upon the sampling results produced between June 1996 and August 1999. Table 3.1 - Treatment Goals for the Burlington Living Machine® - Parameter Goal All units in mg/L Biochemical Oxygen Demand (BOD 5 ) <10 Total Suspended Solids (TSS) <10 Ammonium/Ammonia Nitrogen (NH 3 /NH 4 ) <1 Total Kjeldahl Nitrogen (TKN) <5 Nitrate Nitrogen (NO 3 ) <5 Total Nitrogen (TN) <10 Total Phosphorus (TP) <3 Treated flows at the Burlington Living Machine® were measured and found to be an average of 72,906 gpd during the period between June 1996 to June 1999. This compares with the design flow of 80,000 gpd. 3-4 ------- Wastewater samples are collected on a weekly basis at the Burlington Living Machine®. A summary of the mean influent and effluent data collected during the evaluation period is shown in Table 3 2 below The results for the individual water quality parameters measured are discussed in the following paragraphs Table 3.2 - Mean Wastewater Quality for the Burlington AEES (June 1996 - August 19991) Parameter Influent Effluent Goal All units in mg/L (except for fecal coliform) Carbonaceous BOO 5 (CBOD 5 ), June ‘96 - June’97 227 5 9 <10 Chemical Oxygen Demand (COD) 556 35 9 <502 Total Suspended Solids (TSS) 213 5 3 <10 Ammonium/Ammonia Nitrogen (NH 3 /NH 4 ) 16 3 04 <1 Total Kjeldahl Nitrogen (TKN), June 96 - January 99 28.1 1 6 . <5 Nitrate Nitrogen (NO 3 ) 0 2 4 9 <5 Tota’ Phosphorus (TP) 60 2 0 <3 Total Nitrogen (TN). June ‘96 - December98 29 3 5 6 <102 Fecal Coliform (units MPN/100 mL), June’96 - June97 8x10 6 1.225 <1,0002 Note I Data are the means for the June 1996 through August 1999 period, except where noted otherwise. Note 2 These goals were initiated by the AEES operators after system start-up Based on the data in this table, it can be seen that the Burlington Living Machine® met all of its original design goals during the annual cycle assessed in this evaluation. Additionally, the system achieved the operator initiated goals for COD and TN that were established by the LTI staff at the facility after start-up The individual water quality data for the study period are shown in Figures 3-2 to 3-13. These figures include influent temperature as well as influent and effluent water quality data, in order that seasonal temperature influences might be observed in the process performance. Additionally, figures are included to show the percentage removals for CBOD, NH 3 , and TKN to observe further the effects of temperature on process performance. 3-5 ------- The figures are constructed in a similar manner and show the treatment goal, as well the concentration of the measured parameter in the raw influent and in the final effluent. The graphs for CBOD, COD, TSS, and fecal coliform are plotted on a logarithmic scale owing to the broad range of concentrations observed. Sampling and testing occurred on a weekly basis but are shown on the graphs as monthly means for purposes of clarity. Effluent data for both process trains are also shown on the graphs as well as the mean system effluent. From Figure 3-2, it may be observed that the mean CBOD concentration in the raw sewage at South Burlington from June 1996 through June 1997 was 227 mg/L which is within the range expected for typical municipal wastewaters. During the annual cycle evaluated, the effluent was within the design goals for the facility, although the monthly means for Train A exceeded the goal three times during the year. Two of these exceedances occurred during the colder winter months Train B performed very well during this period which brought the mean effluent of the total system below the 10 mg/L goal. The mean CBOD effluent for the annual cycle was 5 9 mg/L which is well within the design goal for the Living Machine®. Consequently, it can be concluded that the Burlington AEES displayed the capability to reliably remove CBOD to below the 10 mg/L target. Figure 3-3 shows the percentage removal of CBOD during the annual cycle. These data indicate that there was a pronounced drop in CBOD removal between December 1 99ffand January 1997 although the system appears to recover during the following month A slight reduction in mean percentage CBOD removal can be observed from the summer to the winter months but the mean removal remained at 97 3% for the year Monthly mean COD data s shown in Figure 3-4 and demonstrate that the mean effluent of the Burlington Living Machine® successfully met the operator initiated goal of 50 mg/L during the majority of the evaluated period During this period, the mean CBOD influent was 556 mg/L and the mean effluent was 35.9 mg/L, which was well within the intended goal Train A of the AEES exceeded the 50 mg/L goal several times during the study although, once more, the better performance of Train B brought the average system effluent below the target in all but three months. Again, a slight reduction in removal can be observed during the winter months. From this data, it can be concluded that the Burlington AEES can reliably achieve removal of COD. Data for removal of TSS are shown in Figure 3-5 and indicate that the Living Machine® at Burlington is capable of meeting its design goal for TSS. The mean effluent for the study period was 5 3 mgIL compared to the goal of 10 mg/L. However, the mean annual influent to this system of 213 mg/L was less than half the strength of the influent treated at the Frederick AEES. This comparison is expanded upon in Chapter 6 of this report. As with CBOD and COD, Train B of the Burlington Living Machine® outperformed Train A, whose monthly means exceeded the design goal six times during the evaluated period. However, the mean effluent quality indicates the capability of this system to remove TSS dependably 3-6 ------- 1000 Figure 3-2 Influent and Effluent CBOD for the South Burlington Living Machine® Monthly Means (June 1996 to June 1997) C-) C- 0 C, m 100 0 U) w 0 C, OCD ‘< 0) CD CD 0) 0. 3 C O I- Jun-96 Jul-96 Aug-96 Sep-96 Oct-96 Nov-96 Dec-96 /1 Jan-97 Feb-97 Mar-97 Apr-97 May-97 Jun-97 0 Influent CBOD —0-—— Effluent CBOD Train A&B — 4 — Effluent CBOD Train A Mean Influent 227 rng/L — A— Effluent CBOD Train B Design Goal Influent Temperature 25 20 15! 1o& 5 A 0 / A’ A / 0 • Mean Effluent 5.9 mg/L 0 Jul-97 Date ------- Apr-97 May-97 30 25 2O 15. 10 5 Jun-97 Jul-97 Figure 3-3 Percentage Removal of OBOD for the South Burlington Living Machine® Monthly Means (June 1996 to June 1997) 105% 100% Mean Removal 97.3% — g5% o3 0 )0 090% / A 85% —D-----% Removal: CBOD Train A&B — — % Removal: CBOD Train A — -A—- % Removal: CBOD Train B lnfluent Temperature 80% Jun-96 Jul-96 Aug-96 Sep-96 Oct-96 Nov-96 Dec-96 Jan-97 Feb-97 Mar-97 Date ------- Figure 3-4 Influent and Effluent COD for the South Burlington Living Machine® Monthly Means (June 1996 to August 1999) C, m 3 ( X 100 CDCD 3 I- 10 Apr-96 Jul-96 Oct-96 Jan-97 Apr-97 Ju’-97 Oct-9 Jan-98 Apr-98 Jul-98 Oct-98 Jan-99 Apr-99 Jul-99 Date 1000 25 20 -0 C l 3 -‘ C 1 10 5 0 ------- Figure 3-5 Influent and Effluent TSS for the South Burlington Living Machine® Monthly Means (June 1996 to August 1999) Oct-96 Jan-97 Apr-97 Jul-98 Oct-98 Jan-99 Apr-99 Jul-99 1000 100 10 [ Mean Influent 213 mg/L -I 0 D) C,) OD cn (1) 3 (0 I- ilL 0 Influent TSS 0. 5 5 0- -. -‘ —0--— Effluent TSS Train A&B 25 20 ‘5 — 0 -- Effluent TSS Train A — A— - Effluent TSS Train B Design Goal (lOmg/L) lnfluent Temperature / 0’ / A- / ‘I Apr-96 Jul-96 Mean Effluent 5.3 mg/L ‘Ia U / Jul-97 Oct-97 Jan-98 Apr-98 I I- I 0 Date ------- The removal of NH 3 is depicted in Figure 3-6 The mean influent concentration of NH 3 during the annual cycle was 16.3 mg/L which is fairly typical of municipal wastewaters The mean effluent during the period was 0 4 mg/L which was well within the design goal of 1 mg/L The monthly mean exceeded this goal only three tmes during the ‘three-year period as a result of Train A Once again, Train B outperformed Train A over the study period Figure 3-7 shows the percentage removals of NH 3 by the Burlington AEES during the study year. The mean removal of NH 3 achieved by the system was 97.4% From Figure 3-8, it may be seen that the mean monthly effluent concentrations of TKN were well within the Living Machine’s® design goal for all but one month during the study period. In fact, the mean effluent concentration for the period was 1 6 mg/L, less than 35% of the 5 mg/L goal The mean influent TKN during the annual cycle was 28.1 mg/L Again, only Train A failed to achieve the goal (twice during the study period) This caused the system to miss its goal once during the study period However, other than that, the system achieved this goal without any apparent difficulty so it may be concluded that the Burlington AEES can meet its target for TKN. Figure 3-9 shows the percentage removal of TKN for the Burlington facility. A slight drop in TKN removal efficiency may be observed dunng the colder, winter months and it is again apparent that Train B outperformed Train A for the majority of the study period The mean TKN removal percentage for the year was 93 4% Data for effluent NO 3 is shown in Figure 3-10, and demonstrates that the Burlington AEES achieved its design goals for most of the study period The mean effluent for the study period was 4.9 mg/L, which was met during this period using methanol as a carbon source. However, the goal was exceeded in 11 out of 36 months during the study period, June 1996 though August 1999. While the mean NO 3 effluent meets the design goal, it does not achieve it by a large margin Figure 3-1 1 presents influent and effluent data for TN at the Burlington Living Machine®. The failure to meet the operators’ effluent goal around July 1996 was a result of the fact that methanol was not being dosed into the system at that time Once methanol dosing had commenced, the AEES had no problems achieving the operator initiated goal for TN of 10 mg/L The average for the study period was 5 6 mg/L which implies that the Burlington facility can reliably achieve its operators’ goals for TN 3-11 ------- Figure 3-6 Influent and Effluent NH 3 for the South Burlington Living Machine® Monthly Means (June 1996 to August 1999) 25 20 15 10 -s 5 0 25 20 Mean Influent 16.3 mg/L 3 3 15 0 0 (D( 10 5 0 Influent NH3 —0——Effluent NH3 Train A&B — -o — Effluent NH3 Train A — -A— - Effluent NH3 Train B Design Goat (lmg/L) Influent Temperature Begin Methanol Addition (Aug 1996) I Mean Effluent 0.4 mg/L - S - Cease Methanol Addition; commence recycle (Apr 1999) 0 Apr-96 Jul-96 Oct-96 Jan-97 Apr-97 Jul-97 Oct-97 Jan-98 Apr-98 Jul-98 Oct-98 Jan-99 Apr-99 Jul-99 Date ------- Figure 3-7 Percentage Removal of NH 3 for the South Burlington Living Machine® Monthly Means (June 1996 to August 1999) - 30 102% 25 97% CD B o - -. 4 CD B CD CD 10 -i 15 B B87% 0 10 82% — I 77% I 5 Apr-96 Jul-96 Oct-96 Jan-97 Apr-97 Jul-97 Oct-97 Jan-98 Date Apr-98 Jul-98 Oct-98 Jan-99 Apr-99 Jul-99 Mean Removal 97.4% ‘I! •1 i i —0--— % Removal: NH3 Train A&B — - — % Removal: NH3 Train A — - % Removal: NH3 Train B Influent Temperature ------- Figure 3-8 Influent and Effluent TKN for the South Burlington Living Machine® Monthly Means (June 1996 to August 1999) 0 Apr-96 Jul-96 Oct-96 Jan-97 Apr-97 Jan-98 Apr-98 Jul-98 Oct-98 Jan-99 Apr-99 60 50 40 30 20 10 -1 0 0 D) I- 25 20 15 10 5 Jul-97 Oct-97 0 Jul-99 Date ------- Figure 3-9 Percentage Removal of TKN for the South Burlington Living Machine® Monthly Means (June 1996 to August 1999) 105% ‘30 100% ______________ 25 95% CD 3 o ‘20 CD 90% -4 CD —o 3 — CD D) CDCD — 85%’ - ‘15 . 0 z .9 0 Co 80%’ 10 75%, 70% ‘5 Apr-96 Jul-96 Oct-96 Jan-97 Apr-97 Jul-97 Oct-97 Jan-98 Apr-98 Jul-98 Oct-98 Jan-99 Apr-99 Jul-99 Date Mean Removal 93,4% Cease Methanol Addition; commence recycle (Apr 1999) A —0---— % Removal: TKN Train A&B — 0 — % Removal: TKN Train A — -A-- - % Removal: TKN Train B Influent Temperature I- ------- Figure 3-10 Effluent NO 3 for the South Burlington Living Machine® Monthly Means (June 1996 to August 1999) Jan-99 Apr-99 Jul-99 25 20 15 10 5 0 14 12 10 8 6 4 2 z 1 1* 0 CD 0) I- 0 Apr-96 Jul-96 Oct-96 Jan-97 Apr-97 Jul-97 Oçt- 7 Jan-98 Apr-98 Jul-98 Oct-98 Date ------- Figure 3-11 Influent and Effluent TN for the South Burlington Living Machine® Monthly Means (June 1996 to August 1999) Jul-96 Oct-96 Jan-97 Apr-97 Jul-98 Oct-98 Jan-99 Apr-99 ) j.HJl. 1 ii Mean Influent 29.3 mg/L 60 50 40 30 20 10 — I 0 oz :T CD (0 I- o lnfluentlN —C—— Effluent TN Train A&B — -0 — Effluent TN Train A — -A— - Effluent TN Train B Operator Goal (lOmg/L) —— lnfluent Temperature 25 20 •15 ,10 Mean Effluent 5.6 mg/L 0 — Apr-96 Cease Methanol Addition; commence recycle (Apr 1999) Jul-97 Oct-97 Jan-98 Apr-98 Date Jul-99 0 ------- Influent and effluent TP at the Burlington AEES is shown in Figure 3-12, and indicates that the facility achieved its design goal of 3 mg/L for the majority of the study period. However, the influent phosphorus averaged 6 mg/L which is at the low end of the range for typical municipal wastewaters (the typical TP concentration is in the 610 10 mg/L range) This makes it unlikely that the Burlington Living Machine® could reliably achieve its design goal for TP if its influent were more representative of “usual” municipal sewage, since the biological processes of the type used by the AEES have a limited capacity for significant phosphorus removal However, at these influent concentrations (—6 mg/L), it appears that the system can meet its goals most of the time This topic is discussed further in Chapter 6. Figure 3-13 contains data for influent and effluent fecal coliform concentrations These data indicate that the Burlington Living Machine® handled an annual mean influent of 8x10 6 MPN/100 mL, which is very similar to that observed at the Frederick facility The effluent averaged a fecal coliform concentration of 1,225 MPN/100 mL which is slightly over the WHO agricultural reuse standard of 1,000 MPN/1 00 mL and significantly above the operators’ goal of 200 MPN/1 00 mL However, the monthly mean values did fall below the WHO agricultural reuse standard two thirds of the time during the year Although, the system did not reliably meet its operator initiated goals for fecal coliform, simple disinfection with UV equipment would certainly allow these goals to be attained. 3-18 ------- Figure 3-12 Influent and Effluent TP for the South Burlington Living Machine® Monthly Means (June 1996 to August 1999) Jul-96 Oct-96 Jan-97 Apr-97 Jul-97 Oct-97 Jan-98 Apr-98 Date Jul-98 Oct-98 Jan-99 Apr-99 20 18 16 — I 0 -‘ CD Q)U) 3 (0 I - 14 12 10 8 6 0 InfluentTP —0-—— Effluent TP Train A&B — — Effluent TP Train A — -fr- - Effluent TP Train B Design Goal (3mgfL) tnfluent Temperature 25 20 mg ; 1o 4 2 4 0 — Apr-96 Mean Effluent 2.0 mg/L 0 ‘p. __. _ .—--—--G -j. t ‘5 ‘0 Jul-99 ------- T1 CD C, C-). 2. < 0 0 I- 100,000,000 10,000,000 1.000.000 100,000 10,000 .1 ,000 100 10’ Figure 3-13 Influent and Effluent Fecal Coliform for the South Burlington Living Machine® Monthly Means (June 1996 to June 1997) Mean Influent 0 Influent Fecal Coliform 0 Effluent Fecal Coliform Train A&B — -O — Effluent Fecal Coliform Train A — -A— Effluent Fecal Coliform Train B WHO Agricultural Reuse Std. — — — Operator Goal (200MPN/lOOmL) • SSJ\Jly S / Jun-96 Jul-96 Aug-96 Sep-96 Oct-96 Nov-96 Dec-96 Jan-97 Feb-97 Mar-97 Apr-97 May-97 Jun-97 Date 25 20 15 — 0 Jul-97 Influent Temperature — — - A--.__ — — — / 5— Mean Effluent 1,225 MPN/1O j d So --- ---- A / \ S / / \ ------- CHAPTER 4 THE SAN FRANCISCO, CALIFORMA LIVING MACHINE® 4.1 Background The Living Machinec at this location was sited at the Oceanside Water Pollution Control Plant (VVPCP), operated by the Department of Public Works for the City and County of San Francisco. The Oceanside WPCP provides advanced secondary treatment for a design flow of 21 mgd. The site is at a latitude of 37 46 at an elevation of about 10 feet. The mean annual air temperature is 13°C (55°F), with minimum winter temperatures of 4°C (40°F) and, consequently, it was considered that the AEES at this location did not need a protective greenhouse The San Francisco AEES was trailer mounted and designed for the high-rate, tertiary polishing of advanced secondary effluent from the Oceanside WPCP; therefore, it did not include all of the units previously described for either the Frederick, MD or South Burlington, \IT systems. The San Francisco AEES was composed entirely of “ecological fluidized beds,” with two fish tanks as a side stream The intended total flow of the two parallel treatment trains was 50,000 gpd The goal of this AEES was to produce a final effluent which would satisfy the Title 22 water quality requirements of the State of California for unrestricted irrigation reuse. In this case, “unrestricted irrigation reuse” means irrigation of food crops to be eaten raw, and full body contact recreational activities. Title 22 does not have specific limits for wastewater pollutants but is written in terms of treatment functions. A Title 22 effluent must have undergone coagulation, sedimentation, filtration and disinfection in the final polishing processes, or the equivalent thereof. The intent of these requirements is to produce a water with very low turbidity and zero virus. Since monitoring for virus is complex and expensive, California accepts non-detectable levels of total coliforms (<2 2/100 ml) as an acceptable indicator of a virus free water, If alternatives to the Title 22 treatment sequence are proposed, it is incumbent upon the proponents to prove that the alternative treatment produces an equivalent quality, virus-free water. It was the purpose of this Living Machine process to demonstrate that the system is capable of producing an effluent comparable to the Title 22 requirements through the production of an effluent with very low turbidity and total coliforms. The State of California would also have to agree that the process is comparable prior to any widespread use of the AEES process for this purpose. OAI established specific water quality goals for this system. These are compared to the typical effluent quality produced by the Oceanside WPCP in Table 4.1. 4-1 ------- Table 4.1 - Oceanside WPCP Effluent and San Francisco AEES Process Goals Parameter Oceanside WPCP Effluent AEES Goal All units in mg/L BOD 5 17 <10 TSS 22 <10 Turbidity 4 2 Ammonia 22 1 NO 3 1 5 TN Fecal Coliforms (cfu/100 mL) 29 57 <10 <2 2 Although nitrogen removal is not a Title 22 requirement, it was included as an AEES goal in case the treated water is to be used for recharge of sensitive groundwater aquifers However, reducing nitrogen to below the federal nitrate limit of 10 mg/L will not thereby allow direct reuse of this water for drinking water purposes nor will it necessarily allow direct recharge of potable groundwater aquifers. Stai’t-up for this system occurred in February 1995 and it operated intermittently until December 1996 when it was deactivated. Numerous changes and operational modifications were incorporated during this period. The average daily flow rate was about 18,000 gpd during September 1996, which is only 36 percent of the intended 50,000 gpd target flow rate. 4.2 Process Description of the San Francisco Living Machine® The two process trains at this AEES facility each contained seven compartments in series. Each compartment was an EFB which had a surface area of 16 square feet (4 feet x 4 feet) and contained a 6% feet depth of the same gravel media used at the South Burlington Living Machine®. The units originally contained the same pumice gravel used at Frederick, MD but this was replaced owing to excessive abrasion of the pumice and clogging of the drains. When the system was in the treatment mode, the first five units in series served as downflow nitrifying filter beds with water circulation and oxygen provided by a central air lift in each cell The final two cells served in an upflow anoxic mode for denitrification (with methanol addition as a carbon source) with a submersible pump in the center well providing water circulation. Each cell was backflushed as required when aeration lines at the base of the cell convert the entire cell to an airlift mode and thereby flush wastewater solids out of the media. Released solids were removed manually from the top of the cell (see Chapter 2 for a more detailed description of the EFB concept). 4-2 ------- Ten percent of the process effluent was recycled to aerated fish tanks, and ten percent of the fish tank effluent was recycled to the AEES treatment process. The fish tanks contained fathead minnows and striped bass and could represent a potential revenue source. Small potted tree seedlings were also rafted on the water surface in the EFB cells and also may provide a horticultural revenue source. The same bacterial supplements that were used at the Frederick, MD facility (see Chapter 2) were also routinely used at San Francisco. Additionally, calcium carbonate was routinely added to increase the alkalinity levels in the water to support nitrification. Asian clams were also added to the EFB cells and the fish tanks as they were expected to reduce TSS and fecal coliforms in the system. Snails were present in both the fish tanks and on the EFB beds. Each of the 14 EFB cells at San Francisco contained a 6% feet depth of gravel media Ignoring the center well and other piping, that is approximately 128 cubic feet of media per cell or 1,792 cubic feet of media in the whole system This quantity represents about 0 03 cubic feet of media per gpd of design flow This ratio was 0 1 ft 3 /gpd at South Burlington and about 0 07 ft 3 /gpd at Frederick, however, the BOD 5 and TSS enterin the EFB units at Frederick and at South Burlington are significantly higher than the influent to this system 4.3 Evaluation of the San Francisco Living Machine® The AEES facility in San Francisco started operation in February 1995 with a target flow rate of 50,000 gpd. It had reached a “steady state” flow rate of less than 20,000 gpd at the time it was deactivated in December 1996 The original pumice media in these EFB units experienced more significant abrasion than the units at Frederick. The abraded fine particles from the pumice created clogging problems in the piping, requiring extra maintenance activity, as a result this media was replaced with the higher density volcanic stone also used at South Burlington, VT. Typical performance results (September 1996), at an average flow rate of 8,962 gpd per train are summarized in Table 4.2 This system did not demonstrate the capability to meet the 2 2 coliform limit which is required for Title 22 waters, even at the low flow rates at which it operated (less than 10,000 gpd per train) Ultraviolet disinfection would probably be needed to insure satisfactory performance The system was capable of producing a very low turbidity at flow rates under 10,000 gpd. However, it is not clear that the process will be cost effective at a flow rate which is less than 50% of the intended goal. 4-3 ------- Table 4.2 - San Francisco Living Machine® Performance Results for September 1996 Parameter AE ES Influent Effluent Train A Efflue nt Train B All units in rng/L (except coliform) COD 36 29 22 BOD 9 <5 <5 TSS 6 1 1 Total coliform (cfu/100 ml) 66,000 76 41 Fecal coliform (cfu/100 ml) 32,500 47 50 N0 2 /N0 3 1 14 18 NH 3 /NH 4 34 1 0 TKN 36 2 1 TP 2 2 2 - Alkalinity 190 100 70 4-4 ------- CHAPTER 5 THE HARWICH, MASSACHUSETTS LIVING MACHINE® 5.1 Background The AEES unit located in Harwich, Massachusetts was not intended for sewage or wastewater treatment It was developed to improve the water quality in natural water bodies and is called the “Lake Restorer.” The prototype unit was installed on the surface of Flax Pond, in Harwich, MA in October 1992 Harwich is on Cape Cod at a latitude of about 41 40 and an elevation, at the pond site, of about 50 feet. The mean annual temperature is 10°C (50°F) and minimum winter temperatures of about -12°C (11 °F) are experienced The low winter temperatures and occasional ice on the pond do not impact on the routine operation of the “Lake Restorer” but the presence of ice can affect the monttoring program since access by a boat is needed for sampling. 5.2 Process Description of the Harwich Living Machine® The central section of the “Lake Restorer” raft included three “ecological fluidized bed” containers with the same pumice gravel media used at Frederick, MD and originally at San Francisco, CA. The media was supported by a structural bottom so the units were isolated from the in-situ waters in Flax Pond. The six containers on the outside perimeter of the unit did not contain any pumice media and were also open to the waters of the pond. All of these containers were covered with a variety of plants A wind powered electrical generator served to recharge the batteries which provided the power source for the air lift pump which circulated water to the pumice cells in series and then to the outer containers The three EFB units on this raft were about 4 feet x 4 feet x 3 feet deep and contained a total of 144 cubic feet of pumice. The progress reports issued by OAI claim a flow rate of 100,000 gpd for the “Lake Restorer” but a communication from OAI staff in July 1995 indicated an average flow rate of 20,000 gpd (Josephson, 1995). An average flow rate of 20,000 gpd provides a media volume to flow ratio or 0 007 cubic feet of media per gpd of average flow That is an order of magnitude less than provided at the San Francisco AEES and about two orders of magnitude less than that provided at the South Burlington AEES. However, the water in Flax Pond had an ammonia level which was about an order of magnitude less than the wastewater being treated in the other AEES facilities. 5-1 ------- Wind power proved to be an insufficient energy source at this location so an inclined rack of solar cells was added as a supplemental energy source. The airlift pump drew the water from the pond at a depth of about 5 feet. The amount of water circulated was dependent on the availability of wind and solar energy and averaged about 20,000 gpd. Hydrologists have estimated that the basef low into the pond from the adjacent groundwater system is approximately 78,000 gpd (Josephson, 1995). Flax Pond is shaped like an exclamation point” The smaller circular lobe at the eastern end has a surface area of about two acres, the larger and longer end has an area of about 13 acres and a maximum depth of about 20 feet The two segments are separated by a sand bar which is submerged in wet weather and exposed during the dry season and as a result, the two pond segments are not always directly connected. The “Lake Restorer” was anchored in the smaller of the two segments; the maximum water depth in this smaller segment of the pond is about 9 feet. The volume at this end of the pond is about 2,000,000 gallons, so the “Lake Restorer” would have taken approximately 100 days to circulate an equivalent volume through the unit at a 20,000 gpd flow rate. Assuming that about one third of the groundwater recharge entered this southern lobe, all of the contents of this end of the pond could be displaced with contaminated groundwater in less than 80 days. Water exchange between the two pond segments could not be defined with the currently available data Flax Pond intersects the local groundwater table and the former poor water quality in the pond was thought to be a result of the impact of the Harwich landfill and septage pits which are immediately adjacent to the pond and upgradient on the groundwater flow path. The septage pits were closed in 1991 but the landfill remains in operation to date. The “Lake Restorer” remained in place at the same location, on the eastern lobe of Flax Pond from October 1992 until the project was inactivated in October 1996. Specific water quality goals for this unit were not established, the general goal being to restore the “health” and biodiversity in Flax Pond Water quality samples were not taken from any portion of the operating “Lake Restorer”device The impact of the device was measured indirectly via water quality and sediment samples obtained at seven sampling stations in and around the perimeter of Flax Pond. Only three of these were in the eastern lobe of the pond. 5.3 Evaluation of the Harwich, MA Living Machine® The “Lake Restorer” has been in place, and in year-round operation since October 1992. Water quality sampling is not done on or directly around the “Lake Restorer.” The impact of the “Lake Restorer” has been inferred from apparent improvements in water and sediment quality from samples taken at seven sampling points around Flax Pond. Three of the sampling points are in the eastern lobe of the pond which is generally isolated from the larger western lobe. The “Lake Restorer” is located in the smaller eastern lobe of the pond 5-2 ------- It is probable that the waters and sediments in Flax Pond have, in the past, been polluted by the adjacent community landfill and septage disposal pits The sandy glacial till in the area allows a direct connection for contaminated groundwater to flow directly from the landfill to the pond It is believed that the greatest impact occurs in the smaller eastern lobe of the pond. However, operation of the septage disposal pits ceased in 1991, about one year before the “Lake Restorer” was put in place. Unfortunately, the quality of the groundwater directly entering Flax Pond has not been routinely measured prior to or during the five year study period so it is not possible to determine if changes in pond or sediment quality are a result of the action of the “Lake Restorer” or to a cessation of septage pit operations Considering the porous nature of the soils and the close proximity of the pond and land fill, it is likely that much of the liquid fraction of the septage percolated rapidly into the soil and traveled with the upper levels of the groundwater to Flax Pond. Cessation of septage disposal pit operations should have had a noticeable impact on water and sediment quality in the pond, and could account for most of the improvements noted in the western lobe of the pond. As noted in a previous section the “treatment” rate for the Lake Restorer is 20,000 gpd, but the groundwater recharge rate to the pond has been estimated to be 78,000 gpd. It is difficult to understand how the “Lake Restorer” could have a significant impact on water quality when the treatment rate is less than the groundwater exchange rate, unless the groundwater quality has improved since the septage disposal pit operations ceased. The “Lake Restorer”would probably have a local impact on destratification of the pond The available project funding limited the sampling frequency to a few grab samples on a quarterly basis at the seven sampling stations These data provide an inconclusive basis for evaluation of the “Lake Restorer” capabilities. Characterization of the improvements in pond and sediment qualify should include all inputs and sinks before defensible inferences can be drawn regarding the contribution from the “Lake Restorer.” The present database is somewhat confusing and conflicting. The OAI reports claim a significant reduction in sediment depth owing to “digestion” but the method used to estimate sediment depth during most of the five year period is questionable. The progress reports claim a very significant reduction in TKN and other pollutants has occurred in the sediments and infer that the “Lake Restorer” is responsible However, most of the reduction in sediment pollutant concentration is reported in the samples collected from the western lobe of the pond while the “Lake Restorer” is in the eastern lobe. The sediments at Station 6 (in the western lobe), for example, show a TKN concentration of 11,385 mg/kg in 1990 but only 2,942 mg/kg by 1993, which may be linked to the cessation of the septage pit operations. In April 1994 the concentration is 5,110 mg/kg and in April 1995, 3,400 mg/kg, indicating that there has been no apparent further improvement since septage pit operations ceased. The same type of inconsistencies are apparent in the water quality data. In April and May of 1994 the ammonia concentration in the eastern lobe averaged 1 1 mg/L and during the same period in 1995 the ammonia concentration averaged 1.54 mgIL indicating no improvement during the year. In the western lobe, where the “Lake Restorer” would have much less direct influence, 5-3 ------- CHAPTER 6 PERFORMANCE COMPARISON: THE BURLINGTON AND FREDERICK LIVING MACHINES® 6.1 Introduction The detailed process descriptions and performance data for these two demonstrations can be found in Chapter 2 for the Frederick, MD facility, and in Chapter 3 for the Burlington, VT demonstration Conceptually, these two systems had similar performance goals, but the Burlington system may represent a technological advance since it was designed for twice the Frederick flow rate and is located in a colder, more harsh climate. The Burlington facility also takes advantage of the operational experience at Frederick and incorporates the “lessons learned” from that earlier facility. The discussion in this Chapter deals with the performance of the Burlington system through August 1999. Process modifications by the LTI staff in 1999 resulted in significant improvements in performance and reliability. See Chapter 8 for a description of these changes, and the graphs in Chapter 3 for performance data. The basic conclusions of this chapter still apply to the improved Burlington system Some very basic process changes were made in the design of the Burlington Living Machine® based on the experience at Frederick, MD and on the anticipated climatic conditions and wastewater characteristics. The anaerobic bio-reactor used at Frederick, was eliminated at Burlington because of the much colder climate and the anticipated lower strength wastewater. Five aeration tanks were provided at Burlington as compared to two (in each process train) at Frederick. These extra aeration tanks were included because of the lower temperature sewage expected during the winter and to compensate for the eliminated anaerobic bio-reactor. The theoretical hydraulic residence time in these five tanks is about 48 hours at design flow as compared to 18 hours in the aerated tanks at Frederick. The aerated tanks at Burlington are followed by a specifically designed clarifier for sludge separation and removal. Such a clarifier was not included in the original design at Frederick, but was added later owing to excess sludge accumulation on the EFBs There are three EFBs at Burlington, which is the same number used at Frederick, with about the same HRT (19 hours), but they are used differently. The first EFB at Burlington completes the nitrification reactions, the second, anoxic unit provides (with a methanol addition) for denitrification, and the third, aerobic EFB acts as a final filter bed. Since both clarification and denitrification are completed in the EFB units the Burlington operation eliminated the final clarifier and the high rate marsh used at Frederick 6 -1 ------- The theoretical detention time, at design flow, is about 3 days for the entire process at Burlington, and this is about the same as the entire process at Frederick, MD (including anaerobic reactor, aerated tanks, EFB’s, final clarifier, and final marsh) Tracer studies have not been run at Burlington to verify these residence times 6.2 Flow and Temperature Because the influent is pumped into these demonstration systems it has been generally possible to maintain the specific design flow rates at both Frederick and Burlington. The 80,000 gpd design rate for Burlington has been maintained since the system became fully operational in May 1996 (start-up in October 1995). Influent water temperatures, during the winter, in the range of 4° to 7° C (39° to 45° F) were predicted for the design of the Burlington facility However, during the study period, the influent temperatures averaged about 12°C (54°F) during the winters, and never went below 10°C (50°F). The coldest water entered the system during late March and early April which would be the snow melt period in the Burlington area It is very likely that the Burlington sewer system.experiences significant infiltration, and that assumption is confirmed by the relatively low concentrations of some pollutants in the untreated influent at the Living Machine® The water temperatur&s of the effluent leaving the.Burlington Living Machine® over the study year are not readily available so it is not possible to estimate the average process water temperatures in the system, although O&M data suggests that the effluent temperature is typically 2°-3°C (4°-6°F) warmer than the influent temperature. Considering that the HRT is about three days inside a heated greenhouse it is likely that the average process water temperature is at least slightly higher than the influent temperature during the winter months. Similar water temperature data are not currently available for the Frederick facility but, based on experience elsewhere, it is likely that the influent winter water temperatures were in the range of 12° to 15°C (54° to 59°F), As a result, it would appear that the two systems did not experience drastically different winter influent water temperatures. 6.3 Biochemical Oxygen Demand (BOD) Removal Figures 2-2 and 3-2 (shown in Chapters 2 and 3) present BOD performance of the Frederick and Burlington Living Machines®. Figure 2-2 shows monthly Frederick data for the period March 1995 through March 1996, and gives both EPA and OAI data During most of the EPA study period, there were operational problems with the methanol feed and this is reflected in the high effluent BOD values for March, April, and May. As soon as methanol control was established the effluent BOD stabilized at about 4 mg/L, with a mean influent BOD of about 230 mg/L. At the Burlington facility, the mean influent CBOD during the period June 1996 to June 1997 was 225 mg/L, and this system produced an average effluent CBOD of 5.9 mg/L. During this period there were 12 weekly samples (20% of total) which exceeded the 10 mg/L goal. Most of 6-2 ------- these excursions occurred during the winter/spring period On a monthly mean basis, all of the final effluent samples were below the 10 mg/L target value At the Frederick facility, the preliminary anaerobic reactor removed about 68% of the BOD, based upon data collected during the EPA study period As a result the greenhouse components only had to deal with a BOD concentration of about 156 mg/L. On that basis, the greenhouse components at Frederick removed about 97% of the incoming BOD which is identical to the 97% removal produced by the greenhouse components at Burlington. Although the influent water temperature, at Burlington, dropped from about 20°C in the summer months to about 12°C in the winter, there was no significant impact on BOD removal These results suggest that the Burlington facility, at the present flow rate and organic loading, is over-designed for BOD removal Support for this hypothesis can be found by considering the mass loadings and removals in these two systems. If the treatment volume available in the greenhouse is considered to be the aerated volume in the aeration tanks plus the void space in the EFB units, then the available treatment volume would be about 70 ma at Frederick and 360 m 3 at Burlington. The volumetric loading and/or removal rate (the two are essentially the same since almost complete BOD removal was achieved at both sites) would be 0 35 kg BOD/m 3 /d at Frederick and 0.19 kg BOD/m 3 /d at Burlington. In theory, this means that the loading at Burlington could be increased to 0.35 kg/m 3 /d and still achieve successful BOD performance. That in turn means that the flow rate could be increased to over 100,000 gpd if BOD removal were the only concern. On a long-term average basis, these two systems received influent BOD at about the same level and produced comparable effluent BOD concentrations which were well below the 10 mg/L target value. This suggests that the Living Machine® concept, as configured in these two demonstrations, can deal effeôtively with BOD in the range normally expected for municipal wastewaters These results also suggest that both of these systems may have been over-designed for BOD removal 6.4 Chemical Oxygen Demand (COD) Removal Figures 2-3 and 3-4 present COD performance for the Frederick and Burlington Living Machines®. In this case there was a very significant difference in influent COD between the two facilities, with the untreated wastewater at Frederick containing an annual mean of 944 mg/L versus the 556 mg/L study period average at Burlington However, the preliminary anaerobic reactor at Frederick removed about 60% of this COD, so the greenhouse components only had to deal with 378 mg/L. As shown on Figure 2-3, the methanol problem again affected effluent COD values during the EPA study period but as soon as that was stabilized, the long-term effluent concentration averaged about 21 mg/L. The average effluent value at Burlington was about 36 mg/L. For the complete system at Frederick, the COD removal averaged 98%, with the greenhouse components removing 94% of the greenhouse input. The comparable value at 6-3 ------- Burlington is 94% removal. This again indicates that both greenhouse systems are performing the same with respect to COD removal. These results, also demonstrate the importance of the preliminary anaerobic reactor when higher strength, refractory wastewaters are expected. 6.5 Total Suspended Solids (TSS) Removal The removal of TSS for these two systems are shown on Figures 2-4 and 3-5 Once more, there was a significant difference in untreated influent concentrations between the two sites At Frederick, the untreated influent TSS averaged 381 mg/L during the period March 1995 to March 1996, whereas at the Burlington facility, the influent TSS averaged 213 mg/L during the period June 1996 to August 1999. However, the preliminary anaerobic reactor at Frederick was again very effective and removed about 82% of the TSS entering the system, so the influent to the greenhouse at Frederick averaged 70 mg/L, and the final effluent averaged about 2 mg/L over the course of the measured year. The complete system at Frederick removed about 99% of the influent TSS, and the greenhouse components removed about 97% of the greenhouse input TSS. At Burlington, the final effluent averaged about 5 3 mg/L for a 98% removal at this location. Therefore, it can be concluded that the greenhouse components at these two locatior s performed comparably for TSS removal. The improved solids management procedures incorporated at Burlington serve to improve operator efficiency but did not further improve TSS removal capability, since the TSS removals were already at or near their upper limit for this type of process. The combination of effective clarification following aeration, and the EFBs result in excellent TSS removal capabilities, producing an effluent well below the 10 mg/L TSS goal for the Living Machine® process. However, both clarification and filtration are well established conventional treatment processes which are not unique to the Living Machine®. The sludge periodically removed from the Burlington EFBs is pumped to the post-aeration clarifier for final removal. This sludge is then pumped to the municipal wastewater treatment plant at South Burlington, VT for final disposal The use of reed (Phragmites sp.) drying beds has been proposed for sludge management at these Living Machine® facilities but the technique has not been included in any of the federally funded demonstrations. The omission of a sludge dewatering step from this demonstration may have a significant impact on the performance of the basic wastewater treatment components in the system since the liquid leachate from the drying beds is typically returned to the basic process for treatment. This leachate is a high strength wastewater with respect to the organic (BOD/COD) and nitrogen content and must be considered during process design. 6-4 ------- 6.6 Ammonia Nitrogen Removal Figures 2-5 and 3-6 present the ammonia removal performance of these two systems At Frederick the total nitrogen (measured as TKN) entering the system averaged 45 mg/L during the year, about 49% of that nitrogen was in the ammonia form at 22 mg/L. The final effluent, at Frederick (after the methanol dosage was stabilized) averaged 1 2 mg/L for a removal of about 94% during 1995/96. At Burlington, the total nitrogen input (measured as TKN) was approximately 28 mg/L, and about 57% of that was in the ammonia form at 16 3 mg/L The final effluent at this site, during the study period averaged 0 4 mg/L, for a removal of 97%. These removal percentages are based on the measured input and output ammonia concentrations but it is likely that the actual ammonia removal is even better. The organic nitrogen entering these systems represents about 51% of the total nitrogen at Frederick and 39% at Burlington This organic nitrogen is typically associated with the particulate matter entering the system. An undetermined major fraction leaves the system with the removed sludge but the remainder can be converted to ammonia, and adds to the amount requiring removal It is clear that significant improvements in ammonia nitrogen removal have been achieved at the Burlington facility, as a result of the additional aeration capacity provided at this facility plus improvements in management of methanol and solids. The target effluent goal for- ammonia is I mg/L and this was achieved by both of the Living Machine® demonstrations. The combination of extended periods of aeration followed by aerobic contact filtration through a granular media will provide excellent ammonia removal (via nitrification) but neither process is unique to the Living Machine®, nor are they typically considered to be ecologically-based. 6.7 Nitrate Nitrogen Removal In many situations where total nitrogen removal is necessary the conversion of ammonia to nitrate, via nitrification, is only the first treatment step. It is then necessary to remove that nitrate, and the most common procedure for this second step is biological denitrification which converts the nitrate to nitrogen gas which escapes to the atmosphere. The Living Machine® process incorporates biological denitrification. At Frederick, MD the final EFB and the high-rate marsh were the responsible units. In Burlington, \/T the second EFB is all that is required. This biological process also requires a carbon source for the organisms, and after considerable experimentation, the systems at both locations routinely used methanol for that purpose. The target nitrate goal for the Living Machine® process was set at 5 mg/L. If this is combined with the target goal of 5 mg/L for TKN it produces a goal of 10 mg/L for total nitrogen which is typically sufficient to meet the drinking water requirements for nitrate nitrogen. At the Frederick, MD system, the average effluent nitrate concentration was about 10 mg/L during the period June 1995 to May 1996; at the Burlington facility the effluent nitrate averaged 4 9 mgfL during the period June 1996 through August 1999. Insignificant levels of nitrate are typically present in the untreated wastewater so it is not possible to calculate nitrate removals in 6-5 ------- the usual manner. A conservative approach is to assume that all of the ammonia removed in the system is converted to nitrate On that basis, it can be assumed that a nitrate concentration of 20 8 mg/L was produced at Frederick and 15 9 mg/L at Burlington. The nitrate removal would therefore be 52% at Frederick and 69% at Burlington. Based on these data, it can be concluded that the Frederick system never met the 5 mg/L nitrate goal but that the Burlington system does meet the goal, although barely However, improvement is believed possible and this is discussed in Chapter 8 of this report. 6.8 Total Nitrogen Removal As indicated previously, the total nitrogen present in a system can be assumed to be equal to the sum of the TKN and nitrate present. On this basis, the effluent goal f&r the AEES process was set at 10 mg/L total nitrogen At Frederick, MD, during the period March 1995 to March 1996, the system slightly exceeded that goal with an average of 11 mg/L for a removal of 75%. Most of the exceedances were during the winter months of 1996. At Burlington, VT, with one exception (July 1996), the monthly average effluent values were well below the 10 mg/L goal for total nitrogen, with the average concentration being 5.6 mg/L, for a 81% removal. On a mass basis, the system at Frederick removed 65% more total nitrogen than the process at Burlington (5.1 kg/d versus 3 3 kgld), and achieved the same removal percentage on either a mass or concentration basis. On a volumetric basis (treatment volume available in the greenhouse) the Frederick system removed 0 07 kg/m 3 /d and Burlington 0.01 kg/m 3 /d. This would suggest that the “improved” effluent quality at Burlington is the result of an over designed capacity for the more dilute wastewater 6.9 Phosphorus Removal Performance data for phosphorus removal, on a monthly average basis can be found in Figures 2-6 and 3-12. At Frederick, MD the average influent phosphorus was 11 mg/L during the period March 1995 to March 1996. The preliminary anaerobic reactor removed 30% of this phosphorus (most of which was probably associated with the particulate matter removed) so the greenhouse units had an input of 7.7 mg/L and produced a final effluent of 6 mg/L. This is significantly higher than the target effluent goal of 3 mgIL, and represents a 22% removal of the phosphorus entering the greenhouse units. The overall process at Frederick removed a total of 45%. At Burlington, the influent wastewater only contains 6 mg/L which is at the low end of the range for typical municipal wastewaters (6 to 10 mgIL) and this system produced an effluent of 2.0 rnglL which is below the target goal of 3 mg/L. The removal rate at Burlingion was 67% on a concentration basis. On a volumetric basis, the greenhouse components at Frederick removed 0.004 kg/m 3 /d of total phosphorus in the available treatment volume; the comparable rate for the Burlington facility 6-6 ------- was 0.002 kg/m 3 /d It is therefore believed that the “improved” phosphorus performance at Burlington is a result of the more dilute wastewater. As discussed in Chapter 8 of this report biological processes of the type used by the Living Machine® have a limited capability for significant phosphorus removal. Most of the phosphorus actually removed in extended aeration processes similar to those used in this system is associated with sludge removal. 6.10 Fecal Coliform Removal The Living Machine® process is very effective for removal of fecal coliform, primarily because of the filtration which occurs in the EFB units. At the Burlington facility the untreated influent has an average fecal coliform concentration of about 8x10 6 MPN/100 mL, and the final effluent contains about 1,200 MPNI100 mL. Similar results were also achieved at the Frederick facility. These effluent concentrations are not low enough to meet either typical irrigation or bathing water standards, but addition of disinfection with UV equipmentwould certainly produce acceptable effluents 6.11 Summary A summary of the treatment performance at these two demonstration facilities can be found in Table 6.1. It is clear from this summary table that the Living Machine® S process can provide excellent removal of BOD, COD, TSS, and ammonia, and that the two pilot systems have provided comparable results. The removal of nitrate and total nitrogen at the Burlington facility met the target effluent goals and it is considered that further improvements in efficiency are possible. Phosphorus. removal in both cases was limited, and the only reason the effluent phosphorus at Burlington was below the design goal was because of the low concentration of phosphorus in the influent wastewater. The physical, chemical and biological processes utilized in the Living Machine® process have no special capability for phosphorus removal They can be expected to remove about 50%, with most of that leaving the system with the removed sludge Either phosphorus should be dropped as an AEES treatment goal or some more effective method for its removal should be included in the system These data also suggest that the Burlington facility is oversized (as originally configured) for BOD at the current flow rate. 6-7 ------- Table 6.1 Performance Summary Frederick, MD and Burlington, VT Living Machines® FREDER IC BURLINGTON PARAMETER INFLUENT EFFLUENT % REMOVAL INFLUENT EFFLUENT % REMOVAL mg/L mg/I % mg/I mg/L BOD 156 4 97 227 59 97 COD 378° 21 94 556 359 94 TSS 70° 2 97 213 53 98 NH 3 22 1 2 94 163 04 98 NO 3 208 b 10 52 159 b 49 69 TN 44 11 75 293 56 81 TP 110 6 45 60 20 67 a. Influent to greenhouse at Frederick, MD b Assumes all removed ammonia is converted to nitrate. 6-8 ------- CHAPTER 7 COST COMPARISON: THE LIVING MACHINE® VS. CONVENTIONAL TECHNOLOGIES 7.1 Introduction In order to determine the cost of the Living Machine® technology and to relate the costs to the conventional technologies currently available in the marketplace, a direct comparison is drawn in this chapter. The capital, operating and total present worth costs are compared for three different flow rates The costs for the Living Machine® were prepared by LTI staff while the costs for the conventional technologies were prepared by an independent consultant 7.2 Basis of Comparison The cost comparison of the two technologies, capable of producing the same quality effluent, was made at flow rates of 40,000, 80,000 and 1,000,000 gpd for both the Living Machine® and conventional wastewater treatment technologies. The influent quality selected was that of typical municipal wastewater and the specific influent concentrations and the design effluent requirements used are shown in Table 7.1 Phosphorus was not included as a effluent requirement for this comparison since the Living Machine® demonstrations have not yet demonstrated the capability to remove phosphorus to low levels with the present configuration. Table 7.1 lnfluent and Effluent Water Quality for Cost Comparison Parameter Design Influent Design Effluent All units in mg/L BOD 250 10 TSS 200 10 TN 40 10 NH 3 /NH 4 25 1 N0 2 /N0 3 - 5 Alkalinity >200 - 7-1 ------- The selected site location for the treatment plants for purposes of design temperature and costing was Baltimore, MD, and the minimum influent temperature was 13°C. The costs for the original Living Machine® estimates were in August 1995 dollars (ENR CCI 5506), the original costs for the conventional technologies were in August 1997 dollars (ENR CCI 5854). All of these costs have been updated to May 2000 (ENR CCI 6223) for this report. Operating costs were converted to equivalent present worth costs using a 20-year period and an interest rate of 7% The cost estimates include sitework; process electrical and instrumentation (including flow meters), yard piping, as necessary, sludge handling, treatment and disposal; and UV disinfection. Table 7.2 Cost Estimate: Assumptions, Inclusions and Exceptions Cost items that were included as a multiplier of costs were Mobilization - 5% Bonds - 3% After the subtotal of capital costs were determined, the following percentages were added - Design engineering - 10% Contractor’s overhead and profit - 15% Construction services and start-up - Contingencies - 15% 10% Items that were not included in the construction costs were Headworks Fences Roads Laboratory Influent pumping Administration building The operations and maintenance costs included: Skilled operator (inc. fringes) - $30/hour Assistant (Inc fringes) - $15/hour Power - $0 08/kWh Maintenance - 2% of construction Final sludge disposal - $530/dry ton 7-2 ------- 7.3 Conventional System Costs Each of the conventional wastewater treatment systems selected to be used in this comparison were generic “package” plants that can be provided by a number of manufacturers. Specifically, these systems areS 40000 gpd: An extended aeration secondary treatment plant with an anoxic filter for denitrification and filtration, followed by UV disinfection was selected for this flow rate Methanol is added to the filter to achieve denitrification in the filter. The plant is prefabricated and placed on a concrete slab on grade The plant consists of two complete concentric circular steel tanks and the necessary hydrostatic division walls to insure process operation. Principal items of equipment included the aeration tank; an air distribution system, comprising blowers, a main header, removable diffuser drop pipes, and valves for air regulation; a clarifier complete with drive, influent assembly, sludge collector mechanism, double-sided effluent launder, scum baffle, stilling well and scum removal system; return sludge and waste activated sludge system consisting of an airlift pump and return sludge/waste sludge splitter box, digester supernatant return consisting of an airlift pump with vertically adjustable intake, stairway, bridge and walkways with handrails; an aerobic sludge digestion tank, and electrical contro’s for equipment operation: Influent and effluent flow meters are also provided along with a dissolved oxygen probe. Costs for this alternative were developed in 1997 and updated to May 2000 using appropriate ENR adjustment factors. • 80,000 gpd A sequencing batch reactor (SBR) was selected for this flow rate. Equipment includes the tank, blowers, mixers, decanters and an aerobic sludge digester After secondary treatment, the effluent is filtered and disinfected using UV. The SBR is a prefabricated steel unit. Costs for this alternative were developed in 1997 and updated to May 2000 using appropriate ENR adjustment factors • 1,000,000 gpd (1 mgd): A Carrousel oxidation ditch treatment process with typical aeration/anoxic zone tanks, final clarifiers, and sludge return pumping, a polishing filter and UV disinfection. Methanol is not needed for this process because the wastewater BOD 5 provides sufficient carbon for denitrification in the anoxic zone of the oxidation ditch. Costs for this alternative were originally developed in 1995 and updated to May 2000 using appropr!ate ENR adjustment factors (May 2000, ENR CCI 6223). Wasted sludge for all three processes is applied to on-site sand beds with reeds for dewatering and long-term stabilization Leachate from these beds is returned to the wastewater unit for treatment It is assumed that sludge is removed from these beds for final disposal on a seven-year cycle. Estimated sludge production, drying bed sizes, final disposal quantities and costs can be found in Table 7.3. Table 7.4 summarizes the capital costs for the three conventional treatment systems while the operation and maintenance costs for these treatment systems are shown in Table 7 5. Table 7.6 summarizes the total present worth costs for the three selected conventional wastewater treatment technologies 7-3 ------- Table 7.3 Sludge Management for Conventional Treatment Systems $91,873 $133,355 $457,359 $397,224 $613,046 $2,831,081 $19,861 $30,652 $141,554 $11,920 $18,391 $84,932 $429,006 $662,089 $3,057,567 $42,900 $66,209 $305,757 $42,900 $66,209 $305,757 $64,351 $99,313 $458,635 $64,351 $99,313 $458,635 $643,308 $993,133 $4,586,351 Item 40,000 gpd 80,000 gpd I mgd Sludge wasted, kg/d 72 144 840 Reed bed size, feet 2 7,096 14,191 82,740 Capital cost of bed, $ (1) $91,873 $1 33,355 $457,359 Final sludge disposal, dtfyr 2 8 75 17 5 102.1 Disposal cost, $/yr $4,650/yr $9,302/yr $54,112/yr (1) Same unit costs as Living MachineE estimates. Includes all adjustment factors listed in Table 7 2. (2) Assumed ¾ reduction in solids mass over seven years. Value listed is equivalent annual amount. (3) Equivalent annual amount multiplied by $530/dry ton Table 7.4 Capital Costs for Conventional Treatment Item - 40,000 gpd 80,000 gpd I mgd - $305,351 $479,691 $2,373,722 — Wastewater treatment plant, complete Sludge reed beds SUBTOTAL Mobilization (5%) Bonds, insurance (3%) SUBTOTAL Design, engineering (10%) Construction services & startup (10%) Contractor’s overhead & profit (15%) Contingencies (15%) TOTAL (1) May 2000, $, ENR CCI 6223 — 7-4 ------- Table 7.5 Annual O&M Costs for Conventional Treatment Systems Item 40,000 gpd 80,000 gpd I mgd Energy (1) $10,575 $9,991 $56,405 Methanol $1,698 $0 $0 Labor Skilled Operator © $30/hr $15,600 $31,200 $115,440 (lOhr/wk) (2Ohr/wk) (74hr/wk) Assistant @ $15/hr $7,800 $15,600 $59,280 (lOhr/wk) (2Ohr/wk) (76hr/wk) Final sludge disposal (2) $4,650 $9,302 $54,112 Maintenance $12,870 $19,863 $91,727 TOTAL $53,193 $85,956 $376,964 (1) Electric power @ $0 08/kWh. (2) Froth Table 7 3. (3) Maintenance @ 2% of the total construction costs, including sludge beds. (4) Aeration Only required for 11 hours per day Table 7.6 Cost Summary for Conventional Treatment Systems Item 40,000 gpd 80,000 gpd I mgd Capital costs $643,508 $993,133 $4,586,351 Annual O&M costs $53,193 $85,956 $376,964 Present worth of O&M (‘ $563,528 $910,618 $3,993,567 TOTAL PRESENT WORTH $1,207,036 $1,903,751 $8,579,918 ost per 1,000 gallons treated $4.13 $326 $1 18. (1) Present worth factor 10.594 based on 20 years © 7% interest (2) Daily flow rate, 365 days per year for 20 years divided by 1,000 gallons 7-5 ------- 7.4 Living Machine® Costs The capital costs for the Living Machine® are estimated at three flow rates: 40,000, 80,000, and 1,000,000 gpd and were developed by Living Technologies, Inc. the designers of the Frederick and Burlington systems. The costs for the 40,000 and 60,000 gpd units were based on actual construction costs for the tanks-in-series configurations used at both Frederick and Burlington The costs for the 1 mgd system were extrapolated from the Burlington experience. For purposes of this estimate, the waste sludge from the system was assumed to be applied to a reed bed for dewatering, passive composting and storage as shown in Table 7.7. The 58 kg/d value for wasted sludge at the 80,000 gpd level is based on actual performance at the Burlington facility during 1999/2000 The capital costs for the Living Machine® are shown in Tables 7 8 and 7.9. Table 7.7 Sludge Management for the Living Machines® Item 40,000 gpd 80,000 gpd I mgd Sludge wasted, kg/d 29 58 725 Reed bed size, feet 2 2,842 5,716 71,050 Capital cost of bed, $ $36,795 $53,730 $392,906 Final sludge disposal, dllyr (2) 8 75 17 5 102 1 Disposal cost, $/yr (3) $4,375/yr $8,750/yr $54,1 12/yr (1) Same unit costs as “conventional” estimates Includes all adjustment factors listed in Table 7 2 (2) Assumed 2/3 reduction in solids mass over seven years. Value listed is equivalent annual amount. (3) Equivalent annual amount mulhplied by $530/dry ton. Table 7.8 shows costs including the greenhouse structure whereas Table 7.9 shows the capital costs without a greenhouse In 1997 Living Technologies, Inc proposed a new process configuration that included all system components in a concentric tank. The theoretical construction costs for this new configuration would be less than the costs for the tanks-in-senes configuration shown in Tables 7.8 and 7.9. In 1999 the process configuration of the 80,000 gpd Burlington facility was modified to include recirculation to an anoxic component for denitrification (described in detail in Chapter 8 of this report) This change eliminates the need for methanol and may also result in a reduction of tanks required, which in turn could also reduce the costs. However, the cost comparisons in this report are based on the tanks-in-series configuration used in the Frederick and Burlington demonstrations of the Living Machine® process The O&M requirements are based on the costs at the Burlington facility, after the 1999/2000 process optimization was achieved These O&M costs do not include the costs for disposal of the harvested vegetation 7-6 ------- Table 7.8 Capital Costs of the Living Machine® with Greenhouse (1) Item 40,000 gpd 80,000 gpd I mgd Wastewater treatment plant, inc gh $279,486 $388,397 $2,88,243 Sludge reed beds $36,795 $53,730 $392,906 SUBTOTAL $316,281 $442,127 $3,281,149 Mobilization (5%) $15,814 $22,106 $164,057 Bonds, insurance (3%) $9,488 $13,263 $98,434 SUBTOTAL $341,583 $477,497 $3,543,640 Design, engineering (10%) $34,158 $47,750 $354,364 Construction services & startup (10%) $34,158 $47,750 $354,364 Contractor’s overhead & profit (15%) $51,238 $71,624 $531,546 Contingencies (15%) $51,238 $71,624 $531,546 TOTAL $512,375 $716,245 $5,315,458 (2) May 2000, $, ENR CCI 6223 7-7 ------- Table 7.9 Capital Costs of the Living Machine® without Greenhouse (1) Item 40,000 gpd 80,000 gpd I mgd Wastewater treatment plant only $241,768 $335,955 $2,498,268 Sludge reed beds $36,795 $53,730 $392,906 SUBTOTAL $278,564 $389,685 $2,891,174 Mobilization (5%) $13,928 $19,484 $144,559 Bonds, insurance (3%) $8,357 $1 1,690 $86,735 SUBTOTAL $300,849 $420,859 $3,122,468 Design, engineering (10%) $30,085 $42,086 $312,247 Construction services & startup (10%) $30,085 $42,086 $312,247 - Contractor’s overhead & profit (15%) $45,127 $63,129 $468,370 Contingencies (15%) $45,127 - $63,129 $468,370 TOTAL $451,273 $631,289 $4,683,702 (1) May 2000, $, ENR CCI 6223 Table 7.10 provides the annual operation and maintenance costs for Living Machines® with flow rates of 40,000, 80,000, and 1,000,000 gpd. Where possible, these values reflect the actual experience with energy, sludge management, and methanol costs at the Living Machine® at Burlington; VT during 1999 and 2000. During this period process modifications were made so methanol was no longer required. The same process change would be possible at all flow rates so the cost for methanol in this table is zero. As a result, these costs apply only to the configuration and process operations utilized at the Burlington facility during late 1999 as described in Chapter 8 of this report. 7-8 ------- Table 7.10 Annual Operation and Maintenance Costs for the Living Machine® 40000 gpd 80,00 0 gpd I mgd Item with g-hse wfo g-hse with g-hse wlo g-hse with g-hse wlo g-hse Energy (1) . Electricity $12,000 $12,000 $18,221 $18,221 $101,170 $101,170 Gas $1,730 - $3,500 - $43,750 - Electricity (UV) $117 $117 $234 $234 $876 $876 Methanol $0 $0 $0 $0 $0 $0 Labor Skilled Operator (2) $15,600 $15,600 $31,200 $31,200 $124,800 $124,800 Assistant 3) $7,800 $7,800 $15,600 $15,600 $49,920 $49,920 Sludge disposal (4) Maintenance ‘ $4,375 $10,248 $4,375 $9,025 $8,750 $14,325 $8,750 $12,626 $54,112 $105,949 $54,112 $93,674 Total O&M Costs $53,370 $50,417 $93,830 $88,631 $485,377 $429,352 (1) Electric power at $0 08 kWh (2) Skilled operator at $30/hr. (3) Assistant at $15/hr (4) Final sludge disposal at $530/dry ton. (5) Maintenance at 2% of total construction costs, including sludge beds 7-9 ------- Table 7.10 provides the cost summary, including present worth and costs per unit volume treated, for the Living Machines® with flow rates of 40,000, 80,000, and 1,000,000 gpd Table 7.11 Cost Summary for the Living Machine® 40,00 0 gpd 80,0 00 gpd I mgd Item with g-hse w/o g-hse with g-hse w/o g-hse with g-hse wlo g-hse Capital costs $512,375 $451,273 $716,245 $631,289 $5,315,458 $4,683,702 osts $53,370 $50,417 $93,830 $88,631 $485,377 $429,352 Present worth of O&M (1) $549,511 $518,227 $972,847 $917,769 $5,091,232 $4,497,704 TOTAL PRESENT WORTH $1,077,777 $985,391 $1,710,280 . $1,370,246 $10,457,5421 $9,232,257 Cost per 1,000 gallons treated (2) $364 $332 $289 $265 $142 $126 (1) Present worth factor 10 594 based on 20 years @ 7% interest (2) Daily flow rate, 365 days per year for 20 years divided by 1,000 gallons 7.5 Comparison of Costs A comparison of the present worth costs of the Living Machines® and the conventional systems is presented in Table 7.12. This table suggests that the Living Machine® may be the lower cost treatment system at the lower flow rates. However, cost estimates of this type are considered accurate within a 20 percent range, the cost differences are not significant at the 40,000 or 80,000 gpd flow rates. The cost differences are significant as the flow rate approaches 1 mgd, meaning that the Living Machine® with a greenhouse is probably not cost effective at these flow rates, when compared with the “conventional” technology. Figure 7.1 graphically compares these cost data for the Living Machine® and the conventional technologies. It can be concluded that the Living Machine® without a greenhouse is cost competitive with conventional wastewater treatment technologies at design flow rates approaching 1 mgd. The Living Machine® with a greenhouse is cost competitive up to a flow rate of about 600,000 gpd. If methanol is used for denitrification in the Living Machine®, the comparable point for costs drops to less than 100,000 gpd 7-10 ------- Table 7.12 Present Worth Comparison of Living Machines® and Conventional Systems Process 40,000 gpd 80,000 gpd I mgd Living Machine® with greenhouse $1,077,777 $1,710,280 1 $10,457,542 2 without greenhouse $985,391 2 $1,570,246 2 $9,232,257 1 Conventional System $1,207,036 1 $1,903,751 $8,579,978 2 (1) Cost difference is less than 20 percent, difference is not significant. (2) Cost difference is greater than 20 percent, difference is significant. Figure 7-1 Comparison of Present Worth Costs for the Living Conventional Technologies Over a Range of Flow Rates 1 CD 0 0 00 0 . 0 U) $12.0 $10.0 $8.0, $6.0’ $4.0’ $2.0’ $0.0’ Design Flow Rate (gpd) Machine® and Selected “Living Machine” wI Greenhouse “Living Machine” wlo Greenhouse o Conventional Technology A -,—— ..o 1 ’ 0 200,000 400,000 600,000 800,000 1,000,000 7-11 ------- CHAPTER 8 EVALUATION OF THE LIVING MACHINE® TREATMENT PROCESS 8.1 The Frederick and Burlington Living Machines® Based on the evaluation presented in Chapter 6 of this report, it can be concluded that the Living Machine®, as configured at both the Frederick, MD and Burlington, VT demonstrations, is capable of reliably meeting all of its performance goals with the exception of phosphorus. The major issues of remaining concern are to determine how the system works and if it is cost effective when compared to conventional wastewater treatment technology capable of producing the same quality effluent The initial developers, and supporters of the Living Machine® concept (OAl) claimed that the process depends upon “advanced ecological engineering of living systems to clean was tewater,” that “treatment is primarily dependent on solar-powered, greenhouse based technology without the use of chemicals,” and that “the system uses plants and animals for water treatment with a system focus on ecological harmony’ (OAl, 1994). • Based on the EPA evaluations conducted at Frederick, MD and Burlington, VT, it can be concluded thaU • Plants and animals are present in the AEES process but they do not appear to contribute significantly to treatment performance. • The plant roots are believed to provide the substrate supporting attached biological organisms contributing to treatment. However, the plant root volume at the Burlington facility is relatively insignificant compared to the volume of the large deep tanks resulting in a minimal contribution to treatment As a result, the major treatment response in the aerated tanks at Burlington is probably due to the suspended biomass as occurs in similar activated sludge processes • Solar energy is available and necessary to keep the plants alive but, if the plants are not contributing significantly to treatment, then the plants and the solar energy inputs may be irrelevant to the treatment performance of the system • The plants do contribute significantly to aesthetics and produce a pleasing environment in the greenhouse, and this significantly encourages public acceptance of the s ystem • Instead of solar energy the system depends on the same energy sources commonly used in conventional wastewater treatment (i e, electrically powered pumps and aeration compressors). 8-1 ------- • Chemicals were used in the original process in the form of routine additions of methanol for denitrification. Process changes (discussed in this chapter) in 1999, at the Burlington facility, eliminated the requirement for methanol • Sludge plus other residuals (i e., harvested plants) produced by this process may be comparable to residuals produced by the extended aeration activated sludge process, depending on the types of plants grown. Harvested plant material was very significant at Frederick, MD where water hyacinths were the major plant species The Burlington, VT facility used a wide variety of plants with less need for harvesting. • The system as presently configured is not capable of phosphorus removal to low levels. It is capable of about 50 percent removal. The discussion in the remaining sections of this chapter is intended to provide additional detail on these issues 8 1.1 Vegetated Aeration Tanks These units are a key component in the AEES process, and the plants, floating, or supported at the water surface were originally claimed to provide a major contributiorito treatment Microorganisms attached to the plant roots do provide treatment and if they are present in sufficient numbers they can actually provide a major contribution to treatment. However, sufficient numbers of organisms depend upon the availability of sufficient plant root surfaces. It is believed that there is not a sufficient volume of plant roots in the systems, as configured at Frederick and Burlington, to support a significant contribution to treatment by this source. As part of the EPA study at Frederick, MD, the process performance was evaluated with and without plants on these tank surfaces and it was found that ammonia removal was somewhat enhanced in the presence of the plants but that the overall process could provide essentially the same level of treatment with or without these plants This result does not mean that the plant roots are not supporting treatment, however, it does suggest that there were an insufficient number of plant roots to have a significant impact on treatment at the flow rates and tank volumes which were used at the Frederick, MD facility. This problem is compounded at the Burlington, VT facility since the tanks are even larger and deeper. The treatment value of plant roots and their attached microorganisms was first reported with water hyacinths in aerated shallow basins. In these cases, the plant roots might occupy up to 30% of the available volume. For plants and the microorganisms contained on their roots to have a truly significant impact on treatment, it would be necessary to use shallow basins with a large surface aiea. At the Burlington facility the surface area of the five existing aeration tanks is about 770 ft 2 and the volume about 10,000 ft 3 . If the plant roots were about 15 ft long, on average, and were, to occupy 30 percent of the tank volume the tank depth could not be more than five feet Retaining the same volume used at Burlington and designing basins 5 feet deep would produce a tank surface area 8-2 ------- of about 2,000 ft 2 and the greenhouse would then have to be at least twice as big as it presently is. To be economically competitive, the AEES process must minimize the greenhouse area required and therefore must use deep tanks in colder climates. As a result of this, the plants which are used, are largely there for aesthetic purposes Shallow tanks, without a greenhouse, are of course possible in warm climates, if sufficient land area is available It may be possible to reduce the total greenhouse footprint area, and consequently lower total system costs to some degree, by reducing the space around the reactors. The South Burlington facility was built as a demonstration project and, as such, incorporated extra space for increased accessibility However, such a reduction in greenhouse footprint would make the system less accessible and, therefore, might detract from the educational and community benefits that are promoted by the current designers (Living Machines, Inc ) as one of the advantages of the Living Machine®. Additionally, while this reduction in total footprint might be possible, it is unclear to what extent costs might be significantly reduced Because of the aeration intensity provided, and the design retention time, these aerated tanks can be compared to an activated sludge extended aeration process, which is a well-known conventional wastewater treatment process A traditional extended aeration process can typically produce almost complete nitrification of the ammonia because of the high mixed liquor suspended solids (MLSS) concentration maintained in the tank and the routine sludge return from the clarifier. In contrast, the mixed liquor concentration in the AEES process is maintained at about 1,000 mg/L. This was sufficient to remove the soluble BOD but insufficient to complete the ammonia removal within the existing tank volumes so the first EFB was depended on to complete nitrification at Burlington during the 1995 to 1998 operational period. The functional, and operational changes in the process (described in Section 8.1 5) commencing in 1998 resulted in a final system configuration where nitrification was complete in the aerated tanks An advantage of the low MISS (1,000 mg/L) carried in the aeration tanks at Burlington, combined with the two day hydraulic residence time (HRT) is a significant reduction in the amount of sludge to be wasted. As shown in Table 7 7 the measured sludge wasting at the Burlington facility, in 1999, amounted to 58 kg/d; this is about 40 percent of the amount estimated for conventional treatment systems. 8 1.2 “ Ecological Fluidized Beds ” The EFBs at Burlington originally served to complete the nitrification and denitrification reactions, and provide for final filtration and aeration of the effluent A high quality effluent results as evidenced by the data summary in Table 6.1. The operational aspects of the Burlington units have been improved making it easier to remove and transfer sludge to the system clarifier and improvements have also been made with respect to the media selected for use The initial EFBs at Frederick and elsewhere used pumice gravel as the media. This pumice proved to’be too soft and significant material loss was experienced during the backwash cycle owing to abrasion This 8-3 ------- pumice has been replaced with a harder, higher density, porous volcanic stone that seems to be performing successfully at the Burlington system. During the period at Burlington when methanol was still utilized as a carbon source for denitrification there was a tendency for clogging in these EFB’s requiring frequent and vigorous backwashing The process changes described in Section 8.1.5 eliminated the need for methanol and shifted the nitrification denitrification reactions to elsewhere in the process. As a result, the EFB’s are only needed for final filtration and polishing and it might be possible to reduce the number of these units. A concern remains with respect to the name of these EFB units and the functions implied from that title These units are not ecological, they are not fluidized during the treatment mode or the backwash mode, and the concept is not unique to the AEES process Plants are suspended in the annular space around the perimeter of these tanks but those plants cannot play a significant role in treatment, for the same reasons discussed in the previous section. 8.1.3 Anaerobic Bio-reactor The anaerobic bioreactor used for preliminary treatment at the Frederick, MD facility was essential to the succes ful performance of that AEES process owing to the higher strength wastewater received during most of that study. At Frederick, this unit removed more BOD, COD, TSS, and phosphorus than all of the other system components combined but such a unit was not employed at Burlington because of concerns over low temperature wastewater and lower pollutant concentrations It is believed that incorporation of an anaerobic reactor at Burlington would have provided process benefits Although anaerobic digestion would be minimal during the winter months, the unit would still have provided excellent service for particulate removal. This in turn would reduce the load on the greenhouse units making it easier to remove r itrogen and possibly allowing a significant reduction in the size, or number, of those units Solar water heaters are used throughout Vermont and it is possible that the transfer of heat from this warmed water could sustain at least some anaerobic activity in an insulated reactor during the winter. This anaerobic reactor can be an important component in these systems when high organic strength wastewaters require treatment The Burlington facility demonstrates that such a reactor is not required for normal to low strength wastewaters but its use might have enabled a reduction in the number of aeration tanks provided. The final process modifications at Burlington (see Section 8.1 5) converted the first aerated tank(s) in the process to anoxic reactors to provide the carbon source and conditions necessary for denitrification. A similar result may have been achieved if a mixed anaerobic reactor had been utilized as the initial component at Burlington 8-4 ------- 8.1 4 High-rate Marsh The high-rate marsh used in the Frederick, MD system was intended to complete the denitrification reactions and provide final filtration of the effluent, and for the growth of ornamental plants, which could be sold. The re-designed system at Burlington provides these water quality functions in the basic process, eliminating the need for a marsh unit This also eliminates the potential for plant production but the revenues obtained are marginal. A marsh has a further disadvantage as the final component in the system in that the final effluent may not have sufficient dissolved oxygen to satisfy a discharge permit Based upon experience to date, it can be concluded that a high-rate marsh is an optional alternative in the Living Machine® process Utilizing the EFB’s to achieve the same water quality goals is probably the more efficient choice A subsurface flow gravel bed marsh could still be the final component in the AEES process where it could provide final filtration and polishing, but the marsh does not have to be inside the greenhouse. Such marshes function adequately on a year-round basis in several locations in Vermont in exposed, outdoor settings It would also be possible to include a free water surface wetland for final polishing if provision of wildlife habitat values are a project goal 8 1 5 Process Configurations The-process train used at Frederick and Burlington consisted of parallel sets of tanks, each dedicated to a specific purpose (i.e, aeration, clarification, EFB, etc.). That configuration has worked well and is still incorporated in many of the commercial applications of the AEES process. However, continued research and testing by LTI staff at the Burlington facility from 1998 through early 2000 has resulted in significant process modifications and performance improvement. The original configuration at Burlington is illustrated in Figure 3-1, and consisted of five aerated tanks in series, followed by a clarifier and then three EFB’s in series, in each of the two parallel treatment trains. In this original process, commencing in 1996, biosolids were recycled from the clarifier to the first aerated tank at a rate of about 0 25 Q, and mixed liquor from the fifth aerated tank to the first at a rate of about 0.15 Q. The purpose of these recycles was to “seed” the incoming wastewater with desirable organisms. Again, in this original configuration, the first EFB was needed for completion of nitrification reactions and methanol was added after the first EFB unit and the second EFB unit was maintained in an anoxic state to promote denitrification The third and final EFB was aerobic and was also intended for final filtration and polishing The process modifications adopted in 1999 at the Burlington facility are shown in Figure 8-1 The key element was the conversion of the first aerated tank to a mixed anoxic reactor. Mixing is still accomplished by aeration but the aeration devices were changed from fine bubble to coarse bubble and operated so the dissolved oxygen in the reactor was maintained below 0 4 mg/L Since anoxic reactors receiving untreated wastewaters can be a source of odors this tank was capped with a planted biofilter to scrub any odors The recycle of clarifier biosolids to this tank continued 8-5 ------- Figure 8-1. Process Schematic Diagram of the Burlington, VT Living Machine® with an Anoxic Reactor(Source: “Final Report on the South Burlington, Vermont Advanced Ecologically Engineered System for Wastewater Treatment,” by: David Austin & staff of LTI, January 2000) at a rate of O.25q, and recycle of mixed liquor from the final aeration tank was graduall i increased to a rate of 2.5 Q by July 1999. The purpose of these recycles was to return sufficient carbon .* 4 -. 8-6 ------- sources to the anoxic reactor to support the desired denitrification reactions. The recycle of mixed liquor at a rate of 2 5 0 also allowed the completion of nitrification reactions in the four remaining aerobic aerated tanks. As a result of these modifications nitrification and denitrification are essentially complete prior to the first EFB so methanol is no longer required as a carbon source and the overall process operates more efficiently An additional comparative process change was adopted in March 1999 The first tank in the “A” process train at Burlington continued operation as an anoxic unit A fabric tower was installed in the first anoxic tank in the “B” train as shown on Figure 8-1 The purpose was to evaluate the benefit of this additional substrate in the “B” tank on denitrification Results published by LTI in 2000 show no significant difference in denitrification performance between the “A” and “B” trains so the fabric media is apparently not needed with the type of wastewater treated at Burlington 8.1 6 Summary The Living Machine® process used at Frederick, MD and Burlington; VT is capable of meeting all of the specified treatment goals, with the exception of phosphorus. However, the system does not work in the manner claimed by some of the initial developers and supporters. In the opinion of the authors of this report, the plants which grow on the water surfaces throughout the process-play a minimal role in treatment but are a very significant aesthetic benefit and serve to enhance the public acceptance of the process The mechanisms responsible for the treatment are biological and they are common to the majority of “mechanical” wastewater treatment processes (i e., activated sludge). The AEES process as now modified includes an initial anoxic reactor followed by conventional extended aeration process and final filtration. The unique aspect of the concept is the use of plants on the water surfaces throughout the process which significantly enhances the aesthetic appearance of the system and, consequently, public acceptance. Based on the comparisons in Chapter 7, the AEES process may be cost competitive with conventional wastewater technology up to about 600,000 gpd if operated as shown in Figure 8-1 without methanol additions. If methanol is used, the comparison point drops to less than 100,000 gpd. 8.2 The San Francisco, CA Living Machine® As described in Chapter 4, the San Francisco Living Machine® essentially consisted of EFB units in series The purpose of this demonstration was to produce an effluent meeting the State of California’s Title 22 water quality standard, using secondary municipal influent. The system started operation in February 1995 with a target goal of 50,000 gpd. Operations of the system were terminated in December 1996, when the actual flow rate had reached only 18,000 gpd. The system did produce water with a low turbidity but it did not reliably demonstrate the c pability to meet the coliform or viral limits for Title 22 waters. 8-7 ------- A major source of operational problems with this system was the soft pumice gravel used as media in the EFB units. Nitrogen control is not a Title 22 requirement but nitrogen removal was established as a process goal for this unit. Those nitrogen goals were not met, probably owing to inadequate management of methanol in the denitrification process. It is unlikely that this system will be cost effective at a flow rate which is only 36% of the intended goal, especially when supplemental disinfection must be added to the process to achieve its goals. 8.3 The Harwich, MA Living Machine® The AEES uLake Restore?’ also incorporates a variation of the EFB concept, as described in Chapter 5. The demonstration at this location was inconclusive. Flax Pond was apparently an inappropriate site for the evaluation of the “Lake Restorer.” There are uncontrollable and undocumented external influences on water quality in this Pond so it is not possible to conclusively identify the “Lake Restore?’ as being responsible for water quality Improvements In effect, the concept is analogous to a trickling filter on a raft, with water circulation through the media sustained by air lifts. These EFB components have shown a consistent ability to remove BOD and TSS and to remove ammonia nitrogen via nitrification to nitrate and, therefore, the “Lake Restorer” may find future application in situations where these parameters are a concern. A variation of the “Lake Restorer” was recently considered for use as the primary ammonia removal concept for the 3 mgd design flow at the Hayward Marsh wastewater project in California. 8.4 Other Applications of the Living Machine® The focus of this report has been on the independent EPA sponsored evaluation of those Living Machine® demonstrations funded by the U.S. Congress since 1992. These demonstrations at Frederick, MD, Burlington, VT San Francisco, CA, and Harwich, MA have been discussed in detail in this and in previous chapters. However, in addition to these demonstrations there have been a number of other Living Machine® units designed and placed in operation by LTI, Inc for a variety of clients. Information on some of these other systems is provided in this section to illustrate the range of potential applications of the Living Machine®. Table 8.1 provides a summary listing of some of these projects. All of these systems are similar to the basic Living Machine® configuration as used at Frederick, MD and Burlington, VT As shown in Table 8.1 the wastewaters treated by the various Living Machines® varies from domestic sewage to high strength process wastewaters from food processing industries In all cases but one, the high quality process effluent permits reuse, either for irrigation orfo direct reuse as toilet flushing water at the same location. Disinfection of the Living Machine® effluent precedes the toilet flushing reuse, in all cases In the two Vermont applications, the Living Machine® has replaced failed on-site septic tank in-ground leach field di posal systems which were overloaded due to higher than expected visitor usage The soils at both of these sites were not suitable for 8-8 ------- expansion of the in-ground disposal system. Detailed performance data are collected at the Ethyl M Chocolate operation A summary of these data is given in Table 8 2 through the courtesy of the Ethyl M Chocolates Company, as arranged by the LTI staff The Ethyl M Chocolates system includes covered aerobic reactors for initial treatment and odor control, followed by vegetated aerated tanks, followed by a clarifier and then EFB units. The EFB unit is followed by a constructed wetland and storage in an adjacent pond. Because of the relatively warm climate in Henderson, NV a greenhouse is not used with this system. The pond effluent is disinfected with UV radiation and used to irrigate a cactus garden belonging to Ethyl M Chocolates. Table 8.1 Some Other Applications of the Living Machine® Living Machine® Location Design Flow (gpd) Wastewater Effluent Pathway type Ethyl M Chocolates, Henderson, NV 32,000 Process Reuse, irrigation Cedar Grove Cheese Co, Plain, WI 6,500 Process Surface discharge Audubon Society Corkscrew Swamp 10,000 Sanctuary, Naples, FL Domestic Reuse, toilet flushing . State of Vermont, Welcome Center, 6,000 Guilford, VT Domestic Reuse, toilet flushing The Earth Center, Duncaster, UK 4,500 Domestic Reuse, irrigation State of Vermont, Rest Stop, Hartford, VT 3,000 Domestic Reuse, toilet flushing Table 8.2 Performance Summary of the Ethyl M Chocolates Living Machine® Parameter Influent Living Machine® Effluent mgIL mgIL Wetland Effluent Design Effluent mgIL mgIL BOO 5 1,354 3 4 10 COD 1,960 56 50 80 TSS 312 5 5 10 FOG 1 189 1 1 5 TDS 2,434 - - 1,957 (1) FOG. Fats, oils and greases. 8-9 ------- The data summarized in Table 8 2 were collected from January 1996 through March 1999 and are certainly representative of system capabilities. Nitrogen is not listed in Table 8 2 because it was not a parameter of concern for this particular process since the effluent was to be reused for irrigation It appears from the comparisons in Table 8 2 that performance for all parameters exceeded design expectations However, during the period of record the system was significantly under loaded. The design flow was 32,000 gpd, and during the period of record the actual flow varied from 1,500 gpd to 26,000 gpd depending on process requirements. The average flow during this period was only 9,186 gpd or less than one third of the design rate so the excellent performance is not surprising This is also illustrated by comparing organic loadings; the design organic loading for BOD 5 was 127 kgld, the actual average organic loading was only 45 kgld or about 35 percent of the design expectation. Therefore, it is not possible to conclude, with certainty, that this system would meet design expectations if the actual flows and loadings were equal to design assumptions. However, a linear extrapolation of the actual performance data suggests that effluent quality would be at or close to design expectations under design flow and loading conditions. 8-10 ------- CHAPTER 9 CONCLUSIONS AND RECOMMENDATIONS 1. The Living Machine® as configured at South Burlington, VT in 1999 can reliably meet process goals for removal of BOD, COD, TSS, Ammonia, Nitrate, and Total Nitrogen 2 The Living Machine® as presently configured is not capable, in the general case, of meeting the 3 mg/L phosphorus goal The low phosphorus levels in the South Burlington, VT effluent are primarily the result of low concentrations in the influent wastewater and are not a result of unique phosphorus removal capabilities of the treatment process These treatment systems are typically capable of about 50 percent phosphorus removal 3. The removal of nitrate met the process goal but without much of a safety factor before the 1999 process modifications at Burlington. Since those modifications were adopted, nitrification and denitrification proceeded effectively and overall process performance has improved. 4 The conversion of the first aeration tank(s) at Burlington to an anoxic reactor in 1999 and the recycle of mixed liquor from the last aeration tank to that unit allows denitrification in the first tank and essentially complete nitrification in the remaining aerated tanks. This has significantly improved overall performance of the system and eliminated the need for methanol. These results could not be achieved with the Living Machine® as originally configured and operated at Frederick, MD and Burlington, VT 5. The vegetation as used in the current configurations of the Living Machine® process provides a marginal contribution to treatment. The microorganisms occupying the plant roots are believed to be the responsible plant-related treatment mechanism In the Living Machine®, because of the limited water surfaces on the deep tanks, there are not enough plants (and roots) to play a significant role in treatment. However, the plants do provide a very pleasing aesthetic environment, which significantly enhances public acceptance 6. Solar energy plays an incidental role in the treatment provided by the Living Machine® process The Living Machine® depends upon the same energy sources (at the same levels) as conventional wastewater treatment systems The claims which have been made by the concept’s initial proponents that “the system can treat wastewater to advanced standards using solar-powered, greenhouse based technology, without the use of chemicals” were not valid for the Living Machine® as originally configured. The process modifications adopted in 1999 at the Burlington facility permit successful operation without methanol or other chemicals, but solar energy is still not a significant factor. 7. The residuals (sludges and plant litter) produced by the Living Machine® can be comparable in volume to those produced by an equivalent capacity extended aeration 9-1 ------- activated sludge process, depending on the type of vegetation grown in the system. At the Burlington facility the residuals produced in 1999 were probably less than from conventional wastewater treatment because of the vegetation utilized and the low MLSS concentrations carried in the aeration tanks 8 The Living Machine®, as modified in 1999 at Burlington, can accurately be described as an anoxic reactor followed by extended aeration wastewater treatment unit followed by clarification, followed by a filter These are all well understood and widely used conventional technologies for wastewater treatment. The only truly unique aspect of the Living Machine® is the use of plants on the water surfaces, and this does serve to very significantly enhance public acceptance of the technology. 9 Methanol was routinely used as the carbon source to achieve effective denitrification in the original Living Machine® process. This is the same procedure commonly used in conventional denitrification facilities. If the same process modifications developed at the Burlington facility are used in future Living Machine® applications then methanol should no longer be required 10. Reed beds have been typically proposed for dewatering of the sludges produced by the Living Machine®, but none of the federally supported demonstrations to date have incorporated such unit 11. The cost comparisons discussed in Chapter 7 of this report indicate that the Living Machine® with a greenhouse and without methanol use may be cost competitive with cortventional technology up to about 600,000 gpd. A Living Machine® without a greenhouse and without methanol use may be cost competitive up to about 1,000,000 gpd. 12. The AEES demonstration at San Francisco, CA using EFB units containing pumice gravel was not successful. It is unlikely that this process, as presently configured, can be a cost effective method for producing effluents, which meet the State of California’s Title 22 water quality requirements 13. The AEES demonstration at Flax Pond in Harwich, MA must be considered inconclusive because of potential external influences on water quality in the pond. The concept may have application where removal of BOD, TSS and ammonia are of primary concern, or if pond destratification is an issue. 14. The discussion and conclusions in this report regarding the excellent performance and relative cost of the Living Machine® without chemicals only applies to the process as modified at Burlington, VT in 1999. Future applications of the Living Machine® must utilize the same modified process if similar results are to be expected. 9-2 ------- CHAPTER 10 REFERENCES 1. EPA, 1993 Subsurface Flow Constructed Wetlands for Wastewater Treatment: A Technology Assessment, EPA 832-R-93-008, USEPA, Office of Water, Washington, D.C July 1993 2. EPA, 1996 Interim Report-Evaluation of (he Advanced Ecologically Engineered System (AEES) “Living Machin&’ Wastewater Treatment Technology-Frederick, MD, EPA 832-B- 96-002, USEPA, Office of Water, Washington, D C. 3. EPA, 1997. Response to Congress on the AEES “Living Machine” Wastewater Treatment Technology, EPA 832-R-97-002, USEPA, Office of Water, Washington, DC ,April 1997 4. Etnier, C. and B. Guterstam (eds), 1991. Ecological Engineering for Wastewafer Treatment Proceedings of the International Conference at Stensund Folk College, Sweden 5. Josephson, Beth, 1995. Personal communication - fax message (Ju’y 25, 1995). 6. Landine, R.C , S.G. Bliss, G J. Brown,A A. Cocci, 1992. Anaerobic andAerobic Treatment of Potato Processing Wastewater-Case Study, in Proceedings 46th Purdue Industrial Waste Conference, 1991, Lewis Publishers, Boca Raton, FL. 7. Living lechnologies, Inc., January 2000. Final Report on the South Burlington, Vermont Advanced Ecologically Engineered System for Wastewater Treatment, Burlington, VT. 8. Malina, J.F., F.G. Pohland, 1992. Design of Anaerobic Processes for the Treatment of Industrial and Municipal Wastes, Technomics Inc, Lancaster, PA 9. Mitsch, W.J. and S.E. Jørgensen, 1989. Ecological Engineering, An Introduction to Ecotechnology. John Wiley & Sons. New York City, NY. 10. Nolte & Associates, 1989. Harwich Septage Treatment, Pilot Study Evaluation of Technology for Solar Aquatics Septage Treatment System Ecological Engineering Associates, Falmouth, MA 11. Ocean Arks International, 1994. Descriptive Information and Various Promotional Brochures. 12 Reed, S.C., 1992 SolarAquatics” Treat Resort Wastewater, Journal W.E.F., July 1992, pp 62-66 10-1 ------- 13. Reed, S C, R.W. Crites, E.J. Middlebrooks, 1995 Natural Systems for Waste Management and Treatment, McGraw Hill, New York, NY. 14 Reed, S C, J. Salisbury, L. Fillmore, R. Bastian, 1996. An Evaluation of the “Living Machine” Wastewater Treatment Concept, in. Proceedings, WEFTEC ‘96, Dallas, TX, Water Environment Federation, Alexandria, VA, October 1996 15. Todd, J, B. Josephson, 1996. The Design of Living Technologies for Waste Treatment, Ecological Engineering, Volume 6, pp 109-136, Elsevier Science B.V., Netherlands 10-2 ------- |